Ernesto made its way across Florida as a weak Tropical Storm and then Depression... then exited eastern FL near Cape Canaveral, and now heading NNE toward the SC/NC border. It's also getting better organized each hour that it's over the ocean, and could be upgraded to a minimal hurricane by landfall late tonight. The intensity as of 21Z today was 60kts and 991mb.
You can find an ever-growing radar loop of Ernesto's east coast approach at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/ernesto06/Ernesto_31Aug06_LTX.gif
As of this writing, the center is due east of Georgetown SC, due south of Wilmington NC, and heading NNE toward Cape Fear or perhaps Cape Lookout. A Tropical Storm Warning is in effect for all of SC and NC, and a Hurricane Watch is in effect for northern SC and southern NC up to Cape Lookout
Across the rest of the basin, there is an impressive tropical wave near 11N 25W which certainly bears watching over the coming days. Another circulation can be found about 10 degrees west of that, and also has a shot at development, but the one to the east looks healthier now (better divergence aloft, less shear). The next names on deck are Florence and Gordon.
And of course, http://mcwar.org/tropics/ has the latest satellite imagery, track forecast, and more for the basin.
I'd also like to welcome several new additions to the mailing list, 6 in the past week alone! That brings the total up to about 310 subscribers... homeowners, students, teachers, media, military, enthusiasts, business owners, and more. I'm reminded of and humbled by the large number of people who've opted to subscribe to these updates! This is year #11 for them...
Please visit my tropical Atlantic headquarters.
31 August 2006
29 August 2006
Ernesto heading for Florida...
The center of Ernesto's circulation finally exited north central Cuba at 06Z this morning (2am EDT). Deep convection has been somewhat sparse and slow to come back, but it is gradually increasing in coverage as more of the storm arrives over the ocean. The ocean is at least 26C down to a depth of 80m in the Florida Straight, and the SST is a tad over 30C, so there's no shortage of energy for the storm, just a shortage of time.
You can track the progress of the storm via Miami's long-range radar at: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/ernesto06/Ernesto_29Aug06.gif
(updating loop, new frame added every 6 minutes or so, beginning at 12Z this morning)
At 15Z this morning, the tropical storm was located at 23.3N 79.5W and tracking NW at 11kts. It only has a generous 24 hours over ocean before hitting the southern tip of the FL peninsula, so at this point, intensification to a hurricane seems very unlikely (it's at 40kts and 1005mb now). As of the latest official forecast, the Keys are in the center of the track "cone", but for a storm without an eye, that doesn't matter so much -- all of southern FL will experience stormy weather beginning today and going into tomorrow. Threats of inland flooding and tornadoes are the highest.
After making its way northward across FL, the forecast takes it up into SC, around Charleston, again as a strong Tropical Storm (a minimal hurricane isn't out of the question).
A tropical wave that exited Africa on Sunday is now located at about 12N 29W. It's moving west, and the environment is favorable for slow development.
And last but not least, this morning is the one-year anniversary of Katrina's landfall on Mississippi and Louisiana... and although not the strongest or deadliest landfall, it was the costliest disaster in US history, by far. You can view the radar-based view of that fateful landfall at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/katrina/Katrina_29Aug05.gif
Please visit my tropical Atlantic headquarters.
You can track the progress of the storm via Miami's long-range radar at: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/ernesto06/Ernesto_29Aug06.gif
(updating loop, new frame added every 6 minutes or so, beginning at 12Z this morning)
At 15Z this morning, the tropical storm was located at 23.3N 79.5W and tracking NW at 11kts. It only has a generous 24 hours over ocean before hitting the southern tip of the FL peninsula, so at this point, intensification to a hurricane seems very unlikely (it's at 40kts and 1005mb now). As of the latest official forecast, the Keys are in the center of the track "cone", but for a storm without an eye, that doesn't matter so much -- all of southern FL will experience stormy weather beginning today and going into tomorrow. Threats of inland flooding and tornadoes are the highest.
After making its way northward across FL, the forecast takes it up into SC, around Charleston, again as a strong Tropical Storm (a minimal hurricane isn't out of the question).
A tropical wave that exited Africa on Sunday is now located at about 12N 29W. It's moving west, and the environment is favorable for slow development.
And last but not least, this morning is the one-year anniversary of Katrina's landfall on Mississippi and Louisiana... and although not the strongest or deadliest landfall, it was the costliest disaster in US history, by far. You can view the radar-based view of that fateful landfall at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/katrina/Katrina_29Aug05.gif
Please visit my tropical Atlantic headquarters.
28 August 2006
Ernesto over Cuba...
Debby finally dissipated on Sunday afternoon as an insignificant low-level swirl in the north central Atlantic, now pretty much absorbed by a mid-latitude trough.
Ernesto is still the big story in the basin. The long-range track forecasts from the middle of last week have proven to be very wrong, and the storm has tracked NW instead of W-WNW. So, in this scenario, everyone loses: the storm is scraping over Cuba, which is bad for Cuba and bad for the storm! A Hurricane Watch is in effect for all of southern Florida and the northern Bahamas, and a Tropical Storm Warning is in effect for eastern Cuba and the central Bahamas.
As of 15Z, the intensity is 35kts and 1003mb, barely a tropical storm, but it's also tracking directly over mountainous eastern Cuba.
Once Ernesto leaves Cuba late tonight or early tomorrow morning, it should have a short but critical stay over the ocean before a Florida landfall late Tuesday night. The SSTs will be around 30C and vertical shear 10kts or less, so the trip between Cuba and Florida could allow for rapid intensification. You can keep an eye on the approach via Miami's radar:
http://radar.weather.gov/radar.php?rid=AMX&product=N0Z&overlay=11101111&loop=no
This is an extraordinarily challenging forecast, because it's approaching the Florida peninsula from the south. A SLIGHT east-west error in track forecast could mean landfall in Apalachicola, Key West, Miami, Charleston, or Wilmington! This angle of approach is sensitive to the smallest track deviations. Miami is presently in the center of the target.
As of right now, the official forecast has the storm scraping eastern FL, crossing over the Gulf Stream, then making a 3rd landfall on North Carolina as a strong hurricane too. This is something that clearly should be watched closely by east coast residents.
Elsewhere, there is a significant tropical wave with an embedded 1010mb Low located at about 17N 40W.
Please visit my tropical Atlantic headquarters.
Ernesto is still the big story in the basin. The long-range track forecasts from the middle of last week have proven to be very wrong, and the storm has tracked NW instead of W-WNW. So, in this scenario, everyone loses: the storm is scraping over Cuba, which is bad for Cuba and bad for the storm! A Hurricane Watch is in effect for all of southern Florida and the northern Bahamas, and a Tropical Storm Warning is in effect for eastern Cuba and the central Bahamas.
As of 15Z, the intensity is 35kts and 1003mb, barely a tropical storm, but it's also tracking directly over mountainous eastern Cuba.
Once Ernesto leaves Cuba late tonight or early tomorrow morning, it should have a short but critical stay over the ocean before a Florida landfall late Tuesday night. The SSTs will be around 30C and vertical shear 10kts or less, so the trip between Cuba and Florida could allow for rapid intensification. You can keep an eye on the approach via Miami's radar:
http://radar.weather.gov/radar.php?rid=AMX&product=N0Z&overlay=11101111&loop=no
This is an extraordinarily challenging forecast, because it's approaching the Florida peninsula from the south. A SLIGHT east-west error in track forecast could mean landfall in Apalachicola, Key West, Miami, Charleston, or Wilmington! This angle of approach is sensitive to the smallest track deviations. Miami is presently in the center of the target.
As of right now, the official forecast has the storm scraping eastern FL, crossing over the Gulf Stream, then making a 3rd landfall on North Carolina as a strong hurricane too. This is something that clearly should be watched closely by east coast residents.
Elsewhere, there is a significant tropical wave with an embedded 1010mb Low located at about 17N 40W.
Please visit my tropical Atlantic headquarters.
impending disaster, exactly 1 year ago today...
This is just something to reflect back on, one year to the day of an impending major natural disaster. On the morning of August 28, 2005, a day prior to Katrina's landfall on Mississippi, the New Orleans National Weather Service Office tried to make it clear that a total evacuation was essential (for those who still remained behind). The events that would unfold were told in countless documentaries for a decade or more prior to the Katrina's landfall, owing to the human-engineered disaster-waiting-to-happen. It happened, and with predictable and nightmarish results.
URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1011 AM CDT SUN AUG 28 2005
...DEVASTATING DAMAGE EXPECTED...
.HURRICANE KATRINA...A MOST POWERFUL HURRICANE WITH UNPRECEDENTED
STRENGTH...RIVALING THE INTENSITY OF HURRICANE CAMILLE OF 1969.
MOST OF THE AREA WILL BE UNINHABITABLE FOR WEEKS...PERHAPS LONGER. AT
LEAST ONE HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL
FAILURE. ALL GABLED ROOFS WILL FAIL...LEAVING THOSE HOMES SEVERELY
DAMAGED OR DESTROYED.
THE MAJORITY OF INDUSTRIAL BUILDINGS WILL BECOME NON FUNCTIONAL.
PARTIAL TO COMPLETE WALL AND ROOF FAILURE IS EXPECTED. ALL WOOD
FRAMED LOW RISING APARTMENT BUILDINGS WILL BE DESTROYED. CONCRETE
BLOCK LOW RISE APARTMENTS WILL SUSTAIN MAJOR DAMAGE...INCLUDING SOME
WALL AND ROOF FAILURE.
HIGH RISE OFFICE AND APARTMENT BUILDINGS WILL SWAY DANGEROUSLY...A
FEW TO THE POINT OF TOTAL COLLAPSE. ALL WINDOWS WILL BLOW OUT.
AIRBORNE DEBRIS WILL BE WIDESPREAD...AND MAY INCLUDE HEAVY ITEMS SUCH
AS HOUSEHOLD APPLIANCES AND EVEN LIGHT VEHICLES. SPORT UTILITY
VEHICLES AND LIGHT TRUCKS WILL BE MOVED. THE BLOWN DEBRIS WILL CREATE
ADDITIONAL DESTRUCTION. PERSONS...PETS...AND LIVESTOCK EXPOSED TO THE
WINDS WILL FACE CERTAIN DEATH IF STRUCK.
POWER OUTAGES WILL LAST FOR WEEKS...AS MOST POWER POLES WILL BE DOWN
AND TRANSFORMERS DESTROYED. WATER SHORTAGES WILL MAKE HUMAN SUFFERING
INCREDIBLE BY MODERN STANDARDS.
THE VAST MAJORITY OF NATIVE TREES WILL BE SNAPPED OR UPROOTED. ONLY
THE HEARTIEST WILL REMAIN STANDING...BUT BE TOTALLY DEFOLIATED. FEW
CROPS WILL REMAIN. LIVESTOCK LEFT EXPOSED TO THE WINDS WILL BE
KILLED.
Please visit my tropical Atlantic headquarters.
URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1011 AM CDT SUN AUG 28 2005
...DEVASTATING DAMAGE EXPECTED...
.HURRICANE KATRINA...A MOST POWERFUL HURRICANE WITH UNPRECEDENTED
STRENGTH...RIVALING THE INTENSITY OF HURRICANE CAMILLE OF 1969.
MOST OF THE AREA WILL BE UNINHABITABLE FOR WEEKS...PERHAPS LONGER. AT
LEAST ONE HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL
FAILURE. ALL GABLED ROOFS WILL FAIL...LEAVING THOSE HOMES SEVERELY
DAMAGED OR DESTROYED.
THE MAJORITY OF INDUSTRIAL BUILDINGS WILL BECOME NON FUNCTIONAL.
PARTIAL TO COMPLETE WALL AND ROOF FAILURE IS EXPECTED. ALL WOOD
FRAMED LOW RISING APARTMENT BUILDINGS WILL BE DESTROYED. CONCRETE
BLOCK LOW RISE APARTMENTS WILL SUSTAIN MAJOR DAMAGE...INCLUDING SOME
WALL AND ROOF FAILURE.
HIGH RISE OFFICE AND APARTMENT BUILDINGS WILL SWAY DANGEROUSLY...A
FEW TO THE POINT OF TOTAL COLLAPSE. ALL WINDOWS WILL BLOW OUT.
AIRBORNE DEBRIS WILL BE WIDESPREAD...AND MAY INCLUDE HEAVY ITEMS SUCH
AS HOUSEHOLD APPLIANCES AND EVEN LIGHT VEHICLES. SPORT UTILITY
VEHICLES AND LIGHT TRUCKS WILL BE MOVED. THE BLOWN DEBRIS WILL CREATE
ADDITIONAL DESTRUCTION. PERSONS...PETS...AND LIVESTOCK EXPOSED TO THE
WINDS WILL FACE CERTAIN DEATH IF STRUCK.
POWER OUTAGES WILL LAST FOR WEEKS...AS MOST POWER POLES WILL BE DOWN
AND TRANSFORMERS DESTROYED. WATER SHORTAGES WILL MAKE HUMAN SUFFERING
INCREDIBLE BY MODERN STANDARDS.
THE VAST MAJORITY OF NATIVE TREES WILL BE SNAPPED OR UPROOTED. ONLY
THE HEARTIEST WILL REMAIN STANDING...BUT BE TOTALLY DEFOLIATED. FEW
CROPS WILL REMAIN. LIVESTOCK LEFT EXPOSED TO THE WINDS WILL BE
KILLED.
Please visit my tropical Atlantic headquarters.
27 August 2006
Debby dissipating, Ernesto now a hurricane...
Debby has been slowly decaying, and is now a convectionless 25kt vortex with a 1012mb MSLP. It's heading north into the extratropical realm of the north central Atlantic. Strong vertical shear has overwhelmed moderate SSTs. By Monday-Tuesday, Debby will have lost its identity as it's absorbed by a mid-latitude front.
Ernesto was upgraded to a hurricane on Sunday morning... the first hurricane of the Atlantic season! As of this writing, it is located on the far western tip of Haiti, heading for Jamaica later today. Intensity is 65kts and 997mb and motion is NW at 8kts. Microwave imagery from earlier this morning revealed what appears to be either a very tightly-wound spiral band or the embryonic stages of eyewall development.
The deep-layer shear (850-200mb) has relaxed immensely, thanks to a maturing anticyclone sitting directly over the low-mid-level cyclone. Now that those ingredients are aligned, further intensification will occur more readily -- also, oceanic heat content along the projected track of Ernesto is astronomical... VERY deep warm water will provide a boundless source of energy. The only thing hindering explosive development is land interaction (Jamiaca, Cuba), which should put a brake on rapid intensification. By Tuesday morning however, Ernesto will have cleared Cuba and entered the Gulf of Mexico, potentially poised for rapid development as it heads toward the US coast.
As of now, the forecast track takes it into Tampa, FL on Thursday morning as a strong hurricane.
A Hurricane Watch is in effect for Jamaica and the Cayman Islands... and a Hurricane Warning is in effect for southern Haiti and eastern Cuba. A Hurricane Watch/Warning maybe added for western Florida and western Cuba later today.
Please visit my tropical Atlantic headquarters.
Ernesto was upgraded to a hurricane on Sunday morning... the first hurricane of the Atlantic season! As of this writing, it is located on the far western tip of Haiti, heading for Jamaica later today. Intensity is 65kts and 997mb and motion is NW at 8kts. Microwave imagery from earlier this morning revealed what appears to be either a very tightly-wound spiral band or the embryonic stages of eyewall development.
The deep-layer shear (850-200mb) has relaxed immensely, thanks to a maturing anticyclone sitting directly over the low-mid-level cyclone. Now that those ingredients are aligned, further intensification will occur more readily -- also, oceanic heat content along the projected track of Ernesto is astronomical... VERY deep warm water will provide a boundless source of energy. The only thing hindering explosive development is land interaction (Jamiaca, Cuba), which should put a brake on rapid intensification. By Tuesday morning however, Ernesto will have cleared Cuba and entered the Gulf of Mexico, potentially poised for rapid development as it heads toward the US coast.
As of now, the forecast track takes it into Tampa, FL on Thursday morning as a strong hurricane.
A Hurricane Watch is in effect for Jamaica and the Cayman Islands... and a Hurricane Warning is in effect for southern Haiti and eastern Cuba. A Hurricane Watch/Warning maybe added for western Florida and western Cuba later today.
Please visit my tropical Atlantic headquarters.
25 August 2006
Debby weakens, Ernesto forms...
Debby is having a hard time maintaining deep convection in the face of 25kt shear. The SST is 28C, but that warm water is quite shallow there too. It's located at 23.9N 43.3W and tracking NW at 15kts now, with a satellite-estimated intensity of 35kts and 1003mb... barely holding onto tropical storm status. The forecast is unchanged: fluctuate a bit in intensity and recurve by 55W.
At 21Z yesterday, the strong tropical wave near the Lesser Antilles was upgraded to TD5 based on an aircraft flight into it. Today at 21Z, it was further upgraded to TS Ernesto, again based on aircraft recon. The storm is experiencing decent westerly vertical wind shear, so the low-level center is displaced to the west from the deep convection. Recall that this wave was born in the Ethiopian Highlands way back on August 10 or so, and exited Africa on August 17.
At 19Z today, Ernesto was located at 14.1N 67.3W. The intensity is 40kts and 1004mb... this may be adjusted slightly for the official 21Z advisory.
The forecast for Ernesto is very interesting, particularly for the Gulf coast. Over the next couple of days, it is expected to maintain its WNW heading and somewhat formidable shear, but after that, it enters lower shear, and VERY high oceanic heat content in the western Caribbean. In 5 days, it should pass between Yucatan and Cuba, heading in to the Gulf of Mexico as a possibly powerful hurricane. There is too much uncertainly beyond 5 days, but once in the Gulf, it HAS to hit somewhere.
Elsewhere, a new potent tropical wave is introduced off the African coast around 18W with an embedded 1008mb Low. We're now entering the heart of the "Cape Verde season", so these all need to be watched closely.
Also, today is the 1-year anniversary of Hurricane Katrina's Florida landfall.
http://einstein.atmos.colostate.edu/~mcnoldy/tropics/katrina/Katrina_25Aug05.gif
Please visit my tropical Atlantic headquarters.
At 21Z yesterday, the strong tropical wave near the Lesser Antilles was upgraded to TD5 based on an aircraft flight into it. Today at 21Z, it was further upgraded to TS Ernesto, again based on aircraft recon. The storm is experiencing decent westerly vertical wind shear, so the low-level center is displaced to the west from the deep convection. Recall that this wave was born in the Ethiopian Highlands way back on August 10 or so, and exited Africa on August 17.
At 19Z today, Ernesto was located at 14.1N 67.3W. The intensity is 40kts and 1004mb... this may be adjusted slightly for the official 21Z advisory.
The forecast for Ernesto is very interesting, particularly for the Gulf coast. Over the next couple of days, it is expected to maintain its WNW heading and somewhat formidable shear, but after that, it enters lower shear, and VERY high oceanic heat content in the western Caribbean. In 5 days, it should pass between Yucatan and Cuba, heading in to the Gulf of Mexico as a possibly powerful hurricane. There is too much uncertainly beyond 5 days, but once in the Gulf, it HAS to hit somewhere.
Elsewhere, a new potent tropical wave is introduced off the African coast around 18W with an embedded 1008mb Low. We're now entering the heart of the "Cape Verde season", so these all need to be watched closely.
Also, today is the 1-year anniversary of Hurricane Katrina's Florida landfall.
http://einstein.atmos.colostate.edu/~mcnoldy/tropics/katrina/Katrina_25Aug05.gif
Please visit my tropical Atlantic headquarters.
24 August 2006
Debby struggling...
Debby is presently experiencing the coldest SSTs of its journey thus far, around 26C. There is only minimal convection associated with the storm now, and it looks rather ragged. Over the next few days, the SSTs will increase again (up to almost 29C), likely allowing the storm to reintensify, and PERHAPS finally reach hurricane status.
[**********
skip this part if you're just interested in the headlines...
The SST is an important ingredient in intensity forecasting, but far from the only one. From a strictly thermodynamic viewpoint (disregarding shear, eyewall replacements, land, dry air entrainment, boundary layer humidity, other moisture-related issues), the outflow temperature is just as important. If you assume the outflow of the hurricane to be at about 200mb, you can use the temperature there and find the difference between that and the temperature at the inflow layer (sea surface). It's this difference that controls the lapse rate and instability in the hurricane near-environment. Using Debby as an example (and taking the diagnosed SST along the forecast track from a statistical model called SHIPS), we get the following:
-- Thursday morning SST: 26.1C
-- Thursday morning outflow temp: -53.0C
-- Thursday morning's DIFFERENCE: 79.1C
-- Saturday morning SST: 28.5C
-- Saturday morning outflow temp: -54.1C
-- Saturday morning's DIFFERENCE: 82.6C
So, in a couple days, the temperature difference between the inflow and outflow of the storm will be 3.5C greater, which in the tropics is a big deal, because lapse rates typically vary VERY little there. Taking this morning's data and tweaking it a little just to make a point, suppose the outflow temperature were -56.5C... you'd get exactly the same healthy lapse rate as what is forecast for Saturday morning! In the tropics however, SSTs are of more interest because the outflow temperature typically changes so little. There are subtleties involved with this explanation, but that's the basics!
**********]
The latest intensity estimate (15Z) for Debby is 45kts and 1000mb, and heading WNW at 17kts. It is located at 20.4N 37.8W, basically in the middle of the basin, and heading for even more open ocean. It is forecast to slowly strengthen as it turns to the NW then N, recurving by 55W.
The strong tropical wave that was near 11N 55W yesterday is near 12N 61W today, and not organized enough to be upgraded to a tropical depression, but it is still convectively active and showing signs of at least a mid-level circulation, if not low-level as well. It's tracking W at 15kts and has a 1009mb Low embedded within it. This could be upgraded to TD5 or TS Ernesto within the next 24 hours, and in the long run, stands a very good chance at reaching hurricane intensity as it cruises through the central and western Caribbean -- low shear, 30C SSTs, and significant oceanic heat content!
Please visit my tropical Atlantic headquarters.
[**********
skip this part if you're just interested in the headlines...
The SST is an important ingredient in intensity forecasting, but far from the only one. From a strictly thermodynamic viewpoint (disregarding shear, eyewall replacements, land, dry air entrainment, boundary layer humidity, other moisture-related issues), the outflow temperature is just as important. If you assume the outflow of the hurricane to be at about 200mb, you can use the temperature there and find the difference between that and the temperature at the inflow layer (sea surface). It's this difference that controls the lapse rate and instability in the hurricane near-environment. Using Debby as an example (and taking the diagnosed SST along the forecast track from a statistical model called SHIPS), we get the following:
-- Thursday morning SST: 26.1C
-- Thursday morning outflow temp: -53.0C
-- Thursday morning's DIFFERENCE: 79.1C
-- Saturday morning SST: 28.5C
-- Saturday morning outflow temp: -54.1C
-- Saturday morning's DIFFERENCE: 82.6C
So, in a couple days, the temperature difference between the inflow and outflow of the storm will be 3.5C greater, which in the tropics is a big deal, because lapse rates typically vary VERY little there. Taking this morning's data and tweaking it a little just to make a point, suppose the outflow temperature were -56.5C... you'd get exactly the same healthy lapse rate as what is forecast for Saturday morning! In the tropics however, SSTs are of more interest because the outflow temperature typically changes so little. There are subtleties involved with this explanation, but that's the basics!
**********]
The latest intensity estimate (15Z) for Debby is 45kts and 1000mb, and heading WNW at 17kts. It is located at 20.4N 37.8W, basically in the middle of the basin, and heading for even more open ocean. It is forecast to slowly strengthen as it turns to the NW then N, recurving by 55W.
The strong tropical wave that was near 11N 55W yesterday is near 12N 61W today, and not organized enough to be upgraded to a tropical depression, but it is still convectively active and showing signs of at least a mid-level circulation, if not low-level as well. It's tracking W at 15kts and has a 1009mb Low embedded within it. This could be upgraded to TD5 or TS Ernesto within the next 24 hours, and in the long run, stands a very good chance at reaching hurricane intensity as it cruises through the central and western Caribbean -- low shear, 30C SSTs, and significant oceanic heat content!
Please visit my tropical Atlantic headquarters.
23 August 2006
TD4 upgraded to TS Debby...
At 03Z today (Tuesday night in the US), TD4 was upgraded to the forth named storm of the season, Debby. This was based on infrared and microwave satellite imagery. As of 15Z, the intensity estimate is 45kts and 1000mb. It's located about 5 degrees due west of the Cape Verde islands.
The forecast for Debby is gradual strengthening, possibly reaching minimal hurricane intensity during the weekend. The track should follow a WNW to NW course, which will momentarily take the storm over cool water (25C), but in about 3 days, will be back over 28-29C water. However, combating that increase in SST is an anticipated increase in southwesterly vertical wind shear.
Elsewhere, the tropical wave that was near 50W yesterday is still lacking an organized low-level circulation, but the mid-level circulation is located at about 11N 55W and tracking W at 15kts. It has been convectively active in bursts, and chances of formation seem fairly high by the end of the week. This is the wave that exited Africa back on August 17. If this develops, the forecast would be for a WNW track through the heart of the Caribbean, likely becoming at least a tropical storm, if not a hurricane. The next number/name on deck is 5/Ernesto.
Please visit my tropical Atlantic headquarters.
The forecast for Debby is gradual strengthening, possibly reaching minimal hurricane intensity during the weekend. The track should follow a WNW to NW course, which will momentarily take the storm over cool water (25C), but in about 3 days, will be back over 28-29C water. However, combating that increase in SST is an anticipated increase in southwesterly vertical wind shear.
Elsewhere, the tropical wave that was near 50W yesterday is still lacking an organized low-level circulation, but the mid-level circulation is located at about 11N 55W and tracking W at 15kts. It has been convectively active in bursts, and chances of formation seem fairly high by the end of the week. This is the wave that exited Africa back on August 17. If this develops, the forecast would be for a WNW track through the heart of the Caribbean, likely becoming at least a tropical storm, if not a hurricane. The next number/name on deck is 5/Ernesto.
Please visit my tropical Atlantic headquarters.
22 August 2006
TD4 still organizing...
Based on infrared satellite presentation and a QuikSCAT pass (active microwave scatterometer that can measure surface winds over water), TD4 has been held at Depression status as of 15Z today. It is definitely on the threshold of being named though. The latest intensity estimate is 30kts and 1007mb.
The most recent visible satellite imagery as of this writing shows deep convection over the low-level center, rather well consolidated. There's healthy outflow everywhere, but moreso to the south, as was the case yesterday. Two negatives for it are stable air to the west and north, and slight southeasterly vertical shear. It's tracking WNW at 14kts, and is located just southwest of the Cape Verde Islands.
It's still forecast to gradually intensify and track WNW for a few more days, then recurve northward through an anticipated weakness in the subtropical ridge.
Elsewhere, there are two points of interest, one in the central part of the basin, near 50W, and one still over the heart of Africa, at about 5W. The one still over Africa obviously has a few days before it even hits the ocean, but it looks ominous. And the one nearing the Lesser Antilles is definitely worth keeping an eye on. In fact, there's a broad elongated envelope of enhanced cyclonic vorticity from about 45-60W along ~12N, and there appears to be at least two embedded mid-level circulations.
Please visit my tropical Atlantic headquarters.
The most recent visible satellite imagery as of this writing shows deep convection over the low-level center, rather well consolidated. There's healthy outflow everywhere, but moreso to the south, as was the case yesterday. Two negatives for it are stable air to the west and north, and slight southeasterly vertical shear. It's tracking WNW at 14kts, and is located just southwest of the Cape Verde Islands.
It's still forecast to gradually intensify and track WNW for a few more days, then recurve northward through an anticipated weakness in the subtropical ridge.
Elsewhere, there are two points of interest, one in the central part of the basin, near 50W, and one still over the heart of Africa, at about 5W. The one still over Africa obviously has a few days before it even hits the ocean, but it looks ominous. And the one nearing the Lesser Antilles is definitely worth keeping an eye on. In fact, there's a broad elongated envelope of enhanced cyclonic vorticity from about 45-60W along ~12N, and there appears to be at least two embedded mid-level circulations.
Please visit my tropical Atlantic headquarters.
21 August 2006
Tropical Depression 4 forms in the far eastern Atlantic...
A very strong African Easterly Wave born in far eastern Africa back on August 14 exited the coast Sunday afternoon. It quickly acquired a mid-level circulation and later on Monday developed a low-level circulation as well, prompting the upgrade to TD4. As of this writing, it has deep convection in large spiral bands, but not too concentrated yet over the center... divergence aloft is healthy, with a stronger outflow channel to its south.
The 21Z advisory places the center at 12.3N 21.0W, or just south of the Cape Verde Islands. The satellite-estimated intensity is 30kts and 1007mb. Motion is toward the WNW at 11kts.
It is forecast to slowly intensify and track NW through a weakness in the subtropical ridge. It seems unlikely as of now that this will be the type to travel the full distance across the basin before recurving. The next name on deck is Debby.
Please visit my tropical Atlantic headquarters.
The 21Z advisory places the center at 12.3N 21.0W, or just south of the Cape Verde Islands. The satellite-estimated intensity is 30kts and 1007mb. Motion is toward the WNW at 11kts.
It is forecast to slowly intensify and track NW through a weakness in the subtropical ridge. It seems unlikely as of now that this will be the type to travel the full distance across the basin before recurving. The next name on deck is Debby.
Please visit my tropical Atlantic headquarters.
09 August 2006
Possible Depression forming...
The tropical wave I had been mentioning since LAST Wednesday has finally entered a more favorable environment (the problem was primarily dry, stable air surrounding it) and has been sporting a cold CDO for the past 12-18 hours. However, a recent aircraft flight into the system was unable to find a closed circulation, so for now, it remains a strong tropical wave. There is decidedly a closed mid-level circulation though. It is located over Barbados and tracking W at 15kts. I was perusing a series of soundings from Barbados over the past 48 hours, and the precipitable water increased from 4.34cm to 5.56cm in that time... a likely sign that whatever Saharan Air Layer was present has since weakened/dispersed.
Forecast models take it WNW into the western Caribbean over the next 5 days. Statistical models intensify it to at least a minimal hurricane, while the dynamical models don't even bring it up to a TS. This will be an interesting "competition"! If it develops, it would be TD4 or TS Debby.
The other two easterly waves at 38W and 86W are not of great concern right now; they suffer from dry air and high shear, respectively.
Please visit my tropical Atlantic headquarters.
Forecast models take it WNW into the western Caribbean over the next 5 days. Statistical models intensify it to at least a minimal hurricane, while the dynamical models don't even bring it up to a TS. This will be an interesting "competition"! If it develops, it would be TD4 or TS Debby.
The other two easterly waves at 38W and 86W are not of great concern right now; they suffer from dry air and high shear, respectively.
Please visit my tropical Atlantic headquarters.
07 August 2006
Chris dissipates, TD4 on the horizon?...
TD Chris never did regenerate, and dissipated early Saturday morning
near the northern Cuba coast. The remnants, an open easterly wave, can
still be found in the central Gulf of Mexico.
The potent easterly wave that I first mentioned last Wednesday has
continued its trek across the basin. It formed over the Ethiopian
Highlands around July 26, exited Africa on August 2, and is now about
1500km east of the Windward Islands. It has a very well-defined surface
circulation, but is lacking deep convection (though the trend of that
has been upward the past few hours). Environmental conditions appear
quite favorable for further development, and this will likely become TD4
later today or tonight. The embedded Low has a pressure of about
1009mb, and is located at approximately 12.5N 43.0W, tracking W at
15kts. Forecast models take it WNW toward the Leeward Islands and
Hispaniola over the next 5 days, and intensify it to a strong TS or
minimal hurricane.
Another healthy wave has just exited the African coast on Sunday and is
presently at about 24W.
There is a convectively-active tropical wave also located at about 70W,
but shows no signs of circulation.
Please visit my tropical Atlantic headquarters.
near the northern Cuba coast. The remnants, an open easterly wave, can
still be found in the central Gulf of Mexico.
The potent easterly wave that I first mentioned last Wednesday has
continued its trek across the basin. It formed over the Ethiopian
Highlands around July 26, exited Africa on August 2, and is now about
1500km east of the Windward Islands. It has a very well-defined surface
circulation, but is lacking deep convection (though the trend of that
has been upward the past few hours). Environmental conditions appear
quite favorable for further development, and this will likely become TD4
later today or tonight. The embedded Low has a pressure of about
1009mb, and is located at approximately 12.5N 43.0W, tracking W at
15kts. Forecast models take it WNW toward the Leeward Islands and
Hispaniola over the next 5 days, and intensify it to a strong TS or
minimal hurricane.
Another healthy wave has just exited the African coast on Sunday and is
presently at about 24W.
There is a convectively-active tropical wave also located at about 70W,
but shows no signs of circulation.
Please visit my tropical Atlantic headquarters.
04 August 2006
Chris weakens to a Depression...
Deep convection has failed to regenerate over the center of Chris, and in the face of persistent strong vertical shear, the system was downgraded this morning to a Depression. It's currently a poorly defined low-level swirl over the Turk Islands. The surface circulation is generating heavy rain over Hispaniola to the south.
The majority of forecast models take Chris westward over the next 5 days, ending up in southern TX or northern Mexico. Some track it over Cuba, some track it over the Florida Straight, which will make a huge difference in intensity. The 5-day intensity forecasts vary from minimal TS to minimal hurricane, and the official forecast calls for 45kts in 5 days. The hefty vertical shear lately is due to a tag-team effort of two upper-level Lows... once Chris passes by them, a large ridge centered over the eastern US should shelter the storm and steer it due west.
SSTs in the Gulf are 29-30C, so that will not be a problem: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/sectors/sst/gulf15.php
Elsewhere, the two previously-mentioned easterly waves are still tracking across the basin at about 15kts... they are presently at about 48W and 22W.
Please visit my tropical Atlantic headquarters.
The majority of forecast models take Chris westward over the next 5 days, ending up in southern TX or northern Mexico. Some track it over Cuba, some track it over the Florida Straight, which will make a huge difference in intensity. The 5-day intensity forecasts vary from minimal TS to minimal hurricane, and the official forecast calls for 45kts in 5 days. The hefty vertical shear lately is due to a tag-team effort of two upper-level Lows... once Chris passes by them, a large ridge centered over the eastern US should shelter the storm and steer it due west.
SSTs in the Gulf are 29-30C, so that will not be a problem: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/sectors/sst/gulf15.php
Elsewhere, the two previously-mentioned easterly waves are still tracking across the basin at about 15kts... they are presently at about 48W and 22W.
Please visit my tropical Atlantic headquarters.
03 August 2006
Chris abruptly weakens...
Wednesday was characterized by intense deep convection, even up through early evening. Then, toward the end of the day and throughout the night, the system was attacked by increased northerly vertical shear and very dry low-mid level air, choking off and stripping off all convection. As of this morning, all that remains is a shallow surface circulation, roughly north of eastern Dominican Republic. The latest intensity is 35kts and 1012mb.
http://www.ssd.noaa.gov/goes/flt/t1/vis-l.jpg
You can still find a running radar loop of Chris at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/chris06/Chris_02Aug06.gif ... it begins Wednesday morning and is still being added to. Parental notice: the loop contains a violent dismemberment, only intended for mature audiences (rated TC 13).
Chris is barely holding onto TS status, and is forecast to degenerate into a Depression shortly. Although the official forecast holds the system at 30kts for the next 5 days, it is certainly not out of the realm of possibilities that environmental conditions will improve, and this low-level vortex over steamy SSTs will take advantage of it. The steering flow will remain toward the WNW at 10kts. This will still take Chris, at whatever intensity, near the Florida Straight and into the Gulf over the next 5 days.
There are two other areas of interest in the basin: both African Easterly Waves. One is at 43W, the other at about 19W. Both of these will be monitored for development, as the classic "Cape Verde season" picks up. The next names on the list are Debby and Ernesto.
Please visit my tropical Atlantic headquarters.
http://www.ssd.noaa.gov/goes/flt/t1/vis-l.jpg
You can still find a running radar loop of Chris at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/chris06/Chris_02Aug06.gif ... it begins Wednesday morning and is still being added to. Parental notice: the loop contains a violent dismemberment, only intended for mature audiences (rated TC 13).
Chris is barely holding onto TS status, and is forecast to degenerate into a Depression shortly. Although the official forecast holds the system at 30kts for the next 5 days, it is certainly not out of the realm of possibilities that environmental conditions will improve, and this low-level vortex over steamy SSTs will take advantage of it. The steering flow will remain toward the WNW at 10kts. This will still take Chris, at whatever intensity, near the Florida Straight and into the Gulf over the next 5 days.
There are two other areas of interest in the basin: both African Easterly Waves. One is at 43W, the other at about 19W. Both of these will be monitored for development, as the classic "Cape Verde season" picks up. The next names on the list are Debby and Ernesto.
Please visit my tropical Atlantic headquarters.
02 August 2006
Chris strengthens further...
Beginning Tuesday late afternoon, deep convection began firing closer to the center of Chris, accompanied by much more impressive aircraft data (increasing flight-level winds, noticeable pressure falls). This continued throughout the night, and today TS Chris is sporting a classic CDO (Central Dense Overcast) with cloud tops around -75C, and evidence of northerly wind shear... decreasing with time. Chris is a small storm, and as such, will be easily influenced by shear, but conversely, will be quick to bounce back. SSTs under and ahead of the storm are a cozy 28C.
At 15Z today, TS Chris was located at 19.2N 63.4W, or just north of Anguilla in the northern Leeward Islands. It is heading WNW at 9kts, and the latest intensity is 55kts and 1001mb. A Tropical Storm Warning is in effect for Puerto Rico and the Virgin Islands... a Hurricane Watch is in effect for the western islands of the Bahamas. You can monitor the progress of the storm via radar in San Juan at http://radar.weather.gov/radar.php?rid=JUA&product=N0Z&overlay=11101111&loop=yes
Over the next few days, it is expected to gradually strengthen to a hurricane, and continue a WNW heading, bringing it over the Bahamas on Saturday morning, and passing very close to southern Florida on Monday morning. The forecast track optimizes its stay over warm water and away from mountainous islands, allowing for the most intensification.
In the longer range, the central Gulf coast should be watching Chris with great interest. Once the storm passes over or near southern Florida on Sunday, the storm will enter the Gulf of Mexico. As of now, it appears that LA and TX would be the higher risks.
Elsewhere, a potent tropical wave just exited the African coast today. It had its earliest origins in the Ethiopian Highlands about a week ago and is favored by computer models to develop and become quite strong. The next name on deck is Debby.
Please visit my tropical Atlantic headquarters.
At 15Z today, TS Chris was located at 19.2N 63.4W, or just north of Anguilla in the northern Leeward Islands. It is heading WNW at 9kts, and the latest intensity is 55kts and 1001mb. A Tropical Storm Warning is in effect for Puerto Rico and the Virgin Islands... a Hurricane Watch is in effect for the western islands of the Bahamas. You can monitor the progress of the storm via radar in San Juan at http://radar.weather.gov/radar.php?rid=JUA&product=N0Z&overlay=11101111&loop=yes
Over the next few days, it is expected to gradually strengthen to a hurricane, and continue a WNW heading, bringing it over the Bahamas on Saturday morning, and passing very close to southern Florida on Monday morning. The forecast track optimizes its stay over warm water and away from mountainous islands, allowing for the most intensification.
In the longer range, the central Gulf coast should be watching Chris with great interest. Once the storm passes over or near southern Florida on Sunday, the storm will enter the Gulf of Mexico. As of now, it appears that LA and TX would be the higher risks.
Elsewhere, a potent tropical wave just exited the African coast today. It had its earliest origins in the Ethiopian Highlands about a week ago and is favored by computer models to develop and become quite strong. The next name on deck is Debby.
Please visit my tropical Atlantic headquarters.
01 August 2006
Chris forms near Leeward Islands...
Back on July 24, a tropical wave left the African coast. At 03Z today, that vigorous wave was upgraded to TD3 based on buoy and satellite data. Although initially fairly disorganized, vertical wind shear has relaxed and the Depression was further upgraded to the third named storm of the season, Tropical Storm Chris, at 09Z today. It is still not well-organized -- the center is hard to find and the deep convection is scattered.
It is located just east of the islands of Barbuda and Antigua in the Leeward Island chain and heading for them, moving WNW at 9kts. The latest intensity estimate (15Z) is 35kts and 1009mb. Tropical Storm Warnings and Watches cover the northern Leeward Islands and Puerto Rico, respectively.
The forecast is for continued strengthening over the next several days, and the track should take it over the Virgin Islands, north of Puerto Rico, Hispaniola, and Cuba, and through the Bahamas. It presently appears that the southeast coast of Florida will want to monitor this storm very closely, as it could affect the state by Sunday as at least a strong TS.
Please visit my tropical Atlantic headquarters.
It is located just east of the islands of Barbuda and Antigua in the Leeward Island chain and heading for them, moving WNW at 9kts. The latest intensity estimate (15Z) is 35kts and 1009mb. Tropical Storm Warnings and Watches cover the northern Leeward Islands and Puerto Rico, respectively.
The forecast is for continued strengthening over the next several days, and the track should take it over the Virgin Islands, north of Puerto Rico, Hispaniola, and Cuba, and through the Bahamas. It presently appears that the southeast coast of Florida will want to monitor this storm very closely, as it could affect the state by Sunday as at least a strong TS.
Please visit my tropical Atlantic headquarters.
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