30 October 2010

Hurricanes Shary and Tomas bring a surge of activity to the end of October...

Shortly after recurving away from Bermuda, Shary intensified to a 65kt minimal hurricane and is still headed out to the hurricane graveyard that is the north-central Atlantic.  This makes it the 11th hurricane of the season.  It's 580 miles ENE of Bermuda and racing away from the island at 35kts.  It is rapidly on its way to becoming an extratropical cyclone and will get absorbed into the mid-latitude westerlies.

As I suggested in my update yesterday, the disturbance near the Windward Islands was indeed upgraded to TS Tomas once the aircraft got there to investigate it.  Then, today at 15Z, it was upgraded to Hurricane Tomas, the 12th of the season.  The latest intensity is 65kts/993mb and on a very definite strengthening trend.  It's crossing the Windward Islands as I type this, and will head into the Caribbean, quite likely bound to become the season's 6th major hurricane in the coming days.  There is a long radar loop of the hurricane at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/tomas10/Tomas_29-30Oct10.gif.  Tomas is heading WNW at 13kts and this motion is expected to continue, bringing it near Jamaica in 5 days, probably as a major hurricane.  All interests in the Caribbean should be watching this very closely.  The latest watches, warnings, and track forecast can be found at http://www.nhc.noaa.gov/storm_graphics/AT21/refresh/AL2110W5+gif/


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29 October 2010

Shary forms far east of US coast, two other disturbances worth watching...

In a late-season surge of activity, there are three significant areas of tropical activity.  The first of which was recently upgraded to TS Shary (03Z today), and is located about 950 miles due east of Jacksonville FL.  This is the 18th named storm of the season.  Intensity is estimated at 35kts/1004mb, and it is just about to begin recurvature to the NE... heading directly for Bermuda later tonight.  Intensification will be limited due to the hefty vertical shear and cooling SSTs, so it's unlikely that Shary will become a hurricane.  You can monitor Shary near Bermuda at http://www.weather.bm/radarLarge.asp

Elsewhere, an extremely well-organized easterly wave is nearing the Windward Islands.  It existed the African coast on Oct 23 and has been quite impressive since then, particularly in the past couple of days.  There is a 1006mb Low analyzed with the system, and a plane will be flying into it later today to gather more accurate intensity data.  It's quite likely that this will be upgraded to TD 19 then TS Tomas within 24 hours.  It's presently about 400 miles east of Trinidad and heading WNW toward the southern Windward Islands.  Over the next several days, the eastern Caribbean environment will be favorable for significant development, so this could become the season's 11th hurricane.  The Windward Islands, Virgin Islands, Puerto Rico, and Hispaniola should be very alert for possible impacts.

Finally, there's another area for potential development in the central Atlantic, about 1200 miles east of TS Shary.  It also has its origins from an easterly wave that exited Africa back on Oct 19 (it's the one I mentioned in my update on Oct 21 when it was near the Cape Verde islands).  Conditions are fairly hostile for this system to develop, but if it should, it would be TD22 then TS Virginie, assuming the previous system goes first.

Also assuming that Tomas forms from the disturbance nearing the Windward Islands, that would bring the season up to 19 named storms, a tie with the infamous 1995 season.  2010 is most certainly in the top 4 seasons in recorded history for activity, even if nothing else forms.  As of today (not counting current or future developments), it has seen five major hurricanes, four of which were Cat 4, ten hurricanes, among the most ever recorded in a season, and 18 named storms, also among the the most ever recorded in a season!


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25 October 2010

Richard becomes season's 10th hurricane, hits Belize...

Over the weekend, Richard intensified to an 80kt Cat 1 hurricane prior to making landfall on Belize and tracking across the Yucatan peninsula.  This was the 4th storm to hit that small section of coast (Alex, Karl, Matthew, Richard) this season.  The radar loop of the storm's approach and landfall is at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/richard10/Richard_24-25Oct10_belize.gif

At 15Z today, Richard was downgraded to a 30kt Depression and is still over the southern Yucatan peninsula.  There will most likely be very little left of the vortex once it enters the Bay of Capeche, and all model guidance suggests a minimal TS or remnant low as it limps W-NW across the Bay.

With yet another hurricane added to the ranks, the rarity of such an active season not having a US landfall is even more striking.  In the last 110 years, there has never been a season with 10 hurricanes and 0 US hurricane landfalls.  You may recall that Ike was the last time the US was hit by a hurricane, and that was in early Sept 2008.


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22 October 2010

Richard nearly stationary east of Nicaragua...

Since yesterday's update, very little has changed.  Richard is still a 35kt tropical storm, still forecast to head toward Belize and the Yucatan peninsula, and still forecast to become a hurricane prior to that first landfall.  It's presently in a very weak steering environment, so it's drifting, most recently to the west at 3kts.  Over the next two to three days, the forward motion should pick up as a ridge moves in to the north of it, sending it westward into Belize by Monday morning.  I will have a full radar loop from Belize once the storm is within radar range, so stay tuned.

Depending on how intense it gets prior to that landfall, and how quickly it traverses the Yucatan peninsula, it will enter the southern Gulf of Mexico either as a remnant swirl or as a re-intensifying tropical storm.  Given the magnitudes of those unknowns, any forecast beyond that is total speculation.  To be on the safe side though, areas on the north and east US Gulf coast should be keeping a close eye on Richard next week.

The easterly wave that was near the Cape Verdes continues to look impressive on satellite imagery, but is not yet a Depression.  It's still near the Cape Verdes, but moving toward the NW.  It only has another 1-2 days to develop before it moves into much stronger vertical shear.


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21 October 2010

Richard forms in western Caribbean...

The area of disturbed weather that I mentioned in my last update 6 days ago has been festering and very slowly getting better organized.  As several global models predicted about a week ago, a tropical storm has emerged from the southwestern Caribbean!  At 03Z today, it was upgraded to TD19, then at 15Z today, upgraded again to TS Richard based on aircraft recon, making it the 17th named storm of the season.  It's located about 200 miles ENE of the Nicaragua/Honduras border and the intensity is 35kts/1006mb.  Since 1900, only three other seasons have had this many named storms: 1933, 1995, and 2005, so this is among the most active seasons in recorded history.  Also, the name Richard has never been used before in the Atlantic, though it has been in the rotation for 30 years.

Richard is expected to continue strengthening as it heads slowly toward Belize and the Yucatan peninsula... the 5th storm this season to affect that area (Alex, Karl, Matthew, and Paula have already made their unwelcomed visits).  The official forecast brings Richard to a Yucatan landfall (as a Category 1 hurricane) early on Monday morning, then enters the southern Gulf of Mexico by Tuesday morning.  Beyond that, the states along the north and east Gulf coast (particularly Florida) should be watching this system closely.

Elsewhere, a surprisingly well-organized easterly wave has exited the African coast and is presently south of the Cape Verde islands and showing signs of a surface circulation.  The shear and SSTs are currently not inhibitive for this to become a tropical cyclone in the next couple of days, but the environment does become more hostile after that.  


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15 October 2010

Paula dissipates over Cuba...

Over the last couple of days, Paula skirted turned toward the NE, encountered significant shear, skirted along the northwest coast of Cuba, and just recently has the final advisory written on it as a dissipated Depression over central Cuba.  Yet another landfall to add to the seasonal count, and yet another one that the US dodged.

With the assistance of my colleague Phil Klotzbach, I have a 159-year climatological probability of hurricane landfalls anywhere along the US coast.  In seasons that are this active (as measured by the Net Tropical Cyclone activity, or NTC, which is currently 173.5 compared to an average season with NTC of 100), the US has a 95.4% chance of being hit by at least one hurricane of any category.  Moving the threshold up to major hurricanes only (Cat 3+), the US has a 20.5% chance of being hit by at least one major hurricane.  Clearly, the US coast has been quite fortunate so far this season.

Back to the current state of the tropics, there are hints of a tropical disturbance festering in the extreme southwestern Caribbean, over Panama.  There is low-level convergence along the monsoon trough, some enhanced vorticity centered near Panama, and persistent convection also centered over Panama.  In mid-October, those ingredients at that location is climatologically favored for a north-moving western Caribbean hurricane.  In several long-range global models, a strengthening storm does emerge from this cocoon in the coming 3-4 days, then make its way generally northward toward Cuba in about 9 days.


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13 October 2010

Category 2 Hurricane Paula stalling in Yucatan Straights...

Aircraft recon into Paula on Tuesday afternoon found much stronger winds than expected, and it was immediately upgraded to an 85kt CAT2 hurricane with a central pressure of 981mb.  Since then, it has has changed very little... at 15Z today the intensity is 85kts/984mb.  Though the forecast is for gradual weakening in the face of increasing vertical shear, a short-term temporary increase is possible based on satellite imagery.  There is another recon plane en route to the storm as I type this, so in a couple of hours we will know better what the exact intensity is.  It's a rather small storm, so changes (either increases or decreases) can happen dramatically.

Looking at the long radar loop available at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/paula10/Paula_12-13Oct10.gif, you can see that the motion has slowed down quite a bit, and is now drifting to the NE at roughly 3kts.  The forecast track is for continued slow motion, and turning to the E, then dissipating over the mountains of Cuba.  However, there is large model guidance spread, and anything from completely stalling in the Yucatan Straights for a few days to getting picked up by the trough and heading NE over Cuba/Florida/Bahamas is within the realm of possibilities.  If you are in any of those areas, you can keep up to date on the latest watches and warnings at http://www.nhc.noaa.gov/refresh/graphics_at3+shtml/144014.shtml?5day#contents


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12 October 2010

Hurricane Paula heading for the Yucatan...

A lot has happened in 24 hours... the disturbance that was off the Nicaragua/Honduras border rather quickly got better organized.  A plane flew into the system and found much stronger winds than expected, and at 21Z yesterday, it was upgraded to TS Paula with 50kt winds and a 1000mb central pressure.  Just 12 hours later, it was upgraded to Hurricane Paula, the 9th of the season.  The intensity as of 15Z today is 65kts and 991mb, and it's located 150 miles SSE of Cozumel, Mexico and heading NNW at 9kts.  Hurricane warnings are in effect for the eastern coast of the Yucatan Peninsula: http://www.nhc.noaa.gov/storm_graphics/AT18/refresh/AL1810W_NL+gif/

It is forecast to continue intensifying, and also to slow down.  In 5 days, it is forecast to be in the Yucatan Straights, not far from where it is now.  However, increasing shear is expected to hit it in about 3 days, so it might not make it to a major hurricane.

You can monitor its structure and movement via a radar loop from Cancun: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/paula10/Paula_12-13Oct10.gif


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11 October 2010

Otto becomes extratropical, disturbance brewing in western Caribbean...

Otto spent 1.5 days as a hurricane, though was visibly losing its tropical characteristics in a hurry (weaker and displaced convection, frontal bands, etc.).  At 03Z on Sunday, it was downgraded to a TS, then twelve hours later, advisories were ceased on the system as it became an extratropical cyclone about 400 miles west of the Azores.

There is a 1008mb Low associated with a disturbance that has been festering in the western Caribbean for several days (I mentioned it in my update on Friday).  It's currently located on the tip of the Nicaragua/Honduras border and drifting to the WNW.  The majority of models gradually develop this system into a TS (Paula) as it heads NW toward Cozumel, then recurving to the NE toward Cuba/Florida.  Intensification should be somewhat limited due to the expected proximity to land throughout the next few days.


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08 October 2010

Hurricane Otto heading out to the north central Atlantic...

Since my last update on Tuesday, the disturbance I referenced was upgraded to STD17 on Wednesday morning, STS Otto on Wednesday afternoon, TS Otto on Thursday morning, and now Hurricane Otto as of 15Z today.  Sorry about the lack of updates since Tuesday!
The storm took a while to get organized and acquire purely tropical characteristics, and as such, it was sub-tropical for at least a couple of days.  As I write this, it definitely is tropical, and has a rather impressive satellite presentation with nearly -85C cloud tops in the CDO.  There is not yet an eye apparent in the VIS or IR, but that could certainly change in the coming hours.
The current intensity is 65kts and 979mb, making Otto the 8th hurricane of the season.  Right now, we're just one TS away from matching the active 2008 season which had 16 named storms, 8 hurricanes, and 5 major hurricanes.  The storm is located about 550 miles north of Puerto Rico and tracking ENE at 15kts.  The forecast is for some additional strengthening, then a rapid transition to extratropical as it merges with a mid-latitude trough which will whisk the system out to the north central Atlantic over the next 3 days.

Elsewhere, there's a low-level swirl associated with an easterly wave located north of Panama.  This doesn't look too likely to develop in the foreseeable future.


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05 October 2010

Disturbance near Windward Islands getting organized...

Back on Sept 25, an easterly wave exited the African coast and has been making its way westward through the deep tropics.  For much of the last 1.5 weeks, it has been a feature of interest, but not great interest.  In the past couple of days however, the circulation and convection have become more concentrated, and the system is now just north of Puerto Rico.  Using the long-range radar from San Juan, we can see the weak circulation: http://radar.weather.gov/radar.php?rid=JUA&product=N0Z&overlay=11101111&loop=yes.

It's in about 10kts of vertical shear (expected to decrease slightly over the next couple of days) and over 29C water (remaining steady over the next couple of days).  The majority of models now develop this system, bringing it to TS intensity within a day, and hurricane intensity in 2-4 days.  As far as the track goes, models are in agreement that it will recurve out to the open ocean in about 2 days... drifting to the NW prior to that.
The next name on the list is Otto.

It's truly remarkable that the US has not had a hurricane landfall this season... it's been quite an active season so far, with 14 named storms, 7 hurricanes, and 5 major hurricanes.  But, countries to our south haven't been so fortunate.  It's been a very bad year for landfalls and tropical cyclone effects in most of central America and Mexico... also Bermuda and Newfoundland had noteworthy, historic encounters.


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