23 July 2010

TD3 upgraded to Bonnie, moving over FL today...

Tropical Depression 3 was upgraded to Tropical Storm Bonnie at 03Z today based on aircraft recon.  The storm is still sheared and relatively disorganized, but strong enough to be a TS.  The potent upper-level Low that has been plagueing the system for days has rotated around to the west and is now inducing moderate southeasterly vertical shear over Bonnie.

At 15Z today, the intensity is 35kts and 1008mb, and is located over Biscayne Bay, FL (just south of Miami and north of Homestead).  It will weaken as it spends the next 12 or so hours over land... though historically, the moist flat land of southern FL doesn't weaken tropical systems very much.  Areas in the southern FL peninsula should be prepared for tropical storm conditions throughout the day, including heavy rain, strong gusty winds, and the possibility of tornadoes.

The forecast after crossing the peninsula is for a gradual re-intensification, though most likely not reaching hurricane strength before making another landfall near eastern LA in the morning hours on Sunday.  A Tropical Storm Warning is in effect for the western Bahamas and the entire southern FL peninsula from West Palm Beach, down to the Keys, and up to Tampa.  TS Warnings are also in effect for the north central Gulf coast from Destin FL westward to Morgan City LA.

This will certainly have an impact on the oil spill region, creating large (15-20') swells at sea and large waves at the coast for several days, combined with a small storm surge.

Elsewhere, the area of disturbed weather that was over the Bay of Campeche yesterday moved inland over Mexico before developing.

Please visit my tropical Atlantic headquarters.

22 July 2010

Disturbance upgraded to TD3...

The area of disturbed weather I've been mentioning this week was upgraded to Tropical Depression 3 at 15Z today based on improved satellite presentation and identification of a surface circulation.  An aircraft is scheduled to fly through the system later today to accurately gauge the intensity.  At 15Z, TD3 was located just north of the eastern tip of Cuba (and south of the central islands of the Bahamas), and the intensity was estimated to be 30kts and 1008mb.  It is still being adversely affected by the strong upper-level Low to its north, so intensification should be minimal... perhaps reaching a moderate tropical storm.

The forecast track is to continue WNW, gradually gaining speed with time as it comes under the influence of a ridge to the north.  On this track, it will affect the Bahamas, southern Florida, and eventually the north-central Gulf coast.  Tropical Storm warnings have been issued for the western half of the Bahamas and for the southern tip of the Florida peninsula: http://www.nhc.noaa.gov/storm_graphics/AT03/refresh/AL0310W_NL+gif/.  The circulation should become visible from the radar at Camaguey, Cuba: http://www.insmet.cu/asp/genesis.asp?TB0=PLANTILLAS&TB1=RADAR&TB2=../Radar/04Camaguey/cmwMAXw01a.gif

Another area of interest has been moving slowly across the western Caribbean and into the Bay of Campeche over the last several days.  It's now about 120 miles east of Tampico, Mexico and tracking W at 10kts.  You can also monitor this from the Altamira radar at http://smn.cna.gob.mx/radares/rad-altamira.gif

Please visit my tropical Atlantic headquarters.

20 July 2010

Disturbance getting better organized...

The vertical wind shear is decreasing, and the disturbance I mentioned yesterday was surprisingly quick to take advantage of the less hostile environment.  The SSTs are right around 29C, and with the shear reducing from ~20kts to just 5-10kts, there is a lot of new deep convection located over and around the low-level center.  The 1014mb Low is located just north of the Dominican Republic and still tracking WNW at 8kts.

The forecast is for gradual strengthening and a continued WNW track, bringing it near the FL peninsula on Friday.  The latest model guidance suggests that the intensity at that time will be a strong tropical storm or possibly a minimal hurricane, but 3-day intensity forecasts are a little hazy (recent average 72h forecast error is about +/- 19kts).

Elsewhere, a strong easterly wave just exited the African coast today, so that's worth keeping an eye on over the next few days to see if it develops.

Please visit my tropical Atlantic headquarters.

19 July 2010

Disturbance passing north of Virgin Islands...

An easterly wave that exited the African coast about six days ago is presently just north of the Virgin Islands and moving WNW at 12kts.  An upper-level Low to its north has enhanced the outflow aloft (which has invigorated the convection), but at the same time, has also provided fairly strong vertical wind shear on the order of 20-30kts from the west (which will hinder attempts at organization).

The majority of models do not intensify this system, but if it should happen to survive its current and short-term environment, the large-scale steering pattern would bring it into the Gulf of Mexico by the end of the week.

Please visit my tropical Atlantic headquarters.

01 July 2010

Alex moves inland...

At about 02Z (10pm EDT), Alex made landfall in a rural part of Mexico between the towns of La Pesca and Punta de Piedra at an intensity of 90kts and 948mb.  It was on an intensifying trend, which tends to make the conditions a bit more severe than if it were weakening or steady at the time (the storm is more coupled with the boundary layer and stronger winds can mix down to the surface).  There have been several tornadoes already reported in association with Alex, mostly in the Brownsville area.  Rainfall is the big problem for northern Mexico and southern Texas... Cameron County (the southern tip of Texas) received anywhere from 5-9" of rain yesterday, and it's not over.  An additional foot of rain is possible over these areas as the storm decays.  Up by Galveston, nearly 2" of rain fell as of this morning.  Unfortunately, I wasn't able to locate any real-time rainfall totals from Mexico, but general reports are claiming 6-12" have fallen so far in coastal areas and 20"+ over the higher terrain further inland.

And, even though the storm is inland and weakening rapidly, the ocean is still feeling its effects... large swells up to 10' are propagating away from the storm's path and impacting nearly the entire Gulf (smaller but still amplified swells will reach the western coast of the Florida peninsula).  Oil spill recovery efforts have been put on hold for a few days due to the rough seas.

I attached a couple of images: a radar image from the Brownsville NEXRAD at the time of landfall (~02Z), and a visible satellite image from about one hour earlier (by 02Z, there was barely enough light for a decent look at the storm).  

 Please visit my tropical Atlantic headquarters.