Invest 91L reorganizing; The heat is on (again)
Invest 91L, which is located near 14°N, 57°W, is showing signs of reorganization after a pretty rough weekend. On Saturday, the wave looked ripe to develop with organized convection and the hint of a surface circulation. On Sunday a Hurricane Hunter and NOAA G9 flew into the system only to find it disorganized and negatively influenced by the burst of convection that sprouted on its western edge. Since then, low-level circulation has at least strengthened, if not consolidated, and residents of the Lesser Antilles should be prepared for tropical storm advisories to be posted on short notice. Satellite loops show decent thunderstorm activity and some mid-level circulation, and continued bursts of thunderstorms to the southwest of the invest region. The wave is surrounded by moderately strong wind shear (30-40 knots) on both the north and the south sides, which could delay development. Also, a large mass of dry, Saharan air continues to linger to 91L's north. In a mission this morning, Hurricane Hunters found winds close to tropical storm strength, but no signs of a closed surface circulation—just plenty of winds from the east or southeast. The next mission is scheduled for 2pm EDT, and they will continue every six hours if the system remains a threat.
Figure 1. Visible satellite of Invest 91L at 10:30am EDT as it moves west toward the Lesser Antilles.
Forecast For 91L
Development will probably occur in the next day or two, and the National Hurricane Center is giving the wave a 90% chance in the next 48 hours. The question now is where will it go, and how long will it remain a tropical cyclone. Models are split today, although still leaning toward an Atlantic recurving solution. In the camp of a Gulf of Mexico track are the CMC and the UKMET models. The GFS and the ECMWF are still in favor of the system tracking northwest toward Florida (and coming close) before taking a turn to the northeast. The NOGAPS model is resolving a Florida landfall in this morning's run, and the HWRF hints that it might like that solution, as well, at the end of its run. The GFDL remains conservative and forecasts that the system will turn north and northeast well before making any connection with the U.S. coast. It is notable that although there is still much disagreement on where this system will go, the models have been trending west in their tracks over the past few days. However, it is extremely difficult to nail down a track before a cyclone has even developed. Something we know for sure is that 91L is a threat to the Lesser Antilles and the Caribbean islands including Puerto Rico, Hispaniola, and the Bahamas.
In terms of intensity, both the GFDL and the HWRF are thinking this will eventually get to hurricane strength once it develops, although neither are forecasting it to become stronger than a category 1. SHIPS (which tracks 91L into the far eastern Gulf of Mexico) brings the system up to a category 1 hurricane, and the LGEM does as well, but is slower in its intensification. General consensus this morning is that 91L will max out somewhere between a moderate tropical cyclone and a moderate category 1 hurricane. Again, this is something that is difficult to predict before development itself occurs.
The Heat Is On (Again)
Someone turned the furnace on again in the central U.S., although many would argue that it was never actually turned off after the last heat wave. Heat advisories have been issued from southern Louisiana to North Dakota. Temperatures are expected to climb to 115°F in the central Plains through Wednesday, and heat index values will soar again. Oklahoma has now seen over a month of high temperatures hitting at least 100°. Some reprieve could come later this week.
Figure 2. Weather advisories issued by the National Weather Service. Heat-related advisories are pink.
Angela
Reader Comments
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or a turkey? LOL....Quite a blob out infront of 91L
Which circulation center you think will become dominate. I would think it would have to be the MLC. Thats where the anit cyclonic flow is and the other llc are getting sheared out by that MLC.
agree, doesnt matter if its at 70% or 100% its still has the potential of becoming a TD or TS at anytime
http://tropicalatlantic.com/recon/
Link
I agree. I wasn't writing it off, I'm just wondering why the NHC thinks it's now less likely to develop than it was three hours ago. The percentage thing doesn't work.
Time: 17:31:00Z
Coordinates: 14.8833N 58.9667W
Acft. Static Air Press: 975.5 mb (~ 28.81 inHg)
Acft. Geopotential Hgt: 303 meters (~ 994 feet)
Extrap. Sfc. Press: 1010.3 mb (~ 29.83 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 131° at 29 knots (From the SE at ~ 33.3 mph)
Air Temp: 19.6°C (~ 67.3°F)
Dew Pt: 14.4°C (~ 57.9°F)
Peak (10s) Flt. Lvl. Wind: 31 knots (~ 35.6 mph)
SFMR Peak (10s) Sfc. Wind: 50 knots (~ 57.5 mph)
SFMR Rain Rate: 30 mm/hr (~ 1.18 in/hr)
Have you looked at the models yet?
thank you!!
6:09 PM GMT on August 01, 2011
nah. you can already see the break in the ridge. there's a low moving off the GA/SC coast and it's only gonna dig deeper.
the forecast winds in S. FL tomorrow are out of the SW.
Eugene is looking really good.
The one that got ejected actually looks dominant right now, as a convective band is developing and wrapping around its east side. The MLC still has some surface reflection with it, so there are again two centers (oh joy). If the western center doesn't run away in the eastern Caribbean trade winds, then it will probably stay dominant.
I agree, they need a better look at the south side of that area.
Not good for Tampa.
Serious?
That is the Tampa hit I was joking about yesterday.
Wow.
48Hrs
not good at reding these sorry but i think they found it can someone else check thanks and sorry if im wrong
You think it would help the western circulation if it absorbs that convection to it's southwest? It looks like it's trying too.
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