ATL: RICHARD - Remnant Low - Discussion

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED OCT 20 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SATELLITE IMAGERY AND DATA FROM AN AIR FORCE RESERVE RECONNAISSANCE
AIRCRAFT INDICATE THE LOW PRESSURE SYSTEM CENTERED ABOUT 160 MILES
SOUTHWEST OF GRAND CAYMAN HAS CHANGED LITTLE THIS AFTERNOON.
ALTHOUGH ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY CONDUCIVE FOR
DEVELOPMENT...CONDITIONS ARE EXPECTED TO BECOME SOMEWHAT MORE
FAVORABLE FOR A TROPICAL DEPRESSION TO FORM DURING THE NEXT DAY OR
SO. THERE IS A HIGH CHANCE...70 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT DRIFTS TO THE SOUTH
OR SOUTHEAST. INTERESTS IN THE NORTHWESTERN CARIBBEAN SEA SHOULD
CONTINUE TO MONITOR THE PROGRESS OF THIS DISTURBANCE. REGARDLESS OF
DEVELOPMENT...HEAVY RAINFALL IS POSSIBLE OVER THE CAYMAN ISLANDS
AND JAMAICA DURING THE NEXT COUPLE OF DAYS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER CANGIALOSI/STEWART

[cycloneye]

18z Best Track

AL, 99, 2010102018, , BEST, 0, 171N, 822W, 30, 1008, LO

[GCANE]

Very large, high-rain-rate cell in firing up.

[HURAKAN]

Latest microwave

[HURAKAN]

nice pic by NASA

[SouthDadeFish]

I have a feeling the exposed swirl will get pulled underneath the convection. This area of convection has been quite persistent, and to me it looks like the center is already starting to get a little elongated W-E as if its starting to happen.

[HURAKAN]

latest

[cycloneye]

This afternoon's discussion of 99L by Dr Jeff Masters of Weatherunderground.

Posted by: JeffMasters, 7:11 PM GMT on October 20, 2010

A tropical disturbance (Invest 99L) centered 160 miles southwest of the Cayman Islands is moving south to southeast at 5 - 10 mph. A Hurricane Hunter flight arrived in the storm at about 11am this morning, and found a closed circulation with top winds at flight level (700 feet) of 33 mph. A closed circulation and 30 mph surface winds are necessary conditions for a tropical depression to exist, but the storm must also have a great deal of heavy thunderstorm activity near the center that persists for many hours. In the judgment of NHC, 99L does not qualify as a tropical depression in that regard. The storm is bringing heavy rain to the Cayman Islands; 4.14" inches has fallen over the past 2 1/2 days at Savannah on Grand Cayman Island. Heavy rains have diminished over the Cayman Islands, but have spread to western Jamaica and west-central Cuba this afternoon. Recent satellite imagery shows that the surface circulation center is exposed to view, and 99L has a relatively meager amount of heavy thunderstorm activity. The center is more than 80 miles west of the heaviest thunderstorm activity, and it is likely that 99L's center will relocate itself to the east to be more underneath the heaviest thunderstorms. Wind shear is marginal for development, 15 - 20 knots, due to the clockwise flow of air around an upper-level high pressure system near the coast of Honduras. The high is bringing strong upper-level winds out of the southwest to 99L. Water vapor satellite loops show considerable dry air to the west and north of 99L, and the strong southwesterly winds over the storm are bringing some of this dry into into the core of the storm, keeping all the heavy thunderstorm development confined to the east side of the center. The waters beneath 99L are very warm, 29°C, but 99L will not be able to take advantage of these warm waters until the shear relaxes. A new hurricane hunter aircraft will be in the storm tonight near 8pm EDT.

Forecast for 99L

The current southward movement of 99L is carrying the storm into a region of lower wind shear, and we should see 99L accumulate more heavy thunderstorm activity near its center beginning tonight. The latest SHIPS model forecast predicts that wind shear over the Western Caribbean will decline below 15 knots Thursday afternoon through Saturday afternoon, which should allow the storm to become a tropical depression by Thursday. Steering currents will be weak today through Friday in the Western Caribbean, making it difficult to predict where 99L may go. The models are split into two camps, with the GFDL and HWRF models taking 99L to the west-northwest over the western tip of Cuba or the Yucatan Peninsula on Sunday as a hurricane. The rest of the models take 99L to the south over Honduras on Sunday, and keep the storm below hurricane strength. Given 99L's current southward motion and the possibility that the center will relocate farther to the east later today, this makes a track to the southwest towards Honduras more likely, I predict. NHC is giving 99L a 70% chance of developing into a tropical depression by Friday, which is a reasonable forecast. I expect this will become Tropical Storm Richard by Friday.

[warmer]

the center now seems to move more east instead of s/se

[GCANE]

Pressure falling rapidly at closest buoy

http://www.ndbc.noaa.gov/station_page.php?station=42057

[Extratropical94]

I hope GFDL's future positions won't come true. Has already been an active year for SE Yucatan / Belize.
I would expect a slow motion towards the E/ESE for quite a while and then a very sharp turn (maybe even 180 deg) towards the extreme SW carib, not excluding a Nicaragua or Costa Rica hit.

But, as many said before, it's just a speculation.

[Sanibel]

Worsening dry air issues to its west IMO:



http://www.ssd.noaa.gov/goes/east/gmex/wv-l.jpg

[cycloneye]

Pressure falling rapidly at closest buoy

http://www.ndbc.noaa.gov/station_page.php?station=42057

And the winds are blowing from the West and WSW, meaning center is NW of the bouy.

[Extratropical94]

What i don't get is why the NHC issues a TWO including the advice
"INTERESTS IN THE NORTHWESTERN CARIBBEAN SEA SHOULD
CONTINUE TO MONITOR THE PROGRESS OF THIS DISTURBANCE."
even though the majority of the models is currently taking 99L south of the Honduras/Nicaragua border. (or do they define Nicaragua as a NW carib ctry?)


GFS seems more reasonable for me than the northward-tracking though.

[HURRICANELONNY]

Don't put much into the models until there is Richard. Actually they're useless. Same thing with Paula. People were saying. Florida going to get hit with a major. Before there was even a depression.

[Blown Away]

The trend has gone from being buried into CA to clipping the NE Yucatan and heading for the GOM. NGOM to the east need to keep watching because 99L could take the perfect track and stay over the very warm NW Caribbean waters and head into the GOM as a strong storm, as depicted by some models.

[x-y-no]

Center is looking broader and elongated E-W ... getting a bit closer to strong convection, though. This may qualify for TD by 11pm.

[Blown Away]

Don't put much into the models until there is Richard. Actually they're useless. Same thing with Paula. People were saying. Florida going to get hit with a major. Before there was even a depression.

Not really, most of the models from the beginning showed that strong shear once Paula headed towards the Yucatan channel. 99L has had GFDL/HWRF showing a strong hurricane heading towards SFL, likely not gonna happen but there were no Paula models showing a hurricane for the CONUS.

[Vortex]

For anyone with doubts regarding “it’s too late to get anything strong”…We only have to look back the last 5-15 years and 2 very powerful storms come to mind. Mitch and Wilma formed within days of the current date….The structure of 99 is well defined and once shear decreases over the next 24 hours this system will have all the necessary ingredients to become what the GFDL/HWRF have been advertising… a POWERFUL hurricane….How this storm interacts or doesn’t with the Yucatan and/or western Cuba will have significant impacts on areas to the north to include the eastern Gulf/FL….While a US threat is purely speculation at this point we have seen some increase in this *possible* solution the last 24 hours…

[brunota2003]

Wow...certainly looks better than yesterday. Another DMAX or two should settle things down, and I am surprised they only found peak winds of 33 mph in those storms!