Jason M
(Weather Watcher)
Fri Aug 02 2002 11:38 PM
Updated Tropical Weather Discussion!!!

FORECAST POSTED: 8/02/02/ 7:15 PM EDT

ATLANTIC TROPICAL WEATHER OUTLOOK:

I am sorry for the delay. There was a severe thunderstorm near the area and I had to shutdown the computer for a while do to frequent lightning.

Two Areas of Interest...

Model Analysis For the GOM Low

The CMC model takes the center of circulation just south of the southeast Louisiana coast. The model shows a WNW movement until it is south of central LA. Then, a more NNW track begins with a landfall in the general vicinity of Lake Charles.

the MM5 shows the low developing rather nicely just south of southeast Louisiana before landfall. A slow drift to the north and a landfall between Houma and Grand Isle in about 84H is forecasted by this model.

The NOGAPS probably takes the low farthest south out of all of the models. NOGAPS then shows a NW movememnt towards Grand Isle, Louisiana.

The UKMET also takes the low into southeast Louisiana in roughly 72 hours.

The AVN model still shows the low moving north into the Florida panhandle. Let me just remind you that this is the only model that takes the low this far east.

Model Analysis For the East Coast Low

The CMC shows a very slow ENE track over the next few days with some signs of a more notherly track towards the end of the model run (120H).

The MM5 is having a hard time recognizing the low pressure system. I can't even find it on this model.

The NOGAPS is having the same problems as the MM5.

The UKMET does pick up the low and takes it southwest towards southern Florida in 120H.

The AVN model is hinting on development form this low more than any other model. the AVN takes the low on an ENE track through 108H. The low then begins to move north and NE as a trough to the north is expected to move south.

Gulf of Mexico Circulation Beginning to Develop

There are some indications that a circulation may be trying to develop in the northeast Gulf of Mexico. One of the buoys on the southern side of the system are indicating weak westerly winds. In addition the latest quickscat (QC) is also indicating some signs of a weak circulation.

New model data still forms low in Northern-Central Gulf of Mexico. The Canadian and MM5 are most aggressive with development by forecasting a hurricane forming late Sunday and Monday and heading for the central and southeast Louisiana coastline. The AVN, NOGAPS, UKMET form a broad weak low and track it towards the Louisiana/Texas state line. There are no GFDL runs yet.

Latest visible sat picture shows than an upper level high is developing over atrough trough in the northeast Gulf of Mexico. With sea surface temperatures near 85-90, an upper level ridge developing over the system and no shear, we should see at least a tropical storm. Conditions are favorable for development.

with all that said, it looks like we will see tropical development over the weekend. The intensity is still uncertain, but the potential for a minimal hurricane does exist. The coast of Louisiana won't see any effect until Late Sunday night or Monday. If it goes west, SE Louisiana would still be on the wet side, bringing heavy rain to the area.

Right now its rainmaker more than anything else...unless we see it bomb like Opal, but we'll cross that bridge when we actually get a system. Residents from Houston to Pensacola to continue to closely monitor the progress of this developing storm. If I had to narrow it down a little farther, it would be between Lake Charles and Biloxi.

We are watching yet another low pressure system that is associated with the same trough of low pressure. This low is located just off the east coast, east of Jacksonville. The NRL site has an INVEST up for the system and Satellite Analysis Branch (SAB) estimates are 1.0. The National Hurricane Center will send out a recon tomorrow to investigate this low.

I believe that the Gulf low has a better chance of development, despite the rapid development of the east coast system being that it was an upper low and that moved down to the surface all in one day. (The LLC is still in a developing stage).

There are a couple reasons why I don't expect development from the low. Well for one, its looks less organized than it did earlier. #2 Once the Gulf of Mexico disturbance develops further, we could see an increase of shear over the Bahamas. And #3 A trough is forecasted to move south, pulling the low northward in a few days. Now one model does take the low southwest, towards Florida. But so far the chances of that happening are unlikely. Currently, I am forecasting the low not to do much (Both strength and movement shouldn't change a whole lot) over the next few days. The trough moving south should eventually pull the low NEWD and it shouldn't affect any landmasses. Hopefully, we will be able to get a better handle on this low tomorrow.

As for the remainder of the Atlantic basin, there is a westward moving wave just east of the Leeward Islands. This wave was also mentione in the National Hurrucane Central tropical weather outlook early this morning. However, this wave is moving into an area with sinking air. Therefore, development shouldn't occur.

A tropical wave is emerging off the coast of Africa. The wave has gained a bit of convection over the last few hours. However, this wave is also moving into another area with sinking air. Development from this wave is unlikely. There is yet another wave behind this one over the continent of Africa. The first wave could increase the moisture levels across the eastern Atlantic, causing conditions to become increasingly favorable for the next wave to move off the coast. While it is too early to speculate on whether or not the second wave will develop, it is something that we will have to watch over the next few days.

The rest of the Atlantic is quiet. The Bermuda is much farther south than average. This is in response to the subtropical low over the central Atlantic. Until the low moves NEWD and out of the picture, the central Atlantic will continue to be covered in sinking air (subsidence).

There are three decent waves over the continent of Africa this evening. This may be the beginning of the African wave train. It will be interesting to see what happpens to these waves once the emerge off the coast. Usually the last one to move off has the greatest potential for development. This is because the waves out ahead of the last one, casuses an increase in the moisture levels across the eastern Atlantic. All three waves have potential but the last one has the better chance. I will be closely monitoring these waves over the next few days as conditions are forecasted to become increasingly favorable for development. Its just a matter of time!

The rest of the discussion is from my discussion posted yesterday. Not much has changes since then...

Sea Surface Temperatures

The trend of warming ssts in the eastern Atlantic Continues

http://152.80.49.210/products/OTIS/otis_glbl_sstanomaly.gif


http://www.cdc.noaa.gov/~gtb/tele/nao.gif


There are no signs of the sea surface temperatures in the eastern Atlantic beginning to cool. In fact, there are still some signs that the waters in the region are still warming. Like I said a few days back, this is in respopnse to two things...#1 The weak easterlys across the Atlantic basin. This is normal for an El Nino episode. #2 The North Atlantic Oscillation (NAO) has turned negative as forecasted. As long as the NAO stays negative, we will continue to see sea surface temperatures warm off the coast of Africa and also off the east coast. The models continue to show negative NAO conditions through the forecast period.

Long Range Computer Models Continue To Show Increasingly Favorable conditions acros the Eastern Atlantic through the week...No change from the post a few days ago


http://wwwt.emc.ncep.noaa.gov/gmb/STATS/maps/opnl/latest/f12.gif



http://wwwt.emc.ncep.noaa.gov/gmb/STATS/maps/opnl/latest/f180.gif


The 180H operational AVN model shows the 15 degrees celsius line in the central Atlantic much farther north than the 12 hour forecast. This means that the cooler subsiding air will likely begin to diminish, which will allow the ITCZ to move farther north. Bastardi also mentioned this a few days back. I also mentioned this on a few of the weather forums.

This also relates to the North Atlantic Oscillation forecasted to turn negative. The troughs over the northwest Atlantic stay farther north, allowing a ridge to build to the south. The NAO turning negative is a good sign that the tropics willbegin to heat up rather soon.

FORECASTER: Jason Moreland



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