1650 EDT JULY 29
Don looks a little better this afternoon. Nothing great but it is clearly STILL a TD– tropical depression or bare minimal tropical storm. Its clear that DON will not make it to Minimal category 1 Hurricane before landfall .
1000 EDT JULY 28
DON looks lile crap this morning. NHC says that it has several centers and none of them had become the dominant one and whenever that is the case you always have a row the weak disorganized system. It is possible that Don might collapse over the next 6-10 hours… But if it survives conditions should improve as it approaches the Southern Texas Coast.
1730 EDT JULY 27
The recon found a really strong system… mean sea level pressure (MSLP) of 1006 MB and Max flight winds 45 knots with Gust to 57 knots. I dont know for certain that NHC will upgrade this system directly to Tropical storm status at 5pm… but they should. Especially given that this baby is only 60-72 hours away from landfall… and the Hurricane models are increasing this system to strong TS threshold…. and a few Hurricane models show a borderline Min Cate 1 cane at impact.
The Forecast has NOT changed. The SEVERE biased GFDL model should be ignored because that Model has a strong NORTH or Poleward Bias. The SYNOPTIC situation clearly shows that there is little chance of Tropical storm DON making landfall above Galveston Bay/ Houston. The GFS and GFDL models once again show the WEAKEST ” dome” over the southest states of any of the Models and because they do… DON turns to the NW much sooner… and hence an impact at Galveston Bay.
1400 PM EDT JULY 27
Tropical Disturbance 90L is now RAPIDLY developing … that much is clear from the Midday IR and VIS` satellite picture. There is a pool of 90 degree F sea surface temps in the Yucatan Channel that is also having some sort of impact. The recon is on its way and I would be stunned if they did NOT find a Tropical Depression later on today.
1900 EDT JULY 26
We finally have a significant tropical system to focus on here at the end of July. This system has been designated 90L by the tropical prediction center (NHC). As you can see from the satellite pictures this is a fairly well organized system which have developed significantly in last 24 HRS has moved into the western and northwestern portions of the Caribbean Sea.
This feature has the potential to develop into a tropical storm and I suppose IF… if there were to rapidly develop over the next 36 hours it might even make hurricane strength but the odds of strongly against that happening. Some of the hurricane model intensity forecast do show in approaching the borderline threshold… which you can see here.
The forecast itself with regard to this potential tropical cyclone is interesting and it shows why one must take a look of the overall pattern as opposed to JUST using hurricane models. Here is the latest forecast package regarding the hurricane models– the 18z JULY 26. As you can see most of the models are taking this system into far southern Texas and that area certainly could use the rain!!
Interestingly for most of the past 90 days there has been a monster dome in the jet stream centered over Texas and Oklahoma. This dome of course is one reasons why they have had such an extreme drought over that portion of the nation and the drought has been sustaining the dome itself so the two features — the dome and the drought– are locked in some sort of bizarre symbiotic relationship .
The point here is that for the first portion of summer and probably for most of the 2ND hald of the Summer and Autumn the drought and the dome over Texas and Oklahoma is going to prevent most of the tropical cyclone activity in the Gulf of Mexico from hitting Texas. Anything that moves thru the Western Gulf of Mexico will probably be deflected by this huge dome and be forced to turn its west southwest or even southwest into northern or Central Mexico south of Brownsville. But at this particular time the pattern has the dome breaking down.
Over the next few days the dome was going to redevelop over the southeast states –which will cause our region to turn quite hot for three of four days. But more importantly if tropical disturbance 90L were to to develop it sets up a pathway for the 90L to follow the dome’s SW periphery and turn WNW into the Gulf of Mexico and perhaps make a landfall of north of Brownsville TX. We can see how this might develop by taking a look of the GFS model at 500 MB at 36 hrs and 72 hrs and 96 hrs.
In addition over the past 24 hours MSLP have fallen significantly over the Northern Gulf of Mexico.
Longer term the over all atmosphere across the equatorial regions and the subtropical regions are about to move into a much more favorable pattern. This image from CPC shows 200 MB Vertical Velocities.
Without getting too technical the BROWN areas shows “sinking air“ and conditions which are hostile to tropical cyclone development … while the GREEN areas show rising motion which enhances the potential of any tropical disturbance into becoming a tropical cyclone. In this image the features move from left to right so as you can see right now over the Gulf of Mexico the Caribbean and the tropical Atlantic is in BROWN areas or the sinking year. But as you can see… coming in from the Pacific and even as far west as China …there is a large expanse of area rising motion which is represented by the GREEN regions. Over the next week this energy will begin to move into the Gulf of Mexico and Western Caribbean and then rapidly spread into the entire tropical Atlantic region at the same time as the counter moves into August.
Do not be surprised if we see a significant burst of activity in the tropical Atlantic during the first two weeks of August. La cities