TD 2 nearly dead; African disturbance 90L gathering strength
Tropical Depression Two is near death, but is still worth watching. The dry, Saharan air to the north and west of the depression, combined with moderately high levels of wind shear of 15 - 20 knots, have almost completely destroyed all of TD 2's heavy thunderstorms. Satellite loops of the storm show a well-formed circulation, but almost no heavy thunderstorm activity.
Wind shear over TD 2 is expected to remain in the modereate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C three days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that TD 2 will not be able to intensify quickly, and some of the models indicate the TD 2 may get destroyed in the next day or two. However, several models still predict TD 2 will become a tropical storm. The HWRF model predicts TD 2 will become a hurricane five days from now, but this seems unlikely given the dry air and relatively high wind shear affecting the storm.
Figure 1. Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).
African tropical wave 90L
A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.
I'll have an update Friday morning.
Jeff Masters
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Wrong on every front. Shear is 10 knots. No where near the 30 that was hitting TD2. Also it has a LLC that is elongated and in the convection. The convection is rather strong and all this needs to be classified is for the LLC to become tighter.
Sure looks like it is affecting it on the satellite loops, along with dry air.
our leeward island friends best to keep there heads up for this one
Yea, looks pretty soggy, especially with that little wave passing just south of here, may enhance our rain. A lot of it just offshore too. Looks like just rain and nothing severe. Need to watch 90 very closely next week. If I recall, this is close to the Hugo setup. Trough strong enough to pull the system north a little, but not strong enough to recurve out to sea, then the high builds back in and pushed Hugo ashore. Still a long way to go, but the GFS has been trending towards a less amplified trough which is good for us, but unfortunately targets someone else. I DO NOT see 90 going out to sea.
Have a great Friday everyone.
See ya later.
Looks can be deceiving as we've learned. Stormchaser2007 explained it pretty well.
That's for sure.
Wish we could get through with all of our Katrina repairs and PAPERWORK before another bomb. Thank you so much for keeping us informed. Weather Center just doesn't tell enough!
I couldn't have said it better
I also live in Okeechobee. The right storm comes through and we could have ourselves another Katrinia. The dyke is in horrible condition!
Old TD2 has been fighting the Dry air for a long time......the Shear has what has caused it not to take off.....WEll the Shear is much less now.....Take off is coming.
Loooong time lurker, this place is where I go all the time for the latest and greatest info. Good stuff Storm, Tampa, Orca and the rest of the crew...
Got a question for you all, is it just me or are the models bringing 90L dangerously close to an Hebert box?
This is a great blog to be on during the season.. you have so many good folks that provide great information on all fronts to keep you up-to-date... :-)
90L looking very good and ominous....Check in in a few days......WW
That makes Sence StormW but, Old TD2 has been fighting that and Shear for a long time now....Shear has dropped a ton on it now...will be interesting to see what happens when all it has to fight is just the dry air....
Another August day in the tropics...
Morning...
it is in 10kts of shear but as it moves westward it will be going into 5kts wind shear
Well,it's been the pattern for the last day or two, fires something up, then it goes, fires up, then it goes... etc.
Storm, the GFS of course has the storm plowing into the Lesser/Greater Antilles without any real recurvature. The Euro curves it before it reaches the top of the Windwards.
Now, both models seem to think the B/A High will be sitting basically over the Azores. But, the GFS has it - seemingly - about 10mb stronger, with a greater forward speed (although the Euro has it going more up, it hasn't reached 60W while the GFS has it on top of Hispaniola. Both at 168hrs.)
Is this speed and pattern variance due to just the trough, or the strength of the high or both? Or indeed, something else.
they won't issue advisories at starting at 2pm if the storm isn't close to land.
it would have to be 11am or 5pm for them to issue advisories if a depression forms.
NOUS42 KNHC 141400
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1000 AM EDT FRI 14 AUGUST 2009
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 15/1100Z TO 16/1100Z AUGUST 2009
TCPOD NUMBER.....09-078
I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY: PSBL LOW LEVEL INVEST
FOR 16/1800Z NEAR 17.0N AND 55.0W ON THE REMNANTS
OF TD-02.
3. NOTE: 1- THE G-IV WILL FLY A RESEARCH MISSION AROUND
THE REMNANTS OF TD-02 TODAY DEPARTING TBPB 14/2000Z.
2- BOTH NOAA43 AND G-IV WILL FLY RESEARCH MISSIONS
IN AND AROUND THE REMNANTS OT TD-02 DEPARTING TBPB
15/2000Z.
II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK.....NEGATIVE.
WVW
Surely not time to run for the hills but, this weekend would be a good time to double check your preparedness and make sure the generator is operable ect....
Yes, usually, but they can issue advisories before. They issued the first TD2 advisory - if I'm remembering correctly - at 6am ET. Which is for neither the formal or the intermediate.
I've not seen any renumbering yet, and the circulation still isn't tight enough. Dvorak isn't yet strong enough, either. I'd be surprised if it's upgraded before tonight (unless things change rapidly) but tomorrow may be a surer bet.
Sweet!!! G-IV mission to sample the area close to the Leeward Islands... that should help a lot defining upcoming forecast models specially for the 00Z runs onward.
Red is -70 buddy
Press, I saw this last night. Maybe my favorite comment ever. kudos.
I'm not seeing any of the hallmark arc clouds typically produced when battling dry air??
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