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Gulf of Mexico Distubance--30% Chance to Develop; TD 9 Struggling; 95L May Develop

By: Jeff Masters 2:35 PM GMT on September 17, 2015

An area of disturbed weather has developed along the boundary of an old front in the Eastern Gulf of Mexico off the coast of Florida, and is bringing heavy rains to portions of the Florida Peninsula, where 2 - 3" of rain are expected over the next few days. The disturbance is under high wind shear of 20 - 30 knots, and it unlikely to develop in the Gulf. Satellite loops on Thursday morning showed little signs of rotation, and only a modest area of heavy thunderstorms. However, the disturbance is moving to the northeast, and will emerge over the waters off the coast of South Carolina by Saturday, when the GFS and European models predict that wind shear may fall to the moderate range, 15 - 20 knots. This drop in shear may be enough to allow some development. None of our three reliable models for predicting tropical cyclone genesis are showing development of a tropical depression, though. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 10% and 30%, respectively.


Figure 1. Latest satellite image of the Gulf of Mexico, courtesy of NOAA.

Tropical Depression Nine no big deal
Tropical Depression Nine continues to chug to the northwest at 6 mph over the open Atlantic, well away from any land areas. Satellite images show that high wind shear has exposed the surface circulation of TD 9 to view, and the storm has lost almost all of its heavy thunderstorms. The long-range fate of TD 9 is complicated to predict, since the storm will interact with Invest 95L to its southeast. In any case, TD 9 is very unlikely to threaten any land areas, and will be of most concern to trans-oceanic sailors and fish.


Figure 2. Latest satellite image of TD 9.

Invest 95L may develop
A tropical wave (Invest 95L) located about 600 miles southwest of the Cape Verde islands on Thursday morning was moving west-northwestwards at about 10 - 15 mph. Satellite images showed little change to the wave on Thursday morning; 95L has pretty of spin, but dry air is keeping heavy thunderstorm activity meager. Conditions are favorable for development, with wind shear a light 5 - 10 knots, ocean temperatures at 28°C (83°F), and only a modest amount of dry air from the Saharan Air Layer lying to the north of the disturbance. Our three reliable models for predicting tropical cyclone genesis, the UKMET, European, and GFS models, forecasted in their 00Z Thursday runs that 95L would develop into a tropical depression by Monday. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave 95L 2-day and 5-day odds of development of 70% and 80%, respectively. 95L will turn more to the north over the Central Atlantic over the weekend, and it unlikely to ever pose a threat to the Caribbean or North American coast.


Figure 3. Latest satellite image of 95L.

I'll have a new post by noon EDT, when the results of NOAA's monthly report on August global temperatures will be available.

Jeff Masters

Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Thanks Doc! You hit the nail on the head, as usual.
Thanks Doc

From the last blog:

Quoting 600. Barefootontherocks:

596. tornadodude
2:29 PM GMT on September 17, 2015

Check out the "space" over Iowa. That's where things would pop, IF they're gonna pop.
Midlevels SEerlies? I did not look. If so, that adds fuel to the fire, so to speak.


Hard to tell exactly what will happen, certainly some good ingredients for severe storms. If there is any sort of boundary, then a tornado is certainly possible. But I don't know, overall flow isn't great for tornadoes.
Pompano Beach is reporting 5.35" of rain in the past 24 hours.
4.95" at the Pompano Beach Air park.
3.29" in Miami Beach
Pretty cloudy over Iowa right now, but it's moving out.





Thanks for the update Dr. Masters.
Quoting 3. Sfloridacat5:

Pompano Beach is reporting 5.35" of rain in the past 24 hours.
4.95" at the Pompano Beach Air park.
3.29" in Miami Beach

So THAT'S why the coastal flood watch was extended to Homestead.

thanks for the post!
could the low in the gulf by sw fl get any stronger before it goes over fl tomorow if it just sits there for the next 24 hours ? tia
A lot of pockets of raining heading north into S Fla. Will it fizzle out before making it is another question.
Thanks for the Update Doc....
Quoting 7. 7544:
could the low in the gulf by sw fl get any stronger before it goes over fl tomorow if it just sits there for the next 24 hours ? tia


Read Dr. Master's entry - he covers it quite well.
You do realize that it cannot both sit there for 24 hours and then go over FL tomorrow.
Here comes one potential outflow boundary for later:

12. vis0
Can this be an early preview as to LOWs forming in the GoMx then riding up the East coast as with the storm of the century v.1.0?  as to just banter sar2401 and others on another long gone TS, ...though he did give what you are seeing  one of the scenarios... see my zilly pg3. cmmnt#120
Quoting 7. 7544:

could the low in the gulf by sw fl get any stronger before it goes over fl tomorow if it just sits there for the next 24 hours ? tia


Possible but not likely due to high wind shear. Dr. Masters addresses your question in his blog.
Have gotten no more than a trace of rain from this so far. Looks like the Tampa tropical rain shields may be functioning properly again after a glitch in early August.
hey doc i was thinking the 1st thing you be bloging about today was the 8.3 last night in chile and the TSUNAMI

TSUNAMI ADVISORY SUPPLEMENT

Excerpt:

HILO HI 19.7N 155.1W 1406Z 0.93M / 3.0FT 18MIN


Anyone know if 3 ft at Hilo is significant?
Quoting 3. Sfloridacat5:

Pompano Beach is reporting 5.35" of rain in the past 24 hours.
4.95" at the Pompano Beach Air park.
3.29" in Miami Beach
In the meantime, Naples picked up a whopping 0.02" yesterday, and we're closing in on 0.03" for the day. If this keeps up, we could receive close to 0.10" before the event is over. That'll certainly deliver a knockout punch to the drought! But on the positive side, at least we're avoiding all that pesky sunshine that usually plagues us this time of year; there's nothing that draws tourist dollars like a drab, overcast sky that hangs around for days on end... ;-)
Quoting 17. Neapolitan:

In the meantime, Naples picked up a whopping 0.02" yesterday, and we're closing in on 0.03" for the day. If this keeps up, we could receive close to 0.10" before the event is over. That'll certainly deliver a knockout punch to the drought! But on the positive side, at least we're avoiding all that pesky sunshine that usually plagues us this time of year; there's nothing that draws tourist dollars like a drab, overcast sky that hangs around for days on end... ;-)


Yeah, we haven't seen much sun lately on the S.W. coast. I've been waiting for a nice day to do some snorkeling. I might have to wait for the dry season to kick in sometime in October.
In the meantime, Naples picked up a whopping 0.02" yesterday, and we're closing in on 0.03" for the day. If this keeps up, we could receive close to 0.10" before the event is over. That'll certainly deliver a knockout punch to the drought! But on the positive side, at least we're avoiding all that pesky sunshine that usually plagues us this time of year; there's nothing that draws tourist dollars like a drab, overcast sky that hangs around for days on end... ;-)



LOL......what's funny about this...is perspective.....here in el paso........that's a decent day of rain
Quoting 14. BobinTampa:

Have gotten no more than a trace of rain from this so far. Looks like the Tampa tropical rain shields may be functioning properly again after a glitch in early August.

It looks like it is operational once again. Brought out the big umbrella for today, haven't used it once!
Quoting 17. Neapolitan:

In the meantime, Naples picked up a whopping 0.02" yesterday, and we're closing in on 0.03" for the day. If this keeps up, we could receive close to 0.10" before the event is over. That'll certainly deliver a knockout punch to the drought! But on the positive side, at least we're avoiding all that pesky sunshine that usually plagues us this time of year; there's nothing that draws tourist dollars like a drab, overcast sky that hangs around for days on end... ;-)


OMG, I was sitting here and all of a sudden everything got BRIGHT.. I thought for a second we had been struck by a supernova of something... it was a break in the clouds...
12 miles to the west, I received 1 1/2 inches yesterday.

Quoting 17. Neapolitan:

In the meantime, Naples picked up a whopping 0.02" yesterday, and we're closing in on 0.03" for the day. If this keeps up, we could receive close to 0.10" before the event is over. That'll certainly deliver a knockout punch to the drought! But on the positive side, at least we're avoiding all that pesky sunshine that usually plagues us this time of year; there's nothing that draws tourist dollars like a drab, overcast sky that hangs around for days on end... ;-)
Thank you, Doc. It has been raining on and off most of the morning here in Ft Lauderdale as others have mentioned. However, the sun has finally popped out. We'll see how long that lasts.
Quoting 22. swflurker:

12 miles to the west, I received 1 1/2 inches yesterday.




I'm at 8.68" for the month just S.E. of Fort Myers with .76" in the last 24 hours.
Currently I've got a steady light rain falling here.
Quoting 22. swflurker:

12 miles to the west, I received 1 1/2 inches yesterday.




I'm enjoying it here. It is a nice change from constant hot sun. Just a very light rain at the moment.
Quoting 581. ricderr:

Good morning Ric. This is true, chances are remote, but I believe there will be rough weather for Florida, especially north of the Sarasota- Fort Pierce line.


i would agree hydrus...and mornin to you also......it's just ratio to probabilities......i guess an example would be....if you you increased the chances of winning the lottery by half.....there would probably be twice as many winners...however your chances as the winner....would still be slim to none
There is one possibility. If the primary storm track this winter is far to the south, it could mean more in the way of severe weather for the state.It would be even more enhanced if there is some return flow, which is exactly what happened during the 1998 Tornado Outbreak over Florida.Hard to see here, but the subtropical jet coming west across the gulf was 140 kts, and the low level jet was out of the south at 60 kts. Throw in some outflow boundaries and tornadoes are a certainty.

I apologize, I cannot get the graph to post. Heres the radar anyway.


There is one possibility. If the primary storm track this winter is far to the south, it could mean more in the way of severe weather for the state.It would be even more enhanced if there is some return flow, which is exactly what happened during the 1998 Tornado Outbreak over Florida.Hard to see here, but the subtropical jet coming west across the gulf was 140 kts, and the low level jet was out of the south at 60 kts. Throw in some outflow boundaries and tornadoes are a certainty.


from what i've read from NOAA...you hit the nail on the head!!!!!....it's the placement of the jetstream that will determine numbers and severity
Quoting 14. BobinTampa:

Have gotten no more than a trace of rain from this so far. Looks like the Tampa tropical rain shields may be functioning properly again after a glitch in early August.


Yup, rain falling apart again today as it approaches us. I would think that will change as the low gets closer and becomes a bit better organized.
Thanks Doc..Another odd year in the tropics..October may be interesting , especially in the gulf.


maybe invest 96L SOON
Thank You Dr.  Little chance of current development into a TD or tropical storm until after the Gulf area crosses Florida; however, a slow moving tropical soaker nonetheless for the State without the wind gusts associated with a designated TD or TS............

Latest Rap Model run...last frame at hour 18

Quoting 32. weathermanwannabe:

Thank You Dr.  Little chance of current development into a TD or tropical storm until after the Gulf area crosses Florida; however, a slow moving tropical soaker nonetheless for the State without the wind gusts associated with a designated TD or TS............




Notice how those storms are dying out as they got near Central Fl.
Quoting 35. Bucsboltsfan:



Notice how those storms are dying out as they got near Central Fl.


Lot's dry air pushing down from the Gulf-Panhandle that is probably drying out parts of the frontal trof. As you can see on the loop, the sun popped out over us in Tallahassee over the last 1/2 hour...............Have to how long it lasts as the low inches towards the NE over the next 48.
I saw blue sky for the first time since Tuesday, good amount too. Wonder if that might be all it needs to fire up some more storms down here in a few hours.
JeffMasters has created a new entry.
Quoting 23. SFLstevez1:

Thank you, Doc. It has been raining on and off most of the morning here in Ft Lauderdale as others have mentioned. However, the sun has finally popped out. We'll see how long that lasts.
The sun could heat up the atmosphere and spark more severe storms like this morning was
Might as well post. I have lurked on this blog since it started. Read Dr. Masters blogs on Katrina as it approached se fla. I worked in Canada as meteorologist many many moons ago -- I might have even Grothar beat in age :)
I really enjoy the fact that WU has grown exponentially since its debut. Some ridiculous posters but it's still the finest weather enthusiast blog out there
BTW, I live on the beach just south of Naples. Calm winds, but pressure has dropped from 1018 mbs last evening to 1015 this morning.
I saw the sun briefly today too. Had to stop and bask in it to stave off a lack of Vit D. It' had been days since I've seen it.

Half expect the low in the Gulf of Mexico to be a broad, sheared low coming across the state & tighten up more off the east coast.