Disturbance 90L close to tropical depression strength; TD 2 may rise again

By: Dr. Jeff Masters , 2:02 PM GMT on August 14, 2009

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A strong tropical wave (90L), with a large circulation and a moderate amount of heavy thunderstorm activity, is a few hundred miles southwest of the Cape Verdes Islands, off the coast of Africa. This morning's QuikSCAT pass shows that 90L has a large circulation, but this circulation is not yet well-formed, as it is elongated along an east-west axis. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are gradually becoming better organized, with some spiral banding evident on the south side of the storm. Satellite intensity estimates from NOAA already put 90L at tropical depression strength with 30 mph winds, but the storm does not yet have a well enough formed circulation to be classified as a depression. 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 was. However, there is some dry air from the SAL being sucked into the circulation of 90L, and this is retarding its development.

Wind shear is moderate, about 10 - 15 knots, but is forecast to fall to the low range, 5 - 10 knots, later today. Shear is then forecast to remain low for the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow 90L to develop into a tropical depression by Saturday, and potentially reach hurricane strength by Wednesday. Most of our reliable models strengthen 90L into a hurricane by Wednesday, when the storm is expected to be near the northern Lesser Antilles Islands. One important outlier is the ECMWF model, which has 90L passing to the north of the islands, and eventually recurving out to sea east of Bermuda. The ECMWF was by far the most reliable model for forecasting hurricane tracks last year. However, all of our models are pretty unreliable going out 5 days in advance for systems that have yet to reach tropical depression strength. Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.


Figure 1. The remnants of Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

Tropical Depression Two may come back
Tropical Depression Two died yesterday, but may rise again. Satellite loops of the remnants of the storm show that heavy thunderstorms are again attempting a comeback near the axis of what is now a tropical wave. However, dry air continues to interfere with the development of the thunderstorm activity, and moderately high wind shear of 15 - 20 knots is also inhibiting the process. Wind shear over the remnants of TD 2 is expected to remain in the moderate range, 10 - 20 knots, over the next four days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C two days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to the north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that any re-development of the storm will be slow to occur. NHC has given the system a medium (30 - 50% chance) of becoming a tropical depression again by Sunday morning. Only one reliable model, the NOGAPS, is predicting regeneration of TD 2. The NOAA Hurricane Hunters are flying research missions into the remnants of TD 2 today and Saturday.

I'll have an update Saturday morning, or earlier, if significant developments occur.

Jeff Masters

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4734. jipmg
the ensemble models all take TD 3 out to sea
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Quoting FSUstormnut:


where are you seeing this?


Navy site
Member Since: August 10, 2009 Posts: 3 Comments: 672
4732. Brallan
Is Ana going back to TD status?
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Quoting IpswichWeatherCenter:


Don't ask - in my 3 or 4 seasons of being here, I never understood it. (under various not used handles)


eat crow, Informal. to be forced to admit to having made a mistake, as by retracting an emphatic statement; suffer humiliation: His prediction was completely wrong, and he had to eat crow.
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Quoting DestinJeff:


you should be a hostage negotiator.

"KMAN: Attorney at Law, Negotiator for the Law"


You think Priceline would have a place for me LOL
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4728. snotly
Quoting Chavalito:
I've been seeing that models tend to move 90L more northerly than previous runs. ?would that mean that Puerto Rico will be out of danger?


as a very general rule strong storms move more towards the poles and weaker storms move more towards the west
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Guys, we have TD3 lol and WU knows it early.
It will be up at 11 AM on the NHC site.
Member Since: August 10, 2009 Posts: 3 Comments: 672
TS Ana sure is low

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Link


Link
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Quoting Weather456:
Guys the third tropical depression has form

estimated surface winds are near 35 mph


where are you seeing this?
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Quoting P451:


Did you see the GFS model? It wants to develop the current African wave into a second monster that follows 90L.




yea....but have not been paying much attention just yet.
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Quoting HaboobsRsweet:
I think we just got TD3...front page here has Invest03L and correct me if I am wrong but it looks just like 90L. Must be starting to transition it to TD status no?

Your right


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Quoting LightningCharmer:


To my untrained eye, it's not dissipating. Been watching this wave for two days. Haven't noticed west winds on any Florida Keys buoys yet.

If you use ADDS you can see when the winds shift

METAR JAVA map
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Quoting SeniorPoppy:
The tropical wave right at the Keys is the one to watch for the Panhandle and upper Gulf Coast. I agree with the comment before that is rare to see a direct south Florida hit on the east coast. A recurvature from the south or a glancing blow with the storm going straight into the gulf is more likely depending on the ridge. Ofcourse Ana and 90L might just curve out to sea or skim the east coast.
what do you mean by "rare" ?
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Good morning everyone,

The Portlight Disaster Relief Blog is now open for comments and has our current response plan in it. Please stop by and look it over when you get a chance. We are always looking for input and feedback to help improve our efforts.

Thanks, hope everyone has a great Saturday!
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Guys the third tropical depression has form

estimated surface winds are near 35 mph
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be back later.
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Quoting HaboobsRsweet:
I think we just got TD3...front page here has Invest03L and correct me if I am wrong but it looks just like 90L. Must be starting to transition it to TD status no?


Yes, I'm confused too.
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THREE, AL, L, , , , , 03, 2009, DB, S, 2009081306, 9999999999, , , , , , WARNING, 3, AL032009
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Thanks cotillion hurricanefcast and drgodowncountry ^_^
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4710. Bayside
What's going on here?
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Quoting hurricanelover236:
I told you guys. Yuo should listen to me. Im always right about this stuff. I said ana woulsd die due to dry air and shear and its already happening. Both of these storms will amount to nothing. Florida can breath easy. Whoever is getting their hopes up for getting ana or potential Bill are gonna be very disapointed.


Well now that you've cleared things up goodbye everyone.... thanks for your knowledge and expertise
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GoM surprise storm being stirred up for your entertainment and for some, their terror....
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I've been seeing that models tend to move 90L more northerly than previous runs. ?would that mean that Puerto Rico will be out of danger?
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4706. geepy86
sorry for double post awhile back. me and my computer are noy bonding this morning. lol
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4705. Relix
TD3/Bill's models have shifted north it seems. w00t better news for PR, bad for the coasts =(
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This would be a very sharp turn...Link
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we have tropical depression 3
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I think we just got TD3...front page here has Invest03L and correct me if I am wrong but it looks just like 90L. Must be starting to transition it to TD status no?
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Probably saw this already...

invest_RENUMBER_al902009_al032009.ren
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting Tazmanian:
i think the E PAC now has other cat 4


000
WHXX01 KMIA 151253
CHGE77
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1253 UTC SAT AUG 15 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

EAST PACIFIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE GUILLERMO (EP102009) 20090815 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090815 1200 090816 0000 090816 1200 090817 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 18.8N 132.6W 19.5N 135.7W 20.3N 138.8W 21.2N 141.9W
BAMD 18.8N 132.6W 19.8N 135.1W 21.1N 137.4W 23.1N 139.4W
BAMM 18.8N 132.6W 19.9N 135.6W 21.0N 138.3W 22.5N 141.0W
LBAR 18.8N 132.6W 19.7N 135.1W 21.3N 137.5W 23.2N 139.8W
SHIP 110KTS 105KTS 88KTS 72KTS
DSHP 110KTS 105KTS 88KTS 72KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090817 1200 090818 1200 090819 1200 090820 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 22.1N 144.8W 24.2N 150.3W 26.6N 155.9W 29.6N 161.5W
BAMD 25.4N 141.0W 30.4N 142.2W 30.1N 140.2W 25.1N 144.1W
BAMM 24.4N 143.4W 28.9N 147.9W 31.9N 150.6W 32.3N 152.0W
LBAR 25.5N 141.7W 30.4N 143.4W 31.9N 140.8W 29.3N 139.7W
SHIP 56KTS 35KTS 20KTS 0KTS
DSHP 56KTS 35KTS 20KTS 0KTS

...INITIAL CONDITIONS...
LATCUR = 18.8N LONCUR = 132.6W DIRCUR = 285DEG SPDCUR = 14KT
LATM12 = 18.2N LONM12 = 129.7W DIRM12 = 284DEG SPDM12 = 15KT
LATM24 = 17.6N LONM24 = 126.7W
WNDCUR = 110KT RMAXWD = 15NM WNDM12 = 95KT
CENPRS = 954MB OUTPRS = 1008MB OUTRAD = 165NM SDEPTH = D
RD34NE = 100NM RD34SE = 80NM RD34SW = 70NM RD34NW = 100NM



Whats the link to the guidance again? I've lost it ):
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Wow it looks like TS Ana will come to FL as a weak TS and 90L is for the fish!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Weather456:
90L is still at 12N maybe even more south




nic photo of TD 3 lol
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The tropical wave right at the Keys is the one to watch for the Panhandle and upper Gulf Coast. I agree with the comment before that is rare to see a direct south Florida hit on the east coast. A recurvature from the south or a glancing blow with the storm going straight into the gulf is more likely depending on the ridge. Ofcourse Ana and 90L might just curve out to sea or skim the east coast.
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90L is a beast, now I see what the models were saying
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Quoting IpswichWeatherCenter:


Hahah, if TD3 skips TD status then we will need soccer crow.
Crow

Sorry, shouldn't get personal (couldn't resist), but in the case of a group "we", might need more crows (think Alfred Hitchcock).
Going running b4 I get banned (& while we still have a beach).
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Quoting hurricane556:
surface low forming southeast of the florida keys


If you change the loops to 40 on the radar, you can see the cyclonic turning east of Marathon

Key West Radar
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heh the nhc keeps saying that Hurricane GUILLERMO will WEAKENING but it ends up geting stronger and stronger
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90L is still at 12N maybe even more south

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L8 Tornado Vortex Signature?????
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Quoting SwirlOfDoom:


Thanks all for the answer!


no problemo
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Quoting WeatherStudent:



Good morning, KMan. I hope you and yours are doing well this morning my good ol' friend. So, according to your observations this morning, do you think this critter is as good as R.I.P, sir? Also, what are your thoughts in some of the models taking this up to cane status as it threatens SF? :) Have a good day. Thanks.


Good morning to you too. I wouldn't go so far as to say RIP because this system has been very tenacious. Having said that you will recall from yesterday that I thought it would struggle to come back, if it did at all, and given the state of its current organization it may well be downgraded again by the NHC if present trends continue.

The atmosphere ahead of it is completely devoid of moisture and Ana is a very small system prone to dry air intrusion. You can also see the ULL to the N pulling off moisture from it if you run the WV loop.

For now you will just have to watch it but it is on a downward trend at the moment. Too early to worry about next week IMO. Let's see where matters stand by Monday as Ana is several days away from the East coast if it survives.
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Quoting 7544:
gfs dosent even show anna is that bill ???

Link
The GFS does not develop Ana so yes, thats Bill.
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Quoting Tazmanian:
i think the E PAC now has other cat 4


000
WHXX01 KMIA 151253
CHGE77
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1253 UTC SAT AUG 15 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

EAST PACIFIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE GUILLERMO (EP102009) 20090815 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090815 1200 090816 0000 090816 1200 090817 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 18.8N 132.6W 19.5N 135.7W 20.3N 138.8W 21.2N 141.9W
BAMD 18.8N 132.6W 19.8N 135.1W 21.1N 137.4W 23.1N 139.4W
BAMM 18.8N 132.6W 19.9N 135.6W 21.0N 138.3W 22.5N 141.0W
LBAR 18.8N 132.6W 19.7N 135.1W 21.3N 137.5W 23.2N 139.8W
SHIP 110KTS 105KTS 88KTS 72KTS
DSHP 110KTS 105KTS 88KTS 72KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090817 1200 090818 1200 090819 1200 090820 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 22.1N 144.8W 24.2N 150.3W 26.6N 155.9W 29.6N 161.5W
BAMD 25.4N 141.0W 30.4N 142.2W 30.1N 140.2W 25.1N 144.1W
BAMM 24.4N 143.4W 28.9N 147.9W 31.9N 150.6W 32.3N 152.0W
LBAR 25.5N 141.7W 30.4N 143.4W 31.9N 140.8W 29.3N 139.7W
SHIP 56KTS 35KTS 20KTS 0KTS
DSHP 56KTS 35KTS 20KTS 0KTS

...INITIAL CONDITIONS...
LATCUR = 18.8N LONCUR = 132.6W DIRCUR = 285DEG SPDCUR = 14KT
LATM12 = 18.2N LONM12 = 129.7W DIRM12 = 284DEG SPDM12 = 15KT
LATM24 = 17.6N LONM24 = 126.7W
WNDCUR = 110KT RMAXWD = 15NM WNDM12 = 95KT
CENPRS = 954MB OUTPRS = 1008MB OUTRAD = 165NM SDEPTH = D
RD34NE = 100NM RD34SE = 80NM RD34SW = 70NM RD34NW = 100NM



110kts = 125mph.

Still a Cat 3.

That said, it has strengthened unexpectedly. EPac storms have a tendency to do that.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting hurricanelover236:
I told you guys. Yuo should listen to me. Im always right about this stuff. I said ana woulsd die due to dry air and shear and its already happening. Both of these storms will amount to nothing. Florida can breath easy. Whoever is getting their hopes up for getting ana or potential Bill are gonna be very disapointed.


Why do I think StormTop is here but actually being a bit more clever by not doing CAPS LOCK ON EVERYTHING?
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.