Invest 90L: East Atlantic-Discussions,Analysis,Sat Pics

[Derek Ortt]

SHIPS must have had a problem... blank in the official output as well

[cycloneye]

No intensity in the 12:00 UTC run but here are the tracks.

[wxman57]

wxman, I got an sudden warm and fuzzy feeling reading your post... it's good to know that you and others here, armed with experience and knowledge, are keeping an eye on this. Thanks!

Yea, but the only problem I had with that post was him saying the 06z GFS couldn't find it at all.

Here's the 06z GFS showing it entering the Caribbean @ 126 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_126m.gif

It appears my browser loaded a cached 06Z loop from the 9th of August. 06Z GFS does see it. Brings it to Mexico. The only thing certain is we don't know where it'll go yet after 5 days.

Here's the 06Z GFDL intensity forecast, up to 93kts at 126hrs:

HOUR: .0 LONG: -22.06 LAT: 11.98 MIN PRESS (hPa): 1008.56 MAX SURF WIND (KNOTS): 24.50
HOUR: 6.0 LONG: -23.28 LAT: 12.84 MIN PRESS (hPa): 1006.96 MAX SURF WIND (KNOTS): 40.25
HOUR: 12.0 LONG: -26.10 LAT: 12.65 MIN PRESS (hPa): 1005.73 MAX SURF WIND (KNOTS): 33.23
HOUR: 18.0 LONG: -27.89 LAT: 12.72 MIN PRESS (hPa): 1007.41 MAX SURF WIND (KNOTS): 50.13
HOUR: 24.0 LONG: -30.05 LAT: 12.62 MIN PRESS (hPa): 1003.00 MAX SURF WIND (KNOTS): 47.43
HOUR: 30.0 LONG: -32.39 LAT: 12.25 MIN PRESS (hPa): 1003.58 MAX SURF WIND (KNOTS): 49.52
HOUR: 36.0 LONG: -33.89 LAT: 12.21 MIN PRESS (hPa): 1001.08 MAX SURF WIND (KNOTS): 42.22
HOUR: 42.0 LONG: -35.39 LAT: 12.22 MIN PRESS (hPa): 1002.07 MAX SURF WIND (KNOTS): 41.12
HOUR: 48.0 LONG: -37.35 LAT: 12.15 MIN PRESS (hPa): 999.31 MAX SURF WIND (KNOTS): 44.13
HOUR: 54.0 LONG: -38.91 LAT: 12.22 MIN PRESS (hPa): 999.48 MAX SURF WIND (KNOTS): 43.23
HOUR: 60.0 LONG: -40.54 LAT: 12.56 MIN PRESS (hPa): 997.89 MAX SURF WIND (KNOTS): 51.92
HOUR: 66.0 LONG: -42.26 LAT: 12.66 MIN PRESS (hPa): 996.69 MAX SURF WIND (KNOTS): 51.36
HOUR: 72.0 LONG: -44.01 LAT: 12.98 MIN PRESS (hPa): 992.50 MAX SURF WIND (KNOTS): 54.94
HOUR: 78.0 LONG: -45.75 LAT: 13.48 MIN PRESS (hPa): 992.50 MAX SURF WIND (KNOTS): 64.56
HOUR: 84.0 LONG: -47.76 LAT: 13.90 MIN PRESS (hPa): 990.21 MAX SURF WIND (KNOTS): 62.18
HOUR: 90.0 LONG: -49.53 LAT: 14.28 MIN PRESS (hPa): 989.02 MAX SURF WIND (KNOTS): 65.60
HOUR: 96.0 LONG: -51.32 LAT: 14.77 MIN PRESS (hPa): 985.70 MAX SURF WIND (KNOTS): 77.39
HOUR:102.0 LONG: -53.06 LAT: 15.16 MIN PRESS (hPa): 981.81 MAX SURF WIND (KNOTS): 83.63
HOUR:108.0 LONG: -54.76 LAT: 15.44 MIN PRESS (hPa): 981.73 MAX SURF WIND (KNOTS): 75.00
HOUR:114.0 LONG: -56.21 LAT: 15.66 MIN PRESS (hPa): 977.61 MAX SURF WIND (KNOTS): 82.31
HOUR:120.0 LONG: -57.84 LAT: 15.83 MIN PRESS (hPa): 974.84 MAX SURF WIND (KNOTS): 86.02
HOUR:126.0 LONG: -59.28 LAT: 16.00 MIN PRESS (hPa): 972.91 MAX SURF WIND (KNOTS): 92.95

[skysummit]

wxman, I got an sudden warm and fuzzy feeling reading your post... it's good to know that you and others here, armed with experience and knowledge, are keeping an eye on this. Thanks!

Yea, but the only problem I had with that post was him saying the 06z GFS couldn't find it at all.

Here's the 06z GFS showing it entering the Caribbean @ 126 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_126m.gif

It appears my browser loaded a cached 06Z loop from the 9th of August.

Ok then...you're forgiven

[cyclonic chronic]

SYNOPSIS...TROPICAL WAVES ALONG 76W AND 85W WILL CONTINUE TO MOVE W
IN THE WESTERN CARIBBEAN THROUGH TUE. FRESH ELY TRADES WILL PERSIST
OVER THE CENTRAL CARIBBEAN THROUGH MON. 1006 MB LOW PRES NEAR 12N22W
EXPECTED TO MOVE INTO THE TROPICAL N ATLC WATERS THU...POSSIBLY AS A
TROPICAL CYCLONE.

[windstorm99]

Any thoughts on what What could be a power tropical cyclone moving over the hebert box mean for southeast florida?

[wxman57]

Any thoughts on what What could be a power tropical cyclone moving over the hebert box mean for southeast florida?

All we can say with certainty now is that after 60W it could go anywhere from Mexico to Bermuda. Pointless to speculate. If it was to head toward Florida, then you have about 9-10 days to prepare.

[Aquawind]

Any thoughts on what What could be a power tropical cyclone moving over the hebert box mean for southeast florida?

Rather not.. not yet..

[windstorm99]

Jeff Masters thoughts on things....

Thunderstorm activity in association with a surface trough of low pressure over the Western Caribbean remains disorganized. None of the computer models than reliably forecast tropical storm formation are calling for development in this region. Wind shear is about 20 knots, which will keep any development slow.

A strong tropical wave exited the coast of Africa Friday, and is now a 1006 mb low pressure system with heavy thunderstorm activity about 200 miles south of the Cape Verde Islands. NHC is referring to this system as 90L. This morning's QuikSCAT satellite pass at 3:48am EDT found an elongated circulation centered near 12.5N 23W, with top winds of 30 mph. Satellite imagery at the NRL Monterey web site that most people use to track eastern Atlantic storms is not available this weekend. A substitute source of imagery is available at the main Navy weather web site. The thunderstorm activity surrounding 90L is currently not very expansive, thanks in part to relatively cool SSTs of 26-27C and high wind shear of 20 knots. However, the cloud pattern has gotten more organized this morning, with some spiral banding starting to occur. SSTs should increase above 27C by Tuesday, as 90L moves away from the African coast at 15-20 mph. Wind shear should drop to 10-20 knots, and I expect 90L will become a tropical depression on Monday or Tuesday.


What the computer models say
Watching the computer model runs for 90L is not for the faint of heart. All the major models except the NOGAPS develop the system into a tropical storm or hurricane that tracks westward over the Atlantic, reaching the lesser Antilles Islands as early as Thursday night, August 16. There are four possible scenarios to consider:

1) A strong trough of low pressure is forecast to move off the East Coast of the U.S. at that time, and this trough may deflect 90L northwards so that it misses the Lesser Antilles Islands, and then recurves harmlessly out to sea.

2) In keeping with the steering pattern we've observed since late July, the trough is expected to rapidly move onward, allowing a ridge of high pressure to build in. If the trough is not strong enough to recurve 90L out to sea, the storm will be forced to the west once more and eventually hit the East Coast of the U.S. This is the solution of last night's ECMWF model.

3) 90L will be far enough south and next weekend's trough will be weak enough that 90L will plow through the Caribbean, and not be deflected north of the Lesser Antilles Islands. The storm would eventually track into the Gulf of Mexico. This is the solution preferred by this morning's GFS model.

4) 90L will never develop, or will never become more than a weak tropical storm, due to unfavorable wind shear, dry air, or other factors. This is the solution of the NOGAPS model.

Of the four scenarios, I believe #2 or #3 are most likely to occur--90L will develop into a tropical storm or hurricane that will affect the Caribbean and/or U.S. East Coast. Residents throughout the Caribbean and U.S. should anticipate the possibility that 90L may become a hurricane--and possibly a major hurricane--that will not recurve. If you plan on being in the Lesser Antilles Islands Thursday August 16 - Sunday August 19, keep in mind there is a heightened risk of a tropical storm or hurricane during that period. Be prepared to adjust your travel plans.

[astrosbaseball22]

how long would we have to prepare in houston?

[KatDaddy]

I am estimating about 12 days should it head to Houston. Keep in mind it could end up going anywhere. No need to worry. We will all know much more next weekend if will be a GOM threat, Florida threat, or EC threat.

[MiamiensisWx]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Personally, I think 90L has maintained sufficient convection and organization to be classified as a TD. Undoubtedly, there is a closed low-level circulation, and the system has displayed some "banding" signatures. Look at the EUMETSAT IR loop. There are some uncertainities because of insufficient additional obs, so I supported the TPC's initial conservative attitude. I think the system has passed the "hurdles" - it deserves a classification today, IMO. I do think we could see our next tropical system by tonight or tomorrow morning.

Additionally, there is a strong directional mid to upper-level SW flow over the Leeward Islands - it is associated with the interaction between the Florida upper low and western Atlantic trough. This trend would present a hostile obstacle to any TC approaching the islands, but I see some indications the East Coast trough could be deamplifying and weakening over the next 36 hours. The upper-level easterly steering flow should become more dominant (in accordance with these obs and model guidance) - look at the latest shortwave loop.

http://www.ssd.noaa.gov/goes/east/tatl/loop-ir2.html

You can clearly spot the building anticyclone over the region, so shear should decrease over the next few days as 90L approaches the islands. The main issue deals with the possible LLC relocations; the rate of development; and whether the East Coast trough lingers over the area, which would allow a possible northward jog - the possible presence of a low could enhance this movement, too.

On another note, you can extrapolate the system's forward motion based on the low to mid-level steering currents. It looks (based on my personal observations) like 90L could maintain an average forward motion greater than 12 mph through the next three or four days. I don't see any perturbances which could inhibit this steady movement, so I think it is a reasonable estimate. That movement would place the system further west than initially indicated by some models. The islands could be under the gun sooner than we think - I think you should closely monitor this system.

[windstorm99]

Jeff Masters thoughts posted above.

[astrosbaseball22]

anyone think TD by 5p?

[windstorm99]

Its also very possible the GFS may be over doing the Bermuda High.

[Cyclone1]

It's definitely not a TD right now, maybe by 5pm or 11pm, but most likely 11am tomorrow.

[Extremeweatherguy]

I am estimating about 12 days should it head to Houston. Keep in mind it could end up going anywhere. No need to worry. We will all know much more next weekend if will be a GOM threat, Florida threat, or EC threat.

yeah 11 or 12 days would sound about right. If it develops and does come this way, we should be in the 5-day cone starting this upcoming Saturday or Sunday. Hopefully though this storm decides it doesn't want Texas BBQ and heads somewhere else.

[Weathermaster]

Discussion from NWS in San Juan, PR....

"LOOKING AHEAD...THIS PORTION OF THE FORECAST IS STILL MANY DAYS
AWAY AND IS SUBJECT TO SIGNIFICANT CHANGES AND ERRORS. THIS
FOLLOWING DISCUSSION IS MEANT ONLY AS A GENERAL OUTLOOK OF
POTENTIAL FEATURES.

HOWEVER...THAT SAID...A VIGOROUS AND FAIRLY WELL ORGANIZED
TROPICAL WAVE/LOW CURRENTLY LOCATED ABOUT 300 MILES
SOUTH-SOUTHEAST OF THE SOUTHERNMOST CAPE VERDE ISLANDS IS BEING
MONITORED AND PER TPC/NHC...COULD BECOME A TROPICAL DEPRESSION
DURING THE NEXT DAY OR TWO AS IT MOVES WESTWARD AT 15 TO 20 MPH.

INTERESTINGLY...THIS FEATURE HAS BEEN FORECAST WITH AMAZING
CONSISTENCY NOW FOR 6 DAYS AND BASICALLY 24 CYCLES OF THE GFS
MODEL...TO BECOME MORE ORGANIZED AND STRENGTHEN INTO WHAT...
POTENTIALLY...COULD BECOME A RATHER IMPRESSIVE TROPICAL CYCLONE AS
IT MOVES WEST TO WEST NORTHWEST ACROSS THE ATLANTIC AND IN THE
GENERAL DIRECTION OF THE EAST AND/OR NORTHEAST CARIBBEAN BY LATE
THIS COMING WEEK OR EARLY NEXT WEEKEND. THE GFS MODEL HAS ALSO
BEEN JOINED BY THE UKMET...CANADIAN...ECMWF AND WRF MODELS IN
INDICATING THE SAME GENERAL IDEA...AGAIN WITH DECENT CONSISTENCY
AND SIMILARITY. SO...ALTHOUGH THERE IS STILL TREMENDOUS
UNCERTAINTY AND REALIZING THAT CURRENTLY THIS FEATURE IS STILL
ONLY A TROPICAL WAVE/LOW AND STILL MANY DAYS AWAY...IT WOULD BE
PRUDENT FOR ALL LOCAL RESIDENTS AND VISITORS OF THE U.S. VIRGIN
ISLANDS AND PUERTO RICO TO MONITOR LOCAL WEATHER FORECASTS DURING
THE NEXT SEVERAL DAYS."

[cycloneye]

The sal is not a big factor judging by the graphic.

[ronjon]

There appears to be a developing consensus in the models on an elongated SE US/Western Atlantic Upper Level Ridge in 7-10 days. Could spare the east coast of the US if it comes true.

From HPC Morning Disc:

SOUTHERN PLAINS/LOWER MS VALLEY/TN VALLEY/SOUTHEAST...

THE MODELS ARE IN GOOD AGREEMENT ON THE DEEP LAYER ANTICYCLONE AND CORE OF THE HOT AIR MASS REMAINING ACRS THE SOUTHERN PLAINS AND
LOWER MS VALLEY AND DRIFTING EAST DAYS SIX/SEVEN. THERE IS ALSO AGREEMENT ON THE DEEP LAYER SOUTHWEST ATLANTIC RIDGE BUILDING WEST TO THE SOUTHEAST COAST...WITH THE POSSIBILITY OF THE TWO MERGING INTO ONE LARGE/ELONGATED RIDGE ACRS THE SOUTHERN PLAINS TO THE SOUTHEAST COAST BY DAY SEVEN. MODEL DIFFERENCES ARE ON THE LEVEL OF DETAIL SO A CONSENSUS SHOULD SUFFICE.