Dangerous Eastern Caribbean disturbance near tropical depression strength

By: Dr. Jeff Masters , 1:50 PM GMT on October 13, 2008

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A very vigorous and potentially dangerous tropical disturbance (98L) is approaching tropical depression strength over the eastern Caribbean, a few hundred miles south of the eastern tip of the Dominican Republic. This morning's QuikSCAT pass showed a well-defined closed surface circulation, but did not scan the eastern portion of the storm, where the heaviest thunderstorms are. Eastern Caribbean buoy 42059 is in the heavy thunderstorm region to the east of 98L's center, and winds there were sustained at 20-26 mph this morning. Satellite loops show an impressive amount of heavy thunderstorm activity that is increasing in intensity and coverage. Wind shear is a high 20 knots over the disturbance, due to strong upper level winds out of the west. These strong winds are keeping 98L's heavy thunderstorms pushed over to the east side of the center of circulation. The storm is a little too far from Puerto Rico radar to see rotation of the rain. The rain area is poorly organized, with no spiral rain bands evident. Dominican Republic radar was down this morning.


Figure 1. Current satellite image of 98L.


Figure 2. Current radar-estimated rainfall from 98L.

The track forecast for 98L
The storm is drifting slowly west-northwestward, and this motion is expected to continue through Tuesday. An upper-level low pressure system is expected to separate from the jet stream and park itself to the north of Puerto Rico by Tuesday. The counter-clockwise flow of air around this low should draw 98L to the northeast across Puerto Rico or the Dominican Republic by Wednesday. Up to five inches of rain has already fallen over the Virgin Islands and eastern Puerto Rico (Figure 2), and additional heavy rains of 5-10 inches are likely over these islands through tonight. Heavy rains of 5-10 inches per day will likely spread to the eastern Dominican Republic and the northern Lesser Antilles Islands by Tuesday morning, and continue through Wednesday night. Over Puerto Rico, isolated rain amounts in excess of 20 inches are possible before the storm clears the islands by Thursday. It currently appears that Haiti will only get 1-3 inches of rain from 98L, but this forecast could change if the storm progresses father west than expected.

The intensity forecast for 98L
Wind shear is expected to fall to the moderate 10-20 knot range over the next three days, and waters will remain warm, 29°C. This should allow 98L to intensify into a tropical storm by Tuesday. The HWRF and GFDL models both intensify 98L into a hurricane before it hits Puerto Rico on Wednesday. This seems overly aggressive, given the moderate 10-20 knots of wind shear expected. The SHIPS model forecast of a strong tropical storm on Wednesday is more reasonable. NHC is giving 98L a high (>50% chance) of developing into a tropical depression by Wednesday. A Hurricane Hunter aircraft will investigate the storm this afternoon.

Links to follow
Puerto Rico radar
Eastern Caribbean buoy 42059
San Juan, Puerto Rico weather

Nana
Tropical Storm Nana, the fourteenth named storm of this busy Atlantic hurricane season, formed yesterday over the middle Atlantic Ocean. Nana is one of those "blink and you'll miss it" storms, as high wind shear of 30 knots is in the process of tearing the storm apart. The UKMET model did a nice job forecasting the development of this storm, up to a week in advance.

New disturbance in the Southwest Caribbean
An area of disturbed weather has formed in the Southwest Caribbean, from the Cayman Islands southwards to Costa Rica. The region is under a low to moderate amount of wind shear, 5-15 knots. The NOGAPS model forecasts the development of a tropical depression in this region by Thursday. The model predicts the storm will move northwest and threaten Jamaica, the Cayman Islands, and western Cuba by early next week. I put odds a tropical depression forming in this region by Friday at moderate (20-50%).

Saturday's update on Hurricane Ike relief efforts
I got this very nice email Friday, giving appreciation for all those who helped out through the portlight.org Hurricane Ike charity effort:


I just wanted to express my sincere gratitude, on behalf of the City of Houston, the Mayor, and our community partners over at TIRR/Memorial Hermann, for all of your involvement in bringing medical supplies and equipment together to help Texans with disabilities affected by Hurricane Ike. I can't tell you how much we all appreciate the fact that you so quickly mobilized and leveraged such a tremendous amount of support to bring these needed items to Houston and other Texas cities.

An email simply doesn't do justice to the generous spirit and initiative that you, Paul Timmons, and your partners took to make this happen, nor to our gratitude. However, I just want you to know that we think about you all in appreciation every single day over here, and there are many who are directly benefiting from your generosity.

By the way, Paul Timmons mentioned that it looks like another shipment of 30-50 wheelchairs can be sent over here. All I can say is wow! Thank you for not forgetting about us, and for realizing that we still have a lot of needs here that we are trying to meet - even 4 weeks after the hurricane.

Again, please accept my sincere thanks. I hope that you have a wonderful weekend!

Michelle Colvard, MPH
Executive Director
Mayor's Office for People with Disabilities

Contributions to this highly worthy portlight.org charity fund are fully tax-deductible, and will go to provide relief supplies for those smaller communities typically bypassed by the traditional relief efforts. More details can be found at StormJunkie's blog.

I'll have an update this afternoon.
Jeff Masters

Crystal Beach - 1 month after Hurricane Ike (BlueFire)
Crystal Beach - 1 month after Hurricane Ike

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104. npenta519
4:10 PM GMT on October 13, 2008
I gotta ask again:

Going on vacation (Bahamas cruise Oct 20-24) Anyone got any info about any possible storm encounters??

TIA
103. surfmom
4:02 PM GMT on October 13, 2008
"vigorous little beast" --- description fits my first born starting from his seedling stage.....could be in for it......now why did I want Omar to be.... oh yeah -- TAZ -- I'm going to pay for this....LOL
Member Since: July 18, 2007 Posts: 30 Comments: 26536
102. surfmom
3:59 PM GMT on October 13, 2008
Was going to bust my butt working to get out and paddle-- think I'll wait a day.

redtide@myfwc.com - FOR INFORMATION regarding Redtide in the State of FL.....although sometimes the locals see it first!!
Member Since: July 18, 2007 Posts: 30 Comments: 26536
101. surfmom
3:57 PM GMT on October 13, 2008
STillwaiting - BIG thanks for the redtide observation. I went out for a paddle yesterday, late afternoon -- and did not notice anything...(kill) but I what I did note was that after swimming/paddling with so many mullet they were bumping into the board -- yesterday NADA - no bait fish, no mullet. Hoping this East winds blows it OUT
Member Since: July 18, 2007 Posts: 30 Comments: 26536
100. benirica
3:10 PM GMT on October 13, 2008
Quoting WxLogic:
12Z NAM has been progressively implying that TD15 could miss the developing trough in the assumption that it stays weak enough not to feel the developing trough.

NAM hasn't doing to bad with trends... not saying with the exact placement of High/Lows... but the trends it develops have been pretty close so should be something to watch.


Unfortunately, TD15 doesnt look like it wants to stay weak. Its a vigorous little beast.
Member Since: August 3, 2006 Posts: 0 Comments: 1143
99. WxLogic
3:06 PM GMT on October 13, 2008
12Z NAM has been progressively implying that TD15 could miss the developing trough in the assumption that it stays weak enough not to feel the developing trough.

NAM hasn't doing to bad with trends... not saying with the exact placement of High/Lows... but the trends it develops have been pretty close so should be something to watch.
Member Since: August 14, 2008 Posts: 4 Comments: 4976
98. stillwaiting
3:02 PM GMT on October 13, 2008
Quoting surfmom:
58stillwaiting -- hey... we're in this together neighbor -- no biggies - just little buoy rockers please LOL..... we just need chest high waves to ride.....saving your $ for a board?????....if you find mangos by your door they're from me



working on saving $$,should be no prob.,love the mango's,saw some dead fish along shore at my beach last night,no bait fish or any fish for that matter in the last 48hrs,still seeing traces of red tide blooms,hope it DIES soon.....99L should be a TD by 5pm and the track looks more likely to be NW thru 48hrs then turning either North or NNE going over or near the western tip of CUBA in about 72-96hrs..JMO but this weekend could be intersting for us here in FL....IMO
Member Since: October 5, 2007 Posts: 20 Comments: 4970
97. Thundercloud01221991
3:01 PM GMT on October 13, 2008
NEW BLOG FROM DR. MASTERS
Member Since: August 1, 2006 Posts: 28 Comments: 3716
96. antonio28
3:00 PM GMT on October 13, 2008
Ok its oficial Omar will be in PR!!
Member Since: July 15, 2008 Posts: 0 Comments: 799
94. surfmom
2:57 PM GMT on October 13, 2008
Yup, that stinking MJO is here... I thought I asked one of you guys to put a chain on that monkey!!
Member Since: July 18, 2007 Posts: 30 Comments: 26536
92. benirica
2:57 PM GMT on October 13, 2008
Why would this be a Hurricane before Puerto Rico?
Is that really realistic? Isn't shear only going to get "almost favorable" and then unfavorable?
Member Since: August 3, 2006 Posts: 0 Comments: 1143
91. Relix
2:56 PM GMT on October 13, 2008
@87: The through NHC predicted is already forming. You can see it in the Water Vapor.
Member Since: August 3, 2006 Posts: 0 Comments: 2725
90. surfmom
2:56 PM GMT on October 13, 2008
58stillwaiting -- hey... we're in this together neighbor -- no biggies - just little buoy rockers please LOL..... we just need chest high waves to ride.....saving your $ for a board?????....if you find mangos by your door they're from me
Member Since: July 18, 2007 Posts: 30 Comments: 26536
89. panamasteve
2:56 PM GMT on October 13, 2008
Just curious--this increase in activity does seem related to the current phase of the MJO. It seems all the MJO predictors were right on track.
Member Since: June 2, 2008 Posts: 0 Comments: 157
87. 21N71W
2:55 PM GMT on October 13, 2008
Morning All,
For TD 15 they say :THE DEPRESSION IS MOVING TOWARD THE NORTHWEST NEAR 2 MPH...3 KM/HR.
LITTLE SIGNIFICANT MOTION IS EXPECTED DURING THE NEXT 24 TO 36
HOURS...HOWEVER...A NORTHEASTWARD MOTION IS FORECAST TO BEGIN ON
WEDNESDAY.
Now any chances that will not happen ...? what about the Turks and Caicos in that case?
Member Since: August 1, 2006 Posts: 0 Comments: 180
86. Seastep
2:53 PM GMT on October 13, 2008
Quoting Seastep:


Actually either should work... in spanish it is Republica Dominicana. ;)
Member Since: September 9, 2008 Posts: 6 Comments: 3414
84. benirica
2:53 PM GMT on October 13, 2008
Quoting kmanislander:


Where is RD ?


RD - Republica Dominicana ( Dominican Republic, DR)
Member Since: August 3, 2006 Posts: 0 Comments: 1143
83. surfmom
2:53 PM GMT on October 13, 2008
In for two seconds.... TAZ - looks like we got an Omar in the works....maybe a P-storm as well
Member Since: July 18, 2007 Posts: 30 Comments: 26536
82. JRRP
2:51 PM GMT on October 13, 2008
Quoting kmanislander:


Where is RD ?

I mean Dominican Republic
Member Since: August 16, 2007 Posts: 0 Comments: 5963
80. Tazmanian
2:49 PM GMT on October 13, 2008
too me any way TD 15 looks a lot stronger then a TD this AM


Member Since: May 21, 2006 Posts: 5091 Comments: 115256
79. kmanislander
2:49 PM GMT on October 13, 2008
Quoting JRRP:

do you think that here in RD we will have TS conditions ??


Where is RD ?
Member Since: August 19, 2006 Posts: 0 Comments: 15842
78. Relix
2:48 PM GMT on October 13, 2008
Oh snap!!
Member Since: August 3, 2006 Posts: 0 Comments: 2725
76. JRRP
2:47 PM GMT on October 13, 2008
may be a hurricane NE of PR
Member Since: August 16, 2007 Posts: 0 Comments: 5963
75. THUNDERPR
2:47 PM GMT on October 13, 2008
AT THIS TIME...THE
OFFICIAL FORECAST IS A BLEND OF THE STATISTICAL MODEL SHIPS AND THE
DYNAMICAL MODELS GFDL AND HWRF. IN FACT...THE GFDL AND HWRF
FORECAST THE DEPRESSION TO BE A HURRICANE AS IT MOVES NEAR
PUERTO RICO.
Member Since: August 11, 2006 Posts: 0 Comments: 339
74. JRRP
2:46 PM GMT on October 13, 2008
Quoting Seastep:


Interesting, they put up TD15 but not even a yellow circle on 99L?

I was wondering it too
Member Since: August 16, 2007 Posts: 0 Comments: 5963
73. Tazmanian
2:45 PM GMT on October 13, 2008
you have too wait in tell 2pm for the next two
Member Since: May 21, 2006 Posts: 5091 Comments: 115256
72. IKE
2:45 PM GMT on October 13, 2008
Quoting Seastep:


Interesting, they put up TD15 but not even a yellow circle on 99L?


They will on the 2 pm EDST update.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
71. Patrap
2:44 PM GMT on October 13, 2008
Caribbean Water Vapor (IR-3) Link
Member Since: July 3, 2005 Posts: 426 Comments: 128632
70. Seastep
2:44 PM GMT on October 13, 2008
Quoting JRRP:
Link
NHC


Interesting, they put up TD15 but not even a yellow circle on 99L?
Member Since: September 9, 2008 Posts: 6 Comments: 3414
69. JRRP
2:43 PM GMT on October 13, 2008
0
WTNT35 KNHC 131440
TCPAT5
BULLETIN
TROPICAL DEPRESSION FIFTEEN ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152008
1100 AM AST MON OCT 13 2008

...NEW TROPICAL DEPRESSION FORMS OVER THE EASTERN CARIBBEAN SEA...

A TROPICAL STORM WATCH COULD BE REQUIRED FOR PUERTO RICO AND THE
U.S. VIRGIN ISLANDS LATER TODAY.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR LOCAL WEATHER OFFICE.

AT 1100 AM AST...1500Z...THE CENTER OF NEWLY FORMED TROPICAL
DEPRESSION FIFTEEN WAS LOCATED NEAR LATITUDE 14.8 NORTH...LONGITUDE
69.6 WEST OR ABOUT 340 MILES...545 KM...SOUTHWEST OF SAN JUAN
PUERTO RICO AND ABOUT 175 MILES...285 KM...NORTH-NORTHWEST OF
CURACAO.

THE DEPRESSION IS MOVING TOWARD THE NORTHWEST NEAR 2 MPH...3 KM/HR.
LITTLE SIGNIFICANT MOTION IS EXPECTED DURING THE NEXT 24 TO 36
HOURS...HOWEVER...A NORTHEASTWARD MOTION IS FORECAST TO BEGIN ON
WEDNESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST AND THE DEPRESSION COULD
BECOME A TROPICAL STORM LATER TODAY. AN AIR FORCE PLANE IS
SCHEDULED TO REACH THE DEPRESSION LATER TODAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB...29.68 INCHES.

THIS IS A LARGE DEPRESSION AND BANDS OF HEAVY RAINS WILL LIKELY
SPREAD OVER PUERTO RICO AND THE VIRGIN ISLANDS TODAY.

REPEATING THE 1100 AM AST POSITION...14.8 N...69.6 W. MOVEMENT
TOWARD...NORTHWEST NEAR 2 MPH. MAXIMUM SUSTAINED WINDS...35 MPH.
MINIMUM CENTRAL PRESSURE...1005 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 PM AST.

$$
FORECASTER AVILA
Member Since: August 16, 2007 Posts: 0 Comments: 5963
68. WxLogic
2:42 PM GMT on October 13, 2008
Quoting MichaelSTL:
I wonder why all of these storms of suddenly popping up just as the enhanced phase of the MJO is leaving the Atlantic, as opposed to a week ago when it was in full force?

Image Hosted by ImageShack.us


In my opinion that's how it typically works... basically on the wane of the MJO all that upward motion materializes or takes tapes after it leaves. Is just like the Hurricane Season... in which the heat content of the ocean doesn't really materializes until later in the Hurricane season.
Member Since: August 14, 2008 Posts: 4 Comments: 4976
67. JRRP
2:42 PM GMT on October 13, 2008
Link
NHC
Member Since: August 16, 2007 Posts: 0 Comments: 5963
66. FSUCOOPman
2:42 PM GMT on October 13, 2008
Quoting stillwaiting:
looks like 99l is a pre-me,was supposed to be born in atleast 48hrs,buuuuut.......its appears we may have a new td in less than 12hrs now!!!!,now once we have a closed surface low to track SWFL should be paying VERY close attention,as I personally beleave that 99L could be a VERY large TC!!!!,JMO


High pressure over the GOM looks like it should keep this storm heading west-ish. Do you see something that I don't regarding stearing?
Member Since: August 29, 2008 Posts: 0 Comments: 376
65. Seastep
2:40 PM GMT on October 13, 2008
Quoting btwntx08:
RD??? u meant DR


Actually either should work... in spanish it is Republica Dominicana. ;)
Member Since: September 9, 2008 Posts: 6 Comments: 3414
64. Patrap
2:40 PM GMT on October 13, 2008
GOES WV Loop of Tropical Basin ,LARGE Link
Member Since: July 3, 2005 Posts: 426 Comments: 128632
63. Orcasystems
2:39 PM GMT on October 13, 2008
Quoting StormW:
41. Orcasystems 10:29 AM EDT on October 13, 2008
Quoting clwstmchasr:
Reading StormW's forecast for 99L it looks to move in the Pacific. This is probably goig to be the disturbance that would have been a threat to the conus (in particular, Florida


Thanks Orca!

When I did my forecast, I hadn't even looked at the guidance...didn't realize they had it out that soon!


Anytime StormW.. just showing him you were right.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
62. Thundercloud01221991
2:39 PM GMT on October 13, 2008
In case you did not see this yet

Post season on Cristobal


Link
Member Since: August 1, 2006 Posts: 28 Comments: 3716
61. Tazmanian
2:38 PM GMT on October 13, 2008
see evere one we no longer have 98L be come its now TD 15



TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1324 UTC MON OCT 13 2008

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

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE FIFTEEN (AL152008) 20081013 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
081013 1200 081014 0000 081014 1200 081015 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 14.9N 69.6W 15.2N 70.8W 15.5N 71.9W 15.6N 72.3W
BAMD 14.9N 69.6W 15.1N 70.1W 15.2N 70.2W 15.2N 69.6W
BAMM 14.9N 69.6W 15.2N 70.5W 15.3N 71.2W 15.3N 71.5W
LBAR 14.9N 69.6W 15.3N 70.4W 15.7N 71.0W 16.3N 71.1W
SHIP 30KTS 32KTS 35KTS 41KTS
DSHP 30KTS 32KTS 35KTS 41KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
081015 1200 081016 1200 081017 1200 081018 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 15.3N 72.7W 15.1N 73.7W 16.0N 75.7W 17.0N 78.2W
BAMD 15.9N 67.6W 20.1N 61.5W 26.4N 51.4W 32.9N 42.9W
BAMM 15.2N 71.7W 15.3N 72.3W 16.4N 74.5W 17.5N 77.2W
LBAR 17.5N 70.5W 21.3N 68.1W 24.6N 64.4W 27.6N 60.1W
SHIP 48KTS 56KTS 57KTS 57KTS
DSHP 48KTS 56KTS 57KTS 57KTS

...INITIAL CONDITIONS...
LATCUR = 14.9N LONCUR = 69.6W DIRCUR = 275DEG SPDCUR = 6KT
LATM12 = 14.9N LONM12 = 68.3W DIRM12 = 279DEG SPDM12 = 7KT
LATM24 = 14.4N LONM24 = 67.1W
WNDCUR = 30KT RMAXWD = 75NM WNDM12 = 30KT
CENPRS = 1005MB OUTPRS = 1008MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
Member Since: May 21, 2006 Posts: 5091 Comments: 115256
60. TheTracker08
2:37 PM GMT on October 13, 2008
NO threat right?!?!?! or am i wrong, it seems so
58. stillwaiting
2:37 PM GMT on October 13, 2008
looks like 99l is a pre-me,was supposed to be born in atleast 48hrs,buuuuut.......its appears we may have a new td in less than 12hrs now!!!!,now once we have a closed surface low to track SWFL should be paying VERY close attention,as I personally beleave that 99L could be a VERY large TC!!!!,JMO
Member Since: October 5, 2007 Posts: 20 Comments: 4970
57. kmanhurricaneman
2:36 PM GMT on October 13, 2008
Is it possible i wonder two systems in the caribean merge and form the perfect storm?!!!! nah noy posible fuji*** (dont quite remember the spelling )would take effect i dont believe that 98 will curve that drastically N looking at sat imagery and wind patterns 98l wiil curve to the east of jamaica or possible over jamaica. 99l will push north and though the yucatan passing cayman to the west JMO
Member Since: August 14, 2008 Posts: 0 Comments: 1002

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