97L gets disrupted by Hispaniola

By: Dr. Jeff Masters , 12:53 PM GMT on July 21, 2010

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A tropical wave (Invest 97L) near the north coast of Hispaniola has been disrupted by interaction with the island, plus the effects of moderate wind shear of 10 - 20 knots. The storm is no longer a threat to develop into a tropical depression today, and the Hurricane Hunter flight that was scheduled for today has been postponed until Thursday. The disturbance has brought heavy rains of 8+ inches to Culebra, Vieques, the Virgin Islands, and some of the northern Lesser Antilles Islands. Wunderblogger Weather456 reported that the power was knocked out on the island of St. Kitts for about 24 hours, due to the intense lightning associated with 97L. All of Puerto Rico and the Virgin Islands are under flash flood watches today.

Satellite images of 97L show a relatively meager number of heavy thunderstorms that are not well-organized. The curved bands to the north and east of the center have disappeared, and there is no evidence of low-level spiral banding or of a surface circulation. Surface observations over the northern Dominican Republic show only light winds, with no westerly winds indicating that a surface circulation is forming. Long-range radar loops from San Juan show a much reduced amount of thunderstorm activity.


Figure 1. Total radar-estimate rainfall for 97L.

Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of isolated flooding to the Dominican Republic today, and to Haiti on today and Thursday. Heavy rains from 97L will affect eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas Thursday, and South and Central Florida can expect heavy rains to arrive Thursday night or Friday morning. The latest suite of model runs from 2am EDT this morning (6Z) foresee 97L making landfall on the Florida coast somewhere between Miami and Cape Canaveral on Friday, then continuing into the Gulf of Mexico on Saturday. Only the Canadian model foresees a threat to Texas, and the other models predict a second landfall between eastern Louisiana and the Florida Panhandle.

Intensity Forecast for 97L
The primary detriment to development of 97L today will be its close proximity to the landmass of Hispaniola. Once the storm pulls away from the island tonight, 97L has a better chance of development. Also hindering development over the next two days will be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next three days, which should allow for some steady development of 97L on Thursday and Friday before it reaches Florida. NHC is giving 97L a 60% chance of developing into a tropical depression by Friday, which is a reasonable forecast. I think there is a 70% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development before 97L reaches Florida is unlikely, due to the storm's current state of disorganization and the dry air over the Bahamas. It's very unlikely that 97L has time to organize into a hurricane before hitting Florida. I put the odds of 97L making it to hurricane strength before reaching Florida at 5%, and I give a 20% chance it will be a hurricane in the Gulf of Mexico. The probability of 97L being a hurricane in the Gulf of Mexico will depend heavily upon how long the storm spends over water in the Gulf, which is very uncertain. The environment in the Gulf of Mexico should be favorable for intensification, if passage over Florida does not disrupt the storm too much.

I'll have a new post Thursday morning, or earlier if there's a major change to 97L.

Famed climate scientist Steven Schneider dies
Steven Schneider, one of the most influential and talented climate scientists of our time, died on Monday. Ricky Rood has a tribute to Dr. Schneider in today's blog. Ricky comments, "He is known for feistiness. His last book was Science as a Contact Sport: Inside the Battle to Save Earth's Climate. He was a man who was, bluntly, harassed and threatened by those who did not like his message. He never shrank from the battle."

Jeff Masters

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1812. Keemie
I'm here in the British Virgin Islands, very interested in the weather dynamics & whats not. The area is still on a Flash Flood Watch until 4am Thursday. Here is a link of the damage we've seen thus far.

Link
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Quoting WxLogic:


Jeje... glad that it helped some.


You speak Spanish?
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Quoting robert88:
You guys realize there is a good possibility we will not see a minimal hurricane until mid August. We have negative dry sinking upward motion coming from the Pacific and going to be in place until mid August. Get used to looking at these pathetic invests and TS's like 97L for a while. Climatology seems to rule this season. I am not ready to jump the bus just yet though. I do however have a gut feeling all these weather agencies are going to have a lot of explaining to do at the end of the season with their forecast #'s.


Enough now, you have been reported to admin because you constantly bash those who have logical reasons on why this season will get active, including the NHC. Conditions are now finally coming together for a very active season with 10 or more storms. This is not a 2009 season, this is 2010 with many factors coming in to play for a very active hurricane season, get used to it!
Member Since: July 1, 2008 Posts: 13 Comments: 7437
1809. tkeith
Has this thing moved in the last 48hrs?

It seems to just keep sitting there in the same place...
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1808. leo305
The ULL is also moistining up 97L's path, as the dry air is beginning to fizzle a bit.
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Quoting IKE:
Latest GFS @ 18 hours... puts 97L over eastern Cuba and spins up a BOC low.


Was just looking at the BOC action...
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I wonder the area 15N/65W couldn't become a separate entity to worry about in itself.
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1804. WxLogic
Quoting ElConando:


I've been seeing that though I wasn't sure how to explain what I was really seeing. Thanks, now I know :).


Jeje... glad that it helped some.
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1803. IKE
Latest GFS @ 18 hours... puts 97L over eastern Cuba and spins up a BOC low.
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Quoting Tazmanian:





IKE its has not been update ina long time thats old


LOL
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1788. Once again those winds are in the upper atmosphere not at the surface.
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1800. xcool
reedzone welcome.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Patrap:


I suggest a a tutorial Floodman.

The Guidance Flow dosent just affect a "center"..the flows aloft affect the whole envelope.


Its Guidance..never Gospel

Thats the NHC Line when we get a Named Sytem





I'll be happy to give it to you...should we start with statical mathematics, or just jump into the really hard stuff? LOL

The just so you know, all I was sayng is that the models cannot be correct when the given start cooridnates are incorrect; and yes, I do understand that the models are an approximation based on a huge array of variables...the point I was trying to make (and apparently very badly) is that much like yesterday, when this thing was having serious problems forming a definite LLC the model results were fairly scattered and changed from run to run as this was a weakeer system and the location of the center was hard to pinpoint. Add that to the changing environmental variables and you get more indeterminate results. Now once a system becomes stronger and it's center can be determined with some greater degree of certainty the results of the models come more into consensus and eventually you get the infamous NHC cone of death based on the strength of the modeling consensus...

Did I get my point across that time?
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Anybody else looking at the buildup ahead of that 77/78W Twave? BTW, that's 97L's old ride....
Member Since: October 25, 2005 Posts: 19 Comments: 22736
Quoting HurricaneSwirl:


That reading is also way up in the atmosphere.



ugh
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1795. divdog
Quoting hydrus:
ULL,s do have a tendency to make T-waves look like the bird that hit the uncovered fan..jmo
i think storm is sayin they shear em they dont steer em
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Quoting Tazmanian:
Significant Wind Levels...
Level Wind Direction Wind Speed
1019mb (Surface) 75° (from the ENE) 18 knots (21 mph)
938mb 75° (from the ENE) 21 knots (24 mph)
887mb 85° (from the E) 16 knots (18 mph)
850mb 90° (from the E) 18 knots (21 mph)
789mb 100° (from the E) 17 knots (20 mph)
770mb 85° (from the E) 20 knots (23 mph)
660mb 110° (from the ESE) 22 knots (25 mph)
599mb 100° (from the E) 22 knots (25 mph)
528mb 130° (from the SE) 18 knots (21 mph)
431mb 105° (from the ESE) 25 knots (29 mph)
409mb 135° (from the SE) 17 knots (20 mph)
387mb 145° (from the SE) 14 knots (16 mph)
304mb 145° (from the SE) 18 knots (21 mph)
265mb 190° (from the S) 23 knots (26 mph)
236mb 180° (from the S) 30 knots (35 mph)
207mb 205° (from the SSW) 32 knots (37 mph)
194mb 225° (from the SW) 14 knots (16 mph)
189mb 205° (from the SSW) 11 knots (13 mph)
177mb 165° (from the SSE) 12 knots (14 mph)
170mb 125° (from the SE) 26 knots (30 mph


That reading is also way up in the atmosphere.
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1793. leo305
The ULL is clearly moving much faster than the center at 21.0 N 72.26W

in fact, 97L may be moving slower than 10MPH, while the ULL may be moving at near 20MPH. These are rough estimates but, according to WV and Vis satellite, that's what it seems like to me.

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Quoting muddertracker:
Storm/Levi/Reed/

Can a ULL sometimes help outflow? If so, when?


Well, I am none of those you mentioned, but if an ULL is located in a position so that it is far enough away from a tropical cyclone not to shear it, it can often catch the tropical cyclone's outlfow and act to ventilate it and increase upper air divergence over the cyclone. This is I believe one of the biggest reasons why Rita intensified the way it did. In the image below, you can clearly see the outflow channel leading from the NE portion of Rita to the ULL (out of the frame).

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i smell yellow commeing with the new wave comeing in
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Quoting xcool:




Cleary shows 97L getting it together, thanks for the image. You can see the center starting to get clouded up in the end.
Member Since: July 1, 2008 Posts: 13 Comments: 7437
You guys realize there is a good possibility we will not see a minimal hurricane until mid August. We have negative dry sinking upward motion coming from the Pacific and going to be in place until mid August. Get used to looking at these pathetic invests and TS's like 97L for a while. Climatology seems to rule this season. I am not ready to jump the bus just yet though. I do however have a gut feeling all these weather agencies are going to have a lot of explaining to do at the end of the season with their forecast #'s.
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Significant Wind Levels...
Level Wind Direction Wind Speed
1019mb (Surface) 75° (from the ENE) 18 knots (21 mph)
938mb 75° (from the ENE) 21 knots (24 mph)
887mb 85° (from the E) 16 knots (18 mph)
850mb 90° (from the E) 18 knots (21 mph)
789mb 100° (from the E) 17 knots (20 mph)
770mb 85° (from the E) 20 knots (23 mph)
660mb 110° (from the ESE) 22 knots (25 mph)
599mb 100° (from the E) 22 knots (25 mph)
528mb 130° (from the SE) 18 knots (21 mph)
431mb 105° (from the ESE) 25 knots (29 mph)
409mb 135° (from the SE) 17 knots (20 mph)
387mb 145° (from the SE) 14 knots (16 mph)
304mb 145° (from the SE) 18 knots (21 mph)
265mb 190° (from the S) 23 knots (26 mph)
236mb 180° (from the S) 30 knots (35 mph)
207mb 205° (from the SSW) 32 knots (37 mph)
194mb 225° (from the SW) 14 knots (16 mph)
189mb 205° (from the SSW) 11 knots (13 mph)
177mb 165° (from the SSE) 12 knots (14 mph)
170mb 125° (from the SE) 26 knots (30 mph
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1787. hydrus
Quoting StormW:


No. A ULL wouldn't affect steering of a weak system.
ULL,s do have a tendency to make T-waves look like the bird that hit the uncovered fan..jmo
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1785. cg2916
Quoting Orcasystems:
The G is still flying around to the North



AOI

TS BUSTED FORECAST ALIBI


Where is the KML file for the models. Mine doesn't show intensity.
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Quoting WxLogic:
Interesting to note that as 97L continues to pull away from Hispanola it's starting to pull moisture from the shallow waters in the Bahamas and north Caribbean areas. Notice the feeder bands coming in from the SE from the PR (Mona Channel) region and from the South and SW.



I've been seeing that though I wasn't sure how to explain what I was really seeing. Thanks, now I know :).
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Any thoughts on the EATL wave?
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1781. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting IKE:


26 minutes is old? They only update every hour.




oh


oops send me crow
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Quoting muddertracker:
Storm/Levi/Reed/

Can a ULL sometimes help outflow? If so, when?



ULL helped it's outflow yesterday, today the invest is too close to the ULL to where it is getting sheared. If the ULL moves further away form 97L, it will actually aid in development by providing great outflow, maybe a anticyclone.
Member Since: July 1, 2008 Posts: 13 Comments: 7437
Quoting HadesGodWyvern:
Japan Meteorological Agency
Tropical Cyclone Advisory #31
TYPHOON CHANTHU (T1003)
3:00 AM JST July 22 2010
============================

SUBJECT: Category Three Typhoon In Northern Part Of The South China Sea

At 18:00 AM UTC, Typhoon Chanthu (970 hPa) located at 19.8N 112.2E has 10 minute sustained winds of 65 knots with gusts of 95 knots. The cyclone is reported as moving north northwest at 6 knots.

Dvorak Intensity: T4.0

Storm Force Winds
=================
50 NM from the center

Gale Force Winds
================
150 NM from the center

Forecast and Intensity
=========================
24 HRS: 21.4N 109.9E - 50 knots (CAT 2/Severe Tropical Storm)
48 HRS: 22.7N 107.9E - 30 knots (Tropical Depression)


A real system been watching that one get together. Still rather slow season for the WPAC.
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Time
EDT (UTC) Temperature
F (C) Dew Point
F (C) Pressure
Inches (hPa) Wind
MPH Weather
Latest 5 PM (21) Jul 21 78 (26) 77 (25) 29.89 (1012) E 24 heavy rain showers
4 PM (20) Jul 21 80 (27) 75 (24) 29.87 (1011) E 29
3 PM (19) Jul 21 78 (26) 75 (24) 29.89 (1012) ENE 32
2 PM (18) Jul 21 80 (27) 77 (25) 29.91 (1012) E 24
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1776. IKE
Quoting Tazmanian:





IKE its has not been update ina long time thats old


26 minutes is old? They only update every hour.
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1775. WxLogic
Interesting to note that as 97L continues to pull away from Hispanola it's starting to pull moisture from the shallow waters in the Bahamas and north Caribbean areas. Notice the feeder bands coming in from the SE from the PR (Mona Channel) region and from the South and SW.

Shortwave
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Quoting Tazmanian:





IKE its has not been update ina long time thats old


the ones that are updating are holding steady now
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Quoting Patrap:
Ive put up nuff Imagery in 5 years to retire on easily.

Dollar a Post..would be Like 2.8 Million by now easily.
Have u been out of town? It's prolly ur posts I've been missing.... lol

Seriously, though I've gotten a fantastic set of graphics to pull from, but need to "reconfigure my console" to make them a bit more efficently accessible. Meanwhile the graphics load here is very useful...
Member Since: October 25, 2005 Posts: 19 Comments: 22736
Quoting IKE:
Providenciales, TI (Airport)...at 21.8N and 72.3W
Updated: 26 min 3 sec ago
Heavy Rain Showers
79 °F
Heavy Showers Rain
Humidity: 94%
Dew Point: 77 °F
Wind: 24 mph from the East
Pressure: 29.89 in (Rising)
Visibility: 5.0 miles
UV: 3 out of 16
Clouds:
Scattered Clouds 1500 ft
Mostly Cloudy 2500 ft
(Above Ground Level)
Elevation: 13 ft





IKE its has not been update ina long time thats old
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1771. IKE
SYNOPSIS FOR THE GULF OF MEXICO
430 PM CDT WED JUL 21 2010

.SYNOPSIS...SURFACE TROUGH EXTENDING FROM 28N95W TO 24N96W AND
TO THE SW BAY OF CAMPECHE WILL MOVE INLAND THU AFTERNOON. A
RIDGE FROM NORTHERN FLORIDA TO LOUISIANA WILL CONTINUE THROUGH
EARLY SUN BEFORE RETREATING EASTWARD INTO MON AS A TROPICAL
WAVE OR A LOW POSSIBLY ENTERS THE EASTERN GULF SAT AND SUN
AND INTO THE CENTRAL GULF MON.


SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
530 PM EDT WED JUL 21 2010

.SYNOPSIS...TROPICAL WAVE ALONG 77W/78W IS MOVING W 13 KT. THE
WAVE WILL MOVE TO NEAR BY 82W/83W THU EVENING AND ACROSS THE
REMAINDER OF THE WESTERN CARIBBEAN LATER ON THU NIGHT AND INLAND
THE YUCATAN PENINSULA FRI. ANOTHER TROPICAL WAVE WELL E OF THE
AREA IS FORECAST TO MOVE INTO THE TROPICAL N ATLC WATERS
SAT THROUGH SUN EVENING...THEN INTO THE EASTERN CARIBBEAN SEA
LATE SUN AND MON.
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1770. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #31
TYPHOON CHANTHU (T1003)
3:00 AM JST July 22 2010
============================

SUBJECT: Category Three Typhoon In Northern Part Of The South China Sea

At 18:00 PM UTC, Typhoon Chanthu (970 hPa) located at 19.8N 112.2E has 10 minute sustained winds of 65 knots with gusts of 95 knots. The cyclone is reported as moving north northwest at 6 knots.

Dvorak Intensity: T4.0

Storm Force Winds
=================
50 NM from the center

Gale Force Winds
================
150 NM from the center

Forecast and Intensity
=========================
24 HRS: 21.4N 109.9E - 50 knots (CAT 2/Severe Tropical Storm)
48 HRS: 22.7N 107.9E - 30 knots (Tropical Depression)
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97L looks like a sheared tropical storm
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Flood is right.
All modeling is always GIGO and hence never completely accurate. This is backed up by studies in decreasing scales and chaos theory and its weather related terminology "the butterfly effect" This is why ensembles are important. They help tell how much variance there is in the guidance envelope and how big a role statistically chaos theory and the butterfly effect may alter the outcome. Until we get a scale down to the molecular, GIGO cant be eliminated. And since we cannot view atoms directly due to photon interference, not to mention the processing power and materials that would be necessary to log the location of every atom on earth at any given moment in time, that is a pipe dream. GIGO will be here forever, garbage in garbage out. The science of meteorology does not determine exacts. It is a science of probability and statistics which is why it is so interesting.
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1767. srada
Quoting will45:


she is safe Ike she is up here in NC lol


Thanks Will45!
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1766. Patrap
Technical Attachment

AN OVERVIEW OF NHC PREDICTION MODELS

Bernard N. Meisner
Scientific Services Division
National Weather Service Southern Region



Consensus forecasts, on average, are often more accurate than the forecasts from individual models, and the spread of an ensemble has potential use as a measure of confidence in the forecast. The following two diagrams show the track guidance and verification for two time periods during the lifetime of Hurricane Georges (1998). The first diagram shows the track guidance available at 1800 UTC on September 22nd. The spread of the guidance tracks was relatively small and the 72 hr forecast of the GUNS ensemble (the center of the cyan triangle) was very close to the actual storm track (indicated by the large red dot)
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Quoting Floodman:


Pat, my point is that you can't rely on the end result if the initial data is incorrect...do you now understand what I'm saying? The models aren't worth anything if they don't start where the CC is...the differences come from different variables effecting track from the CC location...that would be kinda like saying "How do I get from KC to NOLA if I start from St Louis?"

**editted**


I think you are trying to be too precise with global models, and since we don't have an obvious CC, one of the members may be correct. From my experience they don't do the center relocation on the global models untill its a well developed system. Under your thinking, we would have to throw out the 12Z CMC, NAM and GFS (AVNO) since they all started at different positions.

AL 97 2010072112 03 CMC 0 193N 718W

AL 97 2010072112 03 NAM 0 201N 705W

AL 97 2010072112 03 AVNO 0 200N 718W
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Quoting Patrap:
Ive put up nuff Imagery in 5 years to retire on easily.

Dollar a Post..would be Like 2.8 Million by now easily.


You talking about collectively on the blog? Then maybe even if we are speaking hypothetically.
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1763. leo305
21.0N 72.25W

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On the "going to Cuba" topic: models on the weekend called for the more southerly track because they were forecasting a weaker system. Looks like they're doing the same again today, hence, imo the retrograde to the left of track.
Member Since: October 25, 2005 Posts: 19 Comments: 22736

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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.

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