Dr. Jeff Masters' WunderBlog

Dangerous Caribbean disturbance 95L close to tropical storm strength
Posted by: Dr. Jeff Masters, 13:57 GMT le 23 septembre 2010 +3
A tropical wave (Invest 95L), moving westward at 15 mph though the south-central Caribbean, will bring gusty winds and heavy rain squalls to the northern coasts of Colombia and Venezuela this morning, as well as the Netherlands Antilles Islands. This disturbance will bring dangerous flooding rains to the countries bordering the Western Caribbean this weekend, and may also be a threat to the U.S. Gulf of Mexico coast late next week. A hurricane hunter aircraft is in 95L, and found a large region of surface winds of 35 - 45 mph to the east of 95L's center. If they find a closed circulation, 95L will be upgraded to Tropical Storm Matthew today. Satellite loops show that heavy thunderstorm activity has increased markedly in recent hours, with a solid curved band of intense thunderstorms growing to the northeast of 95L's center. Low-level spiral bands are also developing to the southeast of the center, but a closed surface circulation is not yet obvious from satellite imagery.


Figure 1. Morning satellite image of 95L.

Forecast for 95L
An upper-level high pressure system lies to the west of 95L, near the coast of Nicaragua. The clockwise flow of air around this high will bring a moderate 10 - 15 knots of wind shear over 95L today. By Friday, 95L will move more underneath this upper-level high, causing the shear to decline. The SHIPS model forecasts that shear will fall to the low range, 5 - 10 knots, by Friday afternoon. This drop in shear may allow for rapid intensification of 95L as it approaches landfall near the Nicaragua/Honduras border on Friday night and early Saturday morning. NHC is giving the disturbance an 80% chance of developing into a tropical depression by Saturday.


Figure 2. Forecast track of 95L from an ensemble of runs of the GFS model done at 2am EDT this morning.

The future of 95L depends critically upon the storm's interaction with land over the coming days. If 95L misses making landfall in Nicaragua and Honduras, and instead skirts the north coast of Honduras, the storm is likely to intensify into a hurricane by Monday, as predicted by last night's 00Z (8pm EDT) run of the GFDL model. However, if 95L spends significant time over Honduras, as predicted by the latest 06Z (2am EDT) run of the GFDL model, the storm will likely stay below hurricane strength. 95L is being forced just north of due west by a strong ridge of high pressure. This ridge will keep the storm moving at 15 mph through Saturday. On Sunday, a trough of low pressure diving southwards over the Eastern U.S. will weaken the steering currents over the Western Caribbean and cause 95L to slow and turn more to the north. 95L will begin a period of slow and erratic movement on Sunday that may last many days, as the storm wanders in the Western Caribbean and over Belize, Honduras, and Mexico's Yucatan Peninsula. If the center of 95L spends significant time over water, the storm could easily develop into powerful and dangerous Hurricane Matthew. If the center remains mostly over land, 95L will still generate extremely heavy rains over Central America, but remain below hurricane strength. By late next week, the trough of low pressure over the Eastern U.S. may lift out, allowing a ridge of high pressure to build in and force 95L westwards across the Yucatan Peninsula and into the Gulf of Mexico's Bay of Campeche. Alternatively, the trough of low pressure over the Eastern U.S. may amplify, drawing 95L northwards across Western Cuba and into Florida. The uncertainties in the long-range fate of 95L are high, and depend strongly on slight variations in its track that determine how much time the storm spends over land. One measure of the uncertainty in 95L's future track can be gained by viewing the ensemble forecast from the GFS model. An ensemble forecast is generated by taking the initial conditions in the atmosphere and making slight variations in the temperature, pressure, and humidity fields. Twenty or so tweaks of the initial conditions are made, and the GFS model run twenty separate times for each new set of initial conditions. The resulting ensemble of model runs gives one an idea of how sensitive the future track of the storm might be to errors in characterizing the initial state of the atmosphere. As one can see from this morning's GFS ensemble run (Figure 2), there are a wide range of possibilities for where 95L might go. The main thing I am confident of at this point is that 95L will generate very heavy rains over Nicaragua, Honduras, Belize, and Mexico's Yucatan Peninsula Friday through Tuesday that will likely cause dangerous flooding rains and life-threatening mudslides.

Tropical Depression Lisa
Tropical Depression Lisa continues to churn the waters of the far Eastern Atlantic. By Saturday night, upper level winds out of the west are expected to increase, bringing high wind shear of 20 - 45 knots over Lisa. The high shear may be capable of destroying the storm by early next week. It appears unlikely that Lisa will affect any land areas.

Elsewhere in the tropics
The remnants of Hurricane Julia are still spinning over the far Eastern Atlantic, and are generating some sporadic heavy thunderstorm to the north of the center of circulation. Julia's remains are being given a 10% chance of re-developing by NHC. There are no other threat areas to discuss, and none of the models is calling for development (except for 95L) over the next seven days.

Hurricane Karl's moisture causing flooding in Minnesota, Wisconsin
A plume of very moist air associated with what was Hurricane Karl last week has surged northwards over the Central U.S. over the past two days. This moisture is now being lifted over a warm front draped over Minnesota and Wisconsin, and has generated flooding rains in excess of six inches in southern Minnesota this morning. Flood warnings and flood watches are posted for a wide swath of the upper Midwest today, including most of Minnesota, northern Wisconsin, and Michigan's Upper Peninsula. The latest forecast discussion from the NWS office in Minneapolis notes that the forecast amount of moisture in the air this afternoon is similar in magnitude to the all-time record for this time of year (set on September 2, 1953.) These kinds of rain events are called Predecessor Rain Events (PREs), because they typically precede the actual arrival of the rain shield of a tropical storm.


Figure 3. Radar estimated rainfall over Minnesota.

Next post
I'll have an update on 95L later today. The timing will depend upon what the Hurricane Hunters find.

Jeff Masters
Categories: Hurricane
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2. WxLogic 13:59 GMT le 23 septembre 2010    
Thx Doc...
Member Since: 14 août 2008 Posts: 4 Comments: 4667
4. hcubed 14:01 GMT le 23 septembre 2010    
So there is a possibility that Matthew may form today.

Bypasses TD, straight to TS.

Have we seen a renumber yet?
Member Since: 18 mai 2007 Posts: 286 Comments: 1639
5. Eugeniopr 14:02 GMT le 23 septembre 2010    
Thank you Doc and Weatherguy3 for the friefings.
Member Since: 1 août 2010 Posts: 0 Comments: 229
6. Minnemike 14:02 GMT le 23 septembre 2010    
Isn't that moisture up here from Georgette? That was my impression, though, perhaps she was the spawn of Karl? All I know, is it's WET up hea!!
Member Since: 31 juillet 2008 Posts: 0 Comments: 1254
7. WxLogic 14:03 GMT le 23 septembre 2010    
Quoting hcubed:
So there is a possibility that Matthew may form today.

Bypasses TD, straight to TS.

Have we seen a renumber yet?


There could be one once the HH finds a TD or TS. Hopefully in ~30 to 1HR we should have a better idea.
Member Since: 14 août 2008 Posts: 4 Comments: 4667
8. Cotillion 14:03 GMT le 23 septembre 2010    
95L may allow for rapid intensification and extreme flooding.

Central America is not going to be having a fun week.

Thanks for the update.
Member Since: 23 août 2008 Posts: 7 Comments: 5300
9. WindynEYW 14:03 GMT le 23 septembre 2010    
thanks Dr M, clear concise easy to understand
Member Since: 13 septembre 2007 Posts: 0 Comments: 331
10. utilaeastwind 14:03 GMT le 23 septembre 2010    
95L looks like a carbon copy of Hurricane Greta of 1978.

I am located on Utila, Honduras 16.10N 86.90W and it looks like we are in for plenty of action!
Member Since: 12 octobre 2007 Posts: 0 Comments: 192
11. Orcasystems 14:03 GMT le 23 septembre 2010    
I should have asked for a new one earlier...thanks Jeff

Complete Update

Lisa - Who knows? Sticking with the NFI model

95L - OMG!!

HH ontask in 95L, can't wait to see what they find.




AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI
Member Since: 1 octobre 2007 Posts: 77 Comments: 26077
14. Minnemike 14:05 GMT le 23 septembre 2010    
how ungrateful of me... THANKS Dr. M!!
:D
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15. Eagle101 14:06 GMT le 23 septembre 2010    
Observation Four from the recon aircraft investigating 95L

Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 23rd day of the month at 13:44Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Mission Purpose: Investigate fifth suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 04

Mandatory Data...

Observation Time: Thursday, 13:45Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 13.9N 73.2W
Location: 326 miles (525 km) to the S (190°) from Port-au-Prince, Haiti.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 7,320 meters
Flight Level Wind: From 120° at 18 knots (From the ESE at ~ 20.7 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: -16°C
Flight Level Dew Point: -22°C
Weather (within 30 nautical miles): Shower(s) (continuous or intermittent precipitation - from cumuliform clouds)
400 mb Surface Altitude: 7,570 geopotential meters

Remarks Section...

Surface Wind Speed (likely by SFMR): 27 knots (~ 31.1mph)
Member Since: 7 janvier 2007 Posts: 0 Comments: 40
16. TerraNova 14:06 GMT le 23 septembre 2010    
Is the FTP site down for anybody else?
Member Since: 30 juillet 2007 Posts: 76 Comments: 4058
17. BLee2333 14:07 GMT le 23 septembre 2010    
Thank you, Sir!!
Member Since: 6 janvier 2009 Posts: 0 Comments: 217
18. hydrus 14:07 GMT le 23 septembre 2010    
Thanks Doc...95L has that classic seedling storm look....
Member Since: 27 septembre 2007 Posts: 1 Comments: 14252
19. Thaale 14:07 GMT le 23 septembre 2010    
Cabo Gracias a Dios is the Honduran/Nicaraguan cape that sticks out into the Caribbean. How about using CGD?
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20. Cotillion 14:07 GMT le 23 septembre 2010    
Quoting TerraNova:
Is the FTP site down for anybody else?


You mean ATCF?
Member Since: 23 août 2008 Posts: 7 Comments: 5300
21. TerraNova 14:09 GMT le 23 septembre 2010    
Quoting Cotillion:


You mean ATCF?


That's the one, I get a 601: FTP_FAILED unknown error.
Member Since: 30 juillet 2007 Posts: 76 Comments: 4058
22. Kristina40 14:09 GMT le 23 septembre 2010    
95L looks to be getting its swirl on this morning. Hopefully it swirls itself into some mountains and dies.
Member Since: 27 juin 2010 Posts: 0 Comments: 681
24. Cotillion 14:09 GMT le 23 septembre 2010    
Quoting TerraNova:


That's the one, I get a 601: FTP_FAILED unknown error.


It's working for me.

(That said, it only works for me on Firefox; been having real problems with it on Chrome).
Member Since: 23 août 2008 Posts: 7 Comments: 5300
25. TerraNova 14:10 GMT le 23 septembre 2010    
Quoting Cotillion:


It's working for me.

(That said, it only works for me on Firefox; been having real problems with it on Chrome).


Yup, I'm using Chrome, I just tried it on IE and it worked normally. Thanks!
Member Since: 30 juillet 2007 Posts: 76 Comments: 4058
26. SeaMule 14:10 GMT le 23 septembre 2010    
Absolutely top notch consensus Dr. Masters...

I live on the eastern shore of Alabama, and this thing is something I got a sneaky feeling is heading in the GOM....the meandering part kinda makes ya pucker up. On the one hand...if Matthew does ramp up and become a dangerous hurricane.....the good reduction in sea surface temperatures will be offset by the flooding rains for the people in the central American region...

Now, let's talk about Matthew when/if he slinks into the GOM...

Now we have a ramped up storm, with unbelievable latent energy.....and no where to go but land....

my guess?

not a clue
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27. hydrus 14:11 GMT le 23 septembre 2010    
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28. StormChaser81 14:11 GMT le 23 septembre 2010    
NHC is giving the disturbance a 60% chance of developing into a tropical depression by Saturday.

Huh?

THERE IS A HIGH CHANCE...80 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
Member Since: 11 août 2008 Posts: 0 Comments: 2315
29. quante 14:11 GMT le 23 septembre 2010    
Like I said, yesterday, all about timing with 95L. HH almost at the storm. Will see what data tells us. Seems a bit further south than yesterday. I can never tell where the COC is though.
Member Since: 2 août 2006 Posts: 0 Comments: 328
31. sarahjola 14:12 GMT le 23 septembre 2010    
thanks for the feedback guys. so this could be good or bad, right? this ull catches up to 95l and disrupts it like the ull have done all season long or this could help it develop and move it in a certain direction. my question is what direction and why? if the ull stays above it would it pull it more north? if the ull gets ahead of 95l would it pull it more west? if the ull and 95l crash would it tear 95l apart? just wanting to know what i should be looking for. i am pretty sure that this ull will play a role with 95l. but who knows?
Member Since: 10 septembre 2008 Posts: 0 Comments: 1291
32. centex 14:12 GMT le 23 septembre 2010    
Sounds like BOC track has become more likely because timing/stalling and trough lifting out. I never did like the only viable tracks being FL/NGOM or buried in Central America.
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33. Stormchaser2007 14:14 GMT le 23 septembre 2010    
Quoting TerraNova:


Yup, I'm using Chrome, I just tried it on IE and it worked normally. Thanks!


I love Chrome to death, but they still have some work to do to fix the bugs.
Member Since: 9 juin 2007 Posts: 4 Comments: 15248
35. DookiePBC 14:15 GMT le 23 septembre 2010    
Quoting cat5hurricane:
That's one of my favorite avatars Dookie. You just let me know when those things start actually doing that...cuz that's when you know that there's trouble a brewin'


So far, squirrel activity in eastern Palm Beach County is at a normal level. They still insist on running in front of my car instead of running off the road. Saw one holding a board with a nail in it, but so far that's it.
Member Since: 1 septembre 2009 Posts: 0 Comments: 433
36. Bobbyweather 14:15 GMT le 23 septembre 2010    
Quoting Cotillion:


It's working for me.

(That said, it only works for me on Firefox; been having real problems with it on Chrome).

Chrome works for me, I'm using this link: Link
Member Since: 7 septembre 2006 Posts: 88 Comments: 2470
38. Patrap 14:16 GMT le 23 septembre 2010    
12z Early Cycle NHC model tracks
Invest95
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Member Since: 3 juillet 2005 Posts: 370 Comments: 111297
40. Bobbyweather 14:17 GMT le 23 septembre 2010    
Hi. It's been a long time since I last posted.
Off topic, but has there been a low pressure system or tropical depression that had an eye?
Member Since: 7 septembre 2006 Posts: 88 Comments: 2470
41. Patrap 14:18 GMT le 23 septembre 2010    
ATCF images (Hurricane Track Models)


Current Storms:
Lisa
Invest95
Member Since: 3 juillet 2005 Posts: 370 Comments: 111297
42. will40 14:19 GMT le 23 septembre 2010    
HH just now descending into 95L
Member Since: 19 septembre 2005 Posts: 2 Comments: 3439
43. TampaTom 14:19 GMT le 23 septembre 2010    
Quoting Bobbyweather:
Hi. It's been a long time since I last posted.
Off topic, but has there been a low pressure system or tropical depression that had an eye?


Sure has... some Nor'Easters develop eyes..

http://en.wikipedia.org/wiki/Eye_%28cyclone%29
Member Since: 20 juin 2005 Posts: 22 Comments: 1048
44. Bobbyweather 14:19 GMT le 23 septembre 2010    
Remnants of Julia is now being tracked by the NHC.
AL, 12, 2010092312, , BEST, 0, 322N, 380W, 25, 1008, LO, 0, , 0, 0, 0, 0,
Member Since: 7 septembre 2006 Posts: 88 Comments: 2470
45. BioChemist 14:20 GMT le 23 septembre 2010    
I would rather this storm go into the US or Cuba than into Central america where thousands could die. Atleast in Cuba or US we are well prepared for these situations, and west cuba has little in the way of mountains

it just looks like a humanitarian disaster
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46. Patrap 14:20 GMT le 23 septembre 2010    
GOM IR Loop




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47. Bobbyweather 14:20 GMT le 23 septembre 2010    
Quoting TampaTom:


Sure has... some Nor'Easters develop eyes..

http://en.wikipedia.org/wiki/Eye_%28cyclone%29

Thanks
Member Since: 7 septembre 2006 Posts: 88 Comments: 2470
48. ackee 14:21 GMT le 23 septembre 2010    
I would not be suprise if 95L CENTRE is found a bit further north
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49. quante 14:22 GMT le 23 septembre 2010    
A great explanation by Dr. M on the GFS ensemble. Thanks Doc.
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50. stillwaiting 14:22 GMT le 23 septembre 2010    
I would look for a special advisory naming 95l ts matthew as soon as the hh are in their for a while ,40mph winds, look for a advisory around 2pm,almost 100% imo...mat has already formed this morning.
Member Since: 5 octobre 2007 Posts: 20 Comments: 4970
51. HCW 14:22 GMT le 23 septembre 2010    
Quoting btwntx08:

dude there not even close to being out of it



Can somebody please tell me the last October storm that hit Texas ?
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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.

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