Matthew dissipates; new Western Caribbean disturbance organizing

By: Dr. Jeff Masters , 5:28 PM GMT on September 26, 2010

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Tropical Storm Matthew has dissipated over the high mountains of Mexico, in the same region where Hurricane Karl came ashore. Matthew's remains will dump very heavy rains over a region that doesn't need it, and flash flooding and mudslide will be a concern over this region of Mexico for the next two days. Guatemala was fortunate--Matthew did dump some heavy rain of up to six inches over the country, but the storm unexpectedly moved well beyond the country, and heavy rains have avoided both Guatemala and Belize today. Venezuela was not so lucky, and heavy rains from Matthew are being blamed for the deaths of seven people in Caracas.


Figure 1. Afternoon satellite image of the Western Caribbean and Central America, showing the remains of Matthew over Mexico, and a large area of disturbed weather beginning to develop over the entire region.

Lisa
Tropical Depression Lisa is being torn apart by wind shear, and will likely not exist by Monday morning.

A wet week for the Western Caribbean
A large region of disturbed weather is developing over the Western Caribbean and Central America today. These sorts of large low pressure systems are very dangerous for Central America and the Western Caribbean, even if they do not spawn a tropical storm. In October 2007, a large low I dubbed "the sleeping giant" spent a week spinning over the region, dumping very heavy rains over all of Central America and the countries bordering the Western Caribbean. Rains from this system triggered flooding that killed 45 people in Haiti, damaged thousands of homes in Cuba, and caused heavy rains in Guatemala, El Salvador, Belize, Mexico, Jamaica, the Cayman Islands, and the Bahamas. The models predict a similar type of storm may evolve over the region over the next few days, and heavy thunderstorms from this disturbance are already affecting the Pacific coasts of Nicaragua, El Salvador, Coast Rica, and Honduras. Heavy rains will likely spread to Jamaica, Cuba, Southwest Haiti, and the Cayman Islands on Monday. These rains may be as great as 3 - 6 inches per day, and will be capable of causing dangerous flooding and mudslides. The models continue to have a poor consensus on the future evolution of this area of disturbed weather. The ECMWF model predicts that by late in the week, the low will get drawn north-northeastwards over Cuba and into South Florida and the Bahamas, and may not develop into a tropical storm. At the other extreme is the GFS model, which predicts that the low will spawn a series of two or three tropical storms over the next ten days, with each of these storms moving northwards across Cuba, South Florida, and the Bahamas. The first of these storms would organize on Monday, moving over South Florida by Wednesday, and would likely be at strongest a 50-mph tropical storm. The Hurricane Hunters are on call to investigate anything that might develop over the Western Caribbean on Monday afternoon. NHC is giving a 10% chance that something might develop in the Western Caribbean by Wednesday.

I'll have an update Monday morning.

Jeff Masters

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1708. OctaviaStreet
1:02 PM GMT on September 27, 2010
Thanks very much, Beell. Seems an odd time of year for tornadoes. We rarely see them, especially not at this time of year (unless in conjunction with a hurricane or strong TS, of course). To read in the local WU forecast that "some thunderstorms may be severe with damaging winds and tornadoes" causes me to double-take.
Member Since: July 16, 2007 Posts: 0 Comments: 41
1707. barotropic
12:58 PM GMT on September 27, 2010
The SW loop shows a pretty defined broad circulation at low level at 19.9N and 86.0w. I think thats the area to watch.
Member Since: August 22, 2010 Posts: 0 Comments: 652
1706. beell
12:42 PM GMT on September 27, 2010
Quoting OctaviaStreet:
You're doing better than we are here in the Charleston area, Patrap. Tstorms and downpours waking us from a sound sleep, some flooding in the usual suspect spots--and the forecast is for more of the same plus maybe some tornadoes this afternoon and evening.

Dropped in to see if anyone was remarking on our weather--would appreciate any input on that tornadoes forecast.


Amateur guess for greatest tornado threat would be along a SW/NE line over central SC and NC this afternoon. Pretty much smack in the middle of the SPC 5% tornado risk area.

The real deal:



DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0724 AM CDT MON SEP 27 2010

VALID 271300Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS THROUGH TONIGHT FROM N FL/SE GA
INTO THE MID ATLANTIC REGION...

...SE ATLANTIC AND MID ATLANTIC REGIONS THROUGH TONIGHT...
A HIGH-AMPLITUDE PATTERN IS IN PLACE OVER THE CONUS THIS MORNING
WITH A RIDGE OVER THE ROCKIES AND A CLOSED LOW OVER NRN MS. THE MS
CLOSED LOW WILL EJECT NEWD TO THE SRN/CENTRAL APPALACHIANS BY
TONIGHT AND EVOLVE INTO MORE OF AN OPEN WAVE...IN RESPONSE TO AN
UPSTREAM TROUGH DIGGING SSEWD FROM ERN ND/MN. AT THE SURFACE...A
WEAK LOW INVOF THE FL BIG BEND WILL DEVELOP NNEWD ALONG A
SLOW-MOVING WARM FRONT TO THE WRN CAROLINAS BY THIS EVENING...IN
ADVANCE OF THE EJECTING MS SHORTWAVE TROUGH.

A BROAD MOIST WARM SECTOR IS PRESENT FROM FL/GA NEWD ACROSS THE ERN
CAROLINAS TO THE CHESAPEAKE BAY AREA...WHERE BOUNDARY LAYER
DEWPOINTS OF 68-72 F ARE COMMON. THE MAGNITUDE OF INSTABILITY HAS
BEEN LIMITED IN THE WARM SECTOR THUS FAR AS A RESULT OF WIDESPREAD
CLOUDS/RAIN AND RELATED POOR MIDLEVEL LAPSE RATES...WHICH ARE
UNLIKELY TO IMPROVE THROUGH THE PERIOD. STILL...A CONTINUED INFLUX
OF LOW-MID 70S DEWPOINTS FROM JUST OFFSHORE...AND A FEW CLOUD
BREAKS...COULD ALLOW ADDITIONAL WEAK DESTABILIZATION IN THE LOW
LEVELS THROUGH THE DAY. THE OBSERVED AND FORECAST THERMODYNAMIC
PROFILES WILL FAVOR RELATIVELY WIDESPREAD THUNDERSTORM DEVELOPMENT
IN MULTIPLE BANDS ALONG AND E OF THE COLD FRONT THROUGH THIS
AFTERNOON/EVENING ACROSS GA AND THE CAROLINAS.

MEANWHILE...A GRADUAL INCREASE IN DEEP-LAYER FLOW AND RESULTANT
VERTICAL SHEAR IS EXPECTED TODAY IN PROXIMITY TO THE SURFACE LOW AND
TRAILING COLD FRONT...AS THE MIDLEVEL TROUGH EJECTS NEWD. THE
OBSERVED UNIDIRECTIONAL SSWLY WIND PROFILES ARE LIKELY TO PERSIST
THROUGH THE DAY IN THE WARM SECTOR...WITH ONLY A MODEST INCREASE IN
THE LLJ EXPECTED UNTIL LATER TONIGHT ACROSS VA/PA WHEN THE PRIMARY
SURFACE LOW BEGINS TO DEEPEN MORE RAPIDLY TOWARD WRN PA. FORECAST
HODOGRAPHS APPEAR SUPPORTIVE OF EMBEDDED SUPERCELLS /ESPECIALLY ON
THE FRONT IN ADVANCE OF THE SURFACE LOW/...AS WELL AS BOWING
SEGMENTS WITHIN THE LARGER CONVECTIVE LINES/CLUSTERS. DAMAGING GUSTS
AND A FEW TORNADOES WILL BE POSSIBLE IN THE MOIST AND WEAKLY
UNSTABLE WARM SECTOR THROUGH TONIGHT.
Member Since: September 11, 2007 Posts: 142 Comments: 16478
1705. WxLogic
12:41 PM GMT on September 27, 2010
Quoting TampaTom:
Are there any forecasts for the cold front entering Florida?

So far, I've seen on the NWS Ruskin site that they are expecting it to advance to a line running from say Fort Myers up to Cocoa Beach...

Any idea how strong it will stay, will there be a reinforcing shot of cold air behind it? Needless to say, this will have a major impact on the path any proto-Nichole takes to the north...


Currently the Mid to Upper level low over MS/AL should starting cutting off in the next 12 to 24 hours. This will allow it to meander across the a region encompassing MS/AL/GA. The associated "cold" front which associated air mass has modified quite a bit should stall across the NFL area. Don't expect it to clear through the state completely and taking all the moisture away for the time being, but in my opinion a line from KFMY to KJAX should be a good divisor of the Wet pattern to the E and drier to the W.

Of course all this will be dependent on the strength and position of the cuff off low as a further W position will favor a wetter pattern for the FL Peninsula and N across the E CONUS and a more E position will favor E FL Peninsula and most of the wet pattern staying offshore up to the E CONUS Coast.
Member Since: August 14, 2008 Posts: 4 Comments: 4965
1704. medic2luv
12:31 PM GMT on September 27, 2010
I'm not a doom caster by any means, but I am wondering, is there a potential for any type of rapid formation possible with this "disturbance"?
Member Since: August 13, 2007 Posts: 0 Comments: 189
1703. 7544
12:29 PM GMT on September 27, 2010
yeap its starting to form and is blowing up at a good speed now if we can get a invest tag that would help so fla to be on alert as it would show the track but i think we all know where its going coffee time
Member Since: May 6, 2007 Posts: 0 Comments: 6750
1701. TampaTom
12:27 PM GMT on September 27, 2010
Are there any forecasts for the cold front entering Florida?

So far, I've seen on the NWS Ruskin site that they are expecting it to advance to a line running from say Fort Myers up to Cocoa Beach...

Any idea how strong it will stay, will there be a reinforcing shot of cold air behind it? Needless to say, this will have a major impact on the path any proto-Nichole takes to the north...
Member Since: June 20, 2005 Posts: 22 Comments: 1052
1700. MsBlanch
12:26 PM GMT on September 27, 2010
Amen to that!

Quoting Patrap:


Always a good thang .
Member Since: August 27, 2006 Posts: 0 Comments: 103
1699. KeysieLife
12:26 PM GMT on September 27, 2010
Morning peeps!

Man, what a great weekend for thunderstorms down here. Looks like Matthew put some leftovers on the stove and the pot's about to boil over...the convection is popping right now!
Member Since: September 10, 2010 Posts: 3 Comments: 409
1698. matilda101
12:24 PM GMT on September 27, 2010
Reguardless if a tropical cylcone develops in the NW Caribbean Sea in the next day or so southern Florida can expect copious amounts of moisture to channeled northward.

It appears that the western Caribbean Sea will be ripe for tropical formation for next 4 weeks.

I would not be surpised at all that when it is all said and done that we get 2-3 named storms out this area by November. Including a Wilma or Mitch like hurricane.
Member Since: August 28, 2005 Posts: 0 Comments: 290
1697. stillwaiting
12:23 PM GMT on September 27, 2010
Quoting dmaddox:
maybe the GFS was right all along:
....I was thinking the exact same thing,that area was festering offshore south of cozumel,max.....hope everyone has their popcorn
And soda,the actions about to start and the next 96hrs should've very intersting....thinking invest status by 11am,they might wait until the h get some data first
Member Since: October 5, 2007 Posts: 20 Comments: 4970
1696. nrtiwlnvragn
12:22 PM GMT on September 27, 2010
Quoting Abacosurf:
Looks like a twist right off of Cozumel.


Some indication of that from Cuban Radar but one could also say.... nah.
Member Since: September 23, 2005 Posts: 14 Comments: 11058
1695. KEEPEROFTHEGATE (Mod)
12:14 PM GMT on September 27, 2010
AOI/XX/XL
MARK
17.23N/81.19W
Member Since: July 15, 2006 Posts: 170 Comments: 53530
1694. OctaviaStreet
12:10 PM GMT on September 27, 2010
You're doing better than we are here in the Charleston area, Patrap. Tstorms and downpours waking us from a sound sleep, some flooding in the usual suspect spots--and the forecast is for more of the same plus maybe some tornadoes this afternoon and evening.

Dropped in to see if anyone was remarking on our weather--would appreciate any input on that tornadoes forecast.
Member Since: July 16, 2007 Posts: 0 Comments: 41
1693. tkeith
12:05 PM GMT on September 27, 2010
Quoting surfmom:
Perhaps quality over quantity?
wish I would have posted that comment.

cool air?......I has it :)

Member Since: November 1, 2004 Posts: 25 Comments: 8924
1692. beell
12:05 PM GMT on September 27, 2010
Quoting P451:
Looks like a Winter Storm!

6 Hour WV Loop:



It sure does!
Thanks for the loop.
Member Since: September 11, 2007 Posts: 142 Comments: 16478
1691. scott39
12:04 PM GMT on September 27, 2010
Hopefully the season will end with no hurricane strikes to the US.
Member Since: June 13, 2009 Posts: 0 Comments: 6751
1689. HurrMichaelOrl
11:56 AM GMT on September 27, 2010
So, we finally have a nearly stationary disturbance in the NW Carribean, over extremely deep, warm waters at the right time of year and yet indications are that it won't amount to much. This just goes to show that TCHP isn't worth anything if the atmospheric conditions aren't there and they just aren't for the most part this year.
Member Since: July 13, 2007 Posts: 0 Comments: 1099
1687. srada
11:55 AM GMT on September 27, 2010
Quoting mcluvincane:


Ecmwf is out to lunch. Gfs, nogaps and cmc look more credible at this point in time


Our local NWS in NC is going with the ECWMF and not the GFS

BUT CLOSE PROXIMITY TO THE FRONT COULD LEAD TO LARGE
FLUCTUATIONS IN WIND DIRECTION. GRADIENT SUGGESTS SPEEDS NO GREATER
THE 15 KT...THOUGH BRIEF PERIODS OF SPEEDS NEAR 20 KT ARE POSSIBLE
IF ANY SURFACE WAVES DEVELOP ALONG THE BOUNDARY. GFS CONTINUES TO
MOVE DEEPENING LOW IN FROM THE SOUTH LATE IN THE PERIOD...BUT NOT
READY TO BELIEVE IT. FAVOR THE ECMWF SOLUTION WHICH HAS A MUCH
WEAKER WAVE AND RESULTS IN SPEEDS JUST SHORT OF SCA THRESHOLDS WED
NIGHT. SEAS IN THE 3 TO 5 FT RANGE...HIGHEST TUE MORNING/AFTERNOON.
Member Since: August 17, 2006 Posts: 1 Comments: 772
1686. scott39
11:54 AM GMT on September 27, 2010
Quoting P451:


According to the HPC by day 6 it should be 2/3rds down the peninsula. South of Tampa, north of Naples. It should kick out to sea rather quickly whatever does form in the NW Caribbean and potentially affect South Florida.
Thanks
Member Since: June 13, 2009 Posts: 0 Comments: 6751
1683. barotropic
11:48 AM GMT on September 27, 2010
Quoting barotropic:


Looks like a low level broad circulation in that are which can be seen well with the shortwave loop (speed up and zoom in).
Link


Just in case here is Link to shortwave. Zoom in and speed up to see circ off cozumel.
Member Since: August 22, 2010 Posts: 0 Comments: 652
1682. barotropic
11:46 AM GMT on September 27, 2010
Quoting Abacosurf:
Looks like a twist right off of Cozumel.


Looks like a low level broad circulation in that are which can be seen well with the shortwave loop (speed up and zoom in).
Link
Member Since: August 22, 2010 Posts: 0 Comments: 652
1681. Patrap
11:46 AM GMT on September 27, 2010
Quoting surfmom:
Perhaps quality over quantity?


Always a good thang .
Member Since: July 3, 2005 Posts: 423 Comments: 127805
1680. WarEagle8
11:45 AM GMT on September 27, 2010
Quoting scott39:
Goodmorning Floridians

Good beautiful Monday morning from delightful Dunedin, Florida! War Eagle! Tigers are #10!
Member Since: August 19, 2008 Posts: 0 Comments: 126
1679. surfmom
11:45 AM GMT on September 27, 2010
Quoting barotropic:
boy is this blog less active than what it used to be. Significantly less posting.
Perhaps quality over quantity?
Member Since: July 18, 2007 Posts: 30 Comments: 26536
1678. scott39
11:43 AM GMT on September 27, 2010
Quoting P451:
Getting much needed soaking rain in NJ this morning.

A little OT but a serious flooding event is unfolding in Wisconsin: Link

And then we have our WV Imagery of the region: 12 hour Loop. A lot of moisture in the Caribbean however there is nothing organized. It will take a day or two of festering for something to really spin up I would think. We also just hit DMax in the region so let us see how this convection evolves as we start heading back towards DMin throughout the day - will it persist or will it wane with the diurnal cycle?





How deep is that trough forecasted to dip down in FL?
Member Since: June 13, 2009 Posts: 0 Comments: 6751
1676. Abacosurf
11:40 AM GMT on September 27, 2010
Quoting Patrap:
GOM IR Loop dee Loop


Looks like a twist right off of Cozumel.
Member Since: August 28, 2008 Posts: 0 Comments: 305
1674. scott39
11:38 AM GMT on September 27, 2010
Quoting scott39:
Nice in LA too!
LAL that is
Member Since: June 13, 2009 Posts: 0 Comments: 6751
1673. scott39
11:36 AM GMT on September 27, 2010
Quoting Patrap:
Schweeeeeeett..


Current Conditions

Uptown, New Orleans, Louisiana (PWS)
Updated: 1 min 13 sec ago
Partly Cloudy
70.0 °F
Partly Cloudy
Humidity: 80%
Dew Point: 64 °F
Wind: 3.5 mph from the North
Wind Gust: 8.7 mph

Nice in LA too!
Member Since: June 13, 2009 Posts: 0 Comments: 6751
1672. Patrap
11:36 AM GMT on September 27, 2010
GOM IR Loop dee Loop


Member Since: July 3, 2005 Posts: 423 Comments: 127805
1671. 7544
11:36 AM GMT on September 27, 2010
looks south of cuba looks like yesterdays nam could be right 96l latter today this could ramp up fast as we see it buliding lots of conv. now as it should move north no shear in the fla straights no dry air this could get stronger as it get drawn north to so fla dont let your gaurd down keep two on eyes on system developing right now one
Member Since: May 6, 2007 Posts: 0 Comments: 6750
1670. southbeachdude
11:36 AM GMT on September 27, 2010
Rain chance of 80% and 90% Tuesday and Wednesday for south Florida...
Member Since: July 29, 2005 Posts: 2 Comments: 696
1669. Patrap
11:35 AM GMT on September 27, 2010
Schweeeeeeett..


Current Conditions

Uptown, New Orleans, Louisiana (PWS)
Updated: 1 min 13 sec ago
Partly Cloudy
70.0 °F
Partly Cloudy
Humidity: 80%
Dew Point: 64 °F
Wind: 3.5 mph from the North
Wind Gust: 8.7 mph

Member Since: July 3, 2005 Posts: 423 Comments: 127805
1667. scott39
11:32 AM GMT on September 27, 2010
Goodmorning Floridians
Member Since: June 13, 2009 Posts: 0 Comments: 6751
1666. QMiami
11:31 AM GMT on September 27, 2010
Member Since: May 12, 2010 Posts: 0 Comments: 125
1664. barotropic
11:28 AM GMT on September 27, 2010
boy is this blog less active than what it used to be. Significantly less posting.
Member Since: August 22, 2010 Posts: 0 Comments: 652
1663. blsealevel
11:28 AM GMT on September 27, 2010
Ok, what's with the three white dots in the gulf?



Link
Member Since: August 23, 2008 Posts: 0 Comments: 1918
1662. aislinnpaps
11:26 AM GMT on September 27, 2010
Well, I'm off to work as well, my classroom awaits me. Have a great Monday everyone!
Member Since: August 22, 2009 Posts: 0 Comments: 3115
1661. aislinnpaps
11:20 AM GMT on September 27, 2010
hmmm, kinda sad day when you think of the mid-eighties as 'cool'.
Member Since: August 22, 2009 Posts: 0 Comments: 3115
1660. weatherwart
11:19 AM GMT on September 27, 2010
Quoting hydrus:
NWS has a low right over South Florida on day 6...


Oh yeah. My local mets are saying that by week's end, an area of low pressure bringing heavy rains, some wind, but not the scary hurricane scenario. You know as well as I, all that could change. Day 6 models and all...
Member Since: August 18, 2008 Posts: 0 Comments: 884
1659. barotropic
11:19 AM GMT on September 27, 2010
Some good news in that It appears that overall the GFS has backed off some of the activity for florida, at least on this run. Though not real important, the intensity of a couple of the systems is reduced and most notable is the lack of a system (previously a hurricane) towards the end of the run.

Member Since: August 22, 2010 Posts: 0 Comments: 652
1658. blsealevel
11:18 AM GMT on September 27, 2010
Member Since: August 23, 2008 Posts: 0 Comments: 1918

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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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