[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 110029
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 10 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0015 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 57W/58W SOUTH OF 17N
MOVING WEST 15 KT. WIDELY SCATTERED MODERATE SHOWERS TO ISOLATED
STRONG THUNDERSTORMS IN THE ATLANTIC OCEAN NOW FROM 9N TO 14N
BETWEEN 57W AND 60W/61W ARE STILL IN AN AREA OF UPPER LEVEL
DIFFLUENT FLOW. UPPER LEVEL FLOW ANTICYCLONIC FLOW AROUND
AN ANTICYCLONIC CIRCULATION CENTER NEAR 15N54W COVERS THE AREA
FROM 10N TO 22N BETWEEN 38W AND 60W.

THE 10/1800 UTC SURFACE MAP ANALYSIS SHOWS A CARIBBEAN SEA
TROPICAL WAVE ALONG 70W/71W SOUTH OF 20N. THIS SAME WAVE WAS
ALONG 60W/61W SOUTH OF 20N AT 09/1800 UTC...IN PART BASED ON
A SMALL LOW TO MIDDLE LEVEL CYCLONIC SWIRL OF CLOUDS NEAR 19N.
IT WAS BELIEVED 24 HOURS AGO THAT THIS SWIRL STILL WAS SOMEHOW
ASSOCIATED WITH THE WAVE. THE SWIRL IS THE REMNANT OF A SURFACE
LOW PRESSURE CENTER FROM A FEW DAYS AGO AS THE WAVE MADE ITS WAY
WESTWARD FROM 50W. THE SWIRL FROM 24 HOURS AGO WAS NEAR 21N63W
AT 10/1800 UTC. IT IS POSSIBLE THAT THE SWIRL FROM 24 HOURS AGO
REALLY HAD NO DIRECT RELATIONSHIP TO THE WAVE'S POSITION
YESTERDAY AND THAT IT CONTINUES TO HAVE NO CONNECTION TO THE
WAVE TODAY. RAWINSONDE DATA FROM THE SURFACE TO ROUGHLY 800 MB
FOR FRENCH GUIANA...TRINIDAD...AND GUADELOUPE FOR THE LAST
2 TO 3 DAYS SHOW EVIDENCE OF WINDS THAT MAY BE ASSOCIATED
WITH A TROPICAL WAVE. MY PERSONAL OPINION IS THAT THE WAVE AT
70W/71W MOVING WEST 10 KT IS ABOUT 5 TO 6 DEGREES OF LONGITUDE
TOO FAR TO THE WEST. THIS WAVE MAY HAVE TO BE RE-LOCATED AT
11/0000 UTC. AN UPPER LEVEL RIDGE EXTENDS FROM THE SOUTHWESTERN
GULF OF MEXICO ACROSS THE YUCATAN PENINSULA INTO THE NORTH
CENTRAL CARIBBEAN SEA AND ACROSS THE BAHAMAS AND BEYOND INTO
THE ATLANTIC OCEAN.

...THE ITCZ...
10N14W 6N32W 10N50W 10N57W 10N59W 10N69W. ISOLATED MODERATE
SHOWERS AND BROKEN MULTILAYERED CLOUDS WITHIN 120 TO 180 NM
ON EITHER SIDE OF 8N19W 5N37W 10N49W 14N54W.

DISCUSSION...
THE GULF OF MEXICO...
A DEEP LAYER TROUGH PASSES THROUGH 31N77W IN THE ATLANTIC OCEAN
ACROSS FLORIDA NEAR LAKE OKEECHOBEE TOWARD THE YUCATAN CHANNEL.
DRY AIR/SUBSIDENCE ON WATER VAPOR IMAGERY COVERS VIRTUALLY THE
ENTIRE GULF OF MEXICO EXCEPT FOR MAYBE THE SOUTHWESTERN CORNER
OF THE AREA...WITH CLOUDS AND SHOWERS FROM THE YUCATAN PENINSULA
LOW PRESSURE CENTER...AND THE SOUTHEASTERN WATERS. THE COLD
FRONT STRETCHES FROM NORTHEASTERN FLORIDA TO THE CENTRAL GULF
WATERS TO THE MEXICO COAST NEAR 24N98W.

THE CARIBBEAN SEA...
AN UPPER LEVEL TROUGH STRETCHES FROM THE NORTHEASTERN CORNER OF
THE AREA TO THE NORTH CENTRAL COAST OF VENEZUELA. THE AMOUNT OF
DRY AIR/SUBSIDENCE APPEARS TO BE SHRINKING IN SIZE AS UPPER
LEVEL MOISTURE IS MOVING ACROSS THE AREA OF THE TROUGH FROM THE
EAST AND WEST. AN UPPER LEVEL RIDGE IS IMMEDIATELY TO THE EAST
OF THE EASTERN CARIBBEAN SEA ISLANDS. UPPER LEVEL ANTICYCLONIC
FLOW COVERS THE REST OF THE AREA WEST OF THE TROUGH. A DEEP LAYER
TROUGH IS APPROACHING THE NORTHWESTERN CORNER OF THE AREA FROM
THE GULF OF MEXICO. ONE LOW LEVEL CYCLONIC CIRCULATION CENTER
ON TOP OF THE YUCATAN PENINSULA AND ANOTHER ONE JUST SOUTH OF
CUBA ALONG 80W AND ACCOMPANYING CYCLONIC FLOW UNDER THE UPPER
LEVEL ANTICYCLONIC FLOW ARE HELPING THE DEVELOPMENT OF SCATTERED
MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS FROM 15N TO 18N
BETWEEN 76W AND 80W...IN SOUTHERN HAITI AND THE NORTHERN COAST
OF THE DOMINICAN REPUBLIC...AND SOUTH OF CUBA FROM 19N TO LAND
BETWEEN 77W AND 82W. THE POSITION OF THE TROPICAL WAVE ALONG
70W/71W MAY BE OR MAY NOT BE AS ACCURATE AS POSSIBLE.

THE ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM 32N59W TO A CYCLONIC
CIRCULATION CENTER NEAR 29N63W TO 27N67W. A SURFACE TROUGH
EXTENDS FROM 30N55W TO A 1011 MB LOW PRESSURE CENTER NEAR 29N57W
TO 26N64W. STRONG SHOWERS/THUNDERSTORMS FROM 26N TO 28N BETWEEN
53W AND 55W...AND FROM 29N TO 30N BETWEEN 54W AND 55W. ISOLATED
MODERATE SHOWERS WITHIN 15 NM ON EITHER SIDE OF 23N61W 25N56W...
AND 26N50W 25N45W 27N40W. A MIDDLE TO UPPER LEVEL TROUGH EXTENDS
FROM A CYCLONIC CIRCULATION CENTER NEAR 32N28W TO 30N30W TO
A SECOND CYCLONIC CENTER NEAR 27N34W TO 23N35W. A SURFACE RIDGE
PASSES THROUGH 32N28W TO 26N38W TO 24N52W. A SEPARATE DEEP LAYER
TROUGH JUST TO THE WEST OF THE 32N28W 23N35W TROUGH IS
PROPELLING A COLD FRONT THAT STILL IS NORTH OF THE AREA TO THE
EAST. AN UPPER LEVEL RIDGE REACHES 34N51W FROM 24N54W. IT IS
POSSIBLE THAT THIS RIDGE IS PART OF THE SAME FEATURE WITH THE
15N54W ANTICYCLONIC CENTER. A DEEP LAYER EASTERN ATLANTIC OCEAN
TROUGH RUNS FROM A CYCLONIC CIRCULATION CENTER NEAR 32N16W TO
24N18W TO THE CAPE VERDE ISLANDS...TO 12N31W TO 8N37W.
A 1012 MB LOW PRESSURE CENTER IS NEAR 31N15W. BROKEN TO OVERCAST
MULTILAYERED CLOUDS AND POSSIBLE SHOWERS FROM 30N TO 33N BETWEEN
13W AND 18W.

$$
MT




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