[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 100018
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 09 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 2345 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 48W/49W SOUTH OF 14N
MOVING WEST 15 KT. A BIT OF CYCLONIC MOTION IN THE LOW CLOUDS
ON THE 09/1800 VISIBLE IMAGERY. SMALL CELLS OF SHOWERS AND
THUNDERSTORMS FROM 7N TO 8N BETWEEN 49W AND 50W. OTHER ITCZ
SHOWERS AND THUNDERSTORMS NEAR THE WAVE WEAKENED WITH WARMING
CLOUD TOP TEMPERATURES DURING THE LAST 4 TO 5 HOURS.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 60W/61W SOUTH OF 20N
MOVING WEST 10 KT. A SMALL LOW TO MIDDLE LEVEL CYCLONIC SWIRL
OF CLOUDS IS NEAR 19N ALONG THE WAVE IN THE NORTHEASTERN CORNER
OF THE AREA. THIS SWIRL IS THE REMNANT OF A SURFACE LOW PRESSURE
CENTER FROM A FEW DAYS AGO AS THE WAVE MADE ITS WAY WESTWARD
FROM 50W. NO DEEP CONVECTIVE PRECIPITATION IS NEAR THIS FEATURE.
AN UPPER LEVEL TROUGH IS ALONG 11N60W 17N56W 20N54W SURROUNDED
BY MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE.

...THE ITCZ...
10N14W 8N30W 10N49W 10N52W 10N61W. ISOLATED MODERATE SHOWERS
AND BROKEN MULTILAYERED CLOUDS WITHIN 180 NM ON EITHER SIDE OF
10N14W 6N30W 7N40W. SCATTERED MODERATE TO STRONG SHOWERS/
THUNDERSTORMS ARE FROM 6N TO 9N BETWEEN 41W AND 44W. STRONG
SHOWERS/THUNDERSTORMS IN THE ATLANTIC OCEAN FROM 12N TO 15N
BETWEEN 53W AND 58W ARE IN AN AREA OF UPPER LEVEL DIFFLUENT
FLOW. UPPER LEVEL FLOW ANTICYCLONIC FLOW AROUND A RIDGE COVERS
THE AREA FROM 10N TO 21N BETWEEN 38W AND 60W.

DISCUSSION...

THE GULF OF MEXICO...
A COLD FRONT APPROACHES THE NORTHERN GULF COAST...THROUGH
GEORGIA AND ALABAMA INTO SOUTHEASTERN LOUISIANA. THE FRONT
BECOMES STATIONARY FROM LOUISIANA INTO EAST TEXAS TO SOUTH
CENTRAL TEXAS. A MIDDLE TO UPPER LEVEL TROUGH PASSES THROUGH
EXTREME SOUTHEASTERN LOUISIANA TO THE WEST CENTRAL GULF WATERS
TO THE MEXICO COAST NEAR 23N98W. A SECOND MIDDLE TO UPPER LEVEL
TROUGH ENTERS THE EAST-CENTRAL TO SOUTHEASTERN GULF WATERS FROM
THE ATLANTIC OCEAN ACROSS THE BAHAMAS. DRY AIR/SUBSIDENCE IS
WEST OF THE WESTERN GULF TROUGH AND EAST OF 87W. AN UPPER LEVEL
RIDGE IS NORTH OF 23N BETWEEN THE TWO AREAS OF CYCLONIC FLOW.
CELLS OF STRONG SHOWERS/THUNDERSTORMS ARE IN THE SOUTHWESTERN
CORNER OF THE AREA...SOUTH OF 22N WEST OF 94W. THIS
PRECIPITATION IS TAKING PLACE CLOSE TO THE BASE OF THE WESTERN
GULF OF MEXICO TROUGH AND SOMEWHAT IN AN AREA OF SOME UPPER
LEVEL DIFFLUENT FLOW.

THE CARIBBEAN SEA...
A 1004 MB NORTHWESTERN CARIBBEAN SEA LOW PRESSURE CENTER
WAS NEAR 18.5N 87.5W...IN THE NORTHWESTERN PART OF THE
BANCO CHINCHORRO ABOUT 15 NM EAST OF THE SOUTHEASTERN YUCATAN
PENINSULA AT 09/1800 UTC. THE LOW CENTER SINCE THEN HAS MOVED
INLAND ALONG THE EAST COAST OF THE YUCATAN PENINSULA...ABOUT
60 MILES NORTH-NORTHEAST OF CHETUMAL MEXICO. THIS LOW CENTER
IS DRIFTING WEST-NORTHWESTWARD AND IS EXPECTED TO REMAIN NEAR
OR OVER THE YUCATAN PENINSULA DURING THE NEXT COUPLE OF DAYS.
THIS LOW PRESSURE CENTER MAY PRODUCE LOCALLY HEAVY RAINFALL
IN SECTIONS OF THE YUCATAN PENINSULA AND BELIZE EVEN THOUGH
DEVELOPMENT OF THIS LOW INTO A TROPICAL CYCLONE IS NOT EXPECTED.
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE IN NORTHERN
BELIZE...AND IN SOUTHERN AND SOUTHWESTERN SECTIONS OF THE
YUCATAN PENINSULA WIDELY SCATTERED TO SCATTERED MODERATE
SHOWERS/ISOLATED STRONG THUNDERSTORMS ARE ELSEWHERE FROM
17N TO 22N BETWEEN 83W AND 91W IN THE NORTHWESTERN CARIBBEAN
SEA WATERS AND INLAND ACROSS THE YUCATAN PENINSULA. AN UPPER
LEVEL TROUGH AND CYCLONIC CIRCULATION CENTER ARE APPROACHING
THE NORTHEASTERN CORNER FROM THE ATLANTIC OCEAN. THE TROUGH
REACHES THE NORTHEASTERN CORNER OF VENEZUELA. DRY AIR/SUBSIDENCE
IS ON THE WESTERN SIDE OF THIS SYSTEM HELPING TO BRING NO DEEP
CONVECTIVE PRECIPITATION TO THE AREA. MIDDLE LEVEL ANTICYCLONIC
FLOW IS BETWEEN THE EASTERNMOST TROUGH AND 70W. MIDDLE LEVEL
CYCLONIC FLOW IS UNDERNEATH AN UPPER LEVEL RIDGE BETWEEN 70W
AND CENTRAL AMERICA AND THE YUCATAN PENINSULA. A MIDDLE LEVEL
CYCLONIC CIRCULATION CENTER IS ON TOP OF THE YUCATAN PENINSULA
WITH AN UPPER LEVEL RIDGE ON TOP OF THAT CYCLONIC CENTER. CELLS
OF STRONG SHOWERS/THUNDERSTORMS ARE IN NORTHERN COASTAL SECTIONS
OF THE DOMINICAN REPUBLIC AND SOUTH OF CUBA FROM 18N TO 20N
BETWEEN 78W AND 80W...IN SOME AMOUNT OF UPPER LEVEL DIFFLUENT
FLOW. OTHER AREAS OF SIMILAR STRONG PRECIPITATION ARE FROM 15N
TO 17N BETWEEN 71W AND 72W...AND FROM 16N TO 17N BETWEEN 76W AND
77W SOUTHEAST OF JAMAICA.

THE ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM 31N62W TO A CYCLONIC
CIRCULATION CENTER NEAR 27N68W...ACROSS THE NORTHERN BAHAMAS
INTO AND BEYOND THE STRAITS OF FLORIDA. DRY AIR/SUBSIDENCE IS
NORTH AND WEST OF 31N62W 25N70W 25N80W. A SURFACE TROUGH RUNS
FROM 28N62W TO A 1010 MB LOW PRESSURE CENTER NEAR 26N65W TO
24N70W. MODERATE TO SCATTERED STRONG SHOWERS/THUNDERSTORMS
WITHIN 15 TO 20 NM ON EITHER SIDE OF 25N64W 27N61W...AND WITHIN
A 30 NM RADIUS OF 27N58.5W. ISOLATED MODERATE SHOWERS FROM 23N
TO 25N BETWEEN 63W AND 68W. A MIDDLE TO UPPER LEVEL TROUGH
PASSES THROUGH 32N43W TO 27N47W. A DISSIPATING COLD FRONT PASSES
THROUGH 32N39W TO 30N41W. A TROUGH CONTINUES FROM 30N41W TO
23N53W. BROKEN TO OVERCAST MULTILAYERED CLOUDS WITH POSSIBLE
SHOWERS WITHIN 120 TO 180 NM ON EITHER SIDE OF LINE THROUGH
31N75W 28N40W 26N44W...AND WITHIN 75 NM ON EITHER SIDE OF
26N44W 25N49W 22N54W. A MIDDLE TO UPPER LEVEL EASTERN ATLANTIC
OCEAN TROUGH RUNS FROM A CYCLONIC CIRCULATION CENTER NEAR
33N14W...ACROSS THE CANARY ISLANDS TO 24N20W...TO A SECOND
CYCLONIC CENTER NEAR 20N22W TO 14N30W TO 11N36W.

$$
MT


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