[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 130001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI OCT 12 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 2315 UTC.

...SPECIAL FEATURE...
THE CENTER OF TROPICAL DEPRESSION FIFTEEN AT 12/2100 UTC IS NEAR
30.8N 49.5W MOVING NORTH 3 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1012 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 25 KT
WITH GUSTS TO 35 KT. PLEASE READ THE NATIONAL HURRICANE CENTER
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC
OR THE PUBLIC ADVISORY UNDER MIATCPAT5/WTNT35 KNHC FOR MORE
DETAILS. THE DEPRESSION HAS BECOME A TIGHT SWIRL OF LOW CLOUDS
WITH NO DEEP CONVECTION. IT APPEARS THAT IT IS WEAKENING RAPIDLY
TO A REMNANT LOW. THE SHEAR IS FORECAST TO INCREASE SIGNIFICANTLY
AND REGENERATION IS NOT ANTICIPATED. THE SYSTEM STILL MAY
PRODUCE INTERMITTENT BURSTS OF SHOWERS/THUNDERSTORMS BEFORE
DISSIPATION. THE DEPRESSION HAS BEEN MEANDERING AND ONLY A SMALL
NORTHWARD DRIFT IS ANTICIPATED DURING THE NEXT 12 TO 24 HOURS.

...TROPICAL WAVES...
A CARIBBEAN SEA TROPICAL WAVE IS ALONG 69W/70W SOUTH OF THE
EASTERN SECTION OF THE DOMINICAN REPUBLIC. A MIDDLE TO UPPER
LEVEL INVERTED TROUGH HAS BEEN MOVING NEARLY IN PHASE WITH
THIS WAVE FOR THE LAST FEW DAYS. ISOLATED MODERATE SHOWERS TO
LOCALLY STRONG THUNDERSTORMS FROM 11N TO 17N BETWEEN 62W AND 72W.
THE COMPARATIVELY COLDEST CLOUD TOP TEMPERATURES RANGED FROM
-70C TO -60C FROM 14N TO 15N BETWEEN 68W AND 69W.

...THE ITCZ...
12N16W 7N23W 7N40W 9N50W 11N69W. NUMEROUS STRONG SHOWERS AND
THUNDERSTORMS IN THE WESTERN TWO-THIRDS OF SIERRA LEONE IN
AFRICA. ISOLATED MODERATE SHOWERS FROM 3N TO 12N BETWEEN
10W AND 30W...AND FROM 3N TO 10N BETWEEN 30W AND 57W.

DISCUSSION...
THE GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL CYCLONIC FLOW COVERS THE GULF OF
MEXICO. THE TROUGH THAT IS RESPONSIBLE FOR THIS FLOW PASSES
THROUGH THE WESTERN FLORIDA PANHANDLE TO THE WEST CENTRAL GULF
WATERS TO THE SOUTHWESTERN CORNER OF THE AREA. DRY AIR/SUBSIDENCE
IS EVERYWHERE. HIGH CLOUDS HAVE ENCROACHED INTO THE SOUTHEASTERN
CORNER OF THE AREA FROM THE NORTHWESTERN CARIBBEAN SEA...FROM
THE SURFACE TROUGH THERE AND THE TWO SURFACE LOW PRESSURE
CENTERS ALONG THE TROUGH. THE SURFACE PRESSURE GRADIENT IN THE
GULF OF MEXICO IS WEAK. THE 1008 MB ISOBAR IS AROUND THE
NORTHWESTERN CARIBBEAN SEA LOW PRESSURE CENTERS IN THE
SOUTHEASTERN CORNER OF THE AREA. THE 1012 MB ISOBAR MOVES FROM
FLORIDA JUST EAST OF THE FLORIDA BIG BEND INTO THE NORTH CENTRAL
GULF WATERS TO NORTHEASTERN MEXICO JUST SOUTH OF THE DEEP SOUTH
OF TEXAS.

THE CARIBBEAN SEA...
A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION CENTER IS NEAR
JAMAICA. ANTICYCLONIC FLOW IS EVERYWHERE...EXCEPT FOR THE MIDDLE
TO UPPER LEVEL INVERTED TROUGH ON TOP OF THE 69W/70W TROPICAL
WAVE. A SURFACE TROUGH EXTENDS NORTHEASTWARD FROM A 1005 MB
NORTH CENTRAL GUATEMALA LOW PRESSURE CENTER TO A 1004 MB LOW
PRESSURE CENTER NEAR 19N87W AT THE NORTHERN EDGE OF THE BANCO
CHINCHORRO...TO CUBA NEAR 22N80W AND BEYOND INTO THE ATLANTIC
OCEAN. STRONG SHOWERS/THUNDERSTORMS ARE SOUTH OF 17N WEST OF 86W
INCLUDING IN THE GULF OF HONDURAS...FROM 20N TO 21.5N BETWEEN
83W AND 84W...OFF THE NORTHWESTERN JAMAICA COAST FROM 18N TO
19.5N BETWEEN 78.5W AND 79.5W...OFF THE SOUTHEASTERN CUBA COAST
FROM 19N TO 20N BETWEEN 75.5W AND 77W...AND ALONG THE HAITI/
DOMINICAN REPUBLIC BORDER NEAR 19N71.5W. THIS PRECIPITATION ALSO
IS OCCURRING IN THE AREA OF UPPER LEVEL DIFFLUENT FLOW...IN
RELATION TO THE MIDDLE TO UPPER LEVEL SOUTHWESTERLY FLOW THAT
IS ALONG AND NORTHWEST OF 31N68W 26N75W 22N86W. MIDDLE TO UPPER
LEVEL CYCLONIC FLOW RIGHT NOW IS IN THE ATLANTIC OCEAN FROM 10N
TO 16N BETWEEN 53W AND 60W...THAT MAY OR MAY NOT MOVE INTO THE
EASTERN CARIBBEAN SEA DURING THE NEXT FEW DAYS.

THE ATLANTIC OCEAN...
THE SOUTHERN END OF A COLD FRONT PASSES THROUGH 32N69W TO 30N71W
TO 27N77W TO THE SOUTHEASTERN FLORIDA COAST NEAR 26N80W. THE
DEEP LAYER TROUGH THAT SUPPORTS THIS TROUGH IS NORTH OF THE AREA.
DRY AIR/SUBSIDENCE IS NORTHWEST OF 32N67W TO 27N72W 26N80W.
MIDDLE TO UPPER LEVEL SOUTHWESTERLY WIND FLOW IS IN THIS AREA
OF DRY AIR/SUBSIDENCE. THE SURFACE TROUGH THAT ORIGINATES FROM
THE 1005 MB GUATEMALA LOW PRESSURE CENTER PASSES THROUGH CUBA
NEAR 22N80W TO THE BAHAMAS NEAR 23N75W TO 26N70W TO 31N66W.
SOME CLUSTERS OF STRONG SHOWERS/THUNDERSTORMS ARE FROM 23N TO
24N BETWEEN 73W AND 75W...FROM GRAND INAGUA TO THE TURKS AND
CAICOS AND FROM 22N TO 23.5N BETWEEN 70.5W AND 71.5W...FROM 23N
TO 26N BETWEEN 67W AND 69W...FROM 28N TO 30N BETWEEN 65.5W AND
67W...AND WITHIN A 15 TO 30 NM RADIUS OF 29N61.5W. A MIDDLE TO
UPPER LEVEL TROUGH STARTS NEAR 31N48W AND STRETCHES TO A
CYCLONIC CIRCULATION CENTER NEAR 24N52W...TO 17N57W TO 9N59W.
NO DEEP CONVECTIVE PRECIPITATION IS NEAR THIS TROUGH. UPPER
LEVEL NORTHERLY FLOW MOVES FROM 32N SOUTHWARD TO 17N BETWEEN AT
LEAST 40W AND 50W AS PART OF UPPER LEVEL ANTICYCLONIC FLOW AROUND
A RIDGE ROUGHLY ALONG 50W FROM 10N BEYOND 32N. A SURFACE FRONTAL
BOUNDARY IS ALONG 31N/32N BETWEEN 32W AND 45W. A RIDGE STRETCHES
FROM A 1019 MB HIGH PRESSURE CENTER NEAR 29N35W TO 23N47W TO THE
NORTHEASTERN CARIBBEAN SEA NEAR 19N64W. A 1010 MB LOW PRESSURE
CENTER STILL IS JUST OFF THE WESTERN EDGE OF THE CANARY ISLANDS.
ITS MIDDLE TO UPPER LEVEL SUPPORT IS A CYCLONIC CIRCULATION
CENTER OVER THE WATERS ABOUT 60 NM TO THE NORTH OF THE CANARY
ISLANDS. SCATTERED MODERATE SHOWERS FROM 30N TO 32N BETWEEN 7W
AND 11W FROM MOROCCO TO THE COASTAL WATERS. ISOLATED MODERATE
SHOWERS FROM 29N TO 30N BETWEEN 14W AND 16W.

$$
MT


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