[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE OCT 27 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0315 UTC FOR GOES-12 IMAGES...AND THROUGH 0515 UTC
FOR METEOSAT-8 IMAGES.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 16N23W ON TOP OF THE
CAPE VERDE ISLANDS...TO 12N25W TO 8N25W...MOVING WESTWARD 10 KT.
SHOWERS ARE POSSIBLE FROM THE AREA OF POSSIBLY-ITCZ-RELATED
PRECIPITATION NEAR 7N TO 17N BETWEEN 20W AND 27W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 56W/57W TO THE SOUTH
OF 17N MOVING WESTWARD 15 KT. AN UPPER LEVEL CYCLONIC
CIRCULATION CENTER HAS BEEN MOVING ACROSS THE VIRGIN ISLANDS
TO PUERTO RICO DURING THE LAST SIX HOURS. CYCLONIC FLOW AROUND
THIS CENTER COVERS THE CARIBBEAN SEA AND THE ATLANTIC OCEAN
FROM 10N TO 25N BETWEEN 53W AND HAITI. ISOLATED MODERATE SHOWERS
AND POSSIBLE THUNDERSTORMS COVER THE AREA FROM 14N TO 17N
BETWEEN 57W AND 61W. OTHER ISOLATED MODERATE SHOWERS ARE FROM
10N TO 21N BETWEEN 50W AND 57W.

...ITCZ...

FROM AFRICA NEAR 11N15W TO 12N24W TO 9N40W TO 9N55W. STRONG
SHOWERS AND THUNDERSTORMS ARE ALONG THE AFRICA COAST WITHIN
A 30 NM RADIUS OF 8N13W...AND IN CLUSTERS FROM 10N TO 12N
BETWEEN AFRICA AND 20W. SHOWERS ARE ELSEWHERE FROM 7N TO 13N
BETWEEN AFRICA AND 20W...FROM 7N TO 11N BETWEEN 30W AND 40W...
AND FROM THE EQUATOR TO 12N BETWEEN 40W AND 50W.

...DISCUSSION...

THE GULF OF MEXICO...
A DEEP LAYER TROUGH THAT IS MOVING THROUGH CENTRAL TEXAS AND
NORTHERN MEXICO SUPPORTS THE CURRENT COLD FRONT THAT PASSES
THROUGH SOUTHWESTERN LOUISIANA TO THE MEXICO GULF COAST NEAR
23N98W. A LARGE-SCALE UPPER LEVEL RIDGE IS IN THE CENTRAL GULF
OF MEXICO. MOSTLY UPPER LEVEL SOUTHWESTERLY WINDS ALSO COVER THE
AREA TO THE EAST OF THE APPROACHING TEXAS TROUGH. A SURFACE
TROUGH GOES FROM 28N86W INTO THE NORTHEASTERN YUCATAN PENINSULA.
IT IS POSSIBLE THAT THIS TROUGH IS A REMNANT OF THE DISSIPATED
FRONT FROM THE LAST FEW DAYS. A TROUGH REMAINS FROM THAT
FEATURE...FROM 31N79W TO 29N81W ALONG THE NORTHEASTERN FLORIDA
ATLANTIC OCEAN COAST. BROKEN TO OVERCAST MULTILAYERED CLOUDS
HAVE BEEN FORMING TO THE SOUTH OF 28N TO THE EAST OF 86W FOR
THE LAST FEW HOURS. PRECIPITATION IS POSSIBLE IN THIS AREA OF
CLOUDS.

THE CARIBBEAN SEA...
AN UPPER LEVEL RIDGE IS CENTERED OVER GUATEMALA NEAR 17N91W AND
CONTINUES TO PROVIDE DRY AIR AND SUBSIDENCE ALOFT OVER THE NW
CARIBBEAN W OF 84W AND OVER PORTIONS OF CENTRAL AMERICA.
HOWEVER...UPPER LEVEL DIFFLUENCE ON THE EASTERN PERIPHERY OF THE
UPPER LEVEL RIDGE IS GENERATING SCATTERED SHOWERS AND ISOLATED
TSTMS N OF 14N BETWEEN 78W-84W AND ACROSS PORTIONS OF CUBA. THIS
ACTIVITY EXTENDS S-SW ACROSS INTERIOR EASTERN HONDURAS...
NICARAGUA AND NORTHERN COSTA RICA. E OF 76W...AN UPPER LEVEL
TROUGH EXTENDS WESTWARD FROM AN UPPER LEVEL LOW CENTERED OVER
THE LEEWARD ISLANDS NEAR 17N60W. PRIMARILY DRY AIR ALOFT IS
NOTED ACROSS THE EASTERN CARIBBEAN ON WATER VAPOR IMAGERY.
MODERATE TRADE WINDS CONTINUE TO USHER IN ISOLATED LOW-LEVEL
SHOWERS E OF 74W THIS EVENING. ELSEWHERE...THE ITCZ AXIS EXTENDS
ACROSS PANAMA ALONG 8N AND IS GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS S OF 10N BETWEEN 77W-81W.

THE ATLANTIC OCEAN...
LARGE-SCALE UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA TO THE
NORTH OF 20N TO THE WEST OF 35W. THIS ANTICYCLONIC FLOW IS ON
TOP OF THE CYCLONIC FLOW THAT IS NEAR PUERTO RICO AND THE VIRGIN
ISLANDS...THAT ALSO COVERS PARTS OF THE ATLANTIC OCEAN. ONE AREA
OF A 700 MB-TO-500 MB VORTICITY MAXIMUM COVERS THE AREA ALONG
68W/69W NEAR 27N. CLOUDS ARE FROM 25N TO 29N BETWEEN 66W AND
71W. A SECOND AREA OF 700 MB-TO-500 MB VORTICITY MAXIMUM IS NEAR
27N54W. THIS FEATURE IS SPREADING CLOUDS FROM 25N TO 29N BETWEEN
50W AND 59W. AN EASTERN ATLANTIC OCEAN DEEP LAYER TROUGH EXTENDS
FROM A CYCLONIC CIRCULATION CENTER THAT IS NEAR 31N27W TO 26N29W
TO 21N35W. A SHEAR AXIS CONTINUES FROM 21N35W TO 21N42W AND
22N53W. THIS AXIS EVENTUALLY FEEDS INTO THE COMPARATIVELY LARGER
AREA OF CYCLONIC FLOW THAT IS MOVING AROUND THE VIRGIN ISLANDS
TO PUERTO RICO DURING THE LAST SIX HOURS. A DISSIPATING COLD
FRONT GOES FROM 32N21W TO 25N26W. POSSIBLE SHOWERS FROM 31N
TO 32N BETWEEN 22W AND 23W. A SURFACE RIDGE IS ALONG 25N32W
TO A 1023 MB HIGH PRESSURE CENTER THAT IS NEAR 31N49W...
TO A SECOND 1023 MB HIGH PRESSURE CENTER THAT IS NEAR 30N64W...
TO 29N73W.

$$
MT





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