[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 242330
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT OCT 24 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE REMAINS TILTED FROM 22N38W TO 12N40W MOVING NW
5-10 KT. WAVE IS AT THE LEADING EDGE OF A MAXIMUM IN TOTAL
PRECIPITABLE WATER WITH SATELLITE DERIVED WINDS SHOWING A
CYCLONIC CURVATURE ALONG THE WAVE AXIS. IN SPITE OF THE
ABUNDANCE OF MOISTURE THERE IS NO ASSOCIATED DEEP CONVECTION
WITH SOME ISOLATED SHOWERS WITHIN 120 NM E OF THE WAVE AXIS N OF
20N.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N13W 7N24W 9N38W THEN ALONG
12N53W 10N62W. ITCZ AXIS IS BEING DISTORTED BY THE TROPICAL WAVE
AND A 1010 MB LOW NEAR 12N50W WITH A SHORT SURFACE TROUGH
EXTENDING THROUGH THE LOW FROM 10N-15N WITH SCATTERED SHOWERS
AND POSSIBLE ISOLATED THUNDERSTORMS FROM 12N-14N BETWEEN 48W-51W.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 120
NM EITHER SIDE OF THE ITCZ FROM 17W-31W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 2N-11N BETWEEN
30W-44W.

...DISCUSSION...

GULF OF MEXICO...
THE COLD FRONT IS BEGINNING TO STALL OVER THE S GULF WHILE
CONTINUING TO MOVE SLOWLY E EXTENDING ACROSS THE FLORIDA
PENINSULA FROM JACKSONVILLE TO TAMPA INTO THE SE GULF TO 23N88W
THEN STATIONARY ALONG 21N93W THEN S INTO THE BAY OF CAMPECHE TO
19N95W. THIS FRONT IS LOSING ITS UPPER LEVEL SUPPORT AS A SECOND
DEEP LAYERED TROUGH IS MOVING ACROSS THE CENTRAL PLAIN STATES.
THE DRY STABLE AIRMASS THAT WAS BEHIND THE FRONT IS BEGINNING TO
GIVE WAY AS TROPICAL MOISTURE IS BEING DRAWN NE ACROSS MEXICO
AND THE GULF. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER
THE SW GULF S OF 22N W OF 90W AND E OF A LINE FROM CUBA NEAR
23N83W TO OVER THE FLORIDA PENINSULA TO NEAR DAYTONA BEACH
COMPLIMENTS OF AN UPPER LOW OVER THE W ATLC/CARIBBEAN AND A
SURFACE TROUGH OVER THE BAHAMAS. THE COLD FRONT IS EXPECTED TO
STALL LATER TONIGHT OVER THE SE GULF AND DISSIPATE ON MON.

CARIBBEAN SEA...
A SURFACE TROUGH...REMNANTS OF A SURFACE LOW...EXTENDS ACROSS
THE SW CARIBBEAN FROM PANAMA NEAR 9N79W TO OFF THE COAST OF
NICARAGUA NEAR 14N83W. SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS ARE WITHIN 90 NM OF THE TROUGH AXIS. A LARGE UPPER
LOW IS CENTERED NEAR THE CAYMAN ISLANDS COVERING THE CARIBBEAN N
OF 13N BETWEEN 72W-87W WITH DRY AIR AND MODERATE/STRONG
SUBSIDENCE COVERING THE NW CARIBBEAN AND THUS CLEAR SKIES FOR
THAT AREA. AN UPPER RIDGE IS ANCHORED OVER E VENEZUELA COVERING
THE E CARIBBEAN ACROSS THE LESSER ANTILLES PROVIDING DIFFLUENCE
ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
SOUTH AMERICA TO OVER THE GREATER ANTILLES BETWEEN 70W-77W.
THE E CARIBBEAN IS UNDER MOSTLY CLEAR SKIES THIS EVENING WITH
SMALL FAST MOVING ISOLATED SHOWERS MAINLY N OF 14N E OF 70W.

ATLANTIC OCEAN...
THE LARGE UPPER LOW CENTERED IN THE NW CARIBBEAN COVERS THE W
ATLC S OF 28N W OF 72W SUPPORTING A SURFACE TROUGH THAT EXTENDS
FROM 26N79W TO THE N COAST OF CUBA NEAR 22N78W AND GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 27N W OF 74W. AN
UPPER HIGH IS JUST TO THE E ANCHORED NEAR 30N68W PROVIDING
DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS N OF 27N FROM 72W-78W. A SWATH OF STRONG
SUBSIDENCE AND DRY STABLE AIR IS ACROSS THE CENTRAL ATLC WITHIN
150/200 NM OF LINE FROM 26N46W 25N62W TO 34N69W THUS LIMITING
SHOWER ACTIVITY. A SURFACE RIDGE IS BUILDING S OVER THE
REMAINDER OF THE W ATLC W OF 50W ANCHORED BY A 1028 MB HIGH OFF
THE CANADIAN MARITIMES. BROAD UPPER TROUGH IS OVER THE CENTRAL
ATLC N OF 24N FROM 30W-50W SUPPORTING A COLD FRONT ALONG THE N
PERIPHERY OF THE REGION THROUGH 32N43W TO 31N47W THEN
DISSIPATING TO 31N53W AND ISOLATED SHOWERS WITHIN 60 NM E OF THE
COLD FRONT.

$$
WALLACE



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