[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 312355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 31 2012

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA INTO THE E TROPICAL
ATLC NEAR 13N16W CONTINUING ALONG 8N26W TO 9N35W. THE ITCZ
EXTENDS FROM 12N45W ALONG 8N53W TO 9N60W. SCATTERED STRONG
CONVECTION IS WITHIN 75/90 NM ON BOTH SIDES OF THE ITCZ BETWEEN
47W-50W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120 NM S
OF THE ITCZ BETWEEN 50W-55W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 90/120 NM OF LINE FROM 5N24W TO ACROSS THE
MONSOON TROUGH TO 10N27W AND WITHIN 90 NM N OF THE ITCZ BETWEEN
50W-54W. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION ARE
FROM 4N-10N BETWEEN 12W-20W...FROM 7N-10N BETWEEN 29W-34W...AND
FROM 7N-12N BETWEEN 55W-61W. A WEAK NEAR STATIONARY SURFACE
TROUGH EXTENDS FROM 14N38W TO 11N40W AND IS NOT PRODUCING ANY
SIGNIFICANT WEATHER. A SECOND SOMEWHAT STRONGER SURFACE TROUGH
IS TO THE E EXTENDING ALONG 26W FROM 10N-17N. ISOLATED SHOWERS
ARE WITHIN 90/120 NM EITHER SIDE OF THAT SURFACE TROUGH.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER TROUGH REMAINS OVER THE E HALF OF THE CONUS TO
OVER THE GULF AND INTO THE W ATLC. A SECOND SURGE IN THE FORM OF
A COLD FRONT EXTENDS FROM THE W ATLC TO ACROSS FLORIDA NEAR VERO
BEACH WHERE IT BECOMES STATIONARY AS IT ENTERS THE GULF S OF
TAMPA TO 29N86W. A SURFACE RIDGE CONTINUES TO DOMINATE THE GULF
ANCHORED BY A 1020 MB HIGH NEAR 24N89W. DRY UPPER AIR REMAINS
ACROSS THE GULF TO OVER THE W ATLC GIVING MOST OF THE GULF FAIR
WEATHER THIS EVENING. THE EXCEPTION IS OFF THE COAST OF TEXAS
AND MEXICO WHERE A BAND OF SCATTERED SHOWERS ARE WITHIN 120 NM
FROM CORPUS CHRISTI TEXAS TO TAMPICO MEXICO. THE FRONT WILL EXIT
THE GULF EARLY THU. SURFACE RIDGE WILL GRADUALLY WEAKEN AND
DRIFT SLOWLY SE THROUGH THU NIGHT THEN SHIFT NE INTO THE NE GULF
SAT.

CARIBBEAN SEA...
SW FLOW ALOFT DOMINATES THE CARIBBEAN W OF 70W. AN INVERTED
UPPER TROUGH COVERS THE SE CARIBBEAN WHILE AN UPPER RIDGE IS
ANCHORED OVER THE LEEWARD ISLANDS COVERING THE REMAINDER OF THE
CARIBBEAN. THIS UPPER RIDGE IS PROVIDING DIFFLUENCE ALOFT TO
GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM
OF LINE FROM 17N73W ACROSS HISPANIOLA TO 20N71W. THE UPPER
TROUGH OVER THE GULF OF MEXICO AND W ATLC EXTENDS A DISSIPATING
COLD FRONT OVER THE W ATLC BECOMING DISSIPATING STATIONARY AS IT
EXTENDS THROUGH THE WINDWARD PASSAGE CONTINUING ACROSS W JAMAICA
TO 18N81W. A SURFACE TROUGH IS IN THE CENTRAL CARIBBEAN
EXTENDING FROM 15N75W TO 11N76W WITH SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 11N-18N BETWEEN 73W-77W. THE MONSOON TROUGH
EXTENDS ACROSS THE SW CARIBBEAN FROM COLOMBIA NEAR 10N74W ALONG
11N76W CROSSING PANAMA INTO THE E PACIFIC REGION NEAR 9N79W WITH
SCATTERED SHOWERS S OF 11N E OF 80W. SURFACE TROUGH WILL
CONTINUE TO TRACK WESTWARD WITH A LOW PRESSURE EXPECTED TO FORM
ALONG THE TROUGH OVER THE SW CARIBBEAN THU NIGHT THROUGH SUN.

ATLANTIC OCEAN...
BROAD UPPER TROUGH THAT COVERS THE GULF OF MEXICO EXTENDS OVER
THE W ATLC N OF 27N W OF 70W SUPPORTING A DISSIPATING COLD FRONT
THAT ENTERS THE REGION NEAR 32N63W ALONG 25N67W BECOMING
DISSIPATING STATIONARY AS IT ENTERS THE CARIBBEAN THROUGH THE
WINDWARD PASSAGE. A SECOND SURGE COLD FRONT ENTERS THE W ATLC
NEAR 32N71W ALONG 29N75W ACROSS FLORIDA NEAR VERO BEACH BECOMING
STATIONARY IS IT ENTERS THE GULF OF MEXICO. A WEAK SURFACE
TROUGH IS TO THE E OF THE FRONT EXTENDING FROM 23N65W TO THE N
COAST OF THE DOMINICAN REPUBLIC NEAR 19N69W. THE UPPER RIDGE
ANCHORED OVER THE LEEWARD ISLANDS EXTENDS A RIDGE AXIS N TO
BEYOND 32N56W AND IS PROVIDING DIFFLUENCE ALOFT TO GENERATE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 150 NM OF LINE
FROM 21N67W TO 25N63W. AN UPPER TROUGH IS OVER THE E ATLC N OF
16N BETWEEN 20W-45W SUPPORTING A COMPLEX SYSTEM N OF THE
DISCUSSION AREA WITH A 992 MB SURFACE LOW NEAR 32N34W AND A
SURFACE TROUGH EXTENDING SW TO 24N47W. A COLD FRONT EXTENDS FROM
A 1005 MB LOW NEAR 32N7W ACROSS THE CANARY ISLANDS TO 26N20W
WHERE IT BECOMES STATIONARY ALONG 22N27W TO 17N35W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 23N BETWEEN 20W-39W AND
WITHIN 120 NM EITHER SIDE OF THE FRONT. THE SURGE COLD FRONT
WILL OVERTAKE THE EASTERN COLD FRONT THEN THE MERGED FRONT WILL
REACH FROM BERMUDA TO WINDWARD PASSAGE FRI NIGHT. THE FRONT WILL
THEN STALL NE OF THE CARIBBEAN SUN AND DISSIPATE THROUGH MON.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW





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