[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130006
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN 12 DEC 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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.

...ITCZ...

ITCZ 9N13W 6N25W 7N40W 9N55W 9N61W. SCATTERED MODERATE TO
ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM 6N TO 10N BETWEEN
28W AND 35W. ISOLATED TO WIDELY SCATTERED MODERATE/LOCALLY
STRONG SHOWERS AND THUNDERSTORMS FROM 3N TO 9N BETWEEN 22W AND
28W...AND FROM 6N TO 10N BETWEEN 39W AND 50W. NUMEROUS STRONG
SHOWERS AND THUNDERSTORMS IN LIBERIA AND THE IVORY COAST FROM 5N
TO 7N BETWEEN 7W AND 10W.

...DISCUSSION...

THE GULF OF MEXICO/THE ATLANTIC W OF 63W/THE FAR NW CARIBBEAN...
DEEP MIDDLE/UPPER LEVEL TROUGH CONTINUES PLOWING EASTWARD ACROSS
THE WESTERN ATLANTIC THIS AFTERNOON...NOW THROUGH 32N67W 28N71W
TO THE CENTRAL BAHAMAS. MUCH COOLER/DRIER AIR HAS BEEN PUSHED
SOUTHWARD BY AN ASSOCIATED COLD FRONT...THROUGH 32N65W 26N70W
20N78W...TO THE HONDURAS COAST NEAR 16N86W TO WESTERN HONDURAS.
STATIONARY FRONT FROM WESTERN HONDURAS TO THE EASTERN ISTHMUS OF
TEHUANTEPEC. THE FRONT IS MARKED BY AN INCREASE IN CLOUDINESS
AND CAN ALSO BE SEEN IN THE UPSLOPE CLOUDINESS/SHOWERS OVER
CENTRAL AMERICA. 1020 MB HIGH IN NW FLORIDA PENINSULA...AND
1021 MB HIGH PRESSURE CENTER IN NORTH CENTRAL GULF NEAR 27N89W.
GENERALLY CLEAR SKIES W OF 88W N OF 22N WITH ONLY SOME PATCHY
STRATOCUMULUS ELSEWHERE ACROSS THE GULF. SCATTERED TO BROKEN
LOW/MIDDLE CLOUDS ARE BEHIND THE FRONT IN THE WESTERN ATLANTIC
WITH THE STRONG COLD AIR-ADVECTION OVER THE WARM OCEAN CAUSING
THE CLOUD INCREASE. ISOLATED SHOWERS AND THUNDERSTORMS WITHIN
120 NM EAST OF FRONT NORTH OF 23N. ANOTHER SHOT OF UPPER ENERGY
SHOULD MOVE SOUTHWARD FOR THE BEGINNING OF THE WEEK... BRINGING
ANOTHER COLD FRONT RAPIDLY INTO THE GULF BY TUESDAY WITH WINDY
CONDITIONS EXPECTED ESPECIALLY IN THE WESTERN GULF.

THE REST OF THE CARIBBEAN SEA...
THE MOST SIGNIFICANT WEATHER FEATURE IS A WEAK LOW-LEVEL TROUGH
JUST NORTH OF COLOMBIA ALONG 75W. THE PRECIPITATION FROM SIX
HOURS AGO APPEARS TO HAVE DISSIPATED. ZONAL FLOW COVERS THE
REGION AS WELL AS MODERATE TO STRONG SUBSIDENCE. CHANCES OF
SHOWERS FOR MOST AREAS ARE LESS THAN AVERAGE EXCEPT FOR MAYBE
THE FAR SOUTHEASTERN CARIBBEAN NEAR TRINIDAD. A BROAD SURFACE
TROUGH EAST OF THE CARIBBEAN SEA NOW SHOULD MOVE CLOSER TO THE
LESSER ANTILLES INCREASING THE CHANCE OF RAIN ESPECIALLY FOR
THE LEEWARD ISLANDS ON MONDAY.

THE REMAINDER OF THE ATLANTIC OCEAN...
CENTRAL ATLANTIC HIGH AMPLITUDE RIDGE THROUGH 32N50W TO 22N58W.
THIS RIDGE SHOULD BUILD EASTWARD AS THE DEEP UNITED STATES EAST
COAST TROUGH REMAINS DURING THE WEEK. TWO MIDDLE TO UPPER LEVEL
CYCLONIC CIRCULATION CENTERS ARE SOUTH OF THE RIDGE. ONE IS NEAR
26N47W AND THE OTHER ONE IS IN THE DEEP TROPICS NEAR 17N50W.
THE NORTHERN CENTER IS SURROUNDED BY DRY AIR WITH NO SIGNIFICANT
IMPACT ON THE WEATHER. THE SOUTHERN CYCLONIC CENTER IS CONNECTED
TO A DEEP TROPICAL FEED OF MOISTURE...PRODUCING ISOLATED TO
WIDELY SCATTERED MODERATE SHOWERS AND THUNDERSTORMS FROM 10N TO
20N BETWEEN 40W AND 56W. BROAD SURFACE TROUGH ALONG 56W/57W FROM
10N TO 20N MOVING WEST 15 KT WITH WIDELY SCATTERED SHOWERS FROM
16N TO 20N BETWEEN 57W AND 60W. AN EASTERN ATLANTIC COLD FRONT
THROUGH 32N13W 25N20W 23N29W...AND DISSIPATING 23N29W 23N38W.
SCATTERED SHOWERS AND POSSIBLY A FEW TSTMS ARE WITHIN 60 NM OF
THE FRONT IN A FAVORABLE REGION OF DIVERGENCE ASSOCIATED WITH A
POWERFUL COLD LOW NEAR 35N21W.  BROKEN LOW/MIDDLE CLOUDS COVER
THE CENTRAL/E ATLC BEHIND THE FRONT E OF 45W...AS WELL AS HIGH
PRESSURE FROM A 1028 MB CENTER NEAR 34N43W.  THE REST OF THE
ATLC HAS BROAD UPPER RIDGING S OF 20N E OF 40W WITH SOME
DIVERGENT FLOW OVER THE ITCZ ENHANCING TSTMS NEAR 7N29W.

$$
MT


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