[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 120526
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI 12 NOV 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...SPECIAL FEATURES...
A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A SURFACE TROUGH IN
THE E CARIBBEAN SEA EXTENDS FROM JUST E OF THE ABC ISLANDS
THROUGH A 1006 MB LOW NEAR 15N64W ACROSS THE GUADELOUPE PASSAGE
TO A 1007 MB LOW NEAR 19N60W TO 23N52W. WHILE PERSISTENT...THIS
AREA HAS SHOWN LITTLE INDICATION OF ORGANIZATION AND SIGNIFICANT
DEVELOPMENT APPEARS LESS AND LESS LIKELY. THE STRONGEST/DEEPEST
CONVECTION CONTINUES TO TREND E AS DRY AIR ASSOCIATED WITH A
MID/UPPER LEVEL TROUGH MOVES INTO THE E CARIBBEAN. THE MAIN AXIS
OF ACTIVITY NOW EXTENDS FROM OVER E VENEZUELA ACROSS THE
WINDWARD ISLANDS INTO THE W TROPICAL ATLC WITH SCATTERED
MODERATE/STRONG CONVECTION WITHIN 60 NM OF LINE FROM 12N62W TO
14N58W INCLUDING BARBADOS. STRATIFORM RAIN AND SCATTERED
THUNDERSTORMS ARE OVER NE VENEZUELA ACROSS THE REMAINDER OF THE
WINDWARD AND ALL OF THE LEEWARD ISLANDS. LOCALLY HEAVY RAINFALL
AND FLOODING IS POSSIBLE OVER THE ISLANDS TONIGHT ESPECIALLY
FROM GUADELOUPE S TO GRENADA.

NON-TROPICAL 1004 MB LOW OVER THE NE ATLC SEVERAL HUNDRED MILES
SW OF THE AZORES NEAR 31N34W. SURFACE PRESSURES HAVE BEEN
SETTLED OVER THE PAST 6 HOURS AND HAVE BEGUN TO RISE AS THE LOW
BEING VERTICALLY STACKED WITH A MID/UPPER LEVEL LOW. SMALL
AREAS OF DEEP CONVECTION ARE PRESENT NEAR THE CENTER OF THE LOW
WITH SOME INDICATION OF THIS ACTIVITY HAS WRAPPED AROUND THE
UPPER LOW. STRONG NORTHERLY FLOW IS NOW INFLUENCING THE SYSTEM
AND FURTHER DEVELOPMENT APPEARS UNLIKELY.

...ITCZ...
ITCZ AXIS IS ALONG 10N11W 5N24W 6N33W 5N43W 7N50W 7N59W.
SCATTERED MODERATE/STRONG CONVECTION IS INLAND AND WITHIN 60 NM
ALONG THE COAST OF THE IVORY AND GRAIN COASTS BETWEEN 6W-10W.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 2N-9N BETWEEN
10W-30W.

...DISCUSSION...
GULF OF MEXICO...
ZONAL WESTERLY FLOW ALOFT EXTENDS OVER THE GULF WITH A SHORTWAVE
TROUGH OVER THE E GULF EXTENDING FROM ALABAMA TO JUST N OF THE
YUCATAN PENINSULA PRODUCING AN AREA OF SCATTERED SHOWERS ALONG A
SURFACE TROUGH EXTENDING FROM THE NW YUCATAN PENINSULA TO THE
FLORIDA PANHANDLE. ISOLATED SHOWERS ARE ALSO NOTED ALONG A COLD
FRONT MOVING ACROSS THE NW GULF FROM THE MISSISSIPPI DELTA SW
INTO MEXICO JUST S OF BROWNSVILLE THEN INLAND OVER MEXICO AS A
STATIONARY FRONT ALONG THE SIERRA MADRE MOUNTAINS. THIS FRONT
WILL SWEEP QUICKLY E ACROSS THE GULF EXTENDING FROM THE FLORIDA
PANHANDLE TO THE SW GULF BY TOMORROW AFTERNOON. MID/UPPER LEVEL
DYNAMICS/LIFT LOOK FAVORABLE FOR SCATTERED SHOWERS/THUNDERSTORMS
ALONG THE FRONT ESPECIALLY N OF 25N. ELSEWHERE...RATHER DRY
CONDITIONS WILL PREVAIL IN THE MID/UPPER LEVELS WITH NO
SIGNIFICANT WEATHER. AT THE SURFACE...STRONG HIGH PRESSURE OFF
THE E COAST OF THE UNITED STATES IS PRODUCING E FLOW OVER
FLORIDA INTO THE E GULF.

CARIBBEAN SEA...
MID/UPPER TROUGH CONTINUES TO BE THE DOMINANT FEATURE EXTENDING
FROM THE CENTRAL ATLC ACROSS HISPANIOLA TO THE SW CARIBBEAN.
HOWEVER...WATER VAPOR IMAGERY INDICATES THE TROUGH IS
PROGRESSING E ALLOWING STRONG SUBSIDENCE AND VERY DRY MID/UPPER
LEVEL AIR TO CONTINUE TO SPREAD E INTO THE E CARIBBEAN.
WIDESPREAD SHOWERS/THUNDERSTORMS CONTINUE THE LESSER ANTILLES
INTO THE W TROPICAL ATLC IN ASSOCIATION WITH AN ELONGATED AREA
OF LOW PRESSURE...SEE SPECIAL FEATURES. THE STRONGEST OF THIS
ACTIVITY WILL CONTINUE E OF THE AREA OVERNIGHT. HOWEVER...A COLD
FRONT DROPPING S OVER PUERTO RICO AND HISPANIOLA FROM THE
CENTRAL ATLC WILL CONTINUE TO PRODUCE SCATTERED LOW LEVEL
SHOWERS. THE BOUNDARY WILL WEAKEN AS IT PENETRATES INTO THE
CARIBBEAN BUT AMPLE LOW LEVEL MOISTURE POOLING WILL CONTINUE TO
SPARK SCATTERED SHOWERS AND A FEW ISOLATED THUNDERSTORMS.
BEHIND THE FRONT...DRY/STABLE AIR WILL SPILL S FROM THE W
ATLC.

ATLANTIC...
THE VAST MAJORITY OF THE W ATLC CONTINUES TO BE DOMINATED BY
MID/UPPER LEVEL SUBSIDENCE AND DRY AIR. BROKEN STRATOCUMULUS
CLOUDS...INDICATING COLD ADVECTION AND STABLE CONDITIONS...COVER
THE ENTIRE AREA W OF A CENTRAL ATLC COLD FRONT EXTENDING FROM
32N49W S TO ALONG THE N COAST OF PUERTO RICO AND THEN STATIONARY
OVER HISPANIOLA. A STRONG 1027 MB SURFACE HIGH IS OFF THE
MID-ATLANTIC COAST PRODUCING NE FLOW BEHIND THE FRONT. FARTHER
E...SHARP MID/UPPER LEVEL TROUGH FROM BERMUDA S OVER HISPANIOLA
CONTINUES TO PROVIDE THE SUPPORT FOR WIDESPREAD CLOUDINESS AND
SHOWERS/THUNDERSTORMS OVER THE CENTRAL ATLC. THE BULK OF THIS
ACTIVITY IS FAVORED ALONG AND TO THE EAST OF AN UPPER LEVEL
SUBTROPICAL JET EXTENDING FROM THE E CARIBBEAN NE TO BEYOND
32N50W. MID/UPPER RIDGE EXTENDS FROM THE DEEP TROPICAL ATLC HIGH
NEAR 9N56W NE TO BEYOND 32N42W. THE AFOREMENTIONED SUBTROPICAL
JET AND ASSOCIATED MOISTURE SURGE RIDE UP AND OVER THIS RIDGE
LEAVING SUBSIDENCE AND DRY AIR E OF THE RIDGE...ESPECIALLY S OF
25N. OVER THE FAR E ATLC...A DEEP LAYERED LOW CONTINUES TO DRIFT
SLOWLY WESTWARD NEAR 30N34W...SEE SPECIAL FEATURES. ELSEWHERE...
THE DEEP LAYERED LOW TRAILS A TROUGH S WELL INTO THE TROPICAL
ATLC ALONG 17N31W TO 5N35W. VERY DRY AIR ALOFT IS PRESENT NEAR
AND W OF THE TROUGH AXIS...SUPPRESSING SIGNIFICANT ITCZ
CONVECTION W OF 35W. HOWEVER THE TROUGH IS ENHANCING CONVECTION
OVER THE E ATLC WITH WIDESPREAD CLOUDINESS AND SHOWERS AND
THUNDERSTORMS EXTENDING FROM THE ITCZ N TO 25N E OF 20W TO THE
COAST OF AFRICA. DEEP CONVECTION EMBEDDED WITHIN THIS LARGE AREA
IS NOTED JUST NW OF THE CAPE VERDE ISLANDS AND MOVING E TO OVER
THE N CAPE VERDE ISLANDS.

$$
WALLACE


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