[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 242358
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON DEC 24 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N10W 7N26W 3N51W. SCATTERED
MODERATE CONVECTION NOTED WITHIN 30 NM EITHER SIDE OF LINE 5N8W
2N14W...AND FROM 3N TO 9N BETWEEN 25W AND 41W...AND OVER AND
INLAND S AMERICA FROM 5N TO THE EQUATOR BETWEEN 52W AND 58W.

...DISCUSSION...
THE GULF OF MEXICO...
A BROAD FRONTAL TROUGH IS STALLING OVER THE STRAITS OF FLORIDA
TO THE NW COAST OF CUBA AND IS ACCOMPANIED BY BROKEN TO LOCALLY
OVERCAST LOW AND MID LEVEL CLOUDS AND LIGHT RAIN SHOWERS.
IMMEDIATELY TO THE NW...A BAND OF CLEARING IS NOTED OVER THE
EXTREME SE GULF WITHIN 60 NM EITHER SIDE OF A LINE FROM FT MYERS
FLORIDA TO CANCUN MEXICO. NW OF THIS CLEARING THE REMAINDER OF
THE GULF IS ALSO COVERED BY BROKEN TO LOCALLY OVERCAST LOW
STRATOCUMULUS AND MID LEVEL STRATIFORM CLOUDS WITH EMBEDDED
LIGHT RAIN SHOWERS. THE UPPER LEVELS OF THE GULF NW OF A LINE
FROM THE FLORIDA BIG BEND TO THE CENTRAL BAY OF CAMPECHE IS
DOMINATED BY A TROPICAL MOISTURE PLUME THAT ORIGINATES FROM E
PAC ITCZ CONVECTION NEAR 12N115W. THIS PLUME IS ADVECTED NE
ALONG AN UPPER RIDGE THAT CRESTS JUST OFF THE CAROLINA
COAST...BUT THE MOISTURE SPREADS AS FAR N AS PENNSYLVANIA. TO
THE NW OF THE PLUME AND UPPER SHORT WAVE IS PUSHING SE TOWARDS
THE TEXAS COAST ACCOMPANIED BY VERY DRY UPPER AIR. THE
PROGRESSIVE AND ZONAL UPPER PATTERN IS EXPECTED TO MOVE THIS
SHORTWAVE TROUGH RAPIDLY E ACROSS SE UNITED STATES WITHIN THE
NEXT 30-42 HRS DRIVING A SURFACE COLD FRONT INTO THE NW GULF WED
AFTERNOON...AND TO THE CENTRAL GULF THU MORNING. THEREAFTER THE
FRONT WILL SLOW UNTIL A STRONGER COLD FRONT MOVES OFF THE TEXAS
COAST ON FRI REACHING THE CENTRAL GULF FRI EVENING. WITH THE
UPPER FLOW PATTERN FORECAST TO RATHER ZONAL OVER MUCH OF THE
SOUTHERN UNITED STATES AND NORTHERN GULF THESE FRONTS LIKE THE
PRESENT ONE SHOULD NOT PROGRESS TOO FAR S INTO THE AREA.

THE CARIBBEAN SEA...
AN UPPER ANTICYCLONE NEAR 7N70W RIDGES N OVER THE CARIBBEAN
ALONG 73W ADVECTING UPPER MOISTURE E ACROSS THE CENTRAL AND
EASTERN WATERS. THE MOISTURE REMAINS S OF AN UPPER ATLC TROUGH
THAT EXTENDS INTO THE NE CARIBBEAN WITH ITS BASE NEAR 15N62W.
OTHERWISE THE SW CARIBBEAN IS DOMINATED BY BROKEN LOW LEVEL
CLOUDS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS S OF 13N W OF
75W. BRISK NE LOW LEVEL FLOW IS NOTED OVER THE NE CARIBBEAN.
A LOW LEVEL INVERTED TROUGH HAS MOVED W ACROSS JAMAICA BUT STILL
EXTENDS N ACROSS CUBA ALONG 79.5W AND IS ACCOMPANIED BY
SCATTERED SHOWERS WHICH ARE MOVING ON THE N CENTRAL COAST OF
CUBA AND THE CAY SAL BANK AT THE MOMENT. W OF THIS TROUGH...NE
LOW LEVEL WINDS ACCOMPANIED BY A FEW LIGHT SHOWERS ARE NOTED
OVER THE CARIBBEAN. EXPECT NE SWELLS IN THE 8-10 FT RANGE TO
CONTINUE TO AFFECT THE NE CARIBBEAN AND PASSAGES THROUGH THE END
OF THE WEEK.

THE ATLANTIC OCEAN...
TWO UPPER FEATURES DOMINATE THE DISCUSSION AREA. AN UPPER RIDGE
ORIGINATING NEAR COLOMBIA DOMINATES THE REGION W OF 62W AND IS
ACCOMPANIED BY VERY DRY UPPER AIR. HOWEVER UPPER MOISTURE IS
NOW SPILLING OVER THE RIDGE INTO THE AREA NEAR 30N60W. A DEEP
LAYERED TROUGH DOMINATES THE AREA BETWEEN 62W AND 35W...WITH ITS
AXIS ALONG 32N37W 20N57W INTO THE NE CARIBBEAN WITH A BASE NEAR
15N62W. THE ASSOCIATED SURFACE FRONT LIES ALONG 32N36W THROUGH A
FRONTAL WAVE LOW AT 24N52W 1015 MB...WITH A TROUGH SW TO 23N56W.
UPPER MOISTURE ALSO ACCOMPANIES THIS UPPER TROUGH WITHIN 180 NM
EITHER SIDE OF LINE 32N38W 19N54W...FOR THE MOST ORIGINATING
FROM CONVECTION NEAR THE FRONTAL WAVE LOW. UPPER LEVEL WESTERLY
FLOW ADVECTS UPPER MOISTURE ACROSS THE TROPICAL ATLC TO THE S OF
16N ALL THE WAY TO THE AFRICAN COAST.

ELSEWHERE AT THE SURFACE...A LOW LEVEL TROUGH ALONG 77W I MOVING
W THROUGH THE NW BAHAMAS AND IS ACCOMPANIED BY SCATTERED
SHOWERS...THE HEAVIEST NOW MOVING THROUGH THE STRAITS OF FLORIDA
W OF ANDROS ISLAND...AND INTO THE CAY SAL BANK. THESE SHOWERS
WILL MOVE ONTO THE SE FLORIDA COAST EARLY THIS EVENING. A
FRONTAL TROUGH...ACCOMPANIED BY OVERCAST LOW CLOUDS LIES ALONG
32N74W TO THE FLORIDA COAT NEAR MELBOURNE AND EXTENDS ACROSS
CENTRAL FLORIDA INT THE GULF OF MEXICO NEAR 27N83W. A LOW LEVEL
RIDGE LIES E OF THIS FRONT AND W OF THE ATLC TROUGH DESCRIBED
ABOVE... AND IS ACCOMPANIED BY BANDS OF OF STRATOCUMULUS CLOUDS.
A SECOND LOW LEVEL RIDGE DOMINATES THE E ATLC...E OF 35W...AND
IS ACCOMPANIED BY LOCALLY BROKEN STRATOCUMULUS.

$$
NELSON





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