[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI DEC 17 2010

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 09N20W 04N33W 05N47W 04N52W.
SCATTERED MODERATE CONVECTION IS FROM 01N-10N BETWEEN 24W-32W.
ISOLATED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF A
LINE FROM 06N33W TO 12N47W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL RIDGING AND STRONG SUBSIDENCE IS NOTED ALOFT ON
WATER VAPOR IMAGERY ACROSS THE GULF THIS EVENING. HOWEVER...AN
UPPER LEVEL TROUGH IS PROGRESSING ACROSS THE SW CONUS AND NW
PORTION OF MEXICO ALONG 107W THAT IS SUPPORTING A COLD FRONT
ANALYZED FROM THE TEXAS AND LOUISIANA GULF COAST BORDER TO NEAR
CORPUS CHRISTI NEAR 27N97W. OVERALL THE FRONT LACKS ANY
SIGNIFICANT CONVECTION...WITH ISOLATED SHOWERS POSSIBLE WITHIN
60 NM OF THE FRONT. MORE IMPORTANTLY...S-SW RETURN FLOW OVER THE
ENTIRE GULF IS ADVECTING LOW-LEVEL MOISTURE AND ISOLATED SHOWERS
OVER THE NORTH-CENTRAL AND NE GULF COAST N OF 27N BETWEEN THE
FLORIDA BIG BEND REGION AND 92W. LOOKING AHEAD FOR THE UPCOMING
WEEKEND...THE WEAK FRONTAL BOUNDARY IS FORECAST TO SWEEP ACROSS
THE GULF BY LATE SATURDAY AND INTRODUCE NORTHERLY WINDS TO 20 KT
OVER THE REGION THROUGH EARLY SUNDAY.

CARIBBEAN SEA...
VERY STRONG SUBSIDENCE AND DRY AIR ALOFT IS NOTED ACROSS THE NW
CARIBBEAN THAT CONTINUES TO SUPPORT A SURFACE RIDGE EXTENDING
FROM THE W ATLC AND FLORIDA PENINSULA TO THE GULF OF HONDURAS N
OF 15N AND W OF 80W. OVERALL STABLE CONDITIONS PERSIST AS A
RESULT...WITH MOSTLY SCATTERED TO BROKEN STRATOCUMULUS CLOUDS
NOTED ON SATELLITE IMAGERY. ON THE SOUTHERN PERIPHERY OF THE
SURFACE RIDGE OVER THE EASTERN AND CENTRAL CARIBBEAN...A SHEAR
LINE IS ANALYZED FROM DOMINICA TO 15N70W TO 16N75W. AN RECENT
17/0202 UTC ASCAT PASS CAPTURED STRONGER E-NE WINDS OVER THE NE
CARIBBEAN NORTH OF THE SHEAR LINE...THEN GENERALLY LIGHTER
EASTERLY TRADES SOUTH OF THE SHEAR LINE AXIS. LOW-LEVEL SPEED
CONVERGENCE IN VICINITY OF THIS BOUNDARY IS PROVIDING FOCUS FOR
WIDELY SCATTERED SHOWERS N OF 15N E OF 78W. ELSEWHERE...A
SURFACE TROUGH IS ANALYZED FROM THE NORTHERN COAST OF COLOMBIA
NEAR 11N74W TO 16N77W. NEAR THE NORTHERN PORTION OF THE TROUGH
AXIS...AND WESTERN EXTENT OF THE SHEAR LINE...STRONGER LOW-LEVEL
CONVERGENCE IS GENERATING SCATTERED SHOWERS FROM 15N-19N BETWEEN
74W-78W.

ATLANTIC OCEAN...
MOSTLY DRY AIR AND STRONG SUBSIDENCE RESIDES WITHIN WESTERLY
ZONAL UPPER LEVEL FLOW ACROSS THE W ATLC W OF 50W THAT CONTINUES
TO SUPPORT A BROAD SURFACE RIDGE ANCHORED BY A 1021 MB HIGH
CENTERED NEAR 28N68W. MOSTLY FAIR CONDITIONS ARE FOUND WITHIN
THE INFLUENCE OF THIS FEATURE. OVER THE CENTRAL ATLC...AN UPPER
LEVEL TROUGH IS NOTED NORTH OF THE DISCUSSION AREA IN THE
VICINITY OF 50W AND SUPPORTS A COLD FRONT THAT ENTERS THE REGION
NEAR 32N46W THEN EXTENDS SW ALONG 24N50W TO GUADELOUPE NEAR
16N61W. THE FRONT BECOMES MORE DIFFUSE S OF 25N...HOWEVER
ISOLATED SHOWERS STILL REMAIN WITHIN 90 NM EITHER SIDE OF THE
FRONT. FARTHER EAST...AN UPPER LEVEL LOW CENTERED NEAR 33N21W
CONTINUES TO IMPACT MUCH OF THE EASTERN ATLC E OF 40W DRIVING A
STRONG 994 MB LOW CENTERED WEST OF THE MADEIRA ISLANDS NEAR
33N21W. THIS PARTIALLY OCCLUDED LOW EXTENDS A COLD FRONT INTO
THE AREA ALONG 32N15W ACROSS THE CANARY ISLANDS NEAR 28N17W THEN
ALONG 23N23W 22N32W. ISOLATED SHOWERS ARE MAINLY OCCURRING
WITHIN 120 NM EAST OF THE FRONT...HOWEVER LOW-LEVEL MOISTURE AND
POSSIBLE ISOLATED SHOWERS LINGER WEST OF THE FRONT FROM 21N-28N
BETWEEN THE FRONT AND 40W.

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

$$
HUFFMAN




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