[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE DEC 21 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED FROM LIBERIA NEAR 6N10W ALONG 4N20W 3N35W
2N50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM THE
EQUATOR TO 4N BETWEEN 9W-14W...AND FROM 1N-7N BETWEEN 14W-19W.
ISOLATED MODERATE CONVECTION IS FROM 1N-5N BETWEEN 21W-27W.
ISOLATED MODERATE/STRONG CONVECTION IS FROM THE EQUATOR TO 8N
BETWEEN 41W-47W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS ALONG THE NE COAST OF SOUTH AMERICA FROM THE EQUATOR TO 6N W
OF 50W.

...DISCUSSION...

GULF OF MEXICO...
MAINLY WEST-NORTHWESTERLY FLOW ALOFT COVERS THE GULF OF MEXICO
AROUND AN UPPER LEVEL RIDGE COVERING MUCH OF THE CENTRAL UNITED
STATES. THE UPPER RIDGE SUPPORTS A SURFACE RIDGE ANCHORED BY A
1023 MB HIGH CENTERED OVER THE GULF COAST OF FLORIDA NEAR
29N83W. WEAK ANTI-CYCLONIC FLOW IS AROUND THE RIDGE WITH
STRONGER SOUTHERLY WINDS UP TO 15 KT W OF 88W. DRY AIR AND
SUBSIDENCE ALOFT ARE MAINTAINING MOSTLY CLEAR SKIES ACROSS THE
BASIN WITH THE EXCEPTION OF AN AREA OF STRATOCUMULUS CLOUDS IN
THE N CENTRAL GULF N OF 26N BETWEEN 85W-94W. EXPECT SURFACE
RIDGING TO DOMINATE THE BASIN FOR THE NEXT SEVERAL DAYS KEEPING
CONDITIONS FAIR.

CARIBBEAN SEA...
THE DRY AIR AND SUBSIDENCE ALOFT THAT COVERS THE GULF OF MEXICO
IS ALSO IMPACTING MUCH OF THE NRN AND WRN CARIBBEAN KEEPING
CONDITIONS FAIR. A LONGWAVE UPPER TROUGH OVER THE W ATLC
SUPPORTS A COLD FRONT THAT CONTINUES AS A SURFACE TROUGH INTO
THE CARIBBEAN THROUGH ANTIGUA NEAR 17N61W ALONG 15N68W TO
13N68W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 75
NM EITHER SIDE OF THE AXIS. A SECOND SURFACE TROUGH IS FARTHER W
ALONG 17N74W TO 13N71W...AS INDICATED BY A WINDSAT SCATTEROMETER
PASS. THE PASS REVEALS NE WINDS UP TO 20 KTS ARE NE OF THE
TROUGH AXIS WITH WEAKER WINDS TO THE SW. CONVERGENCE NEAR THE
TROUGH IS SUPPORTING SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS
WITHIN 60 NM EITHER SIDE OF THE AXIS. POSSIBLE ISOLATED SHOWERS
ARE ALSO N OF 17N BETWEEN 63W-71W. BETWEEN BARBADOS AND SAINT
VINCENT IS A 1009 MB SURFACE LOW CENTERED NEAR 13N60W WITH A
SURFACE TROUGH EXTENDING THROUGH THE CENTER ALONG 16N55W 14N59W
11N61W TO 10N62W. BURSTS OF ISOLATED MODERATE CONVECTION ARE
WITHIN 90 NM E OF THE LOW CENTER AFFECTING BARBADOS AND WITHIN
45 NM OF THE SRN PORTION OF THE TROUGH AFFECTING TRINIDAD...
TOBAGO...AND THE COAST OF VENEZUELA. EXPECT SHOWER ACTIVITY TO
CONTINUE ACROSS PORTIONS OF THE ERN CARIBBEAN...AS WELL AS
ACROSS THE SRN WINDWARD ISLANDS AS A THE LOW PRESSURE SYSTEM
MOVES NORTHWESTWARD OVER THE NEXT 24 HRS.

ATLANTIC OCEAN...
SURFACE RIDGING CENTERED OVER FLORIDA EXTENDS OVER THE FAR W
ATLC KEEPING CONDITIONS GENERALLY FAIR THIS EVENING. A DEEP
LAYER TROUGH IS TO THE E SUPPORTING A BROAD LOW PRESSURE SYSTEM
IN THE NWRN ATLANTIC WITH AN ASSOCIATED COLD FRONT ENTERING THE
DISCUSSION AREA NEAR 32N49W CONTINUING TO THE NRN LEEWARD
ISLANDS ALONG 25N53W 17N61W. SCATTERED SHOWERS/POSSIBLE
THUNDERSTORMS ARE WITHIN 250 NM AHEAD OF THE FRONT N OF 20N...
AND WITHIN 45 NM AHEAD OF THE FRONT S OF 20N. GALE FORCE WINDS
ARE BOTH AHEAD OF AND BEHIND THE FRONT WITH A LARGE AREA OF
STRATOCUMULUS CLOUDS ALSO BEHIND THE FRONT. TO THE SOUTH...A
BURST OF ISOLATED MODERATE CONVECTION ASSOCIATED WITH THE
SURFACE TROUGH WITH THE LOW CENTER AFFECTING THE WINDWARD
ISLANDS MENTIONED ABOVE IS FROM 14N-17N BETWEEN 50W-55W. ACROSS
THE ERN ATLC...A BROAD UPPER LEVEL RIDGE ALONG 40W SUPPORTS A
SURFACE RIDGE ANCHORED BY A 1018 MB HIGH NEAR 25N36W PROVIDING
GENERALLY FAIR WEATHER ACROSS THIS PORTION OF THE BASIN. AN
UPPER LEVEL TROUGH IS TO THE E NE OF THE CANARY ISLANDS TO THE
CAPE VERDE ISLANDS SUPPORTING A LOW PRESSURE SYSTEM N OF THE
DISCUSSION AREA WITH A FADING FRONTAL BOUNDARY ENTERING THE AREA
NEAR 32N14W EXTENDING ALONG 30N22W TO N OF THE AREA NEAR 32N33W.
A PRE-FRONTAL SURFACE TROUGH DEPICTS THE SHIFTING CYCLONIC WINDS
ALONG 31N13W TO 23N21W.

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

$$
MONTALVO/HUFFMAN




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