[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 18 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
2345 UTC.

...ITCZ...
THE ITCZ AXIS IS ANALYZED FROM THE COAST OF LIBERIA NEAR 5N10W
CONTINUING WEST ALONG 5N20W 6N30W 8N40W 9N46W...RESUMING FROM
6N50W TO 4N57W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
IS FROM THE EQUATOR TO 12N BETWEEN 38W AND 47W. SCATTERED
MODERATE TO STRONG CONVECTION IS WITHIN 200 NM ON EITHER SIDE OF
THE ITCZ BETWEEN 19W AND 38W. A SURFACE TROUGH IS EMBEDDED
WITHIN THE ITCZ EXTENDING ALONG 13N48W TO A WEAK 1007 MB LOW
NEAR 10N50W TO 7N48W. SCATTERED MODERATE TO STRONG CONVECTION IS
FROM 8N TO 12N BETWEEN 49W AND 51W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH COVERS THE EASTERN HALF OF THE CONUS AND
SUPPORTS A LOW PRESSURE SYSTEM OVER THE FAR WEST ATLC. A COLD
FRONT EXTENDS SW FROM THE LOW CENTER AND ENTERS THE DISCUSSION
AREA THROUGH NORTHERN FLORIDA NEAR 30N82W...CONTINUING ACROSS
THE GULF TO THE BAY OF CAMPECHE ALONG 27N86W 25N90W 22N93W
18N95W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHING
75 NM EITHER SIDE OF THE FRONT N OF 20N. 15-20 KT N-NE WINDS ARE
BEHIND THE FRONT AS WELL AS LOW LEVEL STRATOCUMULUS CLOUDS. LAST
VISIBLE IMAGES OF THE DAY INDICATED HEAVY DENSE FOG IN THE N
CENTRAL BASIN N FROM 26N TO 29N BETWEEN 87W AND 95W. A
PRE-FRONTAL TROUGH CROSSES THE CENTRAL FLORIDA PENINSULA TO A
1008 MB LOW JUST OFF THE COAST OF FORT MYERS NEAR 26N83W. MOSAIC
DOPPLER RADAR IMAGERY INDICATE SCATTERED SHOWERS WITHIN 65 NM
OVER THE NE QUADRANT OF THE LOW CENTER. WATER VAPOR IMAGERY
INDICATES AN UPPER LEVEL SHORTWAVE EMBEDDED IN THE UPPER TROUGH
CURRENTLY MOVING ACROSS THE NORTH CENTRAL GULF...FURTHER
ENHANCING THE CONVECTION RELATED TO THE FRONT AND LOW PRESSURE
SYSTEM. EXPECT THESE FEATURES TO CONTINUE TO MOVE E OVER THE
NEXT 24 HOURS.

CARIBBEAN SEA...
THE BASE OF AN UPPER LEVEL TROUGH SWINGS BY THE NW CARIBBEAN
SUPPORTING A WEAK 1009 MB LOW MOVING NORTHWARD ACROSS CENTRAL
CUBA NEAR 22N79W. A SURFACE TROUGH EXTENDS ESE FROM THE LOW
CENTER ACROSS THE CENTRAL BASIN ALONG 21N76W 18N75W 15N74W
13N73W TO THE COAST OF COLOMBIA NEAR 12N72W. THE LOW IS
GENERATING SCATTERED SHOWERS AND THUNDERSTORMS N OF 20N BETWEEN
77W AND 81W. SIMILAR ACTIVITY IS FOUND WITHIN 90 NM EAST OF THE
SURFACE TROUGH. WATER VAPOR IMAGERY INDICATES STRONG SUBSIDENCE
WEST OF THE TROUGH...SUPPRESSING DEEP CONVECTION TO DEVELOP WEST
OF 75W. 15-20 KT TRADE WINDS ARE OVER THE EASTERN BASIN E OF 70W
WITH ISOLATED SHOWERS EMBEDDED IN THE FLOW. EXPECT THE SURFACE
TROUGH TO BE DRAWN EASTWARD WITH THE FRONTAL SYSTEM MOVING
ACROSS THE GULF OF MEXICO SUPPORTING SHOWER ACTIVITY OVER THE E
CENTRAL CARIBBEAN OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...
THE UPPER LEVEL TROUGH/SHORTWAVE MOVING ACROSS THE EASTERN CONUS
IS SUPPORTING A LOW PRESSURE SYSTEM NEAR 33N75W AND ASSOCIATED
COLD FRONT MOVING OFF THE EASTERN SEABOARD. A PRE-FRONTAL TROUGH
CROSSES THE CENTRAL FLORIDA PENINSULA FROM 31N80W TO INLAND
FLORIDA NEAR 28N82W INTO THE GULF OF MEXICO. ANOTHER SURFACE
TROUGH IS ANALYZED ALONG 3078 2679 CROSSING THE FLORIDA STRAITS
ALONG 24N81W. IN RESPONSE...WIDESPREAD SHOWERS AND THUNDERSTORMS
ARE ACROSS MUCH OF THE WESTERN ATLC W OF 75W. THIS AREA IS UNDER
DIFFLUENCE ALOFT BETWEEN THE UPPER TROUGH ACROSS THE EASTERN
CONUS AND AN UPPER LEVEL RIDGE ACROSS THE W ATLC. THIS UPPER
LEVEL RIDGE IS SUPPORTING SURFACE RIDGING ACROSS THE REMAINDER
OF THE WEST AND CENTRAL ATLC ANCHORED BY A 1018 MB HIGH NEAR
27N65W PROVIDING MOSTLY FAIR WEATHER CONDITIONS BETWEEN 45W AND
75W. A COLD FRONT ENTERS THE EASTERN ATLC NEAR 32N30W CONTINUING
SW ALONG 26N32W 23N37W BECOMING A SURFACE TROUGH TO 20N45W.
SCATTERED SHOWERS ARE WITHIN 150 NM AHEAD OF THE FRONT N OF 25N.
ISOLATED SHOWERS ARE WITHIN 60 NM ON EITHER SIDE OF THE TROUGH
AXIS. THE SYSTEM IS SUPPORTED BY AN UPPER LEVEL LOW/TROUGH
EXTENDING CENTERED AROUND 32N35W. THE FAR ERN ATLC IS
EXPERIENCING MOSTLY FAIR CONDITIONS DUE TO WEAK SURFACE RIDGING
CENTERED NEAR 18N27W.

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

$$

GARCIA



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