[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181739
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 05N09W 06N20W 06N30W 08N45W...AND
ALONG 08N49W TO 06N56W. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS FROM 2N-8N BETWEEN 18W-30W. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 6N-10N BETWEEN 32W-38W. A SURFACE
TROUGH IS EMBEDDED WITHIN THE ITCZ EXTENDING FROM 05N46W TO
12N47W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 6N-13N
BETWEEN 42W-50W. AN ASCAT PASS INDICATES THAT A SURFACE LOW MAY
BE DEVELOPING ALONG THE TROUGH.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A STATIONARY FRONT EXTENDS FROM A SURFACE LOW
IN THE WEST ATLANTIC THROUGH N FLORIDA NEAR 30N84W TO A SURFACE
LOW NEAR 27N87W WHERE IT BECOMES A COLD FRONT ALONG 26N91W
23N95W TO 19N96W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
ARE WITHING 75 NM EITHER SIDE OF THE FRONTAL BOUNDARIES. 10-15
KT N-NE WINDS ARE BEHIND THE FRONT. A PREFRONTAL TROUGH IS ALONG
26N88W 24N81W 24N94W WITH NO SIGNIFICANT CONVECTION. THIS SYSTEM
IS SUPPORTED BY AN UPPER LEVEL LONGWAVE TROUGH EXTENDING FROM
ONTARIO CANADA DOWN THE EASTERN CONUS INTO THE WESTERN GULF.
WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS...SOME STRONG...
ARE MOVING FROM THE EASTERN GULF OVER THE FLORIDA PENINSULA.
EXPECT THE FRONT AND LOW TO MOVE E OVER THE NEXT 24 HOURS
BRINGING WIDESPREAD SHOWER ACTIVITY TO THE FLORIDA PENINSULA.

CARIBBEAN SEA...
A SURFACE TROUGH IS OVER THE CENTRAL CARIBBEAN EXTENDING FROM
CENTRAL CUBA NEAR 23N80W ALONG 19N79W TO 16N77W. AS OF 1500
UTC...A SURFACE LOW EMBEDDED ALONG THE TROUGH IS ANALYZED NEAR
20N79W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE N OF
THE LOW CENTER ACROSS CUBA WITHIN 100 NM OF THE SURFACE TROUGH.
SCATTERED MODERATE CONVECTION E OF THE TROUGH IS FROM 15N-20N
BETWEEN 74W-76W. A SHEAR LINE IS ENHANCING THE AREA OF
CONVECTION...AND IS ANALYZED ALONG 13N67W TO 16N75W BETWEEN
20-25 KT WINDS TO THE NORTH AND 10-15 KT WINDS TO THE SOUTH.
SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS ARE WITHIN 100 NM
OF THE LINE. IN THE UPPER LEVELS... A RIDGE EXTENDING FROM THE
WESTERN ATLANTIC INTO THE CENTRAL CARIBBEAN PRODUCING STRONG
SUBSIDENCE OVER CENTRAL AMERICA AND THE W CARIBBEAN W OF 77W.
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 FRONTAL SYSTEM MOVING ACROSS THE GULF OF MEXICO IS
SUPPORTING WIDESPREAD SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE
FLORIDA PENINSULA EMERGING OFF THE ERN COAST W OF 77W. THIS AREA
IS UNDER DIFFLUENCE ALOFT BETWEEN A LONGWAVE UPPER TROUGH ACROSS
THE ERN CONUS AND GULF OF MEXICO AND AN UPPER LEVEL RIDGE ACROSS
THE W ATLC. THIS UPPER LEVEL RIDGE IS SUPPORTING SURFACE RIDGING
ACROSS THE REMAINDER OF THE W ATLC ANCHORED BY A 1020 MB HIGH
NEAR 27N67W PROVIDING MOSTLY FAIR WEATHER E OF 77W. A COLD FRONT
ENTERS THE CENTRAL ATLC NEAR 32N34W CONTINUING SW ALONG 28N34W
19N47W BECOMING A SHEAR AXIS TO 15N58W. ISOLATED SHOWERS ARE
WITHIN 150 NM AHEAD OF THE FRONT AND WITHIN 60 NM EITHER SIDE OF
THE SHEAR LINE. THE SYSTEM IS SUPPORTED BY AN UPPER LEVEL TROUGH
EXTENDING FROM NEAR 39N40W TO 23N30W. THE FAR ERN ATLC IS
EXPERIENCING MOSTLY FAIR CONDITIONS WEAK RIDGING ALOFT AND AT
THE SURFACE. A DISSIPATING COLD FRONT HAS NOW MOVED INLAND OVER
NW AFRICA WITH NO ASSOCIATED SHOWER ACTIVITY.

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

$$
MONTALVO/WALTON




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