[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221742
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT DEC 22 2012

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ/MONSOON TROUGH...

THERE IS CURRENTLY NO PORTION OF THE MONSOON TROUGH OVER THE
ATLC WATERS. THE ITCZ BEGINS OVER LAND TO THE SOUTHERN COAST OF
LIBERIA NEAR 5N8W EMERGING OVER WATER ALONG 4N20W 5N39W 5N52W.
ISOLATED MODERATE CONVECTION IS FROM 2N-5N BETWEEN 17W-21W.
SCATTERED MODERATE CONVECTION IS FROM 3N-7N BETWEEN 37W-44W.

...DISCUSSION...

GULF OF MEXICO...
GORGEOUS WEATHER PREVAILS ACROSS THE GULF OF MEXICO TODAY AS
HIGH PRESSURE BUILDS ACROSS THE NORTHERN GULF IN THE WAKE OF A
COLD FRONT THAT PUSHED OUT OF THE BASIN YESTERDAY. THE RIDGE IS
ANCHORED BY A 1029 MB HIGH OVER SE LOUISIANA. STRONG
NORTH-NORTHEAST WINDS ARE STILL ACROSS MUCH OF THE EASTERN GULF
REACHING 15-20 KT WITH LIGHTER EAST-SOUTHEAST WINDS WRAPPING
AROUND THE REMAINDER OF THE RIDGE AXIS. ALOFT...MAINLY NW FLOW
COVERS THE AREA AROUND A DEEP LAYER TROUGH OFF THE EAST COAST OF
THE UNITED STATES...WHICH SUPPORTED THE FRONT THAT PASSED
THROUGH OVER THE LAST COUPLE OF DAYS. AN UPPER LEVEL RIDGE OVER
THE CENTRAL CONUS SUPPORTS THE SURFACE RIDGE THAT IS NOW
DOMINATING THE AREA. THE SURFACE RIDGE IS EXPECTED TO SHIFT EAST
THROUGH THE WEEKEND BEFORE A WEAK FRONT MOVES ACROSS THE
NORTHERN GULF ON MONDAY FOLLOWED BY A STRONGER FRONT THAT MOVES
IN ON TUESDAY.

CARIBBEAN SEA...
A DEEP LAYER TROUGH OVER THE WEST ATLC CONTINUES TO SUPPORT A
COLD FRONT THAT EXTENDS FROM THE ATLC INTO THE NW CARIBBEAN FROM
EASTERN CUBA NEAR 20N75W TO GUATEMALA NEAR 16N90W. ONLY A FEW
POSSIBLE SHOWERS ARE ASSOCIATED WITH IT OVER EASTERN CUBA AND
PORTIONS OF HONDURAS AND GUATEMALA. STRONG NORTH-NORTHEAST WINDS
ARE NORTH OF THE AXIS REACHING UP TO 25 KT. THE REMAINDER OF THE
BASIN IS COVERED BY A MOSTLY DRY AIRMASS WITH ZONAL WESTERLY
FLOW ALOFT. THIS IS PROVIDING MOSTLY FAIR CONDITIONS...EXCEPT
FOR AN AREA OF ENHANCED LOW-LEVEL MOISTURE IN THE SE CARIBBEAN
WHERE SCATTERED/ISOLATED THUNDERSTORMS ARE PRESENT FROM 12N-15N
BETWEEN 64W-71W. TRADEWIND FLOW OF 15-20 KT SPREADS OVER MUCH OF
THE AREA...EXCEPT BEHIND THE FRONT. THE FRONT IS ALREADY SHOWING
EVIDENCE OF DISSIPATING. IT WILL LIKELY CONTINUE TO DO SO
BECOMING A SHEAR AXIS OVER THE NEXT 6-12 HOURS.
SHOWERS/THUNDERSTORMS ARE EXPECTED TO CONTINUE OVER THE SE
CARIBBEAN.

ATLANTIC OCEAN...
A STRONG COLD FRONT CONTINUES TO PUSH THROUGH THE WEST ATLC
SUPPORTED BY A DEEP LAYER TROUGH OVER THE EASTERN CONUS. THE
FRONT CURRENTLY EXTENDS FROM 32N64W TO THE SE BAHAMAS NEAR
22N73W CONTINUING INTO THE NW CARIBBEAN. ISOLATED SHOWERS ARE UP
TO 150 NM EAST OF THE FRONT. WEAK RIDGING COVERS THE REMAINDER
OF THE WEST ATLC AROUND A 1017 MB HIGH NEAR 25N60W. THE RIDGE IS
SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 53W. A SECOND DEEP LAYER
TROUGH IS IMPACTING THE EASTERN ATLC ALONG 34W SUPPORTING A COLD
FRONT ENTERING THE AREA NEAR 32N32W AND CONTINUING ALONG 25N35W
TO 19N43W WHERE IT BECOMES DISSIPATING TO 16N51W. A PRE-FRONTAL
TROUGH IS EAST OF THE FRONT ALONG 31N31W TO 22N37W. SCATTERED
SHOWERS/POSSIBLE THUNDERSTORMS ARE UP TO 250 NM EAST OF THE
FRONT AXIS. A POST-FRONTAL TROUGH IS ALSO WEST OF THE FRONT
ALONG 31N34W TO 26N46W DEPICTING A SECOND WIND SHIFT. THE
REMAINDER OF THE EAST ATLC IS DOMINATED BY SURFACE RIDGING
AROUND A PAIR OF HIGH CENTERS OF SPAIN AND NORTHERN AFRICA. THE
RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 4W.

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

$$
WALTON




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