[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 140543
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI DEC 14 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN
COAST NEAR 08N13W TO 03N34W TO 06N51W. WIDELY SCATTERED MODERATE
CONVECTION IS FROM THE EQUATOR TO 08N BETWEEN 08W-43W.

...DISCUSSION...

GULF OF MEXICO...
MOSTLY WEST-NORTHWESTERLY UPPER LEVEL FLOW IS OVER THE GULF
BASIN THIS EVENING WITH WATER VAPOR IMAGERY INDICATING
RELATIVELY DRY AND STABLE CONDITIONS N OF 23N E OF 95W. WITH THE
SOUTHWESTERN EXTENT OF AN UPPER LEVEL TROUGH PROGRESSING
EASTWARD OVER THE FLORIDA PENINSULA AND INTO THE SW NORTH ATLC
REGION...A LINGERING COLD FRONT EXTENDS THROUGH THE FLORIDA
STRAITS TO WESTERN CUBA NEAR 23N84W THEN BECOMES A DISSIPATING
STATIONARY FRONT TO 21N90W TO 21N94W TO 18N95W. ISOLATED SHOWERS
ARE LIMITED TO THE EXTREME SE GULF WATERS S OF 25N E OF 83W.
OTHERWISE...THE REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF
A SURFACE RIDGE ANCHORED BY A 1027 MB HIGH CENTERED OVER
TENNESSEE NEAR 35N87W. THE RIDGE AXIS EXTENDS SW TO SOUTHERN
TEXAS AND THEN SOUTH ALONG THE MEXICO COAST TO 20N97W. MOSTLY NE
TO E WINDS PREVAIL E OF 95W...WITH E-SE WINDS BEGINNING TO
ESTABLISH THEMSELVES W OF 95W WITH WEAK LOW-LEVEL MOISTURE
CONVERGENCE AND POSSIBLE ISOLATED SHOWERS OCCURRING THROUGH THE
OVERNIGHT HOURS. THE RETURN FLOW IS FORECAST TO CONTINUE
SPREADING EASTWARD THROUGH THE WEEKEND AS THE HIGH OVER THE SE
CONUS SLIDES EAST INTO THE SW NORTH ATLC.

CARIBBEAN SEA...
UPPER LEVEL NORTHWESTERLY FLOW DOMINATES OVER THE CARIBBEAN
BASIN THIS EVENING BETWEEN AN UPPER LEVEL ANTICYCLONIC
CIRCULATION CENTERED IN THE EAST PACIFIC REGION NEAR 12N93W AND
AN UPPER LEVEL LOW CENTERED OVER THE CENTRAL ATLC NEAR 19N50W.
WATER VAPOR IMAGERY INDICATES THAT VERY DRY AND SUBSIDENCE
PREVAILS IN THE MIDDLE AND UPPER LEVELS OF THE ATMOSPHERE. AT
THE SURFACE...THE PRESSURE GRADIENT HAS CONTINUED TO RELAX OVER
THE LAST 24 TO 36 HOURS WITH E-NE TRADES DECREASING IN MAGNITUDE
AND NOW RANGE GENERALLY FROM 10 TO 20 KT. WHILE NO SIGNIFICANT
CONVECTION IS OCCURRING...A FEW ISOLATED SHOWERS AND TSTMS ARE
NOTED ON SATELLITE IMAGERY S OF 11N IN THE SW CARIBBEAN DUE TO
CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS ANALYZED ALONG 10N
FROM NORTHERN COLOMBIA WESTWARD TO CENTRAL COSTA RICA.
ELSEWHERE...THE GREATEST CONCENTRATION OF LOW-LEVEL MOISTURE IS
FOUND OVER THE EASTERN CARIBBEAN WITH WIDELY SCATTERED SHOWERS
OCCURRING WITHIN 150 NM EITHER SIDE OF A LINE FROM 12N62W TO THE
MONA PASSAGE NEAR 18N68W...AND FROM 17N-22N BETWEEN 64W-70W...
INCLUDING PUERTO RICO AND THE US/UK VIRGIN ISLANDS. THIS OVERALL
SYNOPTIC PATTERN IS EXPECTED TO PERSIST THROUGH THE WEEKEND.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS OVER THE SW NORTH
ATLC WITH AXIS EXTENDING FROM 37N65W TO A BASE OVER THE CENTRAL
FLORIDA PENINSULA NEAR 28N81W. THIS TROUGHING SUPPORTS A COLD
FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N70W THAT EXTENDS
SW TO THE NW BAHAMAS NEAR 26N78W AND INTO THE FLORIDA STRAITS
NEAR 24N81W. LOW-LEVEL MOISTURE CONVERGENCE NEAR THE FRONT IS
GENERATING ISOLATED SHOWERS WITHIN 90 NM EITHER SIDE OF THE
FRONT...AND N OF 27N BETWEEN 58W AND THE FRONT IN AN AREA OF
WEAK FRONTAL TROUGHING. FARTHER EAST...A MIDDLE TO UPPER LEVEL
LOW IS CENTERED NEAR 19N50W THAT SUPPORTS A 1012 MB LOW NEAR
19N49W WITH A SURFACE TROUGH AXIS EXTENDING FROM THE LOW TO
16N48W TO 10N53W. SATELLITE IMAGERY PRESENTS THIS SYSTEM WITH
THE CLASSIC COMMA CLOUD SIGNATURE AS MIDDLE TO UPPER LEVEL
MOISTURE CONTINUES TO WRAP INTO THE LOW CENTER. WATER VAPOR
IMAGERY ALSO INDICATES DRIER AIR WRAPPING INTO THE LOW CENTER
FROM THE WEST AND NORTHWEST. GIVEN INCREASED INSTABILITY AND
MAXIMIZED UPPER LEVEL DIFFLUENCE EAST OF THE LOW...SCATTERED
SHOWERS AND TSTMS ARE OCCURRING FROM 18N-25N BETWEEN 47W-54W...
AND OVER A LARGER AREA FROM 08N-25N BETWEEN 30W-50W. THE
REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED NEAR 29N30W.

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

$$
HUFFMAN




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