[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141144
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN
COAST NEAR 08N13W TO 02N29W TO 03N45W TO 02N50W. SCATTERED
MODERATE AND ISOLATED STRONG CONVECTION IS FROM 03N-07N BETWEEN
09W-13W. WIDELY SCATTERED MODERATE CONVECTION IS FROM THE
EQUATOR TO 07N BETWEEN 18W-41W.

...DISCUSSION...

GULF OF MEXICO...
MOSTLY WEST-NORTHWESTERLY UPPER LEVEL FLOW IS OVER THE GULF
BASIN THIS MORNING WITH WATER VAPOR IMAGERY INDICATING
RELATIVELY DRY AND STABLE CONDITIONS E OF 90W. WITH THE
SOUTHWESTERN EXTENT OF AN UPPER LEVEL TROUGH PROGRESSING
EASTWARD OVER THE FLORIDA PENINSULA AND INTO THE SW NORTH ATLC
REGION...A DISSIPATING STATIONARY FRONT EXTENDS FROM THE FLORIDA
STRAITS TO THE NORTHWESTERN CUBA COAST NEAR 23N84W TO 21N87W IN
THE YUCATAN CHANNEL. ISOLATED SHOWERS REMAIN LIMITED TO THE
FLORIDA STRAITS AND AREAS S OF 24N E OF 82W. OTHERWISE...THE
REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED BY A 1028 MB HIGH CENTERED OVER SE TENNESSEE NEAR
35N86W. THE RIDGE AXIS EXTENDS SW THROUGH 30N90W TO THE MEXICO
COAST NEAR 20N97W. MOSTLY NE TO E WINDS PREVAIL E OF 92W...WITH
E-SE WINDS ESTABLISHING THEMSELVES W OF 92W WITH WEAK LOW-LEVEL
MOISTURE CONVERGENCE AND POSSIBLE ISOLATED SHOWERS OCCURRING W
OF 96W. 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 MORNING BETWEEN AN UPPER LEVEL ANTICYCLONIC
CIRCULATION CENTERED IN THE EAST PACIFIC REGION NEAR 13N93W AND
AN UPPER LEVEL LOW CENTERED OVER THE CENTRAL ATLC NEAR 20N50W.
WATER VAPOR IMAGERY INDICATES THAT VERY DRY AIR 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
07N/08N FROM NORTHERN COLOMBIA WESTWARD TO SOUTHERN COSTA RICA.
ELSEWHERE...THE GREATEST CONCENTRATION OF LOW-LEVEL MOISTURE IS
FOUND OVER THE EASTERN CARIBBEAN WITH WIDELY SCATTERED
LOW-TOPPED SHOWERS OCCURRING WITHIN 120 NM EITHER SIDE OF A LINE
FROM 12N61W TO 16N69W...AND FROM 16N-21N BETWEEN 65W-72W...
INCLUDING PUERTO RICO AND THE MONA PASSAGE. OTHER ISOLATED
SHOWERS ARE S OF 15N BETWEEN 76W-85W. THIS OVERALL SYNOPTIC
PATTERN OF FAIRLY TRANQUIL WEATHER IS EXPECTED THROUGH THE
WEEKEND.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS OVER THE SW NORTH
ATLC WITH AXIS EXTENDING FROM 36N62W TO A BASE OVER THE SOUTHERN
FLORIDA PENINSULA NEAR 26N82W. THIS TROUGHING SUPPORTS A COLD
FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N66W THAT EXTENDS
SW TO THE NW BAHAMAS NEAR 25N78W AND INTO THE FLORIDA STRAITS AS
A DISSIPATING STATIONARY FRONT TO BEYOND 24N82W. LOW-LEVEL
MOISTURE CONVERGENCE NEAR THE FRONT IS GENERATING ISOLATED
SHOWERS WITHIN 120 NM EITHER SIDE OF THE FRONT...AND N OF 26N
BETWEEN 58W AND THE FRONT IN AN AREA OF WEAK PRE-FRONTAL
TROUGHING. FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW IS
CENTERED NEAR 20N50W THAT SUPPORTS A 1008 MB LOW NEAR 19N50W
WITH A SURFACE TROUGH AXIS EXTENDING NORTH FROM THE LOW TO
26N48W AND SOUTH-SOUTHWEST TO 16N50W THEN TO 07N56W. SATELLITE
IMAGERY PRESENTS THIS SYSTEM WITH A 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...WIDELY SCATTERED SHOWERS AND TSTMS ARE
OCCURRING FROM 17N-25N BETWEEN 45W-52W...AND SCATTERED SHOWERS
AND TSTMS OVER A LARGER AREA FROM 09N-25N BETWEEN 32W-48W. THE
REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED NEAR 29N31W.

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

$$
HUFFMAN




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