[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291203
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST TUE DEC 29 2009

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 THE 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1130 UTC.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE WEST AFRICA COAST NEAR THE
NORTHERN COAST OF LIBERIA CONTINUING ALONG 4N20W 3N30W 2N40W TO
NORTHEASTERN BRAZIL NEAR THE CITY OF BELEM. MODERATE TO STRONG
CONVECTION IS DEVELOPING ALONG THE ITCZ BETWEEN 33W AND 41W.
ANOTHER AREA OF MODERATE CONVECTION IS EMBEDDED WITHIN THE ITCZ
FROM THE EQUATOR TO 4N BETWEEN 26W AND 29W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL RIDGE OF HIGH PRESSURE IS PASSING OVER THE REGION
BRINGING LIGHT SOUTHWEST FLOW ALOFT. STRONG SURFACE HIGH
PRESSURE OVER IOWA HAS BROUGHT A DRY AND COOLER AIRMASS TO THE
BASIN. SHIP AND BUOY OBSERVATIONS ARE SHOWING NNE WINDS 10 TO 15
KT ACROSS THE BASIN. OVER THE PAST 6 HOURS...A TIGHT GRADIENT OF
TEMPERATURE BETWEEN LAND AND SEA CREATED A TROUGH ALONG THE
MEXICO COAST FROM 25N97W NEAR MATAMOROS TO 18N93W NEAR CIUDAD
DEL CARMEN. NOW...THE COOLER AIRMASS FROM THE GULF WATERS HAVE
PUSHED THE TROUGH BACK INLAND. THE TROUGH IS NOW ANALYZED ALONG
26N98W 23N99W 20N100W. WATER VAPOR IMAGERY SHOWS UPPER LEVEL
MOISTURE BEEN ADVECTED BEHIND THE TROUGH BY A SHORTWAVE
CURRENTLY ENTERING THE WEST MEXICO COAST...AND EXPECTED TO REACH
THE BASIN OVER THE NEXT 24 HOURS. COMPUTER MODELS SUGGEST THAT
THIS TROUGH WILL SHIFT NORTH TO THE CENTRAL COAST OF TEXAS AND
DEVELOP INTO A SURFACE LOW PRESSURE SYSTEM OVER THE NEXT 24 TO
36 HOURS...BRINGING CONVECTIVE WEATHER TO THE NARROWEST BASIN.

THE CARIBBEAN SEA...
UPPER LEVEL RIDGE OF HIGH PRESSURE COVERS THE ENTIRE CARIBBEAN
SEA...SUPPRESSING DEEP CONVECTION IN THIS REGION. WATER VAPOR
IMAGERY SHOWS STRONG SUBSIDENCE OVER THE EAST AND CENTRAL
BASIN...WITH SOME MID LEVEL MOISTURE WEST OF 78W. SHIP AND BUOY
OBSERVATIONS SHOW EASTERLY WINDS 10 TO 15 KT ACROSS THE
BASIN...EXCEPT FOR THE NW CORNER OF THE BASIN WHERE OBSERVATIONS
SHOW NORTH-NORTHEAST WINDS 10 TO 15 KT. HIGH PRESSURE WEATHER
WILL CONTINUE TO DOMINATE OVER THE ENTIRE BASIN FOR THE NEXT 24
HOURS.

THE ATLANTIC OCEAN...
A COLD FRONT IS ANALYZED OVER THE WESTERN ATLANTIC PASSING
THROUGH 32N64W TO 27N67W TO THE SOUTHERN BAHAMAS NEAR 22N72W.
WEAK CONVECTION IS SEEN 50 NM EAST OF THIS FRONT COVERING AN
AREA FROM 25N TO 32N BETWEEN 61W AND 67W. A SECONDARY FRONT IS
FOUND 150 NM BEHIND THE FIRST ALONG 30N67W 28N68W 25N71W. THIS
FRONT STANDS OUT FOR BRINGING 15 TO 30 KT. AS THESE FRONTS MOVE
EASTWARD...EXPECT GALE FORCE WINDS TO DEVELOP OVER THE NEXT 24
HOURS AHEAD OF THE FIRST FRONT NORTH OF 27N BETWEEN 63W AND 59W.
A 1026 MB HIGH IS FOUND NEAR 32N47W. THIS HIGH PRESSURE IS
BRINGING LITTLE ACTIVITY TO THE CENTRAL ATLANTIC REGION AND WILL
MOVE EAST TO NEAR 31N35W AS UPPER LEVEL TROUGH PUSHES INTO THE
CENTRAL ATLANTIC REGION IN THE NEXT 24 HOURS. WATER VAPOR
IMAGERY SHOWS AN TROUGH OVER THE EASTERN ATLANTIC PASSING
THROUGH THE 25W LINE BETWEEN 22N AND 32N. THIS TROUGH IS
DISSIPATING AS IT ENTERS THE NORTH AFRICAN REGION.
THEREFORE...THE FRONTAL BOUNDARY ASSOCIATED TO THIS TROUGH IS
PLOTTED FROM 30N17W THROUGH 20N23W 18N40W 17N50W TO 20N60W. OVER
THE PAST 6 HOURS THIS BOUNDARY HAD FEATURES OF A COLD
FRONT...BUT NOW HAS WEAKENED TO STATIONARY FRONT. ALTHOUGH THIS
FRONTAL SYSTEM IS STARTING TO DISSIPATE...SHOWERS ARE POSSIBLE
WITHIN 100 NM TO 150 NM ON EITHER SIDE OF THE FRONTAL BOUNDARY.

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

$$

GARCIA





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