[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON JAN 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 7N10W 4N20W 4N30W 3N40W THEN EQUATOR AT
50W. SCATTERED MODERATE CONVECTION IS FROM EQ-6N BETWEEN
27W-40W. SIMILAR CONVECTION IS WITHIN 80 NM S OF AXIS BETWEEN
15W-25W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A STATIONARY FRONT EXTENDS ACROSS SOUTH-CENTRAL
FLORIDA AND THE GULF WATERS ALONG 26N82W 25N90W TO THE BAY OF
CAMPECHE NEAR 18N93W. A WIDE BAND OF MULTILAYERED CLOUDS WITH
EMBEDDED SHOWERS IS ASSOCIATED WITH THE FRONT. DOPPLER RADAR
REVEALS SCATTERED SHOWERS OVER SOUTH FLORIDA AND COASTAL WATERS
INCLUDING ALSO THE FLORIDA KEYS. THIS STATIONARY FRONTAL
BOUNDARY WILL BE REINFORCED TUE BY A SECOND COLD FRONT...THAT
WILL PUSH QUICKLY ACROSS THE NW GULF EARLY TUE MORNING AND MERGE
WITH THE STALLING FRONT EXTENDING FROM THE FLORIDA KEYS TO THE
EXTREME W CARIBBEAN BY TUESDAY EVENING. NLY WINDS OF 20 TO 30
ARE EXPECTED IN THE WAKE OF THE FRONT WITH THE STRONGEST WINDS
BLOWING ACROSS THE BAY OF CAMPECHE AND THE ISTHMUS OF
TEHUANTEPEC. THIS WILL RESULT IN A GAP WIND EVENT WITH GALE
FORCE WINDS IN THE EPAC REGION. IN FACT...AN EARLIER QSCAT PASS
INDICATED NW WINDS OF 20 TO 30 KT BEHIND THE FRONT OVER THE SW
PORTION OF THE GULF. SIMILAR SPEED WINDS ARE ALSO OBSERVED OVER
THE GULF OF TEHUANTEPEC EARLY THIS EVENING. IN THE UPPER
LEVELS... STRONG SOUTHWESTERLY FLOW WITH SIGNIFICANT UPPER LEVEL
MOISTURE COVERS THE ENTIRE GULF REGION. THESE UPPER-LEVEL WINDS
ARE AHEAD OF A BROAD LONG-WAVE TROUGH LOCATED OVER THE CENTRAL
CONUS WHICH WILL SUPPORT THE AFOREMENTIONED FRONTS.

CARIBBEAN SEA...
A TIGHT SURFACE PRESSURE GRADIENT BETWEEN HIGH PRES N OF AREA
AND THE SEMI-PERMANENT SFC LOW OVER COLOMBIA/PANAMA IS PRODUCING
MODERATE TO STRONG TRADEWINDS WITH OCCASIONAL GUSTS TO GALE
FORCE ACROSS THE BASIN. AS USUAL...THE STRONGEST WINDS ARE NEAR
THE COAST OF COLOMBIA. ABUNDANT CLOUDINESS COVERS THE WEST AND
CENTRAL CARIBBEAN WITH A BAND OF TRANSVERSE HIGH CLOUDS
EXTENDING FROM CENTRAL AMERICA TO BETWEEN CUBA AND JAMAICA THEN
TURNING SE ACROSS THE EASTERN CARIBBEAN. THESE CLOUDS ARE MOVING
AROUND A STRONG UPPER-LEVEL RIDGE WHICH EXTENDS FROM EASTERN
COLOMBIA AND WESTERN VENEZUELA NWD ACROSS HISPANIOLA INTO THE
WEST-CENTRAL ATLC TO BEYOND 32N55W. MODERATE TO STRONG
UPPER-LEVEL SUBSIDENCE DOMINATES THE E CARIBBEAN COURTESY OF
THIS RIDGE. THE NEXT COLD FRONT IS FORECAST TO REACH WESTERN
CUBA AND THE NW CARIBBEAN LATE TUE THEN WILL EXTEND FROM CENTRAL
CUBA TO HONDURAS ON WED.

ATLANTIC OCEAN...
A COLD FRONT ENTERS THE FORECAST AREA NEAR 31N71W THEN CONTINUES
SW TO SOUTH-CENTRAL FLORIDA CROSSING JUST SOUTH OF LAKE
OKEECHOBEE. A ROPE CLOUD DELINEATES THE LEADING EDGE OF THE
FRONT OVER THE W ATLC. JUST AHEAD OF THE FRONT...SW TO S WINDS
OF 20 TO 25 KT PREVAIL WHILE NE WINDS OF AROUND 15 KT ARE SEEN
BEHIND THE FRONT. THE REMAINDER OF THE AREA IS UNDER THE
INFLUENCE OF A SFC RIDGE ANCHORED BY A 1029 MB HIGH SITUATED
WEST OF THE AZORES NEAR 36N33W. THIS SYSTEM WILL CONTINUE TO
MOVE EWD DURING THE NEXT 24 HOURS. MOSTLY FAIR WEATHER IS NOTED
BETWEEN 35W-65W. ALOFT...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES
THE DISCUSSION AREA. THE UPPER-LEVEL TROUGH STRETCHES ACROSS THE
CENTRAL ATLC INTO THE DEEP TROPICS WITH THE BASE OF THIS TROUGH
REACHING 10N58W. UPPER DIFFLUENCE BETWEEN THIS TROUGH AND AN
UPPER-LEVEL RIDGE OVER THE E ATLC IS SUPPORTING A LARGE AREA OF
MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS THAT COVERS MUCH OF
THE E ATLC FROM THE ITCZ ALL THE WAY N TO AROUND 32N.

$$
GR




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