[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU JAN 15 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...
THE ITCZ AXIS IS CENTERED ALONG 5N10W 2N20W...CROSSING THE
EQUATOR ALONG 30W TO 1S40W INTO NORTHEASTERN BRAZIL NEAR 3S45W.
ISOLATED MODERATE CONVECTION IS WITHIN 90 NM SOUTH OF AXIS
BETWEEN 14W-17W. SIMILAR CONVECTION IS NEAR 4N20W...AND NEAR
5N18W.

...DISCUSSION...

THE GULF OF MEXICO...
STRONG COLD SURFACE HIGH PRESSURE SYSTEM OVER THE CENTRAL CONUS
IS INVADING THE GULF OF MEXICO AND THE STATE OF FLORIDA. THIS
SYSTEM WILL PRODUCE A NOTICEABLE INCREASE IN WINDS AND SEAS
ACROSS THE GULF THIS EVENING TO LATE FRIDAY...AND WILL ALSO KEEP
MAX AND MIN TEMPERATURES BELOW NORMAL ACROSS SOUTH FLORIDA
THROUGH THE UPCOMING WEEKEND. MULTILAYERED CLOUDS WITH EMBEDDED
SHOWERS COVER THE MAJORITY OF THE GULF WATERS. SWLY WINDS ALOFT
CONTINUE TO TRANSPORT ABUNDANT MID/UPPER LEVEL MOISTURE FROM THE
EPAC ACROSS SOUTH-CENTRAL MEXICO INTO THE GULF AND THE STATE OF
FLORIDA. A 110-130 KT JETSTREAM CROSSES THE N GULF WATERS AND
THE SE CONUS THEN CONTINUES INTO THE ATLANTIC OCEAN. THE NEXT
COLD FRONT IS EXPECTED TO MOVE SE ACROSS THE GULF SUNDAY EVENING
THROUGH MONDAY.

THE CARIBBEAN SEA...
A STATIONARY FRONT EXTENDS FROM CENTRAL CUBA TO THE GULF OF
HONDURAS NEAR 16N88W. SCATTERED MODERATE CONVECTION IS NEAR THE
TAIL END OF THE FRONT. THE STRONG HIGH PRES COVERING THE GULF OF
MEXICO WILL BUILD NORTH OF THE FRONT TONIGHT AND FRIDAY WITH AN
INCREASE IN WINDS OVER THE NW CARIBBEAN. MEANWHILE...THE FRONT
IS FORECAST TO MOVE TO EAST CUBA TO GULF OF HONDURAS FRI NIGHT
AND REMAIN NEARLY STATIONARY. ELSEWHERE...MODERATE TO STRONG
TRADE WINDS ARE BLOWING ACROSS THE BASIN. SHALLOW MOISTURE
EMBEDDED IN THE TRADE WIND FLOW IS MOVING WWD ACROSS THE
BASIN...MORE CONCENTRATED SOUTH OF HISPANIOLA AND OVER PUERTO
RICO AND THE VIRGIN ISLANDS. IN THE UPPER LEVELS...AN UPPER
RIDGE ANCHORED BY A HIGH NEAR THE COAST OF COLOMBIA DOMINATES
THE ENTIRE REGION. SW WINDS ON THE WESTERN PERIPHERY OF THIS
HIGH ARE ADVECTING SIGNIFICANT MID/UPPER LEVEL MOISTURE ACROSS
THE NW CARIBBEAN AND CUBA INTO THE BAHAMAS AND THE W ATLC.
STRONG SUBSIDENCE AND THE ASSOCIATED DRY AIR MASS IS NOTED OVER
THE REMAINDER OF THE CARIBBEAN SEA...PARTICULARLY E OF 75W.

THE ATLANTIC OCEAN...
A SURFACE TROUGH...REFLECTION OF AN UPPER-LEVEL LOW CENTERED
NEAR 14N53W...IS ALONG 19N52W 15N56W 10N59W. MOISTURE ASSOCIATED
WITH THIS SYSTEM IS ALREADY REACHING THE LESSER ANTILLES. THE
GFS COMPUTER MODEL SUGGESTS THAT THIS SYSTEM WILL MOVE WWD UNDER
THE TRADE WIND FLOW AFFECTING THE LESSER ANTILLES TONIGHT AND
THEN THE US/UK VIRGIN ISLANDS AND PUERTO RICO FRI THROUGH SUNDAY
PRODUCING A SIGNIFICANT INCREASE IN MOISTURE. THIS MAY ALLOW FOR
AN INCREASE IN SHOWER ACTIVITY TO THOSE ISLANDS. ELSEWHERE...A
STATIONARY FRONT ENTERS THE FORECAST AREA NEAR 31N65W THEN
CONTINUES SW CROSSING THE CENTRAL BAHAMAS AND CENTRAL CUBA INTO
THE NW CARIBBEAN. SCATTERED SHOWERS ARE ASSOCIATED WITH THE
FRONTAL BOUNDARY. STRONG HIGH PRES IS BUILDING BEHIND THE FRONT
OVER THE SE CONUS. THE REMAINDER OF THE ATLANTIC FORECAST REGION
REMAINS UNDER THE INFLUENCE OF A SFC RIDGE ANCHORED BY A 1032 MB
HIGH SITUATED SW OF THE AZORES NEAR 37N38W. A SWATH OF MODERATE
TO STRONG TRADE WINDS IS ON THE SOUTHERN PERIPHERY OF THIS RIDGE
MAINLY FROM 10N-22N EAST OF 50W. ALOFT...A RIDGE EXTENDS FROM
THE CARIBBEAN SEA THROUGH HISPANIOLA AND PUERTO RICO INTO THE
CENTRAL AND EASTERN ATLANTIC. SOUTH OF THE RIDGE...THE ABOVE
MENTIONED UPPER-LEVEL LOW. AN UPPER-LEVEL TROUGH IS OVER WEST
AFRICA AND THE EASTERN ATLC E OF 25W.

$$
GR






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