[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111042
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED MAR 11 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N10W 2N17W CROSSING THE EQUATOR
NEAR 22W CONTINUING WSW ALONG 2S30W 3S40W. SCATTERED MODERATE TO
STRONG CONVECTION IS S OF 4N BETWEEN 4W-7W. SCATTERED MODERATE
IS WITHIN 180 NM EITHER SIDE OF THE AXIS BETWEEN 16W-25W AND
WITHIN 180 NM N OF THE AXIS BETWEEN 36W-40W.

...DISCUSSION...

GULF OF MEXICO...
A MID-UPPER LEVEL RIDGE CENTERED OVER THE GULF IS BECOMING
INCREASINGLY ELONGATED DUE TO AN APPROACHING UPPER TROUGH FROM
THE W. A STREAM OF PACIFIC MOISTURE...TRANSPORTED BY A
SUBTROPICAL JET...IS BEING DRIVEN BETWEEN THE RIDGE AND TROUGH
OVER MEXICO AND INTO THE EASTERN CONUS. LITTLE OF THIS MOISTURE
IS ENTERING THE GULF...IN FACT...WATER VAPOR IMAGERY REVEALS
WIDESPREAD DRY AIR ACROSS NEARLY THE ENTIRE AREA...LEADING TO
FAIR CONDITIONS. IN THE LOW LEVELS...A WEAK HIGH PRES RIDGE LIES
OVER THE NE WATERS. THIS FEATURE IS PROVIDING LIGHT WINDS...
EXCEPT 15-20 KT E TO SE FLOW OVER THE WRN WATERS. A COLD FRONT
IS EXPECTED TO MOVE INTO THE NW GULF WED EVENING AND THEN
STALL IN THAT AREA THROUGH FRI.

CARIBBEAN SEA...
TRADE WINDS HAVE SLACKENED OVER THE PAST DAY OR TWO DUE TO A
WEAKENING HIGH PRES RIDGE OVER THE W ATLC. SFC OBS AND QSCAT
DATA SHOW THE STRONGEST FLOW...20-25 KT...OVER THE CENTRAL
CARIBBEAN WITH WINDS REACHING 30 KT NEAR THE COAST OF COLOMBIA.
LOW-LEVEL CLOUDS AND ISOLATED SHOWERS ARE SCATTERED ACROSS THE
AREA ESPECIALLY E OF 72W. IN THE MID AND UPPER LEVELS...A TROUGH
EXTENDING FROM HISPANIOLA TO THE SW CARIBBEAN IS THE MAIN
FEATURE. CONFLUENCE ALOFT IS ENHANCING SUBSIDENCE NEAR AND W OF
ITS AXIS...WHILE DIFFLUENCE IS CAUSING ONLY SLIGHT MOISTENING E
OF THE AXIS. LITTLE CHANGE IN THE LARGE SCALE WEATHER PATTERN IS
ANTICIPATED OVER THE NEXT DAY OR SO.

ATLANTIC OCEAN...
AN OCCLUDED 994 MB LOW PRES SYSTEM CENTERED JUST N OF THE
DISCUSSION AREA NEAR 33N55W IS TRACKING SE NEAR 20 KT. AN
ASSOCIATED COLD FRONT EXTENDS FROM THE TRIPLE PT NEAR 33N50W
SOUTHWESTWARD ALONG 28N51W 24N65W 27N72W THEN DISSIPATING TO THE
SOUTH CAROLINA COAST. WHILE ONLY A NARROW BAND OF LOW-LEVEL
MOISTURE IS NOTED ALONG MUCH OF THE BOUNDARY...SCATTERED SHOWERS
AND TSTMS ARE LIKELY N OF 28N WITHIN 180 NM E OF FRONT. WINDS TO
STORM FORCE ARE ESTIMATED N OF THE FRONT IN THE COLD SECTOR OF
THE LOW. ANOTHER LOW PRES SYSTEM CONTINUES TO PULL AWAY FROM THE
AREA CENTERED NEAR 38N37W WITH A TROUGH EXTENDING S TO 32N34W TO
22N38W. LINGERING EFFECTS OF THIS SYSTEM CONSIST OF SLY 20-30 KT
WINDS WITHIN 240 NM E OF THE TROUGH AND SCATTERED SHOWERS N OF
30N BETWEEN 28W-31W. IN THE DEEP TROPICS...STRONG WLY FLOW ALOFT
IS TRANSPORTING MID-HIGH LEVEL CLOUDINESS FROM THE LESSER
ANTILLES TO AFRICA. FARTHER S...AN UPPER DIFFLUENT PATTERN ON
THE SW PERIPHERY OF A RIDGE IS ENHANCING CONVECTION WITHIN THE
ITCZ E OF 25W.

$$
CANGIALOSI





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