[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED MAY 27 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 75W S OF 14N MOVING W 15-18 KT. WAVE
POSITION BASED ON INTERPOLATION AS IT REMAINS DIFFICULT TO
DEPICT ON VISIBLE SATELLITE IMAGERY. TOTAL PRECIPITABLE WATER
PRODUCT FROM CIMSS SHOWS DECREASING MOISTURE AS THE WAVE
CONTINUES WESTWARD MOVEMENT MAINLY ACROSS INLAND NRN COLOMBIA.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N11W 4N20W CROSSING THE EQUATOR
NEAR 32W AND INTO NE BRAZIL NEAR 2S45W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE S OF 6N BETWEEN 5W-26W.
ELSEWHERE ISOLATED MODERATE CONVECTION IS S OF 5N BETWEEN
26W-38W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS MOVING ACROSS NORTH
TEXAS SUPPORTING A COLD FRONT DRAPED FROM NE TEXAS THROUGH THE
RIO GRANDE RIVER VALLEY. SCATTERED SHOWERS AND TSTMS ARE AHEAD
OF THE FRONT NEAR THE TEXAS GULF COAST AND EXTEND N OF 27N W OF
93W IN THE NW GULF. SOUTHERLY WINDS OF 10 TO 15 KTS DOMINATE
ACROSS THE GULF AHEAD OF THIS NEXT COLD FRONT WHICH IS POISED TO
ENTER THE NW GULF EARLY MORNING THURSDAY. THE REMAINDER OF THE
GULF IS EXPERIENCING RATHER TRANQUIL AND FAIR CONDITIONS THIS
AFTERNOON WITH ONLY A FEW SCATTERED SHOWERS AND TSTMS OVER THE
NE GULF FROM 26N-29N BETWEEN 85W-87W AS A RESULT OF WEAK
LOW-LEVEL SURFACE WIND CONVERGENCE AND ATMOSPHERIC INSTABILITY.
ALOFT...THE SRN GULF IS UNDER THE INFLUENCE OF AN UPPER RIDGE
THAT EXTENDS NWD FROM THE E PACIFIC REGION AND MODERATELY DRY
AND STABLE AIR S OF 27N.

CARIBBEAN SEA...
SURFACE HIGH PRESSURE IN THE W ATLC IS MAINTAINING STRONG E TO
SE WIND FLOW ACROSS THE CARIBBEAN. THE SELY SURFACE FLOW ALONG
WITH A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH ACROSS THE WRN
CARIBBEAN N OF 17N BETWEEN 70W-80W IS GENERATING SCATTERED
SHOWERS AND TSTMS ACROSS JAMAICA...THE WINDWARD PASSAGE...
HISPANIOLA AND THE NEARBY COASTAL WATERS IN THE NRN CARIBBEAN N
OF 16N BETWEEN 72W-81W. AN UPPER LEVEL DIFFLUENT PATTERN AROUND
AN UPPER HIGH OVER THE E PACIFIC IS GENERATING SCATTERED SHOWERS
AND TSTMS IN THE SW CARIBBEAN S OF 12N W OF 77W. THE NW
CARIBBEAN REMAINS UNDER FAIR WEATHER CONDITIONS AS NW FLOW ALOFT
PROVIDES A STABLE SUBSIDENT ATMOSPHERE. IN ADDITION...A TROPICAL
WAVE IS OVER THE S/CENTRAL CARIBBEAN ALONG 75W. PLEASE SEE
TROPICAL WAVE SECTION ABOVE FOR FURTHER INFORMATION.

ATLANTIC OCEAN...
A 1010 MB SURFACE LOW IS CENTERED NORTH OF THE DISCUSSION AREA
IN THE W ATLC NEAR 33N75W. THIS LOW CONTINUES TO PROVIDE THE W
ATLC S OF 32N WITH MOIST AND UNSTABLE SLY SURFACE WINDS UNDER A
MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH ACROSS FLORIDA AND THE W
ATLC. ALL OF THESE FACTORS COMBINED ARE GENERATING SCATTERED
SHOWERS AND ISOLATED TSTMS FROM 23N-29N BETWEEN 74W-80W AND FROM
THE NRN COASTS OF THE GREATER ANTILLES ISLANDS N OF 18N TO
BEYOND 32N BETWEEN 65W-72W. THE LOW AND ASSOCIATED UPPER LEVEL
TROUGH ARE FORECAST TO CONTINUE MOVING NORTH OVER THE NEXT 24
HOURS. FURTHER EAST...A RIDGE OF HIGH PRESSURE EXTENDS FROM
NORTH OF THE REGION TO 20N BETWEEN 48W-65W. THE PRESENCE OF THIS
SURFACE RIDGE IS LIMITING THE SWD EXTEND OF A COLD FRONT THAT
LIES ALONG 33N BETWEEN 47W-60W. ACROSS THE CENTRAL ATLC...A
SURFACE TROUGH IS ANALYZED FROM 23N47W ALONG 29N44W TO BEYOND
32N42W. SCATTERED SHOWERS ARE OBSERVED WITHIN 30 NM E OF THE
SURFACE TROUGH AS A RESULT OF WEAK LOW-LEVEL CONVERGENCE ALONG
THE BOUNDARY. A SURFACE RIDGE IS PRESENT ACROSS THE E ATLC WITH
FAIR WEATHER CONDITIONS N OF 7N E OF40W. UPPER LEVEL DIVERGENCE
ASSOCIATED WITH AN UPPER HIGH NEAR 8N25W IS ENHANCING CONVECTION
ALONG THE ITCZ.

$$
HUFFMAN




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