[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 301735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT MAY 30 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
1615 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 53W S OF 11N MOVING W 10-15 KT. TOTAL
PRECIPITABLE WATER IMAGERY SHOWS A WELL-DEFINED MAXIMUM IN
MOISTURE EAST OF THE WAVE AXIS. THE WAVE HAS LITTLE SURFACE
SIGNATURE AT THIS TIME...BUT IS ANALYZED IN THE GFS 700 AND 850
MB WINDS AS A DISTINCT TROUGH AND VORT MAX.  SCATTERED MODERATE
CONVECTION IS S OF 6N BETWEEN 38W-50W.

A NEW TROPICAL WAVE IS ANALYZED TO BE ALONG 21W MOVING ABOUT 15
KT.  LITTLE TO NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH
IT AND ONLY A MODEST MAXIMUM IN THE TOTAL PRECIPITABLE WATER
IMAGERY CAN BE OBSERVED JUST EAST OF THE WAVE AXIS.  RAWINSONDE
OBSERVATIONS FROM DAKAR AND BAMAKO INDICATE THAT THE SHALLOW
WAVE EXITED THE WEST COAST OF AFRICA YESTERDAY.  THE GFS
ANALYSES DO NOT DEPICT THE WAVE CLEARLY...THOUGH THE ECMWF
APPEARS TO HAVE A BETTER HANDLE ON THE LOCATION AND AMPLITUDE OF
THE WEAK WAVE.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N12W 3N25W CROSSING THE EQUATOR
NEAR 36W AND INTO NE BRAZIL NEAR 1S45W. SCATTERED MODERATE
ISOLATED STRONG CONVECTION IS S OF 6N E OF 5W. SCATTERED
MODERATE CONVECTION IS S OF 3N BETWEEN 38W-50W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT IS PRESENT ACROSS THE GULF AND AT 30/1500 UTC
EXTENDED FROM THE FLORIDA PENINSULA JUST SOUTH OF TAMPA
WEST-SOUTHWESTWARD TO 23N 90W AND THEN WESTWARD TO 23N 96W.  THE
NUMEROUS BUOYS AND AN 1158 UTC QUIKSCAT PASS ALLOWED FOR
RELATIVELY EASY IDENTIFICATION OF THIS SOMEWHAT STRONG COLD
FRONT FOR THIS TIME OF YEAR.  AHEAD OF THE FRONT EAST OF 88W
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS OBSERVED AS
INDICATED BY INFRARED AND VISIBLE SATELLITE IMAGERY...LIGHTNING
DATA...AND COASTAL RADARS.  ADDITIONALLY...ISOLATED MODERATE
CONVECTION HAS ALSO DEVELOPED NEAR THE WESTERN END OF THE
FRONT.  SURFACE WINDS AWAY FROM THE DEEP CONVECTION ARE LESS
THAN 20 KT.  IN THE UPPER LEVELS...WINDS ARE UNIFORMLY WESTERLY
UP TO A MAXIMA OF 70 KT.

CARIBBEAN SEA...
DEEP CONVECTION OVER THE CARIBBEAN IS UNDER QUITE SUPPRESSED
TODAY AS A SAHARAN AIR LAYER COVERS MOST OF THE SEA...AS SHOWN
BY THE TOTAL PRECIPITABLE WATER IMAGERY.  SCATTERED SHOWERS ARE
OCCURRING IN THE SOUTHWESTERN CARIBBEAN...PERHAPS BEING FORCED
BY A MID-LEVEL TROUGH ANALYZED BY THE GFS.  SURFACE WINDS ACROSS
THE CARIBBEAN MAX ONLY AROUND 20 KT AS THE PRESSURE GRADIENT IS
NOT PRONOUNCED WITH THE BERMUDA HIGH SOMEWHAT WEAK AND DISPLACED
NORTHEASTWARD.  IN THE UPPER LEVELS...SUBSIDENT TROUGHING
DOMINATES WITH A CLOSED LOW PRESENT JUST NORTH OF PUERTO RICO.

ATLANTIC OCEAN...
A 1026 MB SURFACE HIGH IS LOCATED NEAR 31N49W.  JUST EAST OF
THIS HIGH...A WEAKENING STATIONARY FRONT EXTENDS FROM 31N27W TO
25N37W TO 26N44W.  ISOLATED SHOWERS ARE LOCATED WITHIN 30 NM OF
THE FRONTAL BOUNDARY.  A SURFACE TROUGH IS LOCATED BETWEEN
25N57W SOUTHWARD TO 19N57W.  THIS FEATURE HAS BEEN RELATIVELY
STATIONARY DURING THE LAST DAY AND IS PRODUCING ISOLATED SHOWERS
WITHIN 120 NM OF THE TROUGH AXIS.  BY FAR THE MOST CONVECTIVELY
REGION IS IN ASSOCIATION WITH THE COLD FRONT OVER THE FLORIDA
PENINSULA AND A TROUGH EAST OF THE FRONT.  THE TROUGH EXTENDS
FROM 31N76W TO 27N78W AND SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS OCCURRING WITHIN 300 NM EAST OF THE TROUGH AXIS.
THE FRONT AND TROUGH ARE SUPPORTED BY A RATHER VIGOROUS
SHORT-WAVE TROUGH OVER THE SOUTHEASTERN US.  SURFACE WINDS AWAY
FROM THE DEEP CONVECTION ARE GENERALLY LIGHT ACROSS THE ATLANTIC
WITH WINDS ONLY UP TO 20 KT.

$$
LANDSEA




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