[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 011130
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON JUN 01 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
1030 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS LOCATED OVER THE SE CARIBBEAN ALONG 62W S OF
14N MOVING W 15-20 KT. THIS WAVE IS ASSOCIATED WITH A NARROW
MAXIMUM IN TOTAL PRECIPITABLE WATER AHEAD OF DRY LOW-MID LEVEL
AIR IN PART ASSOCIATED WITH SAHARAN DUST. THE POSITION OF THE
WAVE IS BASED MAINLY ON THIS TPW FIELD...AS LITTLE SIGNATURE IS
APPARENT IN THE LOW-MID LEVEL CLOUDS OR IN SFC OBSERVATIONS.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N11W 3N23W 2N34W 1N45W TO THE
EQUATOR ALONG 50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 2N-7N BETWEEN 10W-22W. SIMILAR CONVECTION IS S OF 6N
BETWEEN 24W-34W. SCATTERED MODERATE CONVECTION IS S OF 3N
BETWEEN 35W-49W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH REPRESENTING THE REMNANTS OF A FRONT IS
MEANDERING OVER THE SE AND S CENTRAL GULF FROM NEAR FORT MYERS
FLORIDA TO 25N87W TO JUST W OF THE NW CORNER OF THE YUCATAN
PENINSULA. LOW LEVEL CONVERGENCE IS SUPPORTING ISOLATED SHOWERS
AND TSTMS ALONG AND S OF THE TROUGH. SUBSIDENCE ASSOCIATED WITH
WEAK SURFACE HIGH PRESSURE OVER THE N WATERS IS RESULTING IN
GENERALLY FAIR WEATHER...WHERE LIGHT WINDS PERSIST.
SOUTHWESTERLY FLOW ALOFT CONTINUES TO ADVECT MOISTURE OVER THE
WESTERN WATERS...WHERE HIGH LEVEL CLOUDINESS IS INCREASING. IR
IMAGERY AND LIGHTNING DATA SHOW SOME TSTM ACTIVITY JUST OFF THE
COAST OF MEXICO FROM 21N-23N W OF 96W. LOOKING AHEAD A DAY OR
TWO...NWP MODELS SUGGEST THAT THE OLD FRONT WILL GRADUALLY
DISSIPATE ALLOWING SFC RIDGING TO BECOME BETTER ESTABLISHED
ACROSS THE AREA.

CARIBBEAN SEA...
THE MID-UPPER PATTERN IS QUITE AMPLIFIED OVER THE CARIBBEAN WITH
A RIDGE OVER THE WRN HALF AND TROUGHING OVER THE ERN HALF.
DIFFLUENCE ALOFT COUPLED WITH LOW-LEVEL CONVERGENCE ALONG AN OLD
FRONT OVER THE SE GULF OF MEXICO IS PRODUCING SCATTERED SHOWERS
AND ISOLATED TSTMS OVER THE YUCATAN PENINSULA...YUCATAN
CHANNEL...AND W CUBA. SIMILAR ACTIVITY IS OCCURRING OVER
PORTIONS OF CENTRAL AMERICA ENHANCED BY THE ITCZ.  THE
ATMOSPHERE IS MORE STABLE OVER THE CENTRAL CARIBBEAN IN AN UPPER
CONFLUENT AREA BETWEEN THE TROUGH AND RIDGE. SW FLOW ALOFT E OF
THE TROUGH AXIS IS ADVECTING MOISTURE ACROSS THE SE CARIBBEAN...
BUT IT IS NOT RESULTING IN ANY SIGNIFICANT SHOWER OR TSTM
ACTIVITY. IN THE LOWER LEVELS...SHORTWAVE IR IMAGERY...SFC
OBS...AND QUIKSCAT DATA SHOW EVIDENCE OF A WEAK TROUGH OVER AND
N OF THE VIRGIN ISLANDS. THIS WEAK FEATURE IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS IN ITS VICINITY. TRADE
WINDS REMAIN 20-30 KT ACROSS THE S CENTRAL PORTION DUE TO THE
PRESSURE GRADIENT BETWEEN A HIGH OVER THE SUBTROPICAL CENTRAL
ATLC AND LOWER PRES OVER NRN SOUTH AMERICA. WINDS NEAR 20 KT
EXIST OVER THE TOPOGRAPHICALLY ENHANCED GULF OF HONDURAS. LITTLE
CHANGE IN THESE FLOWS ARE FORECAST OVER THE NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...
WEATHER CONDITIONS ACROSS MUCH OF THE ATLC DISCUSSION ZONE ARE
QUIET...WITH ONLY A FEW AREAS OF UNSETTLED WEATHER TO MENTION.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE LOCATED OVER THE WRN
BAHAMAS ASSOCIATED WITH AN UPPER JET AND AN OLD FRONTAL
BOUNDARY. THE ASSOCIATED THINNING DEBRIS MOISTURE HAS SPREAD
WELL TO THE NE THRU BERMUDA BY STRONG SW FLOW ALOFT. HIGHLY
AMPLIFIED DEEP LAYER RIDGING DOMINATES THE CENTRAL ATLC...THOUGH
AN UPPER LOW AND SFC TROUGH NEAR THE VIRGIN ISLANDS ARE
INTERRUPTING THE RIDGE SLIGHTLY. NONETHELESS...FAIR WEATHER
DOMINATES THE MAJORITY OF THE REGION WITH THE EXCEPTION OF NEAR
THE SFC TROUGH...S OF 22N BETWEEN 61W-67W WHERE SCATTERED
SHOWERS AND ISOLATED TSTMS ARE LIKELY. THE E ATLC IS MAINLY
UNDER AN UPPER TROUGH WITH A RELATED FRONT NEARING THE N BORDER
AND A WEAK SFC TROUGH S OF IT EXTENDING FROM 31N24W TO 25N29W.
LITTLE SIGNIFICANT SHOWER ACTIVITY IS ALONG THE BOUNDARY. IN
FACT...CONVECTION OVER THE E ATLC APPEARS CONFINED TO THE ITCZ.

$$
CANGIALOSI





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