[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 280556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN JUN 28 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 11N40W TO 6N42W TO THE EQUATOR
ALONG 42W MOVING W NEAR 10 KT AND IS AFFECTING PORTIONS OF THE
TROPICAL ATLC. THIS WAVE IS ANALYZED NEAR THE LEADING EDGE OF AN
ELONGATED MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL
PRECIPITABLE WATER PRODUCT FROM CIMSS. THE QUIKSCAT PASS AROUND
27/2040 UTC INDICATES CYCLONIC CURVATURE IN THE LOW LEVEL FLOW
NEAR THIS WAVE. COMPUTER MODEL GUIDANCE SUGGESTS THAT AN AREA OF
STRONGER LOW LEVEL CYCLONIC CIRCULATION IS EMBEDDED FARTHER
EASTWARD INTO THE ELONGATED DEEP LAYER MOISTURE MAXIMUM...
APPROXIMATELY ALONG 35W S OF 10N. THIS AREA WILL CONTINUE TO BE
MONITORED FOR THE PRESENCE OF A TROPICAL WAVE.

A TROPICAL WAVE IS ALONG 72W S OF 20N MOVING W NEAR 10 KT AND IS
AFFECTING PORTIONS OF THE CENTRAL CARIBBEAN. THIS WAVE IS NOT
PARTICULARLY WELL DEFINED. HOWEVER...COMPUTER MODEL GUIDANCE
SUGGESTS THAT THE WAVE COINCIDES WITH WEAK LOW LEVEL CYCLONIC
CIRCULATION. ALSO...THE SOUNDING FROM CURACAO AT 27/1200 UTC
INDICATES ANOMALOUS SOUTHEASTERLY FLOW IN THE LOW
LEVELS...SUGGESTING THE WAVE AXIS WAS WEST OF CURACAO AT THAT
TIME. THE PRESENCE OF DRY LOW/MID-LEVEL SAHARAN AIR OVER
PORTIONS OF THE CENTRAL AND E CARIBBEAN IS INHIBITING DEEP
CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED SHOWERS ARE
OCCURRING FROM 16N-18N BETWEEN 68W-71W INCLUDING PORTIONS OF
HISPANIOLA.

A VIGOROUS TROPICAL WAVE EXTENDS FROM 23N86W TO 16N90W TO 10N90W
IN THE E PACIFIC REGION MOVING W 10-15 KT AND IS AFFECTING
PORTIONS OF THE W CARIBBEAN SEA AND E PACIFIC REGION. SURFACE
OBSERVATIONS INDICATE CYCLONIC CURVATURE IN THE LOW LEVEL FLOW
NEAR THE WAVE. LOW LEVEL CONVERGENCE NEAR THE WAVE IS SUPPORTING
SHOWERS AND THUNDERSTORMS OVER PORTIONS OF THE W CARIBBEAN. IN
PARTICULAR...NUMEROUS MODERATE CONVECTION IS FROM 18N-22N
BETWEEN 82W-87W. ALSO...SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 14N-20N BETWEEN 86W-92W INCLUDING N PORTIONS
OF SOUTH AMERICA AND SE PORTIONS OF MEXICO. ALL OF THIS
CONVECTION IS ALSO BEING SUPPORTED BY UPPER LEVEL DIVERGENCE
ASSOCIATED WITH AN UPPER LEVEL RIDGE OVER THE W AND CENTRAL
CARIBBEAN. WHILE NO DEVELOPMENT OF THIS SYSTEM IS EXPECTED AS IT
MOVES ACROSS THE YUCATAN PENINSULA...SOME SLOW DEVELOPMENT IS
POSSIBLE AFTER IT MOVES INTO THE SOUTHERN GULF OF MEXICO LATER
TODAY OR TONIGHT. THERE IS A LOW CHANCE...LESS THAN 30
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS. MEANWHILE...LOCALLY HEAVY RAINS AND GUSTY WINDS
WILL CONTINUE TO AFFECT PORTIONS OF THE YUCATAN PENINSULA AND
WESTERN CUBA THROUGH TONIGHT.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 10N25W 9N36W 7N46W 5N54W.
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 9N-11N BETWEEN
16W-19W. SCATTERED MODERATE CONVECTION IS FROM 1N-11N BETWEEN
19W-21W. SCATTERED MODERATE CONVECTION IS ALSO FROM 2N-4N
BETWEEN 27W-29W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS CENTERED OVER THE W GULF NEAR 22N96W.
ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS UPPER LEVEL LOW IS
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS S OF 20N W OF
95W. ALSO...UPPER LEVEL DIFFLUENCE BETWEEN THE AFOREMENTIONED
UPPER LEVEL LOW AND AN UPPER LEVEL RIDGE OVER THE W AND CENTRAL
CARIBBEAN...AS WELL AS DEEP LAYER MOISTURE...ARE SUPPORTING
SCATTERED SHOWERS S OF 24N BETWEEN 85W-87W. ELSEWHERE ACROSS THE
N AND W GULF...SUBSIDENCE IN CONFLUENT EASTERLY FLOW ALOFT
BETWEEN AN UPPER LEVEL HIGH OVER N TEXAS AND THE AFOREMENTIONED
UPPER LEVEL LOW OVER THE W GULF...AS WELL AS DEEP LAYER DRY
AIR...ARE RESULTING IN GENERALLY FAIR WEATHER. SHOWERS AND
THUNDERSTORMS OVER THE W CARIBBEAN ARE ASSOCIATED WITH A
TROPICAL WAVE EXTENDING FROM 23N86W TO 16N90W TO 10N90W. WHILE
NO DEVELOPMENT OF THIS SYSTEM IS EXPECTED AS IT MOVES ACROSS THE
YUCATAN PENINSULA...SOME SLOW DEVELOPMENT IS POSSIBLE AFTER IT
MOVES INTO THE SOUTHERN GULF OF MEXICO LATER TODAY OR TONIGHT.

CARIBBEAN SEA...
SHOWERS AND THUNDERSTORMS OVER THE W CARIBBEAN ARE ASSOCIATED
WITH A TROPICAL WAVE EXTENDING FROM 23N86W TO 16N90W TO 10N90W.
PLEASE SEE THE TROPICAL WAVES SECTION ABOVE FOR MORE INFORMATION
ON THIS SYSTEM. ACROSS THE CENTRAL CARIBBEAN...AN UPPER LEVEL
RIDGE IS PRESENT...WITH SUBSIDENCE AND ATMOSPHERIC STABILITY
SUPPORTING GENERALLY FAIR WEATHER ACROSS MUCH OF THE CENTRAL
CARIBBEAN. HOWEVER...UPPER LEVEL MOISTURE STREAMING SOUTHWARD IS
SUPPORTING SCATTERED SHOWERS N OF 15N BETWEEN 71W-77W INCLUDING
PORTIONS OF HISPANIOLA AND E CUBA. ACROSS THE E CARIBBEAN...DEEP
LAYER DRY AIR...INCLUDING LOW/MID-LEVEL DRY SAHARAN AIR...IS
RESULTING IN GENERALLY FAIR WEATHER.

ATLANTIC OCEAN...
ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER LEVEL TROUGH
OVER THE SW NORTH ATLC IS SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS N OF 27N BETWEEN 65W-75W. ALSO...UPPER LEVEL
DIFFLUENCE AND UPPER LEVEL MOISTURE ARE SUPPORTING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS FROM 23N-26N BETWEEN 73W-79W
INCLUDING PORTIONS OF THE NW BAHAMAS. FARTHER TO THE
E...GENERALLY FAIR WEATHER IS PRESENT ACROSS MUCH OF THE CENTRAL
AND E ATLC...WHERE SUBSIDENCE IS OCCURRING NEAR A BROAD SURFACE
RIDGE. THIS SURFACE RIDGE IS ASSOCIATED WITH A 1022 MB SURFACE
HIGH NEAR 31N46W AND A 1021 MB SURFACE HIGH NEAR 22N37W.
HOWEVER...AN UPPER LEVEL TROUGH N OF 19N E OF 26W IS SUPPORTING
A SURFACE TROUGH THAT EXTENDS FROM 23N44W TO 28N31W TO 31N24W
AND A COLD FRONT THAT EXTENDS FROM 31N24W TO 32N19W TO NE OF THE
DISCUSSION AREA. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED
SHOWERS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH AND COLD
FRONT. ALSO...ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER
LEVEL LOW NEAR 25N53W IS SUPPORTING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS FROM 23N-27N BETWEEN 52W-56W. ACROSS THE
TROPICAL ATLC...MOIST EASTERLY FLOW ALOFT IS PRESENT...WITH
UPPER LEVEL DIFFLUENCE SUPPORTING CONVECTION ASSOCIATED WITH THE
ITCZ AND THE TROPICAL WAVE THAT EXTENDS FROM 11N40W TO 6N42W TO
THE EQUATOR ALONG 42W.

$$
COHEN




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