[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200603
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT JUN 20 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
0530 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 10N43W TO 6N44W TO 1N45W MOVING W
AROUND 10-12 KT. THIS WAVE COINCIDES WITH A RELATIVELY LOW
AMPLITUDE MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL
PRECIPITABLE WATER PRODUCT FROM CIMSS. THE QUIKSCAT PASS AROUND
19/2045 UTC INDICATED CYCLONIC CURVATURE IN THE LOW FLOW IN THE
VICINITY OF THIS WAVE. ADDITIONALLY...RECENT SATELLITE IMAGERY
DEPICTS CYCLONIC CIRCULATION IN THE MOTION OF LOW LEVEL CLOUDS
NEAR THIS WAVE...WHICH IS CONFIRMED BY THE CIMSS WAVETRAK
PRODUCT. SCATTERED MODERATE CONVECTION IS FROM 6N-9N BETWEEN
43W-45W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 7N23W 5N36W 5N49W AND
INTO NE BRAZIL NEAR 4N53W. NUMEROUS MODERATE/SCATTERED STRONG
CONVECTION IS FROM 2N-13N BETWEEN 9W-14W INCLUDING ADJACENT
PORTIONS OF W AFRICA. SCATTERED MODERATE CONVECTION IS FROM
3N-5N BETWEEN 15W-17W. SCATTERED MODERATE CONVECTION IS ALSO
FROM 8N-10N BETWEEN 21W-26W.

...DISCUSSION...

GULF OF MEXICO...
ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER LEVEL LOW
CENTERED OVER THE NW CARIBBEAN NEAR 21N84W IS SUPPORTING
SCATTERED SHOWERS AND THUNDERSTORMS OVER THE S GULF S OF 21N W
OF 90W. ACROSS THE N AND CENTRAL GULF...DEEP LAYER DRY AIR IS
SUPPORTING GENERALLY FAIR WEATHER...WHERE EASTERLY FLOW ALOFT
IS OCCURRING BETWEEN THE AFOREMENTIONED UPPER LEVEL LOW OVER THE
CARIBBEAN AND AN UPPER LEVEL HIGH OVER THE SE UNITED STATES.
THIS UPPER LEVEL HIGH IS ASSOCIATED WITH A 1015 MB SURFACE HIGH
OVER THE CENTRAL GULF NEAR 29N88W. ANTICYCLONIC FLOW AROUND THE
SURFACE HIGH IS AFFECTING MUCH OF THE GULF...WITH SE WINDS OF 15
TO 20 KT OCCURRING ACROSS PORTIONS OF THE W GULF IN RESPONSE TO
A BROAD SURFACE TROUGH OVER MEXICO AND THE SOUTHERN PLAINS OF
THE UNITED STATES. THIS SURFACE HIGH IS FORECAST TO MEANDER OVER
THE CENTRAL GULF WATERS THROUGH SATURDAY NIGHT...BEFORE A WEAK
COLD FRONT MOVES SOUTHEASTWARD INTO THE NE GULF LATE SUNDAY.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS OVER THE NW CARIBBEAN AND IS CENTERED NEAR
21N84W. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS UPPER LEVEL
LOW IS IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS OVER
THE W CARIBBEAN N OF 13N W OF 77W INCLUDING PORTIONS OF
CUBA...HONDURAS...NICARAGUA...AND COSTA RICA. ACROSS THE E
CARIBBEAN...UPPER LEVEL MOISTURE AND HIGH LEVEL CLOUDS ARE
STREAMING NORTHEASTWARD TO THE E OF AN UPPER LEVEL TROUGH AXIS
THAT EXTENDS FROM 18N71W TO 12N71W. THIS MOISTURE IS INTERACTING
WITH ATMOSPHERIC INSTABILITY TO RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS OVER THE NE CARIBBEAN N OF 16N E OF 72W
INCLUDING PORTIONS OF HISPANIOLA. MODERATE TO FRESH EASTERLY
TRADES ARE FORECAST TO OCCUR S OF 16N THROUGH SUNDAY TO THE S OF
A SURFACE RIDGE OVER THE CENTRAL ATLC.

ATLANTIC OCEAN...
SUBSIDENCE IN NORTHWESTERLY FLOW ALOFT IS SUPPORTING GENERALLY
FAIR WEATHER ACROSS THE SW NORTH ATLC. HOWEVER...UPPER LEVEL
DIFFLUENCE AND UPPER LEVEL MOISTURE ARE SUPPORTING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS FROM 23N-27N W OF 68W
INCLUDING PORTIONS OF THE NW BAHAMAS. TO THE E...AN UPPER LEVEL
TROUGH OVER THE CENTRAL ATLC IS ASSOCIATED WITH A WARM FRONT
EXTENDING FROM NW OF THE DISCUSSION AREA TO 32N60W TO 31N58W...A
STATIONARY FRONT EXTENDING FROM 31N58W TO 31N59W...AND A COLD
FRONT EXTENDING FROM 31N49W TO 32N47W TO NE OF THE DISCUSSION
AREA. LOW LEVEL CONVERGENCE NEAR THESE FEATURES IS INTERACTING
WITH MOISTURE IN DIFFLUENT AND MOIST WESTERLY FLOW ALOFT TO
RESULT IN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 28N
BETWEEN 45W-55W. ACROSS MUCH OF THE CENTRAL AND E ATLC...
GENERALLY FAIR WEATHER IS PRESENT WHERE SUBSIDENCE IS OCCURRING
NEAR A BROAD SURFACE RIDGE. HOWEVER...A DEEP LAYER LOW OVER THE
E ATLC IS ASSOCIATED WITH A SURFACE TROUGH EXTENDING FROM 31N20W
TO 32N20W TO N OF THE DISCUSSION AREA. LOW LEVEL CONVERGENCE
NEAR THIS SURFACE TROUGH IS SUPPORTING SCATTERED SHOWERS N OF
30N BETWEEN 18W-22W. ACROSS THE TROPICAL ATLC...A BROAD UPPER
LEVEL RIDGE IS S OF 15N E OF 53W WITH AN UPPER LEVEL HIGH NEAR
13N23W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL
HIGH AND UPPER LEVEL RIDGE IS SUPPORTING THE CONVECTION
ASSOCIATED WITH THE ITCZ AND WITH THE TROPICAL WAVE THAT EXTENDS
FROM 10N43W TO 6N44W TO 1N45W.

$$
COHEN



This weather bulletin was brought to you by:
www.nashvilleweather.net