[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222334
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUN 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 15N56W TO 9N59W TO 3N60W MOVING W
15-20 KT. THIS WAVE IS NEAR THE LEADING EDGE OF A RATHER
ELONGATED MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL
PRECIPITABLE WATER PRODUCT FROM CIMSS. COMPUTER MODEL GUIDANCE
INDICATES CYCLONIC CURVATURE IN THE LOW LEVEL FLOW IN THE
VICINITY OF THIS WAVE. SCATTERED MODERATE CONVECTION IS FROM
11N-15N BETWEEN 52W-61W. SCATTERED MODERATE CONVECTION IS ALSO
FROM 8N-10N BETWEEN 50W-52W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 7N26W 5N38W 6N45W AND
INTO NE BRAZIL NEAR 5N53W. SCATTERED MODERATE CONVECTION IS FROM
5N-8N BETWEEN 13W-28W. SCATTERED MODERATE CONVECTION IS ALSO
FROM 4N-7N BETWEEN 32W-36W.

...DISCUSSION...

GULF OF MEXICO...
ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER LEVEL LOW
ACROSS E MEXICO IS SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS OVER THE S GULF S OF 25N W OF 90W. THIS ACTIVITY
IS ALSO BEING SUPPORTED BY LOW LEVEL CONVERGENCE ASSOCIATED WITH
A SURFACE TROUGH OVER THE SW GULF THAT EXTENDS FROM 23N96W TO
20N96W TO THE COAST OF MEXICO NEAR 19N95W. ACROSS THE N AND E
GULF...DEEP LAYER DRY AIR IS SUPPORTING GENERALLY FAIR
WEATHER...WHERE SOUTHEASTERLY FLOW ALOFT IS OCCURRING BETWEEN
THE AFOREMENTIONED UPPER LEVEL LOW OVER E MEXICO AND AN UPPER
LEVEL HIGH OVER N LOUISIANA. THE UPPER LEVEL HIGH IS ASSOCIATED
WITH A 1013 MB SURFACE HIGH OVER THE N GULF NEAR 28N91W.
ANTICYCLONIC FLOW AROUND THE SURFACE HIGH IS AFFECTING MUCH OF
THE GULF...WITH E TO SE WINDS OF 15 TO 20 KT OCCURRING ACROSS
PORTIONS OF THE SW GULF. THE SURFACE HIGH IS FORECAST TO MOVE
WESTWARD TONIGHT AND THEN MEANDER OVER THE WESTERN WATERS OF THE
GULF THROUGH WEDNESDAY.

CARIBBEAN SEA...
UPPER LEVEL MOISTURE IN DIFFLUENT NORTHERLY FLOW ALOFT ACROSS
THE N CARIBBEAN IS INTERACTING WITH ATMOSPHERIC INSTABILITY TO
RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS N OF 17N BETWEEN
70W-83W INCLUDING PORTIONS OF CUBA...JAMAICA...AND HISPANIOLA.
ACROSS THE SW CARIBBEAN...ATMOSPHERIC INSTABILITY ASSOCIATED
WITH AN UPPER LEVEL TROUGH IS SUPPORTING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS S OF 12N BETWEEN 73W-84W INCLUDING
PORTIONS OF NICARAGUA...COSTA RICA...PANAMA...AND N COLOMBIA.
ACROSS THE E CARIBBEAN...DEEP LAYER DRY AIR AND CONFLUENT
WESTERLY FLOW ALOFT ARE PRESENT...WHERE GENERALLY FAIR WEATHER
IS OCCURRING. HOWEVER...UPPER LEVEL MOISTURE AND HIGH LEVEL
CLOUDS ARE STREAMING NORTHEASTWARD ACROSS THE FAR SE CARIBBEAN.
THE TROPICAL WAVE EXTENDING FROM 15N56W TO 9N59W TO 3N60W IS
FORECAST TO MOVE INTO THE E CARIBBEAN ON TUESDAY.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH OVER THE W ATLC IS ASSOCIATED WITH A 990 MB
SURFACE LOW NEAR 40N67W. THE TIGHT PRESSURE GRADIENT SE OF THIS
SURFACE LOW IS SUPPORTING GALE FORCE WINDS WITHIN 660 NM IN THE
SE QUADRANT OF THE SURFACE LOW N OF 31N. THE DEEP LAYER LOW IS
ALSO ASSOCIATED WITH A STATIONARY FRONT EXTENDING FROM NW OF THE
DISCUSSION AREA TO 32N82W TO 31N81W...A COLD FRONT EXTENDING
FROM 31N81W TO 29N74W TO 32N65W TO NE OF THE DISCUSSION
AREA...AND A SURFACE TROUGH EXTENDING FROM 29N69W TO 27N75W TO
28N79W. LOW LEVEL CONVERGENCE NEAR THE FRONTS AND SURFACE
TROUGH...AS WELL AS ATMOSPHERIC INSTABILITY...UPPER LEVEL
DIFFLUENCE...AND ABUNDANT DEEP LAYER MOISTURE...ARE SUPPORTING
SCATTERED SHOWERS AND THUNDERSTORMS N OF 21N BETWEEN 64W-79W
INCLUDING THE 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 1024 MB SURFACE HIGH NEAR 35N35W.
ACROSS THE TROPICAL ATLC...A BROAD UPPER LEVEL RIDGE IS S OF 15N
E OF 42W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL
RIDGE IS SUPPORTING THE CONVECTION ASSOCIATED WITH THE ITCZ.

$$
COHEN


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