000
AXNT20 KNHC 201740
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 10N46W TO 2N48W MOVING W NEAR 10 
KT. WAVE CONTINUES TO BE FAIRLY DIFFICULT TO TRACK AS IT IS A 
VERY LOW AMPLITUDE WAVE. SMALL AREA OF SCATTERED MODERATE 
CONVECTION IS EMBEDDED WITHIN THE ITCZ WITHIN 45 NM OF LINE FROM 
8N47W TO 7N50W. 

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N13W 5N28W 9N42W AND INTO 
SOUTH AMERICA NEAR 5N54W. SCATTERED MODERATE CONVECTION WITH 
EMBEDDED SMALL CLUSTERS OF ISOLATED STRONG CONVECTION ARE FROM 
2N TO JUST INLAND OVER SW AFRICA BETWEEN 1W-10W. CLUSTERS OF 
SCATTERED MODERATE CONVECTION ARE FROM 2N-8N BETWEEN 12W-20W AND 
FROM 7N-11N BETWEEN 20W-24W. 

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE ANCHORED OVER E TEXAS DOMINATES MOST OF THE 
GULF GIVING THE AREA N OF 24N CLEAR SKIES AS A WEAK SURFACE 
RIDGE EXTENDS FROM THE W ATLC ACROSS FLORIDA THROUGH A 
PERSISTENT 1015 MB HIGH NEAR 28N86W TO OVER THE LOWER 
MISSISSIPPI VALLEY. AN ELONGATED UPPER LEVEL LOW CENTERED OVER 
THE N YUCATAN PENINSULA WITH THE UPPER TROUGH EXTENDING FROM W 
CUBA TO VERA CRUZ MEXICO IS SUPPORTING SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS IN THE SW GULF SW OF A LINE FROM JUST N 
OF TAMPICO TO JUST W OF CIUDAD DEL CARMEN. THIS SURFACE HIGH IS 
FORECAST TO MEANDER OVER THE E/CENTRAL GULF WATERS THROUGH 
TONIGHT BEFORE A WEAK COLD FRONT CLIPS THE NE GULF LATE SUNDAY.

CARIBBEAN SEA...
AN ELONGATED UPPER LEVEL LOW CENTERED OVER THE N YUCATAN 
PENINSULA WITH THE UPPER TROUGH EXTENDING FROM W CUBA TO VERA 
CRUZ MEXICO IS SUPPORTING SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS OVER W CUBA AND THE ADJACENT COASTAL WATERS N OF 
21N BETWEEN 81W-84W. AN UPPER RIDGE IS UNDERCUTTING THE ABOVE 
UPPER LOW EXTENDING FROM THE E PACIFIC REGION ACROSS CENTRAL 
NICARAGUA TO NEAR 13N73W PROVIDING DIFFLUENCE ALOFT GENERATING 
DENSE CLOUD COVER OVER THE W CARIBBEAN S OF 19N W OF 79W AND 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM OF LINE 
FROM THE TIP OF HONDURAS/NICARAGUA NEAR 16N84W TO CENTRAL PANAMA 
NEAR 9N79W. MODERATE TO FRESH EASTERLY TRADE WINDS ARE ACROSS 
MUCH OF THE REGION USHERING IN LOW LEVEL ISOLATED SHOWERS E OF 
65W ACROSS THE LESSER ANTILLES. 

ATLANTIC OCEAN...
THE BROAD UPPER RIDGE ANCHORED OVER E TEXAS EXTENDS E INTO THE 
FAR W ATLC NEAR SOUTH CARLINA AND INTO THE REGION AS FAR S AS 
23N W OF 76W PROVIDING UPPER DIFFLUENCE TO GENERATE SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS OVER THE CENTRAL BAHAMAS FROM 
22N-26N BETWEEN 74W-80W. A SURFACE TROUGH IS IN THE W ATLC 
EXTENDING FROM 31N76W TO JUST N OF THE BAHAMAS NEAR 27N78W. 
TO THE E...AN UPPER LEVEL TROUGH IS OVER THE N/CENTRAL ATLC WITH 
AN ASSOCIATED STATIONARY FRONT EXTENDING JUST INTO THE REGION 
THROUGH 32N45W SW TO 29N53W. LOW LEVEL CONVERGENCE NEAR THE 
FRONT IS INTERACTING WITH MOISTURE RESULTING IN ISOLATED SHOWERS 
N OF 28N BETWEEN 43W-53W. ACROSS THE REMAINDER OF THE ATLC 
GENERALLY FAIR WEATHER IS PRESENT WHERE SUBSIDENCE IS OCCURRING 
WITH A BROAD SURFACE RIDGE ANCHORED BY A 1022 MB HIGH NEAR 
30N36W. 

$$
WALLACE