000
AXNT20 KNHC 202345
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE EXTENDS FROM 10N47W TO 3N49W MOVING W NEAR 13 
KT. WAVE CONTINUES TO BE EMBEDDED WITHIN THE ITCZ AND LOW-LEVEL 
CYCLONIC CURVATURE IS NOTED IN THE CLOUD FIELD NEAR THE WAVE 
AXIS. SCATTERED MODERATE CONVECTION IS OBSERVED WITHIN 60 NM OF 
A LINE FROM 10N44W TO 7N51W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 6N24W 9N45W 6N51W AND 
INTO SOUTH AMERICA NEAR 5N53W. CLUSTERS OF SCATTERED MODERATE 
CONVECTION ARE FROM 1N-5N BETWEEN 14W-20W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE ANCHORED OVER NE TEXAS DOMINATES MOST OF THE 
GULF GIVING THE REGION CLEAR SKIES AS A WEAK SURFACE RIDGE 
EXTENDS FROM THE W ATLC ACROSS FLORIDA THROUGH A 1015 MB HIGH 
NEAR 28N88W TO OVER THE LOWER MISSISSIPPI VALLEY. AN ELONGATED 
UPPER LEVEL LOW IS CENTERED OVER THE YUCATAN PENINSULA WITH THE 
UPPER TROUGH EXTENDING FROM CUBA TO VERACRUZ MEXICO. THIS UPPER 
REGIME IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS 
INTERIOR CUBA AND PORTIONS OF THE WRN YUCATAN SPREADING HIGH 
LEVEL DEBRIS CLOUDINESS WWD OVER THE NEARBY COASTAL GULF WATERS. 
THE SURFACE HIGH IS FORECAST TO REMAIN QUASI-STATIONARY OVER THE 
N/CENTRAL GULF AS A WEAK COLD FRONT SLIDES SEWD ACROSS THE SE 
CONUS AND NRN FLORIDA PENINSULA...INCLUDING THE NE GULF WATERS 
BY LATE SUNDAY.

CARIBBEAN SEA...
AN ELONGATED UPPER LEVEL LOW CENTERED OVER THE YUCATAN PENINSULA 
WITH THE UPPER TROUGH EXTENDING FROM CUBA TO VERACRUZ MEXICO IS 
SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS OVER INTERIOR 
CUBA AND PORTIONS OF THE YUCATAN PENINSULA. AN UPPER RIDGE IS 
LOCATED SOUTH OF THE UPPER LOW EXTENDING FROM THE E PACIFIC 
REGION ACROSS NICARAGUA AND HONDURAS TO NEAR 18N78W OVER 
JAMAICA. THIS IS PROVIDING A DIFFLUENT PATTERN ALOFT AND 
GENERATING SCATTERED SHOWERS AND TSTMS OVER THE WRN CARIBBEAN S 
OF 20N W OF 75W. THE MOST INTENSE SHOWER AND TSTM ACTIVITY ON 
SATELLITE IMAGERY IS LOCATED ACROSS PANAMA AND COSTA RICA AS THE 
ITCZ AXIS EXTENDS EWD FROM THE E PACIFIC REGION TO A 1006 MB LOW 
CENTERED OVER NRN COLOMBIA. AN EARLIER SCATTEROMETER PASS 
INDICATES MODERATE TO FRESH EASTERLY TRADE WINDS CONTINUING 
ACROSS MUCH OF THE REGION WHICH IS USHERING IN LOW-LEVEL 
ISOLATED SHOWERS NE OF A LINE FROM TRINIDAD TO SWRN HISPANIOLA 
ACROSS THE NE CARIBBEAN WATERS. 

ATLANTIC OCEAN...
THE BROAD UPPER RIDGE ANCHORED OVER NE TEXAS EXTENDS EWD INTO 
THE W ATLC TO 70W. HIGH LEVEL CLOUDINESS IS OBSERVED ON 
SATELLITE IMAGERY MOVING SEWD ACROSS THE W ATLC WATERS N OF 28N 
W OF 69W. FARTHER TO THE E...AN UPPER LEVEL TROUGH IS OVER THE 
N/CENTRAL ATLC WITH AXIS EXTENDING ALONG 32N61W TO 26N62W. UPPER 
DIFFLUENCE GENERATED DUE TO THE UPPER TROUGH IS RESULTING IN 
SCATTERED SHOWERS AND POSSIBLE ISOLATED TSTMS OVER AN AREA 
COVERING ATLC WATERS FROM 25N-32N BETWEEN 58W-68W. ACROSS THE 
REMAINDER OF THE ATLC GENERALLY FAIR WEATHER IS PRESENT WHERE 
SUBSIDENCE IS OCCURRING UNDER A MIDDLE TO UPPER LEVEL RIDGE 
ACROSS THE CENTRAL ATLC AND A BROAD SURFACE RIDGE ANCHORED BY A 
1022 MB HIGH CENTERED NEAR 30N37W. 

$$
HUFFMAN