000
AXNT20 KNHC 190539
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN APR 19 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.

...ITCZ...
THE ITCZ IS CENTERED ALONG 5N8W 2N15W...CROSSING THE EQUATOR 
NEAR 20W TO 3S30W AND INTO NE BRAZIL NEAR 3S40W. NO SIGNIFICANT 
CONVECTION IS OBSERVED IN THE DISCUSSION AREA.

...DISCUSSION...

GULF OF MEXICO...
MOIST WESTERLY FLOW ALOFT CONTINUES TO INCREASE ACROSS THE GULF 
REGION AHEAD OF A DEEP LAYER TROUGH OVER THE CENTRAL CONUS. THE 
RETURN FLOW AROUND A 1021 MB SURFACE HIGH CENTERED OVER THE W 
ATLC NEAR 33N76W IS RESULTING IN E TO SE WINDS OF 15 TO 20 KT 
ACROSS MUCH OF THE GULF REGION. THESE WINDS ARE ADVECTING 
ABUNDANT LOW-LEVEL MOISTURE ACROSS THE GULF REGION...RESULTING 
IN INCREASED INSTABILITY ACROSS THE NRN GULF. THIS INSTABILITY 
IS COMBINING WITH MIDDLE TO UPPER LEVEL ATMOSPHERIC DIFFLUENCE 
ACROSS THE NW AND N/CENTRAL GULF TO SUPPORT SCATTERED SHOWERS 
AND TSTMS N OF 26N W OF 90W. ACROSS THE E AND SE GULF...STABLE 
ATMOSPHERIC CONDITIONS ARE RESULTING IN GENERALLY FAIR WEATHER 
CONDITIONS. A SURFACE COLD FRONT ASSOCIATED WITH THE CENTRAL 
CONUS DEEP LAYER TROUGH IS FORECAST TO MOVE OFF THE TEXAS COAST 
EARLY SUNDAY...AND EXTEND FROM THE FLORIDA BIG BEND TO THE BAY 
OF CAMPECHE ON MONDAY. INCREASED NLY WINDS AND RELATIVELY COOLER 
AND DRIER CONDITIONS ARE FORECAST N OF THIS FRONT.

CARIBBEAN SEA... 
A SURFACE RIDGE BUILDING OVER THE W ATLC IS FORECAST TO 
MAINTAIN FRESH NE TO E TRADE WINDS ACROSS THE CARIBBEAN SEA 
THROUGH WEDNESDAY. GENERALLY FAIR WEATHER IS PRESENT ACROSS THE 
CARIBBEAN...WHERE DEEP LAYER DRY AIR AND SUBSIDENCE IS RESULTING 
FROM CONFLUENT WESTERLY FLOW ALOFT. HOWEVER...LOW LEVEL 
CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 90 NM EITHER 
SIDE OF A WEAKENING SURFACE COLD FRONT IN THE NRN CARIBBEAN THAT 
EXTENDS FROM THE W ATLC ACROSS HISPANIOLA NEAR 19N70W TO 18N77W 
17N82W TO 20N87W. SCATTERED SHOWERS ARE ALSO NOTED SE OF THE 
FRONT OVER PUERTO RICO AND THE SURROUNDING ADJACENT COASTAL 
WATERS.

ATLANTIC OCEAN...
SUBSIDENCE IN NW FLOW ALOFT ACROSS THE W ATLC IS ASSOCIATED WITH 
A 1021 MB SURFACE HIGH CENTERED NEAR 33N76W. A SURFACE RIDGE 
EXTENDS S-SE FROM THIS HIGH INTO THE SW NORTH ATLC...WHERE 
GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT. FARTHER TO THE 
E...AN UPPER LEVEL TROUGH OVER THE W AND CENTRAL ATLC WITH AXIS 
ALONG 61W IS ASSOCIATED WITH A SURFACE COLD FRONT THAT EXTENDS 
FROM NE OF THE DISCUSSION AREA TO 32N50W TO 25N58W TO NW OF 
HISPANIOLA NEAR 20N67W. LOW LEVEL CONVERGENCE AND ATMOSPHERIC 
INSTABILITY ARE SUPPORTING SCATTERED SHOWERS WITHIN 75 NM EITHER 
SIDE OF THIS FRONT S OF 25N WITH NUMEROUS SHOWERS AND ISOLATED 
TSTMS WITHIN 120 NM EITHER SIDE OF THIS FRONT N OF 25N. W OF 
THIS FRONT...A TRIO OF WEAK 1014 MB SURFACE LOWS EXTEND ALONG A 
STATIONARY FRONT THAT LIES WITHIN A LINE FROM 30N56W SW TO 
25N65W. A COLD FRONT EXTENDS FROM THE SWRN LOW NEAR 25N65W TO 
23N70W TO 25N73W. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED 
SHOWERS WITHIN 60 NM EITHER SIDE OF THE FRONTAL BOUNDARY. ACROSS 
THE E ATLC...SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE IS 
RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. THIS SURFACE 
RIDGE IS ANCHORED BY A 1028 MB SURFACE HIGH NEAR 33N25W. ACROSS 
THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 10N E OF 60W 
WITH UPPER LEVEL HIGHS CENTERED NEAR 5N11W AND 4N50W. UPPER 
LEVEL DIVERGENCE ASSOCIATED WITH THESE FEATURES IS ENHANCING THE 
CONVECTION ASSOCIATED WITH THE ITCZ OF WHICH IS LOCATED MAINLY S 
OF THE EQUATOR.

$$
HUFFMAN