000
AXNT20 KNHC 010558
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI MAY 01 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.

...THE ITCZ...

THE ITCZ AXIS EXTENDS FROM W AFRICA AT 06N10W TO THE EQUATOR AT 
29W TO NE BRAZIL NEAR 02S44W. SCATTERED MODERATE CONVECTION IS 
NOTED WITHIN 90 NM N OF AXIS BETWEEN 25W AND 30W. 

...DISCUSSION...

GULF OF MEXICO...
A RIDGE OF HIGH PRES EXTENDS ACROSS THE NORTHERN GULF FROM THE 
WESTERN ATLC. LOW PRES REMAINS IN PLACE OVER THE MEXICAN 
PLATEAU. THE RESULTING PRESSURE GRADIENT BETWEEN THESE FEATURES 
IS SUPPORTING 15 TO 20 KT E TO SE FLOW FROM THE STRAITS OF 
FLORIDA TO THE TEXAS COAST. CMAN SITES IN THE FLORIDA KEYS SHOW 
WINDS HAVE DIMINISHED SLIGHTLY FROM YESTERDAY...ALTHOUGH A 00Z 
QUIKSCAT PASS FROM 00Z SHOWED PERSISTENT 25 KT FLOW OFF THE NW 
CUBAN COAST. FLOW ALOFT REMAINS GENERALLY ZONAL BETWEEN AN UPPER 
SHORT WAVE TROUGH OVER THE MISSISSIPPI VALLEY AND AN UPPER RIDGE 
TO THE SOUTH. LITTLE CHANGE IS EXPECTED THROUGH SATURDAY.

CARIBBEAN SEA...
A 1030 MB SURFACE HIGH CENTERED WELL NORTH OF THE AREA OVER THE 
NW ATLC IS MAINTAINING GENERALLY MODERATE MAINLY NE TRADES WINDS 
ACROSS THE CARIBBEAN...ALTHOUGH SOMEWHAT HIGHER ALONG THE SOUTH 
AMERICAN COAST ESPECIALLY OFF COLOMBIA. SCATTERED SHOWERS ARE 
EMBEDDED IN THE NE TRADE WIND FLOW MAINLY OVER THE NE 
CARIBBEAN...BUT OTHERWISE NO SIGNIFICANT CONVECTION IS NOTED.
   
ATLANTIC OCEAN...
W OF 50W...UPPER TROUGH AXIS EXTENDS FROM 32N55W TO THE SOUTHERN 
BAHAMAS. DIFLUENT FLOW ALOFT ON THE SE SIDE OF THE UPPER TROUGH 
IS SPONSORING AN ELONGATED SURFACE TROUGH FROM ROUGHLY 30N55W TO 
THE LEEWARD ISLANDS. SATELLITE IMAGERY SHOWS COPIOUS CLOUD COVER 
AND LIKELY WIDESPREAD SHOWER ACTIVITY WITHIN 180 NM EITHER SIDE 
OF THE SURFACE TROUGH. PROGRESSIVE UPPER PATTERN IS LIMITING THE 
SOUTHWARD PUSH OF A COLD FRONT ORIENTED EAST TO WEST ALONG 
32N...AND THIS FEATURE WILL STALL AND DISSIPATE W OF BERMUDA 
TODAY. 1030 MB SURFACE HIGH IS CENTERED WELL N OF BERMUDA BEHIND 
THE FRONT. BUOYS AND SCATTEROMETER DATA SHOW A BAND OF NE TRADES 
AROUND 15 TO 20 KT S OF 25N BETWEEN THE HIGH PRES AND THE 
SURFACE TROUGH. SCATTERED SHOWERS EMBEDDED IN THIS FLOW DIMINISH 
AS THE MOVE WEST AWAY FROM THE MOIST TROUGH AND INTO DRIER AND 
MORE STABLE AIR NEAR THE BAHAMAS.
E OF 50W...A SURFACE RIDGE EXTENDS FROM A 1030 MB HIGH PRES CELL 
OFF THE SPANISH COAST THROUGH THE AZORES TO A 1028 MB HIGH NEAR 
30N44W. THIS RIDGE HAS BEEN WEAKENING AND SHIFTING EAST AHEAD OF 
A BROAD UPPER TROUGH DIGGING THROUGH THE CENTRAL ATLC. 
SCATTEROMETER DATA SHOW PERSISTENT 20 TO 25 NE WINDS OFF THE NW 
AFRICAN COAST THROUGH THE CANARY ISLANDS BETWEEN THE SURFACE 
RIDGE AND LOW PRES OVER W AFRICA. GENERALLY 15 TO 20 KT TRADES 
PERSIST ELSEWHERE S OF 25N ON THE SOUTHERN PERIPHERY OF THE 
RIDGE.

$$
CHRISTENSEN