000
AXNT20 KNHC 011035
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...THE ITCZ...

THE ITCZ AXIS EXTENDS FROM W AFRICA AT 06N10W TO THE EQUATOR AT 
26W TO NE BRAZIL NEAR 03S41W. SCATTERED MODERATE CONVECTION IS 
NOTED WITHIN 60 NM OF AXIS BETWEEN 10W AND 15W...AND WITHIN 120 
NM N OF AXIS BETWEEN 25W AND 28W. 

...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 SHOWED 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 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 
KT WITHIN ONLY A FEW PATCHES OF 20 KT...MAINLY 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 1026 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. GENERALLY DRY STABLE AIRMASS REMAINS IN PLACE WITH THE 
ONLY NOTABLE CONVECTION WELL TO THE SOUTH ALONG THE ITCZ OFF THE 
COAST OF LIBERIA.

$$
CHRISTENSEN