000
AXNT20 KNHC 240529
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI APR 24 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...
ITCZ AXIS IS CENTERED ALONG 5N9W 2N17W CROSSING THE EQUATOR NEAR 
23W TO 2S34W TO NE BRAZIL NEAR 3S40W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS WITHIN 180 NM N OF THE AXIS E OF 
18W. ISOLATED MODERATE CONVECTION IS ELSEWHERE S OF 3N.

...DISCUSSION...

GULF OF MEXICO...
SFC HIGH PRESSURE IS LOCATED OVER THE NE WATERS PROVIDING LIGHT 
AND VARIABLE FLOW IN ITS VICINITY. HOWEVER...E TO SE WINDS HAVE 
INCREASED TO 20-25 KT ACROSS MUCH OF THE REMAINDER OF THE GULF 
DUE TO THE TIGHT PRESSURE GRADIENT BETWEEN THE HIGH AND BROAD 
SFC TROUGHING OVER MEXICO. THIS STRONG FLOW IS ELEVATING SEAS TO 
8 FT OVER THE WRN WATERS BUT WILL LIKELY INCREASE A FEW MORE FT 
OVER THE NEXT DAY OR TWO AS WINDS REMAIN STRONG. DRY AIR AND 
ZONAL FLOW IN THE MID AND UPPER LEVELS IS SUPPORTING FAIR 
WEATHER ACROSS THE ENTIRE REGION. A SHORTWAVE TROUGH CURRENTLY 
OVER W TEXAS IS EXPECTED TO SHIFT E INTO THE NW GULF LATER TODAY 
AND SAT...LIKELY BRINGING AN INCREASE IN MOISTURE TO THAT 
PORTION OF THE GULF.

CARIBBEAN SEA... 
SCATTERED MODERATE CONVECTION CONTINUES OVER THE EXTREME SW 
CARIBBEAN S OF 11N. LOW-LEVEL LIFT FROM CONVERGENCE ALONG THE 
ITCZ AND MOIST SWLY FLOW ALOFT APPEAR TO BE THE PRIMARY 
TRIGGERS. HOWEVER...LOCAL AND SMALL SCALE EFFECTS OVER COLOMBIA 
ARE PROVIDING ENHANCEMENT FOR THE DEEPER ACTIVITY NOTED INLAND. 
THE STRONG SWLY FLOW ALOFT IS SPREADING MOISTURE NE THOUGH IT 
APPEARS TO BE ONLY IN THE FORM OF MID-HIGH LEVEL CLOUDINESS. 
OTHERWISE...PATCHES OF LOW-MID LEVEL CLOUDS WITH EMBEDDED 
SHOWERS ARE SCATTERED ACROSS THE AREA...THICKEST OVER THE NE 
PORTION AND GULF OF HONDURAS. TRADE WINDS ARE IN THE 25-30 KT 
NEAR THE COAST OF COLOMBIA...AND MAINLY 20-25 KT ELSEWHERE. 
LITTLE CHANGE IN THIS WIND REGIME IS EXPECTED THROUGH THE 
WEEKEND AS STRONG HIGH PRESSURE REMAINS OVER THE W ATLC.

ATLANTIC OCEAN...
A LONGWAVE UPPER TROUGH CONTINUES TO PROVIDE SUPPORT FOR A 
FRONTAL BOUNDARY EXTENDING FROM 32N61W TO 24N69W THEN STATIONARY 
TO THE N COAST OF HAITI. MULTILAYER CLOUDINESS WITH EMBEDDED 
SCATTERED SHOWERS ARE LIKELY WITHIN 300 NM E OF THE COLD FRONT 
AND WITHIN 180 NM EITHER SIDE OF THE STATIONARY PORTION. A 
REINFORCING FRONT IS APPROACHING THE AREA EXTENDING ABOUT 150 NM 
NW OF BERMUDA. THIS BOUNDARY WILL LIKELY MERGE WITH THE LEADING 
ONE OVER THE NEXT 24-36 HOURS. SFC HIGH PRESSURE HAS BECOME 
ESTABLISHED BEHIND THE FRONT NEAR 30N70W. THIS FEATURE IS 
EXPECTED TO REMAIN QUASI-STATIONARY AND AMPLIFY OVER THE NEXT 
COUPLE OF DAYS SETTING UP STRONG ELY FLOW ON ITS SRN PERIPHERY. 
FARTHER E...A MID-UPPER LOW IS SITUATED NEAR 26N35W WITH 
TROUGHING EXTENDING WELL SW TO NEAR 5N50W. INSTABILITY 
ASSOCIATED WITH UPPER CYCLONE IS PRODUCING SCATTERED SHOWERS AND 
ISOLATED TSTMS FROM 23N-30N BETWEEN 32W-39W. AN UPPER JET 
ORIGINATES NEAR THE BASE OF THE UPPER TROUGH AND EXTENDS NE 
THROUGH THE CAPE VERDE ISLANDS TO NEAR THE CANARY ISLANDS. THIS 
FLOW IS ADVECTING TROPICAL MOISTURE WELL NE AND LIKELY ENHANCING 
CONVECTION ALONG THE ITCZ.

$$
CANGIALOSI