000
AXNT20 KNHC 041725
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED MAR 04 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 1200 UTC SURFACE ANALYSIS...AND SATELLITE IMAGERY 
THROUGH 1645 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N9W 3N14W CROSSING THE EQUATOR 
NEAR 22W EXTENDING TO 2S31W INTO NE BRAZIL NEAR 4S43W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS S OF 6N BETWEEN 13W-19W. 
SCATTERED MODERATE CONVECTION IS S OF 2N BETWEEN 19W-25W.

...DISCUSSION...

GULF OF MEXICO...
NORTHWESTERLY FLOW ALOFT IS RESULTING IN SUBSIDENCE ACROSS MUCH 
OF THE GULF REGION...WITH AN UPPER LEVEL RIDGE AFFECTING MUCH OF 
THE GULF. THIS SUBSIDENCE IS BEING SUPPORTED BY A SURFACE RIDGE 
THAT EXTENDS SOUTHWARD FROM A SURFACE HIGH OVER SE NORTH 
CAROLINA NEAR 35N79W. ALSO...DEEP LAYER DRY AIR IS PRESENT 
ACROSS MUCH OF THE GULF REGION. AS A RESULT...GENERALLY FAIR 
WEATHER CONDITIONS PERSIST ACROSS THE GULF REGION. THE COOL 
AIRMASS IN THE WAKE OF THE FRONT OVER THE CARIBBEAN AND CENTRAL 
ATLC IS RESULTING IN SCATTERED STRATOCUMULUS CLOUDS ACROSS MUCH 
OF THE GULF. HOWEVER...STABLE ATMOSPHERIC CONDITIONS ARE 
INHIBITING DEEP CONVECTION ACROSS THE GULF REGION. UPPER LEVEL 
MOISTURE CONTINUES TO BE ADVECTED SOUTHEASTWARD ACROSS THE E 
GULF...WHERE SCATTERED HIGH LEVEL CLOUDS ARE PRESENT.

CARIBBEAN SEA...
A DEEP LAYER TROUGH OVER THE W ATLC EXTENDS INTO THE W 
CARIBBEAN...WITH AN ASSOCIATED SURFACE STATIONARY FRONT 
EXTENDING FROM E PANAMA NEAR 9N82W TO 15N74W TO E HISPANIOLA 
NEAR 19N69W INTO THE SW NORTH ATLC. LOW LEVEL CONVERGENCE IS 
SUPPORTING SCATTERED SHOWERS ALONG AND WITHIN 90 NM EITHER SIDE 
OF THIS FRONT. THIS FRONT IS FORECAST TO DISSIPATE TONIGHT. OVER 
THE W CARIBBEAN TO THE W OF THE FRONT...DEEP LAYER DRY AIR IS 
INHIBITING DEEP CONVECTION...WHERE GENERALLY FAIR WEATHER IS 
PRESENT. ACROSS THE E CARIBBEAN...UPPER LEVEL MOISTURE CONTINUES 
TO BE DRAWN NORTHEASTWARD AROUND A RIDGE OVER THE TROPICAL ATLC. 
PATCHES OF LOW LEVEL MOISTURE ARE BEING ADVECTED WESTWARD ACROSS 
THE E CARIBBEAN...WITH SCATTERED SHOWERS EMBEDDED WITHIN THESE 
PATCHES OF LOW LEVEL MOISTURE. THE GREATEST CONCENTRATION OF 
THESE SHOWERS IS FROM 12N-14N BETWEEN 67W-72W.

ATLANTIC OCEAN...
THE AFOREMENTIONED DEEP LAYER TROUGH OVER THE W ATLC AND W 
CARIBBEAN IS ASSOCIATED WITH A SURFACE FRONT THAT EXTENDS FROM 
THE E CARIBBEAN TO E HISPANIOLA NEAR 19N69W TO 22N66W TO 26N62W 
TO 32N59W TO N OF THE DISCUSSION AREA. THIS FRONT IS A 
STATIONARY FRONT S OF 22N...AND IS A COLD FRONT ALONG AND N OF 
22N. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS 
WITHIN 180 NM EITHER SIDE OF THIS FRONT. THIS ACTIVITY IS BEING 
SUPPORTED BY UPPER LEVEL DIVERGENCE ASSOCIATED WITH AN UPPER 
LEVEL JET MAXIMUM TO THE W OF THE FRONT. THIS FRONT IS FORECAST 
TO SLOW ITS EASTWARD PROGRESSION DURING THE NEXT TWO DAYS WITH A 
HIGH AMPLITUDE UPPER RIDGE CURRENTLY IN PLACE OVER THE CENTRAL 
ATLC AND AN UPPER LOW S OF THE UPPER RIDGE NEAR 25N33W. THIS 
UPPER PATTERN IS CHARACTERIZED AS A REX BLOCK PATTERN. THIS 
PATTERN IS FORECAST TO BREAK DOWN LATE THIS WEEK IN ADVANCE OF 
THE AFOREMENTIONED DEEP LAYER TROUGH OVER THE W ATLC AND W 
CARIBBEAN...WITH A SURFACE LOW DEVELOPING IN THE VICINITY OF THE 
FRONT LATE THIS WEEK. IN THE WAKE OF THE FRONT...A RELATIVELY 
COOLER AND DRIER AIRMASS IS PRESENT...WHERE SUBSIDENCE AND 
ATMOSPHERIC STABILITY ARE SUPPORTING GENERALLY FAIR WEATHER 
CONDITIONS. THIS SUBSIDENCE IS BEING SUPPORTED BY A SURFACE 
RIDGE THAT EXTENDS SOUTHWARD FROM A 1034 MB SURFACE HIGH OVER SE 
NORTH CAROLINA NEAR 35N79W. FARTHER TO THE E...A SURFACE TROUGH 
EXTENDS FROM 25N52W TO 29N52W TO 31N53W. LOW LEVEL CONVERGENCE 
IS SUPPORTING SCATTERED SHOWERS WITHIN 90 NM EITHER SIDE OF THIS 
SURFACE TROUGH. ACROSS THE E ATLC...SUBSIDENCE ASSOCIATED WITH A 
SURFACE RIDGE IS SUPPORTING FAIR WEATHER CONDITIONS. ACROSS THE 
TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 10N E OF 58W WITH 
AN UPPER HIGH NEAR 3N47W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH 
THIS UPPER LEVEL HIGH AND UPPER LEVEL RIDGE RIDGE IS ENHANCING 
THE CONVECTION ASSOCIATED WITH THE ITCZ...AS WELL AS SCATTERED 
SHOWERS S OF 1N BETWEEN 43W-51W.

$$
COHEN