000
AXNT20 KNHC 291732
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU JAN 29 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 
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N9W 1N20W 1S30W 2N45W 2N51W. 
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE AXIS 
BETWEEN 15W-27W. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM N 
OF THE AXIS BETWEEN 37W-45W.
 
...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYER TROUGH OVER THE ERN CONUS IS SUPPORTING A COLD 
FRONT EXTENDING FROM JACKSONVILLE FLORIDA SW THROUGH 26N90W TO 
23N94W THEN S THROUGH THE BAY OF CAMPECHE TO SRN MEXICO NEAR 
18N94W. IN THE WAKE OF THE FRONT...A COOLER AIRMASS IS IN PLACE 
ADVECTED BY N-NE 15-20 KT WINDS ACROSS THE NRN AND WRN GULF. LOW 
LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS AND ISOLATED 
TSTMS WITHIN 60 NM ON EITHER SIDE OF THE FRONT N OF 25N. SOME OF 
THIS ACTIVITY IS BEING ENHANCED BY UPPER DIVERGENCE ASSOCIATED 
WITH A JET STREAM MAXIMUM OVER THE SE CONUS. AHEAD OF THE 
FRONT...DRY AIR AND ATMOSPHERIC STABILITY IS INHIBITING ANY DEEP 
CONVECTION. THE AFOREMENTIONED FRONT HAS SLOWED ITS SE 
PROGRESSION...BUT IS FORECAST TO SURGE SEWD EARLY FRI AS AN 
UPPER TROUGH OVER THE WRN CONUS SHIFTS E AND SURFACE HIGH 
PRESSURE BUILDS OVER THE SE CONUS...LEADING TO GALE CONDITIONS 
OVER THE SW GULF.

CARIBBEAN SEA...
A TIGHT PRESSURE GRADIENT...BETWEEN STRONG HIGH PRESSURE OVER 
THE CENTRAL ATLC AND LOWER PRESSURE OVER SOUTH AMERICA...IS 
GENERATING MODERATE TO FRESH TRADES ACROSS THE CARIBBEAN BASIN. 
THESE WINDS ARE FORECAST TO DECREASE ON FRI AS THE HIGH MOVES 
EWD AND A COLD FRONT POSITIONS ITSELF ACROSS THE NW CARIBBEAN. 
NE 20-25 KT WINDS AND RELATIVELY COOLER AND DRIER AIR ARE 
EXPECTED TO BUILD BEHIND THE FRONT BEGINNING FRI NIGHT. IN THE 
MEANTIME...GENERALLY FAIR CONDITIONS PERSIST WITH DEEP LAYER 
SUBSIDENCE AND DRY AIR IN PLACE. HOWEVER...TYPICAL ISOLATED LOW 
LEVEL SHOWERS ARE BEING CARRIED BY THE TRADE WINDS ACROSS THE E 
CARIBBEAN...WHERE SOME UPPER LEVEL MOISTURE IS BEING ADVECTED BY 
SW FLOW ALOFT.
 
ATLANTIC OCEAN...
TRANQUIL WEATHER IS THE THEME ACROSS MUCH OF THE DISCUSSION ZONE 
AS A 1032 MB SURFACE HIGH PRESSURE CENTERED NORTH OF THE AREA 
NEAR 35N46W EXTENDS RIDGING ACROSS THE BAHAMAS TO THE WEST AND 
ALSO ACROSS THE CAPE VERDE ISLANDS TO THE SE. THE ASSOCIATED 
PRESSURE GRADIENT ON ITS SRN PERIPHERY IS PRODUCING A LARGE AREA 
OF NE/E 20-25 KT TRADES S OF 23N E OF 62W. HOWEVER...THE RIDGE 
HAS BEEN WEAKENED OVER THE FAR NW AND NE PARTS OF THE AREA DUE 
TO A PAIR OF COLD FRONTS. THE FRONT OVER THE W ATLC CLIPS THE 
AREA FROM 32N77W TO JACKSONVILLE FLORIDA. WITH SCATTERED SHOWERS 
AND POSSIBLE ISOLATED TSTMS WITHIN 90 NM OF THE FRONT. STRONG 
SLY WINDS ARE BLOWING WITHIN A FEW HUNDRED NM E OF THE BOUNDARY 
WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED TSTMS WITHIN 90 NM 
OF THE FRONT. THE OTHER FRONT EXTENDS FROM 30N31W TO BEYOND 
32N26W. THE ASSOCIATED UPPER SUPPORT IS FORECAST TO SHARPEN 
WHICH WILL ALLOW THE FRONT TO LINGER ACROSS THE NERN ATLC OVER 
THE NEXT 12 TO 24 HOURS. OTHERWISE...ABUNDANT DRY STABLE AIR IS 
LIMITING THE DEVELOPMENT OF DEEP CONVECTION...WITH ONLY THE 
TYPICAL PATCHES OF LOW CLOUDS WITH EMBEDDED ISOLATED SHOWERS 
TRACKING WWD WITHIN THE TRADE WIND FLOW.

$$
HUFFMAN