000
AXNT20 KNHC 232325
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
705 PM EST WED DEC 23 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2245 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N12W 4N24W 3N36W 4N42W 2N50W. 
ISOLATED MODERATE CONVECTION IS WITHIN 150 NM N OF THE AXIS 
BETWEEN 15W-36W.


...DISCUSSION...

GULF OF MEXICO...
THE SURFACE RIDGE THAT HAS DOMINATED THE GULF OF MEXICO OVER THE 
PAST FEW DAYS HAS SHIFTED MOSTLY NE OF THE AREA AS LOW PRESSURE 
BUILDS ACROSS WRN TEXAS. ELY FLOW UP TO 20 KTS IS ACROSS THE ERN 
GULF SHIFTING SE TO S UP TO 25 KT IN THE WRN GULF AHEAD OF THE 
NEXT COLD FRONT FORECAST TO REACH THE NW GULF LATE TONIGHT AND 
EARLY THU MORNING. IN THE UPPER LEVELS...MOIST WLY FLOW 
DOMINATES SUPPORTING A FEW HIGH CLOUDS ACROSS THE BASIN. RADAR 
IMAGERY INDICATES ISOLATED SHOWERS ACROSS THE STRAITS OF 
FLORIDA...AND ACROSS THE NW GULF N OF 26N W OF 87W. EXPECT 
ENHANCED MOISTURE AND PRECIPITATION ALONG WITH SLY RETURN FLOW 
TO INCREASE OVER THE WRN GULF AHEAD OF THE NEXT COLD FRONT 
FORECAST TO REACH THE NW WATERS LATER TONIGHT. STRONG NW FLOW 
WILL FOLLOW IMMEDIATELY BEHIND THE FRONT.  

CARIBBEAN SEA...
HEAVY RAINFALL CONTINUES TO IMPACT THE N CENTRAL CARIBBEAN 
ASSOCIATED WITH A 1009 MB LOW LOCATED JUST S OF HAITI NEAR 
17N74W. A SURFACE TROUGH EXTENDS S FROM THE LOW CENTER TO N OF 
PANAMA...WHILE A STATIONARY FRONT EXTENDS N FROM THE LOW CENTER 
ACROSS W HAITI AND THEN EWD INTO THE CENTRAL ATLC. AN UPPER 
LEVEL TROUGH EXTENDING FROM THE NW BAHAMAS ACROSS CENTRAL CUBA 
TO NICARAGUA SUPPORTS THE SURFACE LOW AND PROVIDES A HIGHLY 
DIFFLUENT ZONE ALOFT ENHANCING A LARGE AREA OF SHOWER ACTIVITY E 
OF THE LOW CENTER. NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS ARE 
N OF 14N BETWEEN 67W-72W BRINGING HEAVY RAINFALL TO MUCH OF 
HISPANIOLA. THE STRONGEST STORMS STILL REMAIN S OF THE ISLAND 
OVER WATER. THE LOW IS FORECAST TO MOVE NE ACROSS HISPANIOLA 
TONIGHT WITH CONTINUED PRECIPITATION INCREASING THE CHANGE FOR 
FLOODING ACROSS THE ISLAND. ELSEWHERE...DRY AIR AND SUBSIDENCE 
COVER THE W CARIBBEAN W OF 76W...AND ACROSS THE E CARIBBEAN E OF 
63W...BRINGING GENERALLY FAIR WEATHER ACROSS THESE PORTIONS OF 
THE BASIN.

ATLANTIC OCEAN...
MOIST SWLY FLOW ALOFT COVERS THE SW N ATLC SUPPORTING POSSIBLE 
ISOLATED SHOWERS S OF 26N W OF 72W INCLUDING THE BAHAMAS. A 
STATIONARY FRONT EXTENDS FROM A 1009 MB LOW S OF HISPANIOLA TO 
NEAR 22N70W CONTINUING E TO NEAR 21N40W. HEAVY SHOWER ACTIVITY 
EXPANDS NWD FROM THE CARIBBEAN ACROSS HISPANIOLA TO THE 
IMMEDIATE COASTAL WATERS. ISOLATED SHOWERS ARE WITHIN 90 NM OF 
THE FRONT ELSEWHERE. A DYING COLD FRONT EXTENDS FROM THE END OF 
THE STATIONARY BOUNDARY NEAR 21N40W TO JUST N OF THE CANARY 
ISLANDS. A SECOND COLD FRONT EXTENDS TO THE W ALONG 32N20W 
28N30W. SURFACE CONVERGENCE NEAR THE FRONTS IS SUPPORTING 
SCATTERED SHOWERS N OF 26N E OF 27W...WITH ISOLATED SHOWERS 
WITHIN 90 NM OF THE FRONT AXIS ELSEWHERE. GALE FORCE WINDS 
PREVIOUSLY BEHIND THESE FRONTAL BOUNDARIES HAVE NOW DIMINISHED 
BELOW GALE STRENGTH. THE FRONTS ARE SUPPORTED BY A BROAD UPPER 
LEVEL TROUGH N OF THE AREA WITH AXIS ALONG 20W. STRONG WLY FLOW 
ALOFT AROUND THE BASE OF THIS UPPER TROUGH COVERS MUCH OF THE 
BASIN. S OF THE FRONT...WEAK HIGH PRESSURE DOMINATES ANCHORED BY 
A 1017 MB HIGH CENTERED BETWEEN THE CAPE VERDE ISLANDS AND THE 
LESSER ANTILLES NEAR 16N36W. THE SURFACE HIGH IS SUPPORTED BY AN 
UPPER LEVEL RIDGE CENTERED E OF THE LESSER ANTILLES NEAR 15N53W 
WITH AXIS EXTENDING E ACROSS THE TROPICAL ATLC. 

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE.

$$
WALTON