000
AXNT20 KNHC 180537
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 AM EST FRI DEC 18 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 
0445 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N9W 4N20W 6N29W 6N40W 5N51W. 
SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 60 NM OF THE AXIS 
BETWEEN 9W-25W.

...DISCUSSION...

GULF OF MEXICO...
ENHANCED MOISTURE CONTINUES TO INVADE THE GULF OF MEXICO TONIGHT 
AROUND THE E SIDE OF AN UPPER LEVEL TROUGH EXTENDING DOWN THE 
GREAT PLAINS INTO THE W GULF. AS OF 0300 UTC...A 1008 MB LOW IS 
S OF LOUISIANA NEAR 28N91W. A COLD FRONT EXTENDS S FROM THE LOW 
ALONG 23N91W TO THE THE BAY OF CAMPECHE NEAR 19N94W. A SQUALL 
LINE IS ANALYZED 120 NM AHEAD OF THE FRONT. A STATIONARY 
BOUNDARY EXTENDS E FROM THE LOW ALONG 29N TO THE BIG BEND OF 
FLORIDA. SURFACE CONVERGENCE NEAR THE LOW AND FRONTAL BOUNDARIES 
ALONG WITH DIFFLUENT FLOW ALOFT IS ENHANCING A LARGE AREA OF 
NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS ACROSS THE CENTRAL AND 
E GULF AFFECTING LOUISIANA...ALABAMA...GEORGIA...AND FLORIDA. 
PORTIONS OF ALL FOUR STATES HAVE CURRENT FLOOD WATCHES AND 
WARNING IN EFFECT. EXPECT CONTINUED SHOWER ACTIVITY...HEAVY IN 
SOME AREAS...TO CONTINUE OVER THE NEXT 24 HRS AS THE LOW CENTER 
DEEPENS AND QUICKLY MOVES E ACROSS THE NRN GULF. 

CARIBBEAN SEA...
SUBSIDENCE AND DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE WITH 
AXIS ALONG 78W CONTINUES TO KEEP THE CARIBBEAN UNDER GENERALLY 
FAIR CONDITIONS. MOISTURE ASSOCIATED WITH THE LOW PRESSURE 
SYSTEM IN THE GULF OF MEXICO HAS PUSHED INTO THE NW CARIBBEAN 
ENHANCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OFF THE 
YUCATAN PENINSULA N OF 16N W OF 84W. A LINE OF ISOLATED SHOWERS 
EMBEDDED IN ELY FLOW CONTINUES TO MOVE QUICKLY FROM THE LESSER 
ANTILLES TO N OF HONDURAS BISECTING THE CARIBBEAN. MODERATE TO 
FRESH TRADEWINDS PREVAIL ACROSS MUCH OF THE BASIN. EXPECT 
ENHANCED MOISTURE OVER THE NW CARIBBEAN AS THE COLD FRONT IN THE 
CENTRAL GULF REACHES THE YUCATAN CHANNEL MUCH LATER TODAY.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH ACROSS THE NW ATLC SUPPORTS A COLD FRONT 
EXTENDING FROM THE CENTRAL ATLC NEAR 32N44W ALONG 26N57W 26N69W 
TO NEAR FREEPORT BAHAMAS CONTINUING AS A STATIONARY FRONT INTO 
THE GULF OF MEXICO. ISOLATED SHOWERS ARE WITHIN 150 NM AHEAD OF 
THE FRONT AXIS. FARTHER E...A SECOND UPPER LEVEL TROUGH CENTERED 
NE OF THE AZORES ISLANDS SUPPORTS A COLD FRONT EXTENDING FROM 
32N15W TO THE CANARY ISLANDS TO THE CAPE VERDE ISLANDS. NUMEROUS 
SHOWERS/POSSIBLE THUNDERSTORMS ARE N OF 13N E OF 28W. A 
SHORTWAVE TROUGH EMBEDDED IN THE LONGWAVE UPPER LEVEL TROUGH IS 
ENHANCING CONVECTION ALONG THE E PORTION OF THE ATLC ITCZ. 

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

$$
WALTON