000
AXNT20 KNHC 121040
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU MAR 12 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1015 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N9W 2N16W CROSSING THE EQUATOR 
NEAR 26W TO 3S40W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
IS WITHIN 60 NM OF THE AXIS E OF 14W. ISOLATED MODERATE 
CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 18W-28W.  

...DISCUSSION...

GULF OF MEXICO...
A SLOW MOVING COLD FRONT HAS ENTERED THE FAR NW WATERS EXTENDING 
FROM THE WRN FLORIDA PANHANDLE ACROSS SRN LOUISIANA TO JUST S 
OF BROWNSVILLE TEXAS. DOPPLER RADAR INDICATES A NARROW BAND OF 
SCATTERED SHOWERS ALONG THE FRONT. THE UPPER TROUGH SUPPORTING 
THE BOUNDARY IS EXPECTED TO FLATTEN LATER TODAY CAUSING THE 
FRONT TO STALL ACROSS THE FAR NRN WATERS. GLOBAL MODELS FORECAST 
ANOTHER SHORTWAVE TROUGH TO COME INTO PHASE WITH THE FRONT SAT 
WHICH MAY PROVIDE SOME SUPPORT TO MAKE IT PROGRESSIVE ONCE 
AGAIN. ELSEWHERE...DEEP LAYER RIDGING CENTERED JUST E OF THE 
AREA REMAINS IN CONTROL PROVIDING FAIR CONDITIONS AND LIGHT TO 
MODERATE ELY SFC WINDS. 

CARIBBEAN SEA...
HIGH PRES CENTERED A COUPLE HUNDRED NM W OF BERMUDA IS PRODUCING 
MODERATE TO FRESH TRADES ACROSS THE CARIBBEAN. SFC OBS AND QSCAT 
DATA SUGGEST THAT THE STRONGEST FLOW...20-25 KT...IS OVER THE 
CENTRAL CARIBBEAN WITH WINDS REACHING 30 KT NEAR THE COAST OF 
COLOMBIA. TYPICAL PATCHES OF LOW-LEVEL CLOUDS AND ISOLATED 
SHOWERS ARE SCATTERED ACROSS THE AREA. IN THE MID AND UPPER 
LEVELS...A TROUGH EXTENDING FROM HISPANIOLA TO THE SW CARIBBEAN 
IS THE MAIN FEATURE. CONFLUENCE ALOFT IS ENHANCING SUBSIDENCE 
NEAR AND W OF ITS AXIS...WHILE DIFFLUENCE IS CAUSING ONLY SLIGHT 
MOISTENING E OF THE AXIS. LITTLE CHANGE IN THE LARGE SCALE 
WEATHER PATTERN IS ANTICIPATED OVER THE NEXT DAY OR SO. 

ATLANTIC OCEAN...
AN OCCLUDED 998 MB LOW PRES SYSTEM HAS MOVED SE INTO THE 
DISCUSSION AREA NEAR 30N46W MOVING ESE 15 KT. THE ATTENDANT COLD 
FRONT EXTENDS FROM THE TRIPLE POINT NEAR 33N41W SWD TO 29N41W 
THEN DISSIPATING ALONG 22N48W 19N60W TO NEAR THE N COASTS OF 
PUERTO RICO AND HISPANIOLA. WHILE LITTLE...IF ANY...PRECIP IS 
EXPECTED ALONG THE FRONT...INSTABILITY NEAR THE LOW IS 
TRIGGERING SCATTERED SHOWERS AND TSTMS N OF 26N BETWEEN 36W-47W. 
WINDS TO GALE FORCE ARE BLOWING WITHIN THE COLD SECTOR DUE TO 
THE TIGHT PRES GRADIENT BETWEEN THE LOW AND A SFC RIDGE OVER THE 
W ATLC. GLOBAL MODELS SHOW THIS FEATURE TRACKING ESE AND 
WEAKENING OVER THE NEXT COUPLE OF DAYS AS IT CUTS OFF FROM THE 
PROGRESSIVE FLOW. AN EVEN DEEPER LOW PRES SYSTEM CENTERED A FEW 
HUNDRED NM NW OF THE AZORES CONTINUES TO PULL AWAY FROM THE AREA 
BUT ITS TRAILING FRONT STILL EXTENDS SWD FROM 32N28W TO 29N29W. 
ONLY SCATTERED SHOWERS ARE POSSIBLE WITHIN 240 NM E OF THE 
FRONT. IN THE DEEP TROPICS...STRONG WLY FLOW ALOFT ON THE N SIDE 
OF A BROAD UPPER-LEVEL RIDGE IS TRANSPORTING MID-HIGH LEVEL 
CLOUDINESS FROM THE LESSER ANTILLES TO W AFRICA. DIFFLUENCE 
ALOFT ON THE S SIDE OF THIS RIDGE IS ENHANCING CONVECTION WITHIN 
THE ITCZ E OF 20W.

$$
CANGIALOSI