[Tropical] Tropical Weather Discussion

[EMWIN Server]

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



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