[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192331
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED MAR 19 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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
2315 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 3N22W 1N30W CROSSING THE
EQUATOR NEAR 35W TO 3S40W. SCATTERED MODERATE CONVECTION IS
WITHIN 60 NM OF THE AXIS BETWEEN 16W-20W. ISOLATED MODERATE
CONVECTION IS FROM THE EQUATOR TO 5N BETWEEN 28W-42W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT IS TRACKING EWD ACROSS THE GULF FROM THE FLORIDA
PANHANDLE TO S MEXICO ALONG 30N86W 23N89W 17N92W. AHEAD OF THE
FRONT...BRISK SLY WINDS ARE CREATING A MILD/HUMID EVENING WITH
MAINLY FAIR SKIES. BEHIND THE FRONT...WINDS SHIFT TO THE W N OF
24N ALLOWING SOME COOLING TO TAKE PLACE...BUT MOST OF THE
AIRMASS CHANGE IS BEHIND A POST-FRONTAL TROUGH...ASSOCIATED WITH
A MID-LEVEL SHORTWAVE...FROM SRN MISSISSIPPI TO 25N93W. THE SFC
FRONT ACTS AS THE MAIN BOUNDARY S OF 24N WHERE NLY GALE FORCE
WINDS ARE STILL OCCURRING. THE COMBINATION OF LOW-LEVEL
CONVERGENCE NEAR THE FRONT AND STRONG SWLY FLOW ALOFT...BETWEEN
AN UPPER TROUGH OVER MEXICO AND RIDGING OVER THE BAHAMAS...IS
PRODUCING WIDESPREAD MULTILAYER CLOUDINESS WITHIN 300 NM SE OF A
LINE FROM MOBILE ALABAMA TO 22N98W. THE ONLY SIGNIFICANT
EMBEDDED TSTM ACTIVITY IS OVER THE FLA PANHANDLE AND COASTAL
WATERS WITHIN 60 NM E OF THE FRONT. THE FRONT IS EXPECTED TO
PUSH THROUGH THE REMAINDER OF THE AREA OVER THE NEXT 24 HOURS AS
IT WEAKENS.

CARIBBEAN SEA...
THE TAIL END OF A WEAKENING COLD FRONT CUTS ACROSS THE LESSER
ANTILLES NEAR 15N62W. COOLER AND DRIER AIR HAS SPREAD WELL S
INTO THE E CARIBBEAN BEHIND THE FRONT. TEMPS ARE MAINLY IN THE
70'S F WITH DEWPOINTS IN THE LOW 60'S F OVER PUERTO RICO...THE
VIRGIN ISLANDS AND THE NRN LEEWARDS. HOWEVER...THE BIG STORY IS
THE TREMENDOUS N SWELLS AFFECTING THESE ISLANDS FROM THE
CONTINUOUS FETCH DRIVEN BY A LARGE LINGERING AND ONCE VERY
POWERFUL LOW PRES SYSTEM OVER THE N ATLC.  SCATTERED SHOWERS ARE
AFFECTING MUCH OF THE NE ISLANDS. ELSEWHERE...TRANQUIL WEATHER
PREVAILS BENEATH A STRONGLY SUBSIDENT MID TO UPPER ENVIRONMENT.
THE TIGHT PRES GRADIENT BETWEEN SEMI-PERMANENT LOW PRES OVER NRN
SOUTH AMERICA AND A 1025 MB HIGH NEAR 30N70W IS PRODUCING GALE
FORCE TRADES NEAR THE COLOMBIAN COAST. THESE CONDITIONS ARE
EXPECTED TO SUBSIDE IN ABOUT 24 HOURS.

ATLANTIC OCEAN...
DEEP LAYER RIDGING DOMINATES THE WRN ATLC...W OF 65W...WITH THE
SFC CENTER ANALYZED 1025 MB NEAR 30N70W. WEATHER CONDITIONS ARE
FAIR BENEATH THIS RIDGE...BUT LARGE SWELLS ARE OBSERVED OVER
MOST OF THIS AREA CREATING HAZARDOUS MARINE CONDITIONS AND LARGE
BREAKING WAVES. SEE THE HIGH SEAS FORECAST (MIAHSFAT2) FOR
DETAILS. THE PATTERN FOLDS INTO DEEP LAYER TROUGHING BETWEEN
35W-65W WITH THE ASSOCIATED SLOW MOVING COLD FRONT ENTERING THE
REGION NEAR 32N41W AND CONTINUING SW TO THE LESSER ANTILLES
ALONG 23N45W 15N62W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE
WITHIN 120 NM E OF THE FRONT N OF 25N AND BEHIND THE FRONT N OF
25N BETWEEN 45W-55W ASSOCIATED WITH A POST-FRONTAL TROUGH. GALE
CONDITIONS ARE OCCURRING N OF 28N WITHIN 240 NM E OF THE FRONT
AND N OF 27N BETWEEN 54W-60W...DUE TO THE TIGHT PRES GRADIENT
BETWEEN THE FRONT AND THE HIGH TO THE W.

THE E ATLC REMAINS IN A TRANQUIL REGIME ON THE S SIDE OF MODEST
SFC RIDGING AND BENEATH FAIRLY ZONAL FLOW AND DRY AIR ALOFT.
THIS PATTERN IS LIMITING LARGE CLUSTERS OF CONVECTION...EVEN
WITHIN THE ITCZ.

$$
CANGIALOSI




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