[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON APR 17 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N10W 4N20W 3N30W 1N38W 4N52W.
NUMEROUS MODERATE/ISOLATED STRONG CONVECTION WITHIN FROM 1N-4N
BETWEEN 15W-24W. SCATTERED MODERATE WITHIN 120 NM OF THE AXIS
BETWEEN 26W-39W. SCATTERED MODERATE S OF 5N BETWEEN 39W-52W...
INCLUDING SPREADING INLAND OVER THE S AMERICAN COASTLINE FROM NE
BRAZIL TO FRENCH GUIANA.

...DISCUSSION...

GULF OF MEXICO...
DEEP-LAYERED RIDGING LIES OVER THE GULF AND IS PRODUCING
MODERATE/STRONG SUBSIDENCE OVER THE ENTIRE AREA. UPPER RIDGE
AXIS EXTENDS FROM NW CARIBBEAN TO E TEXAS/W LOUISIANA...NUDGED A
BIT TO THE E BY A MID/UPPER LOW INLAND OVER MEXICO NEAR 22N99W.
THE LOW IS PULLING AIR FROM THE E PACIFIC NWD OVER THE GULF BUT
EVEN THAT AREA IS EXTREMELY DRY SO MOISTURE IS LIMITED. THESE
DRY CONDITIONS PRODUCED HIGH TEMPERATURES OF 107F AND 103F AT
MONTERREY AND CIUDAD VICTORIA MEXICO YESTERDAY...SO SIMILAR
HIGHS ARE EXPECTED FOR THIS AFTERNOON. LOW-LEVEL MOISTURE AND AN
INCREASED CHANCE OF SHOWERS WILL SPREAD ACROSS PARTS OF FLORIDA
BEGINNING ON TUE AS A BACK-DOOR COLD FRONT APPROACHES FROM THE
NE.

CARIBBEAN...
A LARGE UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE SW
CARIBBEAN NEAR 12N80W WITH A RIDGE AXIS RESTING ALONG THE N
COAST OF S AMERICA TO TRINIDAD AND TOBAGO. 50 KT SLY FLOW ON THE
W SIDE OF THE ANTICYCLONE IS STREAMING A NARROW ZONE OF HIGH
CLOUDS AND HAZE OVER COSTA RICA AND NICARAGUA. THE REMAINDER OF
THE AREA IS UNDER DRY WESTERLY FLOW ALOFT WITH ONLY ISOLATED
SHOWER NEAR JAMAICA...HAITI...NRN LEEWARD ISLANDS...AND W OF
MARTINIQUE/ST. LUCIA. INCIDENTALLY...THE SUBSIDENCE INVERSION
OVER THE NE CARIBBEAN HAS DROPPED TO ABOUT 850 MB...OR 5300
FT...AS PER THE 12Z SAN JUAN SOUNDING AND WILL PREVENT THE
DEVELOPMENT OF DEEP TSTMS.

WEST/CENTRAL ATLANTIC...
A DEEP-LAYERED OCCLUDED LOW IS CENTERED JUST SE OF NOVA SCOTIA
WITH BROAD UPPER LEVEL WLY FLOW REACHING S INTO THE AREA TO THE
GREATER ANTILLES. THE BULK OF THE MOISTURE IS LOCATED CLOSE TO
THE CENTER OF CIRCULATION...N OF 30N...WHILE PREDOMINANTLY DRY
CONDITIONS EXTEND FROM FLORIDA EWD TO 50W. AN ACCOMPANYING
SURFACE RIDGE EXTENDS FROM THE STRAITS OF FLORIDA TO 26N55W AND
IS PRODUCING FAIR SKIES OVER THE ENTIRE SW ATLC. FARTHER E...A
DISSIPATING STATIONARY FRONT EXTENDS FROM 31N42W TO 17N58W WITH
A WEAK 1015 MB LOW ALONG THE BOUNDARY NEAR 26N47W. A SHORTWAVE
TROUGH IS APPROACHING THIS FEATURE ALONG 43W AND IS TRIGGERING
WIDELY SCATTERED MODERATE CONVECTION N OF 26N BETWEEN 37W-45W.
ISOLATED SHOWERS LIE ELSEWHERE WITHIN 60 NM OF THE FRONT
REACHING TOWARDS THE NRN LEEWARD ISLANDS.

EAST ATLANTIC...
STRONG SURFACE HIGH PRES IS CENTERED NEAR THE AZORES WITH A
RIDGE EXTENDING INTO THE AREA ALONG 32N29W 20N40W. THE UPPER
FLOW IS MAINLY ZONAL N OF 15N BUT A SHORTWAVE TROUGH IS NOTED IN
THE FLOW ALONG 22W. THIS FEATURE IS ONLY PRODUCING ENHANCED
CIRRUS COVERAGE N OF 25N E OF 23W TOWARDS MOROCCO. A LARGE UPPER
RIDGE IS LOCATED OVER THE TROPICAL ATLC...ROUGHLY ALONG
33W...ALTHOUGH THERE IS ALSO A NARROWER RIDGE RESTING JUST NE OF
THE S AMERICAN COAST FROM EQ34W TO 13N56W. UPPER DIVERGENCE
ASSOCIATED WITH THIS SHARP AXIS IS ENHANCING DEEP CONVECTION
NEAR THE ITCZ WHICH IS PARTIALLY MOVING INLAND OVER NE BRAZIL.
ELSEWHERE...DRY CONDITIONS PERSIST BENEATH THE LARGE TROPICAL
RIDGE WITH SLIGHTLY HAZY CONDITIONS FLOWING FROM W AFRICA TO
ABOUT 35W.

$$
BERG


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