000 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