000 AXNT20 KNHC 210540 TWDAT TROPICAL WEATHER DISCUSSION... NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT MON APR 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N10W 4N20W 3N32W 1N40W TO THE EQUATOR AT 50W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 25W-32W. SCATTERED MODERATE CONVECTION IS FROM 4N-6N BETWEEN 33W-48W. ...DISCUSSION... GULF OF MEXICO... A MID TO UPPER LEVEL RIDGE IS BUILDING E OVER THE REGION OVERTAKING TROUGHING OVER FLORIDA. THIS WEAKENING TROUGH ...ASSOCIATED WITH A CUT OFF LOW OVER THE MID-ATLANTIC STATES...IS PROVIDING LIMITED SUPPORT FOR A COLD FRONT FROM SOUTHWEST FLORIDA TO 25N89W. THE FRONT IS ONLY MARKED BY A NARROW BROKEN LINE OF LOW CLOUDS WITH EMBEDDED SCATTERED SHOWERS...AS INDICATED ON DOPPLER RADAR. A WEAK 1016 MB HIGH IS SITUATED BEHIND THE FRONT CENTERED OVER THE N CENTRAL WATERS NEAR 29N87W. MAINLY FAIR WEATHER AND LIGHT TO MODERATE WINDS DOMINATES THE MAJORITY OF THE REGION SUPPORTED BY A SUBSIDENT ENVIRONMENT...ESPECIALLY OVER THE SW PORTION. THE FRONT IS EXPECTED TO CONTINUE TO WEAKEN AND SHIFT SE ALLOWING FAIR WEATHER TO CONTINUE OVER THE NEXT DAY OR TWO. CARIBBEAN SEA... A BROAD UPPER TROUGH LIES OVER THE CARIBBEAN SEA AND FLAT RIDGING COVERS MUCH OF THE TROPICAL ATLC AND SOUTH AMERICA. THIS LARGE SCALE PATTERN IS PRODUCING A MODERATE TO STRONGLY SUBSIDENT ENVIRONMENT N OF 14N. S OF 14N...THE ATMOSPHERE IS BEING SOMEWHAT MOISTENED ALOFT BY THIN BROKEN HIGH LEVEL CLOUDS. IN THE LOWER LEVELS...A 2302 Z QSCAT PASS SUGGESTS THAT NE WINDS HAVE DECREASED TO 20-25 KT NEAR THE COAST OF COLOMBIA WITH MODERATE TRADES NOTED ELSEWHERE. THE TYPICAL LOW-LEVEL CLOUD PATCHES APPEAR SUBDUED TONIGHT WITH THE ONLY ORGANIZED PATCH OVER THE NRN LEEWARD ISLANDS. THE TRADE WIND FLOW IS EXPECTED TO WEAKEN FURTHER ON MON AS TROUGHING BECOMES BETTER ESTABLISHED OVER THE W ATLC. OTHERWISE...LITTLE SIGNIFICANT CHANGE IS EXPECTED OVER THE NEXT DAY OR SO. ATLANTIC OCEAN... A LARGE SCALE TROUGH...WITH A FEW EMBEDDED SHORTWAVES...COVERS MUCH OF THE W ATLC. ONE OF THE SHORTWAVES IS SUPPORTING A COLD FRONT FROM 32N76W TO S FLA. DOPPLER RADAR AND LIGHTNING DATA IS SHOWING QUITE A BIT OF TSTM ACTIVITY ALONG THE BOUNDARY N OF THE DISCUSSION ZONE...HOWEVER...ONLY ISOLATED SHOWERS AND TSTMS ARE LIKELY WITHIN 60 NM E OF THE FRONT S OF 32N. SCATTERED SHOWERS AND TSTMS ARE ALSO LOCATED N OF PUERTO RICO FROM 21N-24N BETWEEN 64W-68W. THIS ACTIVITY IS ASSOCIATED WITH BASE OF THE SHARP UPPER TROUGH (VORTICITY MAX) AND LOW-LEVEL CONVERGENCE ALONG A LINGERING SFC TROUGH. DEBRIS MID-HIGH LEVEL CLOUDS COMBINED WITH LOW LEVEL CLOUDS ALONG THE SFC TROUGH FROM 31N51W TO 23N59W IS PRODUCING A FAIR AMOUNT OF CLOUD COVER AND ISOLATED SHOWERS WITHIN 150 NM OF THE SFC TROUGH LINE. THE CENTRAL AND EASTERN ATLC IS DOMINATED BY A QUASI-STATIONARY 1025 MB HIGH NEAR 30N34W. THIS HIGH IS PRODUCING A LARGE AREA OF 15-20 KT NE/E WINDS ACROSS THE TROPICAL BELT. IN THE MID AND UPPER LEVELS...A BROAD RIDGE COVERS MUCH OF THE REGION BETWEEN 25W-50W AND UPPER TROUGHING LIES OVER THE THE NE PORTION FROM THE MADEIRA ISLANDS TO 17N32W. DIFFLUENCE ALOFT TO THE E OF THE TROUGH AXIS IS GENERATING/TRANSPORTING MID-HIGH LEVEL CLOUDS WITHIN 300 NM E OF THE TROUGH LINE...INCLUDING THE CAPE VERDE ISLANDS. BROAD FLAT RIDGING LIES OVER THE TROPICS ENHANCING CONVECTION IN THE ITCZ W OF 25W. $$ CANGIALOSI