000 AXNT20 KNHC 132343 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAR 13 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 5N10W 1N20W CROSSING THE EQUATOR AT 30W THEN ALONG 1S40W INTO NE BRAZIL NEAR 3S46W. SCATTERED MODERATE CONVECTION IS FROM EQUATOR TO 6N EAST OF 24W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OVER NE BRAZIL. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE IS BUILDING ACROSS THE GULF AND THE SE U.S. WHILE A SHORT-WAVE TROUGH IS OVER CENTRAL TEXAS AND NE MEXICO. UPPER MOISTURE IS NOTED OVER THE AREA MAINLY N OF 25N AND IS SPREADING E IN THE NEARLY ZONAL UPPER FLOW OVER N-CENTRAL FLORIDA. MODERATE TO STRONG UPPER DRY AIR IS SEEN OVER THE SE GULF AND SOUTH FLORIDA. AT THE LOW LEVELS A FRONTAL TROUGH... ACCOMPANIED BY SOME CLOUDINESS AND ISOLATED SHOWERS IS OVER THE YUCATAN CHANNEL. A 1017 MB HIGH IS OVER THE NE CORNER OF THE GULF NEAR 29N84W. SLY RETURN FLOW HAS ALREADY ESTABLISHED OVER THE WESTERN GULF AHEAD OF THE NEXT COLD FRONT FORECAST TO ENTER THE NW GULF BY MIDDAY SAT. AN EARLIER ASCAT PASS SHOWED WIND SPEEDS OF 15-20 KT OVER THE WESTERN GULF. AN AREA OF SHOWERS WITH EMBEDDED TSTMS HAS DEVELOPED OVER THE NW QUADRANT OF THE GULF. THIS ACTIVITY IS ASSOCIATED WITH THE MOIST ONSHORE FLOW AND A DIFLUENT PATTERN ALOFT. A JETSTREAM BRANCH WITH CORE WINDS OF 90 TO 130 KT EXTENDS FROM NE MEXICO OVER THE NORTH GULF STATES AND N-CENTRAL FLORIDA INTO THE W ATLC. CARIBBEAN SEA... AN UPPER RIDGE...ANCHORED ON A HIGH JUST EAST OF TRINIDAD AND TOBAGO ISLANDS CONTINUES TO CONTROL THE WEATHER PATTERN ACROSS THE ENTIRE BASIN WITH MODERATE TO STRONG SUBSIDENCE AND IMPLIED DRY AND STABLE AIR MASS. UPPER MOISTURE IN THE FORM OF THIN BROKEN CIRRUS IS STREAMING ANTICYCLONICALLY NE ACROSS THE CARIBBEAN S OF 15N. AT THE LOW LEVELS...A FRONTAL TROUGH LIES OVER CENTRAL CUBA AND THE ISLE OF YOUTH THROUGH THE YUCATAN CHANNEL TO NEAR CANCUN MEXICO AT 21Z. FRAGMENTS OF LOW LEVEL CLOUDS WITH ISOLATED SHOWERS ARE ASSOCIATED WITH THIS TROUGH MAINLY OVER THE PROVINCE OF PINAR DEL RIO AND THE YUCATAN CHANNEL. WEAK SURFACE RIDGING EXTENDS W ACROSS THE NORTHERN CARIBBEAN. POCKETS OF LOW LEVEL MOISTURE EMBEDDED IN THE TRADE WIND FLOW ARE PRODUCING ISOLATED TO SCATTERED PASSING SHOWERS ACROSS THE REGION...MORE CONCENTRATED BETWEEN JAMAICA AND CABO GRACIAS A DIOS NICARAGUA. ATLANTIC OCEAN... A VIGOROUS SHORT-WAVE TROUGH AND AN EXTRATROPICAL CYCLONE ARE NEAR 29N74W RACING NE. THE ASSOCIATED COLD FRONT EXTENDS SW FROM THE LOW ACROSS THE CENTRAL BAHAMAS/CENTRAL CUBA BECOMING DIFFUSE OVER THE NW CARIBBEAN/YUCATAN CHANNEL. A STATIONARY FRONT LIES ALONG 29N67W 30N70W INTO A SURFACE LOW...ANALYZED 1015 MB AT 2100 UTC. AT THE MOMENT...OVERCAST MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS ARE NOTED WELL AHEAD OF THE SFC LOW N OF 27N BETWEEN 58W AND 70W. THIS ACTIVITY IS MOVING QUICKLY EWD CROSSING JUST SOUTH OF BERMUDA. A WEAK SFC RIDGE COVERS THE REMAINDER OF THE FORECAST AREA WITH A COUPLE OF WEAK FRONTAL BOUNDARIES TO THE N OF THE RIDGE. AS PREVIOUSLY MENTIONED...AN UPPER ANTICYCLONE IS JUST EAST OF THE TRINIDAD AND TOBAGO ISLANDS RESULTING IN A BROAD UPPER RIDGE OVER THE TROPICS W OF 40W. MOIST UPPER AIR IS OBSERVED N OF 25N BETWEEN 72W AND 38W AND DRY UPPER AIR IS NOTED GENERALLY S OF 25N. A DEEP LAYERED TROUGH DOMINATES THE EASTERN ATLC EXTENDING SW INTO THE DEEP TROPICS NEAR 10N36W. $$ GR