000 AXNT20 KNHC 161021 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI MAR 16 2007 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...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0915 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 5N10W 5N19W 3N27W 1N38W 1N50W. SCATTERED SHOWERS AND TSTMS WERE MAINLY IN SMALL CLUSTERS NEAR 5N17W..3N26W AND 1N32W. LARGE AREA OF CONVECTION BETWEEN 1N46W TO THE S AMERICAN COAST NEAR 1N50W. ...DISCUSSION... GULF OF MEXICO... A WELL DEFINED SHORTWAVE WITH A MID/UPPER LEVEL LOW CENTER HAS BECOME MOVING NE 25 KT DURING THE PAST FEW HRS. THE LOW IS EMBEDDED IN THE SRN BRANCH OF THE WESTERLIES AND LOCATED OVER SRN GA. A SHORTWAVE IN THE NRN BRANCH IS DIVING SE OVER NW MISSOURI THIS MORNING AND IS EJECTING THE SRN SHORTWAVE. THE TWO WILL CARVE OUT A LARGER SCALE MID LEVEL TROUGH ALONG THE E COAST DURING THE NEXT 24 HR. A WEAK SURFACE LOW VERY NEAR THE MID LEVEL LOW HAS A TROUGH EXTENDING SW OVER THE E CENTRAL GULF. A VERY MOIST SLY FLOW PRESENT E OF THE TROUGH CONTINUES TO AID DEVELOPMENT OF SCATTERED TSTMS OVER THE SE GULF. MOVEMENT OF THE TSTMS HAS BEEN SE. REMAINDER OF THE GULF IS UNDER MODERATE TO STRONG SUBSIDENCE ASSOCIATED DRY AIR ALOFT. A WEAK COLD FRONT IS MOVING SE OVER SE TX THIS MORNING AND WILL SWEEP EWD OVER THE GULF TODAY. CARIBBEAN... BROAD FLAT RIDGING COVERS MUCH OF THE CENTRAL AND ERN PORTIONS OF THE CARIBBEAN WITH UPPER LEVEL SW TO W WINDS OF 40 TO 50 KT. MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR IS EVIDENT ACROSS MOST OF THE REGION. IN THE LOWER LEVELS THE TAIL END OF A FRONTAL TROUGH EXTENDS SW FROM THE ATLANTIC SW TO THE LEEWARD ISLANDS. SLIGHT LOW-LEVEL CONVERGENCE NEAR THIS SLOWLY WEAKENING BOUNDARY IS PRODUCING PATCHES OF LOW AND MID LEVEL CLOUDS WITH ISOLATED SHOWERS FROM THE NE LEEWARDS EWD OVER THE ATLC FOR 120 NM. THE CLOUDINESS HAS BEEN MOVING NW IN MODERATE TO FRESH ELY TRADES. OVER THE NEXT COUPLE OF DAYS A STRONG SFC RIDGE WILL SHIFT EWD. THIS WILL ALLOW THE TRADE WINDS TO DECREASE ACROSS THE ERN CARIB. MEANWHILE A COLD FRONT IS FORECAST TO ENTER THE NW CARIBBEAN LATE TODAY AND SAT WITH SCATTERED SHOWERS AND TSTMS. THE FRONT IS THEN EXPECTED TO WEAKEN IN THE VICINITY OF THE WINDWARD PASSAGE SUN. WESTERN ATLANTIC... A STRONG ZONAL MID LEVEL PATTERN PERSISTS WITH AN EMBEDDED RIDGE ALONG 63W. AN AREA OF MID AND HIGH LEVEL CLOUDS IN THE RIDGE AXIS HAS SCATTERED EMBEDDED CONVECTION. THIS ACTIVITY IS ASSOCIATED WITH A SHORTWAVE TROUGH ALONG 68W IN THE MID LEVELS FOLLOWING THE RIDGE. THE AIR ALOFT IS VERY DRY ALONG 50W WHERE UPPER CONFLUENCE IS QUITE STRONG. A LOW PRES SYSTEM WITH AN ASSOCIATED COLD FRONT ENTERS THE AREA NEAR 31N45W AND EXTENDS SW TO 24N48W WHERE IT THEN CONTINUES AS A WEAKENING SFC FRONTAL TROUGH TO THE NRN LEEWARD ISLANDS. SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM AHEAD OF THE FRONT N OF 24N. ISOLATED TO SCATTERED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE FRONTAL TROUGH. THE FRONT WILL CONTINUE E MAINTAINING CONVECTION WITH IT N OF 26N WHILE THE REMAINDER OF THE FRONTAL TROUGH DISSIPATES OVER THE NEXT 24 HRS. THE NEXT COLD FRONT IS EXPECTED TO MOVE OFF THE U.S. EAST COAST TONIGHT. EASTERN ATLANTIC... AN OPEN RIDGE WITH IT'S AXIS ALONG 37W IS MOVING SLOWLY EWD. MID AND HIGH LEVEL MOISTURE IS EVIDENT THROUGHOUT THE NRN PORTION OF THE RIDGE. UPPER LEVELS QUICKLY DRY OUT E OF THE RIDGE WHERE THE MID LEVEL FLOW DIVES SE INTO A TROUGH ALONG 18W. A STRONG SFC HIGH CENTERED NEAR THE AZORES CONTINUES TO GENERATE A LARGE AREA OF MODERATE TO STRONG NE WINDS ACROSS THE REGION. IN THE DEEP TROPICS S OF 20N...THE UPPER LEVEL JETSTREAM BRANCH EXTENDS ANTICYCLONICALLY FROM THE WINDWARD ISLANDS TO 15N30W TO 10N24W. THE CENTER OF THE UPPER HIGH IS LOCATED NEAR 5N37W. ABUNDANT MID AND HIGH LEVEL MOISTURE EXISTS S OF THE JET AXIS FED BY CONVECTION ALONG THE ITCZ NEAR THE S AMERICAN COAST. OVER THE NEXT COUPLE OF DAYS A SFC HIGH WILL SLOWLY RETREAT NWD BUT SHOULD REMAIN IN CONTROL WITH GENERALLY FAIR WEATHER. $$ RRG