000 AXPZ20 KNHC 281025 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED MAY 28 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1000 UTC. ...SPECIAL FEATURES... A BROAD AREA OF SURFACE LOW PRESSURE DOMINATES THE SW CARIBBEAN AND THE E PAC ALONG THE COAST OF CENTRAL AMERICA. DURING THE LAST SEVERAL HOURS THE OVERALL PATTERN OF THIS AREA HAS BEEN SUGGESTING THAT A SURFACE LOW HAS BECOME MORE IDENTIFIABLE IN THE VICINITY OF 09N88W WITH SCATTERED MODERATE TO STRONG CONVECTION OCCURRING WITHIN 300 NM SE AND 210 NM SW QUADRANTS. SCATTERED STRONG CONVECTION IS WITHIN 90 NM N AND NE QUADRANTS...AND ALSO WITHIN 45 NM EITHER SIDE OF A LINE FROM 07N80W TO 08N84W. NWP MODELS CONTINUE TO SUGGEST THAT THIS LOW PRESSURE WILL BE PRESENT IN THIS AREA FOR THE NEXT 2 TO POSSIBLY 3 DAYS AS IT DRIFTS ENE. THE LOW HAS ACQUIRED THE POTENTIAL TO DEVELOP INTO A TROPICAL CYCLONE OVER THIS PERIOD AS THE UPPER LEVEL PATTERN HAS BECOME MORE FAVORABLE...AND IN ADDITION THE APPROACHING TROPICAL WAVE MENTIONED BELOW MAY ADD THE NEEDED LOW LEVEL VORTICITY TO FURTHER HELP SPIN UP THE LOW DURING THE NEXT 48 HOURS. THE MODELS...FOR THE MOST PART...TRY TO BRING THE LOW OR WHAT IS LEFT OF IT IN A GENERAL NLY TRACK ACROSS OR NEAR THE REMAINDER OF CENTRAL AMERICA LATE FRI AND THROUGH THE UPCOMING WEEKEND. OF NOTE...THE GRADIENT S OF THE E PAC LOW PRESSURE IS ALREADY SUPPORTING SW-W WINDS IN THE RANGE OF 20 TO 25 KT WITH SEAS 8-11 FT. QUIKSCAT DATA FROM YESTERDAY EVENING SHOWED WINDS IN THE 20-25 KT RANGE WITH DIRECTION FROM SW TO W WITHIN THE BROAD LOW PRES AREA BETWEEN 81W-93W. THESE CONDITIONS ARE EXPECTED TO PERSIST S OF THE LOW THROUGH 48 HOURS WITH THE FOOTNOTE THAT THEY MAY HAVE TO BE ADJUSTED UPWARD IF LOW CONTINUES TO GET BETTER ORGANIZED. THE MAIN THING TO CONSIDER FOR TIME BEING IS THE HEAVY RAIN POTENTIAL EXPECTED OVER MUCH OF CENTRAL AMERICA FROM NICARAGUA TO PANAMA AT LEAST DURING THE NEXT 48 HOURS. ...TROPICAL WAVES... A TROPICAL WAVE MOVING W ABOUT 15 KT IS E OF THE AREA OVER W CARIBBEAN SEA NEAR 79W...AND EXTENDS SWD ACROSS PANAMA TO 07N. SCATTERED STRONG CONVECTION IS OVER SRN PANAMA...AND EXTENDS SWD OFF THE COAST PANAMA FOR 60 NM. THIS WAVE WILL MOVE ACROSS CENTRAL AMERICA OVER THE NEXT 36-48 HOURS. ...ITCZ... INTERTROPICAL CONVERGENCE ZONE (ITCZ) IS CENTERED ALONG 11N86W TO 05N92W TO 04N105W TO 06N115W TO 09N128W TO 07N140W. SCATTERED CONVECTION IS NOTED WITHIN 60 NM S OF THE AXIS BETWEEN 92W-96W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM S OF THE AXIS BETWEEN 100W-106W. ...DISCUSSION... A MID/UPPER LEVEL TROUGH EXTENDS SWD INTO THE DISCUSSION AREA THROUGH 32N126W TO 25N128W...AND SW TO NEAR 21N140W. THE TROUGH IS FORECAST TO GRADUALLY MOVE E AND EVENTUALLY LIFT NE OF THE REGION ON THU. BEHIND THE TROUGH...HIGH PRES RIDGING IS NOTED JUST W OF THE AREA...AND WILL BUILD SLIGHTLY INTO THE FAR WRN SECTION OF THE AREA THU AND FRI. UPPER LEVEL MOISTURE IS SPILLING SEWD AROUND THE NRN PERIPHERY OF THE RIDGE INTO THE FAR NW CORNER OF THE AREA. THIS MOISTURE IS THEN BEING PICKED UP BY THE TROUGH AND CHANNELED ENE TOWARDS SRN CALIFORNIA. MID/UPPER LEVEL ANTICYCLONIC FLOW IS PRESENT TO THE SE OF TROUGH WITH ITS ATTENDED UPPER LEVEL ANTICYCLONE ANCHORED OVER WRN MEXICO NEAR 24N104W. ASSOCIATED RIDGING EXTENDS SW FROM THE ANTICYCLONE THROUGH 19N112W TO 17N118W TO 10N127W. THE ANTICYCLONE IS FORECAST TO SHIFT A LITTLE NWD OVER THE NEXT 3-4 DAYS. THE UPPER LEVEL FLOW BETWEEN THE RIDGE AND TROUGH IS SWLY...THEN BECOMES NWLY BEHIND THE TROUGH W OF 130W. ON THE SRN PERIPHERY OF THE RIDGE THE MID/UPPER LEVEL FLOW IS ELY...AND IS SPREADING DEEP TROPICAL FROM THE BROD AREA OF LOW WWD TO NEAR 122W. TO THE E OF THE ANTICYCLONE...AN UPPER LEVEL TROUGH EXTENDS FROM ERN CUBA SW ACROSS THE NW CARIBBEAN TO GULF OF HONDURAS AND TO THE FAR NE PACIFIC NEAR 11.5N93W. THE FLOW PATTERN BETWEEN THE TROUGH AND SE PERIPHERY OF THE ANTICYCLONE BECOMES DIFFLUENT ...AND IS AIDING CONVECTION TIED TO THE BROAD OF AREA OF LOW PRES AS WELL AS ITCZ-RELATED CONVECTION E OF 100W. ADDITIONAL UPPER LEVEL MOISTURE AND RELATED CONVECTION...ALSO SUPPORTED BY THE UPPER FLOW...IS EVIDENT N OF THE ITCZ TO ALONG THE COAST OF GUATEMALA AND EL SALVADOR. SCATTERED MODERATE/ISOLATED STRONG CONVECTION MOVING QUICKLY SSW UNDERNEATH NNE FLOW IS JUST S OF THE GULF OF TEHUANTEPEC WITHIN 30 NM OF 14N96W. OTHERWISE...MOSTLY MODERATE SUBSIDENCE PRODUCING RATHER DRY AND STABLE CONDITIONS COVERS JUST ABOUT THE ENTIRE DISCUSSION AREA WITH SCATTERED STRATOCUMULUS CLOUDS MOVING SSW TO THE N OF 20N W OF 130W. AT THE SURFACE...A DISSIPATING TROUGH ENTERS THE REGION THROUGH 32N13W AND STRETCHES TO 27N140W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 30-60 NM OF THE TROUGH. A RIDGE EXTENDS INTO THE AREA FROM JUST S OF THE TROUGH THROUGH 26N140W...AND EXTENDS ESE TO 13N117W. HIGH PRES COVERS THE AREA N OF 14N AND 118W. QUIKSCAT DATA FROM LATE LAST NIGHT...AND A COUPLE OF SHIP OBSERVATIONS FROM AROUND 0600 UTC SHOWED NW WINDS OF 20 KT ALONG ...AND WITHIN ABOUT 120 NM W OF THE BAJA CALIFORNIA COAST. EXPECT THESE WINDS TO LAST FOR THE NEXT FEW DAYS AS HIGH PRES BECOMES SITUATED NEAR 29N130W...AND LOW PRES REMAINS OVER THE SW UNITED STATES AND GULF OF CALIFORNIA. GAP WINDS...AS RESULT OF THE CIRCULATION AROUND THE LOW PRES AREA MENTIONED ABOVE NLY FLOW IN THE FORM OF 20-25 KT WINDS WILL BEGIN THROUGH THE GULF OF TEHUANTEPEC IN 24 HOURS...THEN INCREASE TO 30 KT IN 48 HOURS. THIS IS HIGHER THAN PREVIOUSLY EXPECTED DUE TO GRADIENT ENHANCEMENT NOW EXPECTED TO THE N OF THE LOW AS IT GETS CLOSER TO CENTRAL AMERICA. $$ AGUIRRE