000 AXPZ20 KNHC 211620 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC MON APR 21 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1600 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 06N78W 03N96W 04N105W 05N110W 06N120W 05N130W TO 04140W. SCATTERED STRONG CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 120W-138W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS FROM 03N-07N E OF 80W TO THE COAST OF COLOMBIA...AND ALSO FROM 04N-08N BETWEEN 100W-109W. SCATTERED MODERATE/ISOLATED STRONG WITHIN 120 NM N OF THE AXIS BETWEEN 80W-87W. ...DISCUSSION... W OF 110W... A MID/UPPER LEVEL TROUGH ENTERS THE AREA THROUGH 32N118W...AND EXTENDS SW THROUGH 27N132W TO A WEAK MID/UPPER LEVEL CYCLONIC CIRCULATION JUST W OF THE AREA NEAR 23N141W. ANOTHER TROUGH EXTENDS FROM 19N138W SE TO 13N132W. THE CYCLONIC CIRCULATION NEAR 23N141W IS FORECAST TO BECOME ABSORBED BY ITS ASSOCIATED TROUGH LATER TODAY. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE NW OF A LINE FROM 28N115W TO 26N126W TO 21N134W TO 19N140W DUE TO A CONFLUENT PATTERN OF NW FLOW INTO THE TROUGH. A VERY PRONOUNCED SUBTROPICAL JET STREAM BRANCH EXTENDS PRETTY MUCH ALONG THIS SAME LINE...AND AS FAR E AS SRN TEXAS WHERE IT THEN DIVES SEWD INTO THE NW GULF OF MEXICO. SATELLITE-DERIVED WINDS ARE INDICATED TO BE IN THE RANGE OF 60-90 KT IN THE JET CORE REGION LOCATED ROUGHLY FROM 19N-24N BETWEEN 121W-128W. BROAD ANTICYCLONIC FLOW COVERS THE AREA TO THE SE OF THE JET STREAM E OF ABOUT 138W. EXTENSIVE UPPER LEVEL MOISTURE IN THE FORM OF HIGH CIRRUS CLOUDS CONTINUES TO BE ADVECTED BY THE JET STREAM NEWD TOWARDS MUCH OF BAJA CALIFORNIA AND...NRN MEXICO AND THE NRN GULF OF MEXICO. AT THE SURFACE...A 1026 MB HIGH IS ANALYZED NEAR 31N138W WITH A RIDGE EXTENDING SE THROUGH 26N128W TO 21N122W TO NEAR 17N117W. HIGH PRES COVERS THE AREA N OF 14N W OF 115W. A SURFACE TROUGH MOVING W 15 KT IS ALONG 130W FROM 5N-10N...AND IS ENHANCING ITCZ CONVECTION IN ITS VICINITY. GLOBAL MODELS SUGGEST THAT WEAK LOW PRES MAY BECOME EVIDENT ON THE TROUGH AXIS LATER TODAY OR ON MONDAY. SCATTERED TO BROKEN MOSTLY STRATOCUMULUS CLOUDS MOVING SW WITH ISOLATED SHOWERS IN NE FLOW ARE SEEN W OF 130W. E OF 110W... A CUT-OFF MID TO UPPER LEVEL CYCLONIC CIRCULATION IS IDENTIFIED TO BE NEAR 4N102W. TO ITS E...THE UPPER LEVEL FLOW BECOMES DIFFLUENT AND IS AIDING IN THE DEVELOPMENT OF ITCZ CONVECTION WITHIN 120-180 NM OF ITS CENTER. A SMALL AND WEAK UPPER LEVEL CYCLONIC CIRCULATION MOVING W 10-15 KT IS NEAR 1N85W. THIS FEATURE IS ENHANCING ITCZ CONVECTION PRIMARILY TO ITS NE AND E...AND TO THE THE COLOMBIAN COAST. THE SURFACE PRES ANALYSIS FROM 12 UTC THIS MORNING SHOWED A WEAK SURFACE TROUGH MOVING W 10-15 KT TO BE ALONG 87W AND FROM 2N-9N. SCATTERED STRONG CONVECTION IS WITHIN 30 NM OF 7N88W. FIRST VISIBLE SATELLITE IMAGES FROM THIS MORNING SUGGEST THAT WEAK LOW PRES MAY FORMING ALONG THE ITCZ AXIS NEAR 6N94W. THE WRN EDGE OF A QUIKSCAT PASS FROM CLOSE TO 12 UTC THIS MORNING ALSO REVEALS THAT LOW PRES MAY BE BECOMING PRESENT ON THE ITCZ BETWEEN 92W-96W. GLOBAL MODELS ARE CONSISTENT IN HANGING ON TO LOW PRES OVER THIS SAME AREA THROUGH THE NEXT FEW DAYS. WITH THE PRES GRADIENT OVER THIS AREA BEING RATHER WEAK AND VERY GOOD CONVERGENCE TAKING PLACE ALONG THE ITCZ AS NOTED IN LOW-LEVEL CLOUD MOTION...EXPECT BURSTS OF MODERATE TO STRONG CONVECTION TO CONTINUE NEAR AND AROUND BOTH THE SURFACE TROUGH AND UPPER LEVEL LOW THROUGH THE NEXT 48-72 HOURS. MODERATE SUBSIDENCE IS NOTED OVER JUST ABOUT THE ENTIRE AREA OUTSIDE THE ITCZ. A MID/UPPER LEVEL RIDGE RUNS FROM COLOMBIA NW TO ACROSS COSTA RICA. MID/UPPER LEVEL RIDGING COVERS ALL OF CENTRAL AMERICA...SE MEXICO AND NW COLOMBIA. CONVECTION HERE REMAINS NON-EXISTENT AS DRY CONDITIONS PREVAIL. ONLY ISOLATED SHOWERS AND TSTMS ARE SEEN ALONG AND WITHIN 60 NM OF THE COASTS OF COSTA RICA AND PANAMA AT THIS TIME. GAP WINDS...NE 20 KT WINDS ACROSS THE GULF OF PAPAGAYO ARE EXPECTED TO CONTINUE IN BRIEF SURGES THROUGH THE THE NEXT 18 HOURS...THEN PERHAPS DIMINISH ENTIRELY. THESE WINDS MAY LINGER AROUND A LITTLE AFTERWARDS BUT IN VERY SMALL AREA IN THE GULF. $$ AGUIRRE