000 AXPZ20 KNHC 071618 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT APR 07 2007 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 6N78W 7N90W 6N100W 5N111W 4N120W 3N130W 2N140W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS FROM 4N-8N BETWEEN 84W-89.5W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM OF THE AXIS BETWEEN 96W-101W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 110W-117.5W...AND WITHIN 30 NM OF THE AXIS BETWEEN 120W-130W. ...DISCUSSION... SOMEWHAT PROGRESSIVE PATTERN DOMINATES THE SUBTROPICS WITH A SERIES OF TROUGHS AND RIDGES SWEEPING ACROSS THE DISCUSSION AREA N OF 20N. THIS IS IN STRONG CONTRAST TO THE MID-LATITUDE PATTERN OVER THE CONUS AND CANADA WHERE LATE SEASON BLOCKING DOMINATES IN A STRONG POSITIVE PNA PATTERN. NEGATIVELY TILTED TROUGH WELL N OF THE AREA EXTENDING SWWD TO 30N132W IS RAPIDLY MOVING EWD TOWARDS THE WRN U.S. A WEAK SHORTWAVE RIDGE WAS NOTED SE OF THE TROUGH FROM 32N121W SWWD TO 27N127W. A CUT-OFF MID/UPPER LOW NOW OVER SW NEW MEXICO OPENING TO A TROUGH CURRENTLY TRAILS A SHEARED MID/UPPER TROUGH SW ACROSS NRN BAJA CALIFORNIA SW TO 25N117W THROUGH 22N124W TO 20N130W TO 19N136W SW TO BEYOND THE AREA AT 17.5N140W. CONFLUENT FLOW WITHIN THE BASE OF THE TROUGH MANIFESTED ITSELF IN AN AREA OF STRONG UPPER LEVEL SUBSIDENCE WITHIN 150 NM EITHER SIDE OF THE SHEARED TROUGH AXIS S OF 25N. THIS AREA OF SUBSIDENCE WAS ALSO OVER THE POLEWARD SIDE OF A SUBTROPICAL JET STREAM WHICH ENTERS THE WRN PART OF THE DISCUSSION AREA THROUGH 16N140W...AND EXTENDS NEWD THROUGH 21N120W TO ACROSS SRN BAJA CALIFORNIA AND THEN TO NRN MEXICO. SOME DEEP TROPICAL MOISTURE IN THE FORM OF SCATTERED/BROKEN CIRRUS CLOUDS WITHIN 360 NM SOUTHEAST OF THE JET STREAM ARE SUGGESTING TRANSVERSE BANDING E OF 114W. RIPPLES OF ENERGY ALONG THE JET STREAM ARE PROPAGATING QUICKLY TO THE NORTHEAST MAINLY EAST OF 132W WHERE SATELLITE DERIVED UPPER AIR DATA INDICATED MAXIMUM JET CORE WINDS IN THE RANGE OF 80-100 KT. A FLATTENING MID/UPPER LEVEL RIDGE HAS SHIFTED EWD OVER CENTRAL MEXICO ALONG 100W. THE MID/UPPER LEVEL FLOW JUST WEST OF THE AREA BECOMES SHARPLY NORTHWEST TO NORTH DUE TO LARGE MID/UPPER ANTICYCLONIC HIGH WEST SITUATED WELL TO THE WEST OF 140W. THIS IS FORECAST TO MOVE INTO THE WRN PORTION OF THE AREA N OF 15N THROUGH EARL;Y NEXT WEEK THEN BECOME ZONAL AND INCREASE DURING THE MIDDLE AND LATTER PART OF NEXT WEEK. WEAKENING MID/UPPER LEVEL TROUGH WILL BE OVER THE FAR ERN PART OF THE AREA N OF 19N BY THE END OF THE NEXT WEEK. A WEAKENING COLD FRONT EXETNDS INTO THE NW PORTION OF THE DISCUSSION AREA FROM 32N130W SW THROUGH 30N135W TO 28N140W. THIS FRONT IS ASSOCIATED WITH THE NEGATIVELY TILTED TROUGH N OF THE AREA. BROKEN LOW AND MID CLOUDS WITH WIDELY SCATTERED SHOWERS ARE WITHIN 30 NM EITHER SIDE OF THE FRONT. SW WINDS OVER THE NW PART OF THE AREA NEAR THE FRONT HAVE DECREASED TO 20 KT WITH NW SWELLS POSSIBLY UP TO 12 FT SPREADING INTO THE AREA. THESE WINDS SHOULD DIMINISH WITHIN 12 HRS...HOWEVER THE NW SWELLS WILL SLOWLY SUBSIDE. IN THE DEEP TROPICS...A MID/UPPER LEVEL TROUGH AXIS EXTENDS FROM ROUGHLY FROM 14N104.5W SW TO 9N105W...THEN S TO BEYOND THE EQUATOR AT 102W. THIS TROUGH IS ENHANCING ITCZ CONVECTION TO ITS EAST. IN ADDITION...THIS CONVECTION ALSO LIES UNDER MID/UPPER LEVEL RIDGING THAT EXTENDS ALONG 8N TO THE EAST OF THE TROUGH TO OVER S AMERICA. THE TROUGH IS FORECAST TO MOVE EAST THROUGH TODAY THEN DISSIPATE TONIGHT AND SUN. BROAD MID/UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA SOUTH OF 16N WEST OF THE TROUGH WITH AN ASSOCIATED MID/UPPER LEVEL ANTICYCLONIC CIRCULATION NEAR 7N119W. THE CIRCULATION IS MOVING NE ABOUT 17 KT. CONVECTION IS ALSO ACTIVE ALONG THE ITCZ FROM 4N-6N W OF 110W. GAP WINDS...A 1247W UTC QUIKSCAT PASS INDICATED THAT NE WINDS IN THE GULF OF TEHUANTEPEC ARE IN THE RANGE 20-25 KT. THESE WINDS ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT WITHIN 12 HRS. PAPAGAYO WINDS MAY BRIEFLY INCREASE TO 20 KT TONIGHT AND SUN MORNING DUE TO THE WIND REGIME ACROSS COSTA RICA ENHANCED BY SLIGHT TIGHTENING OF THE GRADIENT AND INTERACTING UPON THE LOCAL TOPOGRAPHY. $$ AGUIRRE