000 AXPZ20 KNHC 231002 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI MAR 23 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0915 UTC. ...ITCZ... ITCZ IS CENTERED ALONG...2N78W 5N90W 5N100W 4N110W 6N118W 3N130W 3N140W. SCATTERED MODERATE CONVECTION IS WITHIN 30 NM EITHER SIDE OF THE ITCZ BETWEEN 85W-90W AND ALSO BETWEEN 103W-108W. ...DISCUSSION... A LARGE UPPER LEVEL CYCLONIC CIRCULATION LOCATED OVER NRN BAJA CALIFORNIA AS OBSERVED ON SATELLITE WATER VAPOR IMAGERY IS CURRENTLY DRIFTING E. THIS SYSTEM IS EXPECTED TO ACQUIRE MORE OF AN EWD MOTION TODAY TOWARDS NRN MEXICO. A MID/UPPER LEVEL TROUGH EXTENDS S FROM THE CIRCULATION THROUGH 25N114W THEN SW TO NEAR 18N118W. MID TO UPPER LEVEL MOISTURE IS SEEN WRAPPING AROUND THE CIRCULATION CENTER AND RESULTING IN ISOLATED SHOWERS AND WEAK TSTMS OVER THE NRN BAJA PENINSULA AND ADJACENT GULF OF CALIFORNIA WATERS AS SEEN ON LATEST RADAR IMAGERY. ISOLATED SHOWERS AND TSTMS ARE OVER THE MOUNTAINS AND DESSERT REGIONS OF SRN CALIFORNIA AND ARIZONA. THE CYCLONIC CIRCULATION IS FORECAST TO LIFT NEWD SAT AND WEAKENS TO A TROUGH OVER NEVADA. A RATHER EXTENSIVE MOSTLY UPPER LEVEL MOISTURE PLUME...WHICH ORIGINATES FROM THE ITCZ SECTION W OF THE AREA TO THE SE OF THE HAWAIIAN ISLANDS...IS EVIDENT WITHIN 420 NM SE OF THE TROUGH AND MAINLY SEEN FROM 12N-19N W OF 118W. IT CONTINUES TO STREAM ENE TO ACROSS MEXICO FROM PETATLAN TO MAZATLAN...AND FURTHER NE TO THE WRN AND CENTRAL UNITED STATES. A SUBTROPICAL JET STREAM BRANCH WITH SATELLITE DERIVED WINDS IN THE RANGE OF 80-120 KT ENTERS THE WRN PART OF THE DISCUSSION AREA NEAR 21N140W AND DIVES SE THROUGH 18N125W...AND THEN CONTINUES NEWD ROUNDING THE BASE OF THE MID/UPPER LEVEL TROUGH TO ACROSS NRN MEXICO AT 24N107W. THIS JET IS THE DIVIDING LINE BETWEEN THE MOISTURE PLUME DESCRIBED ABOVE AND MODERATE TO STRONG SUBSIDENCE TO ITS N. THIS SUBSIDENCE...HOWEVER...IS SHRINKING WITH TIME AS UPPER LEVEL MOISTURE ADVECTS EWD THEN SWD INTO THE FAR NRN PORTION OF THE AREA AROUND A LARGE AMPLITUDE RIDGE CREST THAT EXETNDS FROM NEAR THE NW UNITED STATES SWWD TO WELL W OF THE DISCUSSION AREA. AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 8N123W AS SEEN ON SATELLITE WATER VAPOR IMAGERY. ITS ASSOCIATED ENVELOPE OF ANTICYCLONIC FLOW HAS BECOME FLATTENED OVER THE PAST 24 HOURS ...BUT MID/UPPER LEVEL RIDGING IS SEEN EXTENDING FROM THE ANTICYCLONE EAST/WEST ALONG 6N W OF 103W. E OF 103W...THE RIDGE EXTENDS NEWD ACROSS SE MEXICO AND INTO THE WRN GULF OF MEXICO. THE ANTICYCLONE IS FORECAST TO LOSE ITS IDENTITY THROUGH SAT. ANOTHER UPPER TROUGH EXTENDS FROM THE FAR WRN ATLC SWD TO OVER COSTA RICA...AND FURTHER S INTO THE FAR ERN PORTION OF THE AREA E OF 85W. SCATTERED MODERATE TO STRONG CONVECTION E OF THE TROUGH THAT WERE NOTED OVER NW COLOMBIA YESTERDAY AND EARLIER TONIGHT HAVE JUST ABOUT DISSIPATED. I DO EXPECT THIS ACTIVITY TO FIRE UP AGAIN LATER TODAY AS DAYTIME HEATING GETS UNDER WAY. THE TROUGH IS FORECAST TO MOVE E OF THE AREA THROUGH SAT. MODERATE TO STRONG SUBSIDENCE AND ASSOCIATED DRY AIR DOMINATES THE REMAINDER OF THE AREA E OF 108W. THE UPPER LEVEL FLOW TO THE SE OF THE ANTICYCLONE IS DIFFLUENT S OF 9N BETWEEN 100W-110W...AND IS AIDING ITCZ CONVECTION IN THAT VICINITY. AT THE SURFACE...A NEARLY STATIONARY 1029 MB HIGH IS ANALYZED JUST N OF THE DISCUSSION AREA NEAR 33N131W WITH A RIDGE STRETCHING SEWD THROUGH 28N132W 24N126W TO 21.5N118W. HIGH PRES IS PRESENT N OF 14N AND W OF 115W. BROKEN TO SCATTERED STRATOCUMULUS CLOUDS WITH POSSIBLE ISOLATED SHOWERS MOVING S TO SW ARE VISIBLE FROM 18N-28N AND W OF 118W. ISOLATED SHOWERS AND TSTMS ARE OVER WATERS ADJACENT THE COSTA RICAN/PANAMANIAN BORDER AS WELL AS WITHIN 30 NM OF 8N84W. WIDELY SCATTERED SHOWERS AND TSTMS DUE TO A SURFACE TROUGH ALONG 119W MOVING W 10-15 KT ARE WITHIN 30 NM EITHER SIDE OF LINE 8N118W 11N114W. GAP WINDS...N-NE 20 KT WINDS IN THE GULF OF TEHUANTEPEC SHOULD CONTINUE THROUGH LATE SAT BEFORE DIMINISHING...THEN INCREASING ONCE AGAIN TO 20 KT SUN MORNING AND LESSENING TO LESS THAN 20 KT LATER ON SUN PER GFS MODEL GUIDANCE. OTHER NWP MODELS SHOW 20-25 KT AND LASTING LONGER. TIGHT PRES GRADIENT OVER THE W CARIBBEAN CONTINUES TO SPILL MODERATE TO STRONG E WINDS ACROSS COSTA RICA AND NRN PANAMA AND INTO THE EXTREME E PACIFIC. EXPECT NE 20-25 KT TO CONTINUE ACROSS THE GULF OF PAPAGAYO THROUGH LATE SAT AFTERNOON...THEN DIMINISH TEMPORARILY BEFORE KICKING BACK UP AGAIN LATE SAT NIGHT INTO SUN MORNING AND DIMINISHING AGAIN SUN NIGHT INTO MON MORNING. GULF OF PANAMA WINDS...WITH THE EXCEPTION OF AN OCCASIONAL N WIND OF 15-20 KT TODAY AND TONIGHT...SHOULD REMAIN LESS THAN 20 KT OVER THE WEEKEND. $$ AGUIRRE