000 AXPZ20 KNHC 280312 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN OCT 28 2012 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 UTC. ...SPECIAL FEATURE... A 1007 MB LOW PRES FEATURE IS EMBEDDED WITHIN THE MONSOON TROUGH ABOUT 520 NM SSW OF MANZANILLO MEXICO NEAR 11N110W. CONVECTION HAS CONTINUED TO INCREASE DURING THE LATE AFTERNOON AND EVENING...AND IS DEPICTED AS THE NUMEROUS STRONG TYPE WITHIN 150 NM OF THE CENTER IN THE NE QUADRANT. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 180 NM OF THE CENTER IN THE SE QUADRANT. THE CIRCULATION AND OVERALL CLOUD PATTERN HAS GRADUALLY BECOME MORE SYMMETRICAL DURING THE PAST SEVERAL HOURS AS OBSERVED IN VISIBLE SATELLITE IMAGERY. THE LOW REMAINS UNDER AN UPPER LEVEL ANTICYCLONE...WHICH FAVORS SOME SLOW DEVELOPMENT THROUGH THE NEXT 48 HRS WITH A MEDIUM PROBABILITY OF TROPICAL FORMATION WITHIN THE NEXT 48 HRS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM FAR NW COLOMBIA NW THROUGH COSTA RICA AND PANAMA TO 12N92W TO LOW PRES NEAR 10N99W 1007 MB TO 12N106W TO LOW PRES NEAR 11N110W 1007 MB TO LOW PRES NEAR 11N121W 1007 MB TO 10N130W AND TO BEYOND 07N140W AS THE ITCZ. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM N OF THE TROUGH BETWEEN 114W-117W. ...DISCUSSION... AN UPPER TROUGH EXTENDS FROM SOUTHERN CALIFORNIA TO 22N131W TO A WEAK ANS SMALL CYCLONIC CIRCULATION AT 18N140W. THE TROUGH AMPLIFIES N OF 20N AS A MID TO UPPER RIDGE WITH A NORTHERN CREST STRETCHING FROM THE PACIFIC NW SW TO THROUGH 25N140W SHIFTS EASTWARD...AHEAD OF A DEEP LAYER TROUGH W OF THE DISCUSSION AREA NEAR 146W. NORTHERN STREAM ENERGY DIVING SEWD AROUND THE RIDGE CREST TOWARDS WESTERN U.S. IS HELPING TO REINFORCE THE UPPER TROUGH. A 1023 MB SURFACE HIGH PRES CENTERED NEAR 34N135W ASSOCIATED WITH THE UPPER RIDGE WILL FLATTEN AND SHIFT SE TO 30N130W SUN AHEAD OF THE ADVANCING DEEP LAYER TROUGH. THE 1830 UTC ASCAT PASS FROM YESTERDAY AFTERNOON AND AN OSCAT PASS FROM NEAR 2130 UTC BOTH REVEALED AN AREA OF MOSTLY NE 20 KT WINDS TO THE S AND SW OF THE RIDGE FROM 10N TO 22N W OF ABOUT 135W. THE SAME ASCAT PASS SHOWED PARTIAL DATA OF NW 20 KT WINDS ACROSS THE CENTRAL GULF OF CALIFORNIA DUE TO THE PRES GRADIENT BETWEEN HIGH PRES OVER THE WESTERN U.S. AND LOWER PRES OVER NW MEXICO AND GULF OF CALIFORNIA. THESE WINDS ARE IN THE PROCESS OF DIMINISHING TO LESS THAN 20 KT. THE AREA OF NE TRADES S AND S OF THE RIDGE IS FORECAST TO ALSO DIMINISH TO 20 KT OR LESS BY SUN EVENING AS THE 1023 MB HIGH CENTER SHIFTS SE WHILE CONTINUING TO WEAKEN. HOWEVER...RESIDUAL MIXED NE AND SW SWELLS WILL RESULT IN 8 FT SEAS FROM 10N-25N W OF 130W...AND ALSO N OF 24N BETWEEN 125W-130W. A SET OF NW SWELLS IS FORECAST TO PROPAGATE INTO THE NW PORTION OF THE AREA BY SUN AFTERNOON...AND CONFINED FROM ABOUT 10-20N W OF 135W BY MON AFTERNOON. SCATTERED MODERATE CONVECTION ALONG THE MONSOON TROUGH W OF 130W HAS LARGELY DIMINISHED AS THE TRADE WIND FLOW SUBSIDED...BUT CONTINUES TO BE EVIDENT FARTHER E ASSOCIATED WITH A 1007 MB LOW PRES NEAR 11N121W...AS WELL AS WITH THE LOW MENTIONED UNDER SPECIAL FEATURE. OPERATIONAL AND GLOBAL MODELS SUGGEST SOME DEVELOPMENT WITH THIS LOW AS WELL AS IT SLOWLY MOVES TO THE WNW. GAP WINDS... A COLD FRONT PUSHING S THROUGH THE SW GULF OF MEXICO IS FOLLOWED BY A COOLER AND DRIER AIRMASS. THIS DENSER AIR IS MIXING DOWNWARD RESULTING IN N-NE WINDS OF 20-30 KT THROUGH THE GULF OF TEHUANTEPEC. THESE WINDS ARE EXPECTED TO LAST INTO SUN EVENING BEFORE DIMINISHING TO 20-25 KT LATE SUN NIGHT AND MON. ACCORDING TO THE NOAA III WAVEWATCH GUIDANCE...THE ASSOCIATED SEAS ARE IN THE RANGE OF 8-11 FT. "SHIP" OBSERVATION AT 15N97W REPORTED COMBINED SEAS OF 11 FT JUST A SHORT WHILE AGO. THESE WINDS ARE FORECAST TO SPREAD SW AND W TO NEAR 103W BY SUN EVENING AT SPEEDS OF 20-25 KT WITH SEAS TO 9 FT. $$ AGUIRRE