000 AXPZ20 KNHC 272205 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SAT OCT 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURE... A 1007 MB LOW PRES FEATURE IS EMBEDDED WITHIN THE MONSOON TROUGH ABOUT 570 NM SSW OF MANZANILLO MEXICO NEAR 11N110W. CONVECTION HAS CONTINUED TO INCREASE DURING THE AFTERNOON...AND IS DEPICTED AS SCATTERED MODERATE TO STRONG INTENSITY WITHIN 240 NM OF THE CENTER IN THE NE AND SE QUADRANTS...AND ALSO WITHIN 120 NM IN THE NW QUADRANT. THE CIRCULATION SHOWS UP WELL IN VISIBLE SATELLITE IMAGERY FROM THIS AFTERNOON. THE LOW IS IDENTIFIED TO UNDER AN UPPER LEVEL ANTICYCLONE...WHICH FAVORS SOME DEVELOPMENT THROUGH THE NEXT 48 HRS. THE LOW HAS A MEDIUM PROBABILITY OF TROPICAL FORMATION WITHIN THE NEXT 48 HRS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM NW COSTA RICA NW TO 12N92W TO LOW PRES NEAR 10N98W 1008 MB TO 12N106W TO LOW PRES NEAR 11N110W 1007 MB TO LOW PRES NEAR 11N121W 1008 MB TO 07N140W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM N AND 60 NM S OF THE TROUGH BETWEEN 114W-121W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM S OF THE TROUGH BETWEEN 122W-124W. ...DISCUSSION... AN UPPER TROUGH EXTENDS FROM SOUTHERN CALIFORNIA TO 22N131W TO 14N140W...REINFORCED IN PART BY A SHORT WAVE TROUGH DIGGING SE ALONG THE CALIFORNIA COAST TOWARD NORTHERN BAJA. 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 N OF 25N MOVING E THROUGH 145W. A 1025 MB SURFACE HIGH PRES CENTERED NEAR 33N135W ASSOCIATED WITH THE UPPER RIDGE WILL FLATTEN AND SHIFT SE TO 30N130W SUN AHEAD OF THE ADVANCING DEEP LAYER TROUGH. THE 1830 UTC PASS FROM THIS AFTERNOON REVEALED AN AREA OF MOSTLY NE 20 KT WINDS TO THE S AND SW OF THE RIDGE FROM 10N TO 22N W OF ABOUT 124W. 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 WILL DIMINISH TO LESS THAN 20 KT IN A FEW HRS AS THE PRES GRADIENT WEAKENS. 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 1025 MB HIGH CENTER SHIFTS S AND WEAKENS. 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 WESTERN GULF OF MEXICO IS FOLLOWED BY A COOLER AND DRIER AIRMASS. THIS DENSER AIR IS FORECAST TO BRING N-NE WINDS OF 20-30 KT THROUGH THE GULF OF TEHUANTEPEC THOUGH EARLY SUN AFTERNOON BEFORE DIMINISHING TO 20-25 KT SUN EVENING AND INTO MON. ACCORDING TO THE NOAA III WAVEWATCH GUIDANCE...THE ASSOCIATED SEAS ARE FORECAST TO BUILD TO 8-11 FT. 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