000 AXPZ20 KNHC 200319 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE OCT 20 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...SPECIAL FEATURE... TROPICAL STORM RICK WAS CENTERED NEAR 19.1W 111.8W AT 0300 UTC OCT...OR ABOUT 290 NM SSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING N OR 350 DEG AT 7 KT. ESTIMATED MINIMUM CENTRAL PRES IS 985 MB. MAXIMUM SUSTAINED WINDS HAVE DECREASED TO 60 KT WITH GUSTS TO 75 KT. LAST VISIBLE AND LATEST IR IMAGERY SHOWED THAT THE OVERALL CLOUD PATTERN HAS BEEN SHEARED WITH THE CENTER JUST MOSTLY EXPOSED FROM THE CONVECTION CLOUD SHIELD. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF THE CENTER IN THE E QUADRANT. SCATTERED MODERATE CONVECTION IS ELSEWHERE OF THE CENTER WITHIN 150 NM IN THE E SEMICIRCLE. RICK IS FORECAST TO WEAKEN FURTHER AS UPPER LEVEL SHEAR INCREASES AND DRY STABLE CONDITIONS PUNCH IN FROM THE W. NEVERTHELESS...RICK REMAINS A SERIOUS THREAT WITH RESPECT TO THE POTENTIAL FOR HEAVY RAINFALL. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 89W FROM 6N-12N MOVING W ABOUT 13 KT. MODERATE EASTERLY SHEAR ALOFT IS NOTE ALLOWING FOR CONVECTION TO ORGANIZE WITH THIS WAVE. ASSOCIATED CONVECTION IS DESCRIBED BELOW UNDER ITCZ. ...ITCZ... AXIS IS CENTERED ALONG 8N78W TO 8N90W TO 13N105W...THEN RESUMES AT 12N113W TO 8N125W TO 13N140W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 86W-90W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 30 NM EITHER SIDE OF THE AXIS BETWEEN 101W-105W...AND BETWEEN 117W-119W. A DEEP LAYER TROUGH IS LOCATED N OF 21N E OF W OF 130W WITH A MEAN AXIS ROUGHLY FROM 32N119W SSE TO 22N115W. MODERATE SUBSIDENCE SUPPORTING DRY AND STABLE CONDITIONS COVERS JUST ABOUT THE ENTIRE AREA N OF 16N. PATCHES OF BROKEN TO OVERCAST STRATOCUMULUS CLOUDS MOVING WSW ARE SEEN OVER THIS AREA. A DEEP LAYER RIDGE W OF 130W IS SLIDING EASTWARD. WNW UPPER FLOW IS PRESENT W OF THE TROUGH AND NE OF THE RIDGE. THE TROUGH WILL ACT TO TURN RICK IN A MORE NE DIRECTION TOWARDS MEXICO OVER THE NEXT 36-48 HOURS. GENERALLY MODERATE EASTERLY FLOW ALOFT IS LOCATED OVER THE TROPICS S OF ABOUT 15N. AT THE SURFACE A 1021 MB HIGH IS LOCATED NEAR 32N136W WITH A RIDGE SE TO NEAR 26N120W. LONG PERIOD NW SWELLS OF 8-10 FT ARE FORECAST TO MIGRATE SE INTO THE NW PORTION OF THE AREA WITHIN THE NEXT 24 HOURS...THEN BUILD TO 9-13 FT IN 48 HOURS. WINDS ALOFT ARE GENERALLY NORTHEASTERLY BETWEEN 90W AND 100W AND BECOME MORE EASTERLY E OF 90W INTO CENTRAL AND SOUTH AMERICA. A WELL DEFINED ANTICYCLONE IS NEAR 09N116W. A SECOND ANTICYCLONE IS OVER THE FAR EASTERN PORTION OF THE AREA NEAR 15N104W...AND IS HELPING TO STEER RICK N FOR THE TIME BEING. GAP WINDS... A GALE WARNING IS CURRENTLY IN EFFECT FOR THE GULF OF TEHUANTEPEC ...BUT IS EXPECTED TO DIMINISH IN ABOUT 18 HOURS AS THE TIGHT PRES GRADIENT ACROSS SE MEXICO WEAKENS. WINDS THROUGH WILL BE ABOUT N-NE 20-25 KT IN 24 HOURS...THE DIMINISH TO LESS THAN 20 KT IN 42 HOURS. $$ AGUIRRE