000 AXPZ20 KNHC 200913 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC TUE OCT 20 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...SPECIAL FEATURE... TROPICAL STORM RICK WAS CENTERED NEAR 19.4W 111.5W AT 0900 UTC OCT...OR ABOUT 230 NM SSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING NNE OR 020 DEG AT 5 KT. ESTIMATED MINIMUM CENTRAL PRES IS 991 MB. MAXIMUM SUSTAINED WINDS HAVE DECREASED TO 55 KT WITH GUSTS TO 65 KT. SATELLITE IMAGERY SHOWED THAT THE OVERALL CLOUD PATTERN HAS BEEN SHEARED WITH THE CENTER ON THE SOUTHWEST SIDE OF THE CONVECTION CLOUD SHIELD. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 75 NM OF THE POINT 20.5N111W. SCATTERED MODERATE CONVECTION IS ELSEWHERE WITHIN 150 NM OVER THE EAST SEMICIRCLE. RICK IS FORECAST TO WEAKEN A LITTLE 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 90W FROM 06N TO 12N MOVING W ABOUT 13 KT. MODERATE EASTERLY SHEAR ALOFT IS NOT ALLOWING FOR CONVECTION TO ORGANIZE WITH THIS WAVE. ASSOCIATED CONVECTION IS DESCRIBED BELOW UNDER ITCZ. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 07N78W TO 07N90W TO 10N105W...THEN RESUMES AT 14N110W TO 08N120W TO 07N130W TO 11N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 90W AND 105W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 110W AND 114W. SCATTERED MODERATE CONVECTION IS WITHIN 75 NM OF THE POINT 08N119W. OTHER SIGNIFICANT CONVECTION... SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE OF A LINE FROM 07N84W TO 11N88W. THIS CONVECTION ORIGINATED ALONG THE COAST OF COSTA RICA AND NICARAGUA AND IS MOVING OUT FROM THE COAST. THE CONVECTION SHOULD WEAKEN DURING THE NEXT SEVERAL HOURS. ...DISCUSSION... MOSTLY UPPER TROUGH AXIS IS ALONG A LINE THROUGH 32N108W TO 23N120W TO 22N140W. A DEEP LAYER TROUGH IS NORTH OF 25N EAST OF 125W AND IS MOVING SLOWLY EAST OVER NORTHERN MEXICO. RIDGE IS BUILDING NORTH OF THE TROUGH WEST OF 128W. SOUTHERLY SHEAR OVER RICK IS SPREADING DEEP LAYER MOISTURE AND MULTI LAYERED CLOUDS NORTH AND NORTHEASTWARD OVER NORTHERN AND CENTRAL MEXICO. THE AREA NORTH OF 15N WEST OF 113W IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH MOSTLY OVERCAST STRATOCUMULUS IN THE LOWER LEVELS. THE STRATOCUMULUS IS BROKEN FROM 24N TO 27N. THE AREA SOUTH OF THE ITCZ WEST OF 120W IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH SCATTERED TO BROKEN STRATOCUMULUS IN THE LOWER LEVELS. EAST OF 113W DIFFLUENCE ALOFT OVER THE AREA IS PRODUCING WIDESPREAD MULTI LEVEL CLOUDINESS WITH AREAS OF EMBEDDED CONVECTION. THE CONVECTION IS MOSTLY IN THE ITCZ REGION FROM 113W TO 89W AND OFF THE COAST OF CENTRAL AMERICA FROM COSTA RICA TO CENTRAL NICARAGUA. A MODERATE RIDGE IS NORTHWEST OF A LINE FROM CENTRAL BAJA CALIFORNIA TO 20N120W TO THE ITCZ AT 140W. ELSEWHERE BESIDES THE TROPICAL CYCLONE THE AREA IS ANALYZED AS A WEAK TROUGH AT THE SURFACE. GAP WINDS... A GALE WARNING IS CURRENTLY IN EFFECT FOR THE GULF OF TEHUANTEPEC ...BUT IS EXPECTED TO DIMINISH IN ABOUT 12 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 36 HOURS. $$ LL