000 AXPZ20 KNHC 191602 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI SEP 19 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1530 UTC. ...TROPICAL WAVES... TROPICAL WAVE ALONG 91W N OF 07N TO ACROSS WESTERN GUATEMALA AND TO SE MEXICO IS MOVING W 10 KT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM W OF THE WAVE FROM 9N-13N. AS THIS WAVE MOVES W IT WILL BECOME ABSORBED INTO A LARGER SCALE CYCLONIC GYRE TO ITS W...SSW OF THE GULF OF TEHUANTEPEC WHICH IS DISCUSSED IN FURTHER DETAIL IN THE PARAGRAPH BELOW. TROPICAL WAVE ALONG 102W/103W FROM 5N-15N IS MOVING W 10-15 KT. THIS WAVE IS PART OF A LARGE AND DISORGANIZED AREA OF ACTIVE SCATTERED MODERATE TO STRONG CONVECTION UNDER DIFFLUENT FLOW THAT EXTENDS FROM 9N-15N BETWEEN 93W-104W. VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW BROAD CYCLONIC TURNING OF THE LOW CLOUD FIELD WITH THE ITCZ AXIS SERVING AS THE FOCAL POINT OF THIS AREA. CONVECTION WITHIN THIS AREA IS PRESENTLY UNDER THE INFLUENCE OF STRONG UPPER EASTERLY SHEAR SO THE AREA WILL REMAIN RATHER BROAD WITH ONLY SLOW DEVELOPMENT EXPECTED OVER THE NEXT COUPLE OF DAYS AS IT SLOWLY MOVES WNW UNDER A SLIGHTLY IMPROVED UPPER LEVEL ENVIRONMENT. TROPICAL WAVE ALONG 120W FROM 6N TO 16N IS MOVING W 10 KT. A WEAK LOW-LEVEL SWIRL IS ON THE WAVE AXIS NEAR 10N120W...BUT WILL PROBABLY NOT LAST ANOTHER 6-12 HOURS. ONLY ISOLATED WEAK CONVECTION IS NOTED WITHIN 60-90 NM OF THE LOW...AND WITHIN 30-60 NM ALONG THE WAVE. OTHER ISOLATED WEAK CONVECTION IS WITHIN 90 NM OF THE WAVE AXIS IN THE VICINITY OF THE ITCZ AXIS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N86W TO 10N100W TO 10N110W TO TO 10N120W TO 8N130W TO 9N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF THE AXIS BETWEEN 105W- 111W...AND BETWEEN 115W-118W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 125W-129W. ...DISCUSSION... E OF 130W... AN ELONGATED E TO W MID/UPPER LEVEL ANTICYCLONE MOVING ESE 15 KT IS IDENTIFIED NEAR 22N112W. A RIDGE EXTENDS SW FROM THE ANTICYCLONE TO 16N130W...WITH ANOTHER RIDGE NE OF THE AREA REACHING TO A CREST WELL N OF THE OF THE NW UNITED STATES. A PRONOUNCED ANTICYCLONIC CIRCULATION IS E OF THE AREA OVER MEXICO NEAR 20N101W WITH A RIDGE WNW TO 21N106W. WATER VAPOR IMAGERY SHOWS WEAK MID/UPPER LEVEL TROUGH IN BETWEEN BOTH ANTICYCLONES WITH A COL REGION CENTERED NEAR 21N107W. A DEEP LAYERED TROUGH N OF THE AREA MOVING INTO NORTHERN AND CENTRAL CALIFORNIA HAS ITS WEAK AXIS EXTENDING SSE TO 32N120W. ANTICYCLONIC FLOW AND MOSTLY STRONG SUBSIDENCE ASSOCIATED WITH THE ANTICYCLONE NEAR 22N112W IS NOTED FROM 24N-30N WHERE IT MERGES WITH CYCLONIC FLOW RELATED WITH THE TROUGH N OF THE AREA RESULTING IN A CONFLUENT FLOW PATTERN ALLOWING FOR A DRY STABLE AIR MASS TO PRESENT OVER THE NRN SECTION OF THE AREA. STRONG UPPER LEVEL EASTERLY FLOW...WHICH IS RESPONSIBLE FOR CREATING THE EASTERLY OVER THE AREA OF DISORGANIZED CONVECTION MENTION ABOVE WITH THE WAVE ALONG 102W/103W...IS EVIDENT TO THE S AND SW OF THE ANTICYCLONE OVER MEXICO NEAR 20N101W. THIS SAME FLOW IS SPREADING UPPER LEVEL MOISTURE WESTWARD E OF 110W...AND ALONG AND NEAR THE ITCZ FROM 4N-14N W OF 110W. MODERATE TO STRONG SUBSIDENCE IS NOTED ELSEWHERE ACROSS THE AREA. AT THE SURFACE...A 1019 MB HIGH IS ANALYZED NEAR 28N129W WITH A WEAK RIDGE SE TO 25N122W. WEAK HIGH PRES COVERS THE AREA N OF 21N W OF 120W. MODEL GUIDANCE SUGGESTS THAT THE N-NE WINDS TO 20 KT IN THE GULF OF TEHUANTEPEC SHOULD DIMINISH IN ABOUT 24 HOURS. SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING WSW WITH POSSIBLE ISOLATED SHOWERS ARE LOCATED FROM 18N-27N BETWEEN 121W-130W. A TILTED NW-SE INVERTED MID/UPPER LEVEL TROUGH MOVING W 15 KT IS OVER THE ITCZ REGION FROM 4N-11N BETWEEN 125W-130W. THIS TROUGH IS ENHANCING ITCZ CONVECTION SOME IN THAT AREA. W OF 130W... THE CORRESPONDING SURFACE FEATURE ASSOCIATED WITH THE DEEP LAYERED TROUGH MENTIONED UNDER E OF 130W IS ANALYZED AS A WEAKENING STATIONARY FRONT EXTENDING THROUGH 32N131W SW TO W OF THE AREA AT 29N140W. BROKEN LOW AND MID LEVEL CLOUDS WITH WIDELY SCATTERED SHOWERS ARE WITHIN 60 NM SE OF THE FRONT. THE IS FORECAST TO BECOME A SHEAR AXIS THROUGH THE NEXT 6-12 HOURS BEFORE DISSIPATING. THE WESTERN EXTENSION OF THE MID/UPPER LEVEL ANTICYCLONE E OF THE AREA NEAR 22N112W EXTENDS SW TO 7N138W. A SMALL MID/UPPER LEVEL CYCLONIC CIRCULATION MOVING E 15 KT IS JUST NW OF THE AREA NEAR 29N142W. ITS ASSOCIATED TROUGH EXTENDS SSE TO 26N139W...THEN SW OF THE AREA AT 20N140W. THE SOUTHERN PART OF THIS TROUGH IS FORECAST TO POSSIBLY CUT-OFF AS A MID/UPPER LOW OVER THE NEXT 36-48 HOURS. A SMALL UPPER LEVEL ANTICYCLONE IS NEAR 13N133W. THE UPPER LEVEL FLOW PATTERN IS CONFLUENT IN BETWEEN BOTH THE CYCLONIC CIRCULATION AND ANTICYCLONE...WHICH IS ALLOWING FOR MODERATE TO STRONG SUBSIDENCE AND ASSOCIATED DRY STABLE AIR TO PREVAIL THROUGHOUT THIS AREA PROHIBITING THE DEVELOPMENT OF ANY DEEP CONVECTIVE ACTIVITY. PATCHES OF BROKEN STRATOCUMULUS CLOUDS WITH POSSIBLE ISOLATED SHOWERS ARE NOTED ELSEWHERE S OF THE WEAKENING FRONT. A VERY NARROW LINE...ABOUT 20 NM IN WIDTH...OF INCREASING SCATTERED SHOWERS AND TSTMS EXTENDS FROM 10N137W TO 13N137W. THIS ACTIVITY IS BEING FORCED BY A WEAK SURFACE TROUGH THAT EXTENDS FROM JUST N OF THE ITCZ NEAR 10N135W NW TO 12N137W TO 13N137W. A WEAK AND SMALL CYCLONIC SWIRL IS ON THE EXTREME SOUTHERN TIP OF THE TROUGH NEAR 10N135W. $$ AGUIRRE