000 AXPZ20 KNHC 011558 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED OCT 01 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 1515 UTC. ...SPECIAL FEATURES... TROPICAL STORM MARIE 14E IS NEAR 17.1N116.3W...APPROXIMATELY 575 MILES...930 KM...SOUTHWEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING 310 DEG AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH HIGHER GUSTS. SEE THE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AN THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. MARIE IS SITUATED ON THE SOUTHWEST SIDE OF AN UPPER ANTICYCLONE...WHERE DIVERGENT SOUTHEAST FLOW ALOFT IS ENHANCING CONVECTION. EASTERLY SHEAR ON THE ORDER OF 10 TO 20 KT SHOULD BEGIN TO DIMINISH DURING THE NEXT 12 TO 24 HOURS AS SUGGESTED BY THE GLOBAL MODELS AND REFLECTED IN THE SHIPS ANALYSIS. CONSEQUENTLY...MARIE SHOULD CONTINUE STRENGTHENING BEFORE ENCOUNTERING COOLER WATERS IN AROUND 48 HOURS. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 14N TO 21N BETWEEN 116W AND 121W. A 1008 MB LOW IS CENTERED NEAR 12N98W...OR APPROXIMATELY 330 NM SW OF THE GULF OF TEHUANTEPEC. THE LOW IS SITUATED SOUTH OF AN UPPER RIDGE AXIS...SUPPLYING MODERATE E SHEAR AND HOLDING CONVECTION DOWNSHEAR TO THE WEST OF THE CENTER. STRONG NE SURFACE WINDS OUT OF THE GULF OF TEHUANTEPEC CONTINUE TO CONVERGE INTO THE NORTH SIDE OF THE LOW...WITH MODERATE TO STRONG SW SURFACE WINDS CONVERGING INTO THE LOW ON ITS EAST SIDE. A QUIKSCAT PASS AT 1252Z SHOWS MANY RAIN CONTAMINATED WINDS OF 25-30 KT IN AN ELONGATED PATTERN. EASTERLY SHEAR IS EXPECTED TO WEAKEN OVER THE NEXT COUPLE OF DAYS...ALLOWING THE POSSIBILITY THAT THE LOW MAY INTENSIFY. THUS...THIS LOW HAS A HIGH POTENTIAL FOR TROPICAL CYCLONE FORMATION WITH THE NEXT 48 HOURS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 11N86W 13N92W 12N100W 12N110W 10N125W 11N135W 09N140W. BESIDES THE CONVECTION MENTIONED IN THE SPECIAL FEATURE SECTION...SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS S OF PANAMA FROM 06N-09N BETWEEN 79W AND 83W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS S OF GUATEMALA FROM 09N TO 14N BETWEEN 89W AND 95W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS IN BETWEEN THE TWO SPECIAL FEATURES FROM 12N TO 18N BETWEEN 107W AND 111W. SCATTERED MODERATE CONVECTION IS FROM 08N TO 12N BETWEEN 134W AND 138W. ...DISCUSSION... E OF 120W... MAIN FORECAST ISSUE FOR AT LEAST THE NEXT COUPLE OF DAYS WILL BE DEVELOPMENT AND TRACK OF TROPICAL STORM MARIE AS MENTIONED ABOVE. 1252Z QUIKSCAT SHOWS A BROAD SWATH OF MODERATE TO STRONG SOUTHWESTERLY WINDS TO THE SOUTH OF THE LOW AT 12N98W CONVERGING INTO THE SYSTEM. QUIKSCAT ALSO SHOWS 20 TO 30 KT NORTHERLY WINDS PERSISTING THROUGH THE GULF OF TEHUANTEPEC...CONVERGING INTO THE LOW NEAR 12N98W. ALOFT...AN UPPER ANTICYCLONE CENTERED NEAR 20N113W WITH A RIDGE AXIS EXTENDING EAST TO GUATEMALA IS PROVIDING MODERATE EASTERLY SHEAR S OF 17N. THE UPPER ANTICYCLONE WILL WEAKEN AS AN UPPER TROUGH DIGS TO THE NORTH OF THE AREA THROUGH THU...ALLOWING THE SHEAR TO DIMINISH. MEANWHILE SOUTHERLY CROSS EQUATORIAL SWELL AROUND 8 FT WILL PUSH AS FAR AS 10N THROUGH THU. W OF 120W... AN UPPER TROUGH IS DIGGING THROUGH 135W N OF 22N. AN ASSOCIATED STATIONARY FRONT EXTENDS FROM 32N130W TO 22N140W. SHIP OBSERVATIONS AND QUIKSCAT DATA SHOW ONLY A SMALL BAND OF 20 KT SOUTH WINDS AHEAD OF THE FRONT N OF 28N. THE FRONT WILL WEAKEN THROUGH TODAY AS THE UPPER SUPPORT LIFTS TO THE NE. EVEN AS THE FRONT WASHES OUT...FRESH SWELL UP TO 12 FT IS EXPECTED TO PUSH INTO THE AREA BEHIND THE FRONT AND PROPAGATE TO THE SE. EXPECT AN AREA OF CONFUSED SEAS BY LATE TODAY FROM 12N TO 24N BETWEEN 120W AND 130W AS THE SWELL ENCOUNTERS SEAS RELATED TO T.S. MARIE MIGRATING WESTWARD. FURTHER SOUTH...A STATIONARY AND WEAK 1011 MB LOW IS EMBEDDED ALONG THE ITCZ NEAR 11N137W WITH ONLY MODEST CONVECTION NOTED. $$ FORMOSA