000 AXPZ20 KNHC 242150 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE AUG 24 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURE... TROPICAL STORM FRANK CENTERED NEAR 15.6N 102.1W AT 24/2100 UTC MOVING WNW AT 7 KT. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 991 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. VISIBLE SATELLITE IMAGERY FROM THROUGHOUT THE DAY HAS CONTINUED TO REVEAL THAT THE OVERALL STRUCTURE OF THE CYCLONE HAS BECOME MORE SYMMETRICAL AS WHAT EARLIER WAS NOTED AS A SMALL CDO (CENTRAL DENSE OVERCAST) FEATURE OVER THE CENTER RECENTLY BECOME A LITTLE LESS DEFINED ...BUT IN RECENT IMAGERY IS SHOWING COMEBACK. TIGHTLY COILED BANDING FEATURES ARE OBSERVED AROUND THE CYCLONE WITH THE MOST PROMINENT ONES TO ITS SW AND W. CONVECTION CONSISTS OF THE SCATTERED STRONG TYPE WITHIN 120 NM W OF THE CENTER...EXCEPT 60 NM IN THE SW QUADRANT. THE MAIN FEEDER BAND INTO FRANK IS LOCATED FROM WITHIN 300 TO 400 SW THROUGH NW OF ITS CENTER... AND CONSISTS OF SCATTERED MODERATE CONVECTION WITH SMALL EMBEDDED ISOLATED STRONG CELLS. LATEST NHC FORECAST GUIDANCE TRACK HAS FRANK MOVING IN A GENERAL WNW DIRECTION PARALLEL TO THE MEXICAN COAST AND SLOWLY GAINING STRENGTH THROUGH AT LEAST THE NEXT 48 HOURS AS FRANK IS NOW EXPECTED TO BECOME A HURRICANE IN ABOUT 30 HOURS AS VERTICAL WIND SHEAR ALOFT LIGHTENS ALLOWING FOR A MORE FAVORABLE ENVIRONMENT FOR INTENSIFICATION TO MATERIALIZE. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS IS CENTERED FROM 9N85W TO 12N95W...THEN RESUMES AT 12N107W 12N119W 11N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF THE 90 NM S OF THE AXIS BETWEEN 103W-107W. ...DISCUSSION... A MID/UPPER RIDGE EXTENDS FROM THE SW SECTOR OF THE U.S. TO W AND NW TO A COL REGION NEAR 34N127W. TO THE SW OF THE COL...AN UPPER LEVEL ANTICYCLONIC LIFTING NNE IS IDENTIFIED NEAR 33N134W WITH A RIDGE SW OF THE AREA AT 25N140W. THIS FEATURE WILL BE A MAIN PLAYER IN THE FUTURE STEERING OF TROPICAL STORM FRANK THROUGH AT LEAST THE NEXT 48 HOURS. TO THE SE OF THE RIDGE...AN INVERTED MID TO UPPER LEVEL TROUGH MOVING WNW EXTENDS FROM 32N127W TO 26N130W. A WEAK CYCLONIC CIRCULATION MAY BE FORMING ALONG THE TROUGH NEAR 31N128W. MOISTURE ASSOCIATED WITH THE TROUGH AND THE CYCLONIC CIRCULATION IS CONFINED TO SE AND S OF THE RIDGE TO 20N AND BETWEEN 124W-131W. SATELLITE WATER VAPOR IMAGERY SHOWS MOSTLY MODERATE SUBSIDENCE WITH RESULTANT DRY AIR PRESENT OVER A LARGE PORTION OF THE AREA OUTSIDE THE ITCZ AND THE TROUGH W OF 114W. ANOTHER MID/UPPER LEVEL TROUGH MOVING WNW STRETCHES FROM 23N118W NE TO NORTHERN BAJA CALIFORNIA...BUT WITH ITS ASSOCIATED MOISTURE BEING LIMITED TO THE MID LEVELS NO SIGNIFICANT SHOWER ACTIVITY IS NOTED WITH THIS FEATURE. AS THE TROUGH ADVANCES WNW...AND A SMALL ANTICYCLONE OVER FAR NE MEXICO MOVES SW THE EFFECTS ON THE UPPER LEVEL FLOW IS TO ACCELERATE IT AS NE-E WINDS ACROSS THE FAR EASTERN PART OF THE AREA TO THE E AND SE OF THE MID/UPPER LEVEL TROUGH INCLUDING THE UPPER ENVIRONMENT TO THE W AND NW OF FRANK. THE UPPER LEVEL FLOW OVER THE EASTERN PORTION BECOMES DIFFLUENT E OF FRANK PROVIDING ADDITIONAL IMPETUS TO IS CONVECTION...ALONG WITH SCATTERED SHOWER AND TSTMS ACTIVITY OCCURRING TO ITS E AND N OF THE ITCZ. THE UPPER NE-E WINDS FOUND IN THE EASTERN PORTION ARE ALSO RESPONSIBLE FOR ADVECTING CIRRUS BLOW FROM THE CONVECTION OCCURRING THERE SW TO 4N BEFORE IT DISSOLVES IN MODERATE SUBSIDENCE AIR. AT THE SURFACE...A RIDGE ENTERS THE REGION THROUGH 30N138W...AND REACHES TO 27N124W. HIGH PRES COVERS THE AREA N OF 19N AND W OF 125W. A NEARLY STATIONARY 1010 MB LOW IS ON THE ITCZ AXIS NEAR 13N123W. WEAKENING SCATTERED MODERATE CONVECTION IS WITHIN 90 NM NE OF THE LOW. WINDS OF 20 KT ARE OCCURRING WITHIN 360 NM OF THE LOW IN THE SE QUADRANT. THE LOW IS FORECAST TO REMAIN ABOUT STATIONARY THROUGH THE NEXT 12-18 HOURS...THEN DISSIPATE CLOSE TO WITHIN 24 HOURS. A 1012 MB LOW IS CENTERED JUST N OF THE ITCZ NEAR 13N132W...MOVING SW 5-10 KT. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE LOW IN THE NE QUADRANT...AND WITHIN 120 NM IN THE SW QUADRANT. A SURFACE TROUGH IS JUST INLAND THE BORDER OF SE MEXICO AND GUATEMALA...AND ANOTHER ONE POSSIBLY BEING THE REFLECTION OF THE MID/UPPER LEVEL TROUGH IS ALONG 116W FROM 19N TO 22N. WITH RESPECT TO MARINE SPECIFIC SWELL ISSUES...CROSS EQUATORIAL S AND SW SWELLS WITH PEAK WAVE PERIODS OF 18-20 SECONDS CONTINUE TO AFFECT THE WATERS PRIMARILY S OF THEN LINE FROM THE EQUATOR AT 140W TO 25N112W...EXCEPT THE GULF OF CALIFORNIA AND N OF GALAPAGOS ISLANDS PRODUCING SEAS OF 8-11 FT. THIS SWELL EVENT WILL CONTINUE TO PROPAGATE AND EXPAND NORTHWARD TO NEAR 25N AND E OF 130W TO THE BAJA CALIFORNIA COAST DURING THE NEXT 24 HOURS...THEN SUBSIDE SLIGHTLY BEGINNING BETWEEN 36-48 HOURS W OF 90W TO LINE FROM 5N140W TO 21N105W EXCEPT N OF THE GALAPAGOS ISLANDS. $$ AGUIRRE