000 AXPZ20 KNHC 271600 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN JUL 27 2014 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURES... TROPICAL STORM HERNAN IS CENTERED NEAR 17.8N 111.1W AT 27/1500 UTC OR ABOUT 310 NM...580 KM SSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING NW OR 305 DEGREES AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. HERNAN IS A LITTLE STRONGER AND IS FORECAST TO REACH HURRICANE STATUS LATER TODAY OR TONIGHT. CURRENTLY...SATELLITE IMAGERY INDICATES NUMEROUS STRONG CONVECTION WITHIN 60 NM OF CENTER. NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 150 NM NW SEMICIRCLE AND NUMEROUS MODERATE CONVECTION IS WITHIN 120 SE SEMICIRCLE. HERNAN IS EXPECTED TO PASS JUST TO THE SOUTHWEST OF SOCORRO ISLAND TODAY. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTPZ23 KNHC FOR MORE DETAILS. TROPICAL DEPRESSION GENEVIEVE HAS CROSSED INTO THE CENTRAL PACIFIC. THE NEXT ADVISORY FOR THIS SYSTEM WILL BE ISSUED BY THE CENTRAL PACIFIC HURRICANE CENTER IN HONOLULU. SATELLITE IMAGERY SHOWS THAT THE CENTER OF A WELL-DEFINED LOW PRES AREA LOCATED NEAR 15N131W REMAINS TOTALLY EXPOSED WITH A CLUSTER OF MODERATE TO STRONG CONVECTION OCCURRING TO THE E FROM 14N TO 16N BETWEEN 129W AND 131W. UPPER-LEVEL WINDS ARE NOW UNFAVORABLE FOR TROPICAL CYCLONE DEVELOPMENT...BUT THEY COULD BECOME A LITTLE MORE CONDUCIVE IN A FEW DAYS AS THE LOW CONTINUES TO MOVE WESTWARD. AN AREA OF FRESH TO STRONG WINDS WITH SEAS TO 11 FT IS EXPECTED TO ACCOMPANY THIS SYSTEM DURING THE NEXT 48 HOURS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 08N84W TO 09N92W TO A 1011 MB LOW PRES NEAR 07N98W TO 08N105W THEN RESUMES SW OF HERNAN FROM 13N114W TO A 1010 MB LOW PRES NEAR 10N121W TO 11N124W. THE ITCZ IS FROM 13N133W TO 12N139W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM N OF TROUGH BETWEEN 91W AND 95W. SIMILAR CONVECTION IS FROM 08N TO 11N BETWEEN 102W AND 104W...AND FROM 12N TO 16N BETWEEN 97W AND 102W. ...DISCUSSION... AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY ROUGHLY ALONG 130W N OF 16N WITH AN UPPER LEVEL RIDGE BEHIND THE TROUGH AXIS CURRENTLY REACHING 140W. MOSTLY DRY AIR ACCOMPANIES THIS TROUGHING GENERALLY N OF 15N AND W OF A LINE FROM 30N125W TO 20N128W TO 15N131W. THE LOW PRES LOCATED NEAR 15N131W IS VERY CLOSE TO THE BASE OF THE TROUGH AXIS. A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER NORTHERN TEXAS AND SOUTHERN OKLAHOMA WITH A RIDGE OVER NORTHERN MEXICO. ANOTHER ANTICYCLONIC CIRCULATION IS CENTERED TO THE NE OF TROPICAL STORM HERNAN NEAR 22N107W. THIS SYSTEM IS PROVIDING A FAVORABLE ENVIRONMENT FOR GRADUAL STRENGTHENING OF HERNAN THROUGH EARLY MONDAY. AFTERWARD...INCREASING WESTERLY SHEAR AND COOLER WATERS ARE EXPECTED TO WEAKEN HERNAN DURING THE REST OF THE FORECAST PERIOD. EXPECT PULSING WINDS OF AROUND 20 KT WITH SEAS OF 6-7 FT ACROSS THE GULF OF PAPAGAYO AND THE GULF OF TEHUANTEPEC DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH THE AID OF THE NOCTURNAL DRAINAGE FLOW. OTHERWISE...A SURFACE RIDGE DOMINATES THE REMAINDER OF THE AREA N OF 20N W OF 115W. THE PRESSURE GRADIENT BETWEEN THE SOUTHERN PERIPHERY OF THE RIDGE AND GENEVIEVE IS STILL PRODUCING AN AREA OF MAINLY FRESH WINDS FROM 14N TO 21N W OF 135W. THE SAME PATTERN IS EXPECTED TO OCCUR AS THE LOW PRES NOW LOCATED NEAR 15N131W CONTINUES TO MOVE WESTWARD OVER THE NEXT COUPLE OF DAYS. SE SWELL FROM THE SOUTHERN HEMISPHERE CONTINUES TO IMPACT THE SOUTH-CENTRAL WATERS...PARTICULARLY W OF 96W TO A LINE FROM 05N105W TO 02S120W. THIS SWELL EVENT WILL CONTINUE TO PROPAGATE FARTHER WEST ACROSS THE FORECAST REGION. $$ GR