000 AXPZ20 KNHC 261537 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI JUL 26 2013 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 FEATURE... TROPICAL STORM FLOSSIE IS CENTERED NEAR 16.1N 132.3W AT 26/1500 UTC MOVING W-NW OR 285 DEGREES AT 16 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. CURRENTLY...NUMEROUS STRONG CONVECTION IS CONCENTRATED IN A CLUSTER NEAR AND N OF THE STORM CENTER. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED IN BANDS ELSEWHERE FROM 12N TO 16N BETWEEN 128W AND 131W...AND FROM 16N TO 19N BETWEEN 131W AND 133W. FLOSSIE WILL TRACK ACROSS WARM SEA SURFACE WATERS WITH FAVORABLE UPPER LEVEL CONDITIONS TODAY LIKELY REACHING THE PEAK INTENSITY OF 50 KT THIS EVENING OR TONIGHT. THEN...THE WATER TEMPERATURES WILL BE COOLER AND THE ATMOSPHERIC CONDITIONS WILL BECOME LESS FAVORABLE AND FLOSSIE IS EXPECTED TO BEGIN A WEAKENING TREND LATE SAT. FLOSSIE IS FORECAST TO CROSS OVER INTO THE CENTRAL PACIFIC OCEAN ON SAT. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. ...TROPICAL WAVE... A TROPICAL WAVE IS ANALYZED FROM 12-21N ALONG 91W WITH ONLY ISOLATED SHOWERS NEAR THE SOUTHERN END OF THE AXIS. THE WAVE WILL LIKELY ENHANCE THE DRAINAGE FLOW OVER THE GULF OF TEHUANTEPEC LATER TONIGHT INTO EARLY SAT MORNING. THE NORTHERLY FLOW COULD BRIEFLY REACH 20-25 KT WITH SEAS TO NEAR 8 FT. THE WAVE WILL LIKELY LOSE IDENTITY BY LATE SAT. TO THE DIURNAL NATURE OF THIS GAP WIND EVENT...THIS WILL NOT BE INCLUDED IN THE HIGH SEAS FORECAST. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 09N84W TO 09N100W 12N122W THEN RESUMES W OF FLOSSIE AT 10N134W TO 1009 MB LOW PRES NEAR 08N130W. NUMEROUS MODERATE SCATTERED STRONG CONVECTION IS N OF 04N E OF 81W. SCATTERED MODERATE ISOLATED STRONG CONVECTION CAN BE FOUND FROM 07N TO 10N BETWEEN 81W AND 86W...AND FROM 07N TO 10N BETWEEN 96W AND 102W. ISOLATED MODERATE TO STRONG CONVECTION IS FROM 11N TO 16N BETWEEN 114W AND 124W. ...DISCUSSION... ALOFT...AN UPPER LEVEL TROUGH ENTERS THE FORECAST REGION NEAR 30N132W THE CONTINUES MAINLY S TO ABOUT 21N136. MODERATE TO STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS IS NOTED ON WATER VAPOR IMAGERY ALONG AND AHEAD OF THE TROUGH AXIS TO NEAR 126W. FARTHER S...AN INVERTED TROUGH IS NOTED EXTENDING FROM 19N136W TO 11N136W. AN ANTICYCLONE LOCATED W OF AREA CLIPS THE WEST- CENTRAL WATERS. ANOTHER ANTICYCLONE LOCATED INLAND NEAR 31N109W DOMINATES THE FLOW OVER NORTHERN MEXICO...THE BAJA CALIFORNIA PENINSULA AND THE NE FORECAST WATERS. EASTERLY WIND FLOW ALOFT COVERS MOST OF THE AREA E OF 110W. AN INVERTED TROUGH EXTENDS FROM THE GULF OF TEHUANTEPEC TO NEAR 11N98W. ANOTHER INVERTED TROUGH EXTENDS FROM 26N119W TO AN UPPER LEVEL LOW NEAR 20N118W. AN ANTICYCLONIC CIRCULATION IS NOTED NE OF FLOSSIE NEAR 19N125W. VERY DRY AIR IS OBSERVED ON WATER VAPOR IMAGERY JUST WEST OF FLOSSIE. SOME OF THIS DRY UPPER AIR WILL AFFECT THE TROPICAL CYCLONE IN ABOUT A DAY AND CONTRIBUTE TO THE FORECAST WEAKENING TREND. PRES GRADIENT BETWEEN FLOSSIE AND HIGH PRES TO THE N WILL MAINTAIN A LARGE AREA OF NE TO E WINDS IN THE 20-30 KT RANGE ON THE N SIDE OF THE STORM. CURRENTLY...SCATTEROMETER DATA INDICATE THAT THESE WINDS ARE WITHIN 390 NM OF THE STORM CENTER. NE-E 15-20 KT WINDS WILL CONTINUE TO PULSE ACROSS THE GULF OF PAPAGAYO THROUGH TONIGHT RESULTING IN COMBINED SEAS OF 6-8 FT IN MIXED SHORT PERIOD E SWELL AND LONG PERIOD SW SWELL. CROSS EQUATORIAL SE AND SW SWELLS RESULTING IN COMBINED SEAS OF OF 8 FT CONTINUE ACROSS THE DEEP TROPICS...PARTICULARLY S OF 04N BETWEEN 105-125W. THIS SWELL EVENT IS FORECAST TO PROPAGATE TO THE NORTH AND WEST ACROSS THE S WATERS DURING THE UPCOMING WEEKEND REACHING AS FAR N AS 07N BETWEEN 95W AND 110W BY SUN. $$ GR