000 AXPZ20 KNHC 271542 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT JUL 27 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 AT 17.8N 139.3W OR ABOUT 900 NM E OF HILO HAWAII AT 27/1500 UTC...MOVING W-NW OR 285 DEG AT 17 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. THE MAXIMUM SUSTAINED WINDS ARE 55 KT WITH GUSTS TO 65 KT. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 240 NM N SEMICIRCLE. FLOSSIE IS TRACKING ACROSS COOLER SEA SURFACE WATERS WITH UPPER LEVEL CONDITIONS ALSO FORECAST TO BECOME LESS FAVORABLE ON SUN. FLOSSIE IS EXPECTED MAINTAIN TROPICAL STORM STRENGTH THROUGH EARLY SUN BUT GRADUALLY WEAKEN DUE OVER THE NEXT TWO TO THREE DAYS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 09N85W TO 10N110W. THE ITCZ AXIS EXTENDS FROM 10N110W TO 07N125W TO 10N133W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM S OF MONSOON TROUGH AXIS E OF 85W...WITHIN 75 NM S OF MONSOON TROUGH AXIS BETWEEN 98W AND 101W...AND 60 NM N OF ITCZ AXIS BETWEEN 113W AND 115W. ...DISCUSSION... AN UPPER CYCLONE CENTERED NEAR 32N125W IS DIGGING SE TOWARD THE COAST OF SOUTHERN CALIFORNIA...COMING INTO PHASE WITH A SHARPLY AMPLIFIED UPPER TROUGH EXTENDING ALONG ROUGHLY 120W FROM 15N TO 25N. THIS SEPARATES A DEEP LAYER RIDGE CENTERED OVER N CENTRAL MEXICO FROM A SMALLER UPPER RIDGE CENTERED NEAR 19N130W IN THE SUBSIDENT AREA ON THE E SIDE OF FLOSSIE. GLOBAL MODELS INDICATE A WEAK SURFACE TROUGH N OF THE AREA RELATED TO THE UPPER LOW...BUT WITH ONLY 15 KT WINDS OUT OF THE N BEHIND THE TROUGH ENTERING THE WATERS S OF 30N...AND SEAS LESS THAN 8 FT. A SECOND UPPER LOW IS CENTERED OVER THE ISTHMUS OF TEHUANTEPEC. THIS HAD BEEN PROVIDING SUPPORT TO A TROPICAL WAVE MOVING THROUGH CENTRAL AMERICA...BUT THE WAVE LOST DEFINITION OVERNIGHT. OBSERVATIONS SHOW WINDS TO BE FAIRLY LIGHT IN THE SURROUNDING AREA...BUT A PAIR OF ALTIMETER PASSES FROM THE PREVIOUS 12 HOURS INDICATED LINGERING SWELL APPROACHING 8 FT NEAR THE GULF OF TEHUANTEPEC...DUE IN PART TO CROSS-EQUATORIAL SOUTHERLY SWELL...BUT ALSO LEFTOVER FRESH GAP WINDS THROUGH TEHUANTEPEC RELATED TO THE EARLIER TROPICAL WAVE AN ITS SUPPORTING UPPER CYCLONE. AN UPPER TROUGH EXTENDING SW FROM THE UPPER CYCLONE IS ENHANCING CLUSTERS OF CONVECTION ALONG THE MONSOON TROUGH BETWEEN 98W AND 101W...ALTHOUGH IS LARGELY DISSIPATING. 1017 MB HIGH PRES OVER THE S CENTRAL GULF OF MEXICO IS SUPPORTING FRESH TO OCCASIONALLY STRONG GAP WINDS THROUGH THE GULF OF PAPAGAYO. THESE WINDS WILL DIMINISH THIS AFTERNOON...BUT INCREASE AGAIN TONIGHT UP TO 20 KT. SEAS TO 8 FT CAN BE EXPECTED DOWNSTREAM OF THE PAPAGAYO GAP WINDS INTO SUNDAY. CROSS EQUATORIAL SE AND SW SWELL RESULTING IN COMBINED SEAS OF OF 8 FT CONTINUE ACROSS THE DEEP TROPICS TO THE S OF 03N BETWEEN 112-130W. THE AFFECTED AREA IS FORECAST TO SHIFT NW TO S OF 05N BETWEEN 103-135W TONIGHT...THEN BEGIN TO SUBSIDE. S-SW SWELL WILL REACH ALONG 11N BETWEEN 90-110W..AND S OF 05N BETWEEN 81- 97W ON SUN NIGHT RESULTING IN COMBINED SEAS TO 8 FT. $$ CHRISTENSEN