000 AXPZ20 KNHC 101606 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT AUG 10 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 1545 UTC. ...SPECIAL FEATURES... A LOW PRESSURE SYSTEM OF 1007 MB IS NEAR 12N119W MOVING NW AT 10 KT. THE LOW REMAINS UNDER MODERATE NE VERTICAL SHEAR THAT IS OCCURRING IN THE SE PERIPHERY OF AN ELONGATED UPPER ANTICYCLONE NEAR 21N125W. HOWEVER...THE LOW REMAINS OVER WARM SEA SURFACE TEMPERATURES. DEEP ATMOSPHERIC MOISTURE HAS INCREASED WITHIN THE IMMEDIATE ENVIRONMENT SURROUNDING THE LOW OVER THE PAST COUPLE OF DAYS. AS A RESULT...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM OF THE LOW IN THE SW QUADRANT...AND ALSO WITHIN 120 NM OF THE LOW IN THE NE QUADRANT. SIMILAR CONVECTION IS ALSO WITHIN 30 NM OF A LINE FROM 16N117W TO 14N119W. WITH NE SHEAR FORECAST TO DECREASE OVER THE NEXT FEW DAYS...THIS FAVORS THE LOW TO HAVE A MEDIUM POTENTIAL TO DEVELOP INTO A TROPICAL CYCLONE OVER THE NEXT 48 HOURS AND A HIGH CHANCE WITHIN THE NEXT FIVE DAYS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM 08N79W TO 08N87W TO 08N99W TO 11N107W. IT RESUMES FROM LOW PRES AT 12N119W 1006 MB TO 13N120W ...THEN ITCZ TO 10N132W TO 09N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 101W- 104W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF AXIS BETWEEN 85W-87W...AND ALSO FROM 04N TO 07N E OF 80W. ...DISCUSSION... WATER VAPOR IMAGERY SHOWS AN ELONGATED UPPER LEVEL ANTICYCLONE NEAR 21N125W WITH A RIDGE STRETCHING SW TO 10N140W...AND ANOTHER ONE NE TO ACROSS SRN BAJA CALIFORNIA...AND TO A S SMALL ANTICYCLONE OVER EASTERN TEXAS. BROAD UPPER SW TO W FLOW IS SEEN N OF THE ANTICYCLONE AND ASSOCIATED RIDGES. THIS FEATURE IS KEEPING THE ATMOSPHERE RATHER DRY AND STABLE THROUGHOUT N AND NW OF A LINE FROM 26N110W TO 17N121W TO 16N130W TO 15N140W AS SUGGESTED BY THE MODERATE TO STRONG SUBSIDENCE OBSERVED ON THE WATER VAPOR IMAGERY. AT THE SURFACE...A 1020 MB HIGH IS ANALYZED AT 28N132W WITH A RIDGE SE TO 23N117W. A WEAKENING COLD FRONT EXTENDS INTO THE NW CORNER OF THE AREA FROM 32N133W TO 29N140W WHERE IT THEN CURVES W AND NW FROM THERE. ONLY ISOLATED SHOWERS ARE POSSIBLE WITHIN ABOUT 30-60 NM OF THE FRONT. THE 1020 MB HIGH IS FORECAST TO DISSIPATE OVER THE NEXT 24 HOURS AS ANOTHER HIGH OF 1021 MB N OF THE AREA AT 36N141W MOVES SE TO NEAR 32N138W. A WEAK PRES BETWEEN THE HIGH AND THE MONSOON TROUGH IS WEAK...HOWEVER WEAK LOW PRES OF 1010 MB IS FORECAST TO FORM NEAR 12N133W IN THIS AFTERNOON OR EVENING. THIS FEATURE IN COMBINATION WITH THE HIGH PRES TO THE N SHOULD ALLOW FOR NE TO E TRADES OF 20-25 KT TO MATERIALIZE FROM 13N TO 16N BETWEEN 129W- 138W BY EARLY SUN WITH SEAS TO 8 FT. BY EARLY MON...THE LOW IS FORECAST TO HAVE MOVED W OF THE AREA WITH THE AREA OF TRADES EXPECTED TO EXIST FROM 13N TO 17N W OF 137W WITH SEAS 8-9FT. TO THE SE OF THE AFOREMENTIONED LINE...THE ATMOSPHERE BECOMES SIGNIFICANTLY MOIST AND UNSTABLE...AND THIS A RATHER BIG CHANGE FROM OVER THE PAST SEVERAL DAYS. ASIDE FROM CONVECTION NOTED IN ASSOCIATION WITH THE SPECIAL FEATURE LOW AND THAT WITH THE MONSOON TROUGH...SMALL CLUSTERS OF TSTMS ARE SEEN MOVING WESTWARD E OF 115W. AN INVERTED MID TO UPPER TROUGH ROUGHLY ALONG 110W IS RETROGRADING WESTWARD TO THE SE OF THE ANTICYCLONE AT 21N125W...AND MARKS THE ONSET OF UPPER LEVEL WINDS BEING MORE EASTERLY WITH WESTWARD ADVECTION OF DEEP MOISTURE. $$ AGUIRRE