000 AXPZ20 KNHC 281600 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED AUG 28 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 1006 MB LOW PRES IS NEAR 19N106W OR ABOUT 120 NM W OF MANZANILLO MEXICO MOVING NW AT 18 KT. THE LOW IS PART OF A BROAD AREA OF LOW PRES ASSOCIATED WITH A VERY ACTIVE MONSOON FLOW PATTERN THAT COVERS THE AREA FROM 09N TO 22N BETWEEN 101W AND 111W. SATELLITE IMAGERY SHOWS LARGE CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION WITHIN 180 NM SW AND 120 NM NE OF THE LOW. SIMILAR CONVECTION EXISTS FROM 12N TO 16.5N BETWEEN 107W-110W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE SEEN N OF 15N TO THE COAST OF MEXICO BETWEEN 102W AND 106W. SATELLITE-DERIVED WINDS SUGGEST THAT THE 1006 MB LOW...AND ASSOCIATED AREA OF BROAD LOW PRES REMAIN UNDER MODERATE TO STRONG NE TO E WINDS ALOFT. A TIGHT PRES GRADIENT BETWEEN THE LOW AND THE COAST OF MEXICO CONTINUES TO SUPPORT GALE FORCE WINDS OF 35 KT WITH SEAS OF 12 TO ABOUT 14 FT OVER THOSE WATERS. THESE CONDITIONS SHOULD GRADUALLY SUBSIDE THROUGH THE NEXT 24-36 HOURS...BUT MAY AFFECT THE SOUTHERN PORTIONS OF THE GULF OF CALIFORNIA AND BAJA PENINSULA THIS AFTERNOON AND TONIGHT. THERE CONTINUES TO BE A MEDIUM CHANCE THAT THE LOW MAY DEVELOP INTO A TROPICAL CYCLONE WITHIN THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT...THE SYSTEM WILL CONTINUE TO BRING LOCALLY HEAVY RAINFALL OVER PORTIONS OF SOUTHWESTERN MEXICO AND THE SOUTHERN BAJA PENINSULA THROUGH THE NEXT 48 HOURS. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM NORTHERN COSTA RICA TO 1009 MB LOW PRES NEAR 12N96W TO 11N102W. IT RESUMES FROM 17N107W TO 1008 MB LOW PRES NEAR 13N111W TO 1009 MB LOW PRES NEAR 11N120W TO 11N125W TO 1008 MB LOW PRES NEAR 13N131W TO BEYOND 10N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED WITHIN 180 NM SE SEMICIRCLE OF LOW NEAR 16N104W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS WITHIN 180 NM S OF THE TROUGH BETWEEN 130W- 136W...AND WITHIN 120 NM S OF THE TROUGH W OF 136W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NOTED FROM 09N TO 12N BETWEEN 114W-120W...AND ALSO WITHIN 60 NM OF THE TROUGH BETWEEN 90W-97W. ...DISCUSSION... SATELLITE WATER VAPOR IMAGERY SHOWS THAT THE UPPER LEVEL ANTICYCLONE THAT YESTERDAY WAS W OF THE BAJA CALIFORNIA PENINSULA HAS SHIFTED EASTWARD TO THE NORTHERN GULF OF CALIFORNIA. A RIDGE EXTENDS SW FROM THE ANTICYCLONE TO A SMALL ANTICYCLONE AT 18.5N130W...AND TO BEYOND THE AREA AT 14N140W. A BROAD UPPER TROUGH IS LOCATED NW OF THE AREA WITH AN AXIS THROUGH 32N135W TO SW OF THE AREA AT 28N140W. SW FLOW IS PRESENT BETWEEN THE TROUGH AND THE ANTICYCLONE/RIDGE. WITHIN THE SW FLOW MODERATE TO STRONG SUBSIDENCE IS NOTED KEEPING RATHER DRY AND STABLE CONDITIONS NW AND W OF THE RIDGE/ANTICYCLONE. PATCHES OF BROKEN TO OVERCAST LOW CLOUDS UNDER THE DRY AND STABLE CONDITIONS ARE PRESENT FROM 18N TO 25N BETWEEN 120W AND 134W. SCATTERED TO BROKEN LOW CLOUDS ARE OVER THE NW PART OF THE AREA W OF A LINE FROM 32N126W TO 24N140W. TO THE SE OF THE RIDGE/ ANTICYCLONE THE ATMOSPHERE BECOMES SIGNIFICANTLY MOIST AND UNSTABLE MAINLY DUE TO THE LARGE MONSOONAL GYRE THERE AND ASSOCIATED LOWS. DIFFLUENT FLOW ALOFT CONTINUES TO ENHANCE THE DEEP CONVECTION ALONG AND NEAR THE MONSOON TROUGH DESCRIBED ABOVE. SATELLITE WATER VAPOR IMAGERY SHOWS AN INVERTED UPPER TROUGH NEAR 116W/117W FROM 12N TO 21N. ANOTHER INVERTED UPPER TROUGH EXTENDS FROM 21N117W NE TO ACROSS SOUTHERN BAJA CALIFORNIA...AND GULF OF CALIFORNIA AND N TO EASTERN ARIZONA. AN UPPER LEVEL ANTICYCLONE IS OVER CENTRAL MEXICO WITH A RIDGE SSW TO NEAR 15N104W. THE UPPER FLOW PATTERN BETWEEN THIS RIDGE AND THE INVERTED TROUGHS IS NE TO E...AND IS WHAT IS HELPING TO SPREAD UPPER LEVEL MOISTURE ASSOCIATED WITH THE DEEP CONVECTION CONFINED IN THE LARGE MONSOONAL GYRE AND BROAD AREA OF LOW PRES WESTWARD TO NEAR 117W BEFORE IT THINS OUT IN DRIER AIR ALOFT. UPPER LEVEL MOISTURE IS BEING ADVECTED NNE FROM THE BROAD AREA OF LOW PRES TO ACROSS NORTHERN MEXICO...AND TO PORTIONS OF THE SW AND S CENTRAL U.S. AT THE SURFACE...THE LOWS MENTIONED ABOVE UNDER ITCZ/MONSOON TROUGH ARE FORECAST TO LINGER INTO THE NEXT 24 TO 48 HOURS. IN ADDITION TO THOSE LOWS...A VERY ILL-DEFINED 1011 MB LOW...REMNANTS OF IVO...IS IDENTIFIED TO BE NEAR 24N117W. NO DEEP CONVECTION IS PRESENT WITH THIS LOW AS IT IS EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS. A WEAK 1016 MB HIGH NEAR 28N130W IS FORECAST TO REMAIN ABOUT STATIONARY OVER THE NEXT 24-48 HOURS. $$ AGUIRRE