000
AXPZ20 KNHC 031625
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON SEP 03 2012

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 
1515 UTC.

...SPECIAL FEATURE...
TROPICAL STORM JOHN NEAR 20.5N 112.6W 1001 MB AT 1500 UTC SEP 03 
MOVING NW OR 305 DEG AT 11 KT. MAXIMUM SUSTAINED WINDS 35 KT 
GUSTS 45 KT. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION 
WAS OCCURRING FROM 60 TO 300 NM ACROSS THE SW QUADRANT...WHILE 
SCATTERED MODERATE TO STRONG CONVECTION WAS OCCURRING FROM 60 TO 
240 NM ACROSS THE N SEMICIRCLE OF JOHN. JOHN CONTINUES EMBEDDED 
WITHIN A LARGER LOW TO MIDDLE LEVEL CYCLONIC ENVELOPE THAT 
ENCOMPASSES AN AREA FROM NEAR THE MEXICAN COAST W TO 116W...AND 
FROM 17N TO 25N. IN ADDITION TO THE OPEN OCEAN WATERS...ABUNDANT 
MOISTURE WITHIN THIS CIRCULATION WILL CONTINUE TO AFFECT COASTAL 
PORTIONS OF MEXICO...THE GULF OF CALIFORNIA...AND THE BAJA 
CALIFORNIA PENINSULA WITH SQUALLS AND THUNDERSTORMS THROUGH 
TONIGHT. A LOW LEVEL WIND SURGE AND ASSOCIATED SQUALLS HAS MOVED 
NNW THROUGH THE GULF OF CALIFORNIA AND THE BAJA PENINSULA 
OVERNIGHT AND THIS MORNING AND HAD REACHED 26.5N. JOHN IS 
EXPECTED TO CONTINUE ON A NW TRACK DURING THE NEXT FEW DAYS...TO 
THE SOUTH OF A HIGH PRESSURE RIDGE CENTERED ACROSS NW 
MEXICO...AND WILL WEAKEN IN A SIMILAR FASHION AS ILEANA AS IT 
CROSSES 115W AND REACHES COOL SST'S. STRONG WINDS...SQUALLS AND 
THUNDERSTORMS...AND LARGE SE SWELL WILL CONTINUE TO AFFECT SOUTH 
PORTIONS OF THE BAJA PENINSULA TODAY...WITH THESE SWELL 
PROPAGATING NW THROUGH THE GULF OF CALIFORNIA WATERS. SEE THE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N75W TO 09N78W TO 
11N85W TO 08N96W TO 11N101W...WHERE IT HAS BROKEN...THEN RESUMES 
FROM NEAR 15N111W TO 11N120W TO 09N132W...THEN ITCZ TO BEYOND 
09N140W.  SCATTERED MODERATE BETWEEN MONSOON TROUGH AND 04N FROM 
88W TO 100W.  

...DISCUSSION...
UPPER LEVEL SHORTWAVE TROUGH EXTENDS SW INTO THE BASIN FROM 
39N131W TO 28N132W TO 23N139W...AIDING IN PRODUCING A LARGE ZONE 
OF MID TO UPPER CONVERGENCE AND SUBSIDENCE ACROSS MUCH OF THE 
AREA N OF 10N W OF 126W. UPPER RIDGE CENTERED ACROSS NW MEXICO 
IS N OF 23N AND EXTENDS W THEN SE TO 21N130W. TUTT AXIS EXTENDS 
INTO E PORTIONS OF THE AREA FROM VIGOROUS TUTT LOW ACROSS NW 
BAHAMAS TO THE YUCATAN TO 11N98W...AND IS HELPING TO AMPLIFY A 
DEEP LAYERED PERTURBATION ALONG THE MONSOON TROUGH ALONG 
94W-96W. 

THE REMNANTS OF ILEANA CURRENTLY NEAR 21.5N126.5W HAVE 
MAINTAINED A WELL DEFINED LOW TO MID LEVEL SWIRL OF CLOUDS 
MOVING WSW UNTIL THIS MORNING...BUT ARE ENCOUNTERING THE ZONE OF 
SUBSIDENCE MENTIONED ABOVE ATTM...WITH THE W HALF OF THE 
CIRCULATION BEGINNING TO ERODE. 1032 MB HIGH PRES NW OF THE 
REGION NEAR 38N147W IS MAINTAIN MODERATE NE WIND FLOW NW OF THE 
REMNANTS OF ILEANA.  

E OF 110W LIGHT TO MODERATE MONSOONAL FLOW PREVAILS...WITH 
ACTIVE CONVECTION OCCURRING ON BOTH SIDES OF THE TROUGH. LIGHT 
WIND SHEAR ALOFT AND ABUNDANT MOISTURE EXPECTED TO MAINTAIN 
CLUSTERS OF DEEP CONVECTION THERE NEXT 48 HOURS. 

$$
STRIPLING