000
AXPZ20 KNHC 022146
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC FRI AUG 02 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURES...                             
TROPICAL STORM GIL...JUST DOWNGRADED FROM HURRICANE...AT 14.6N
129.40W AT 02/2100 UTC MOVE W OR 270 DEG AT 10 KT.  ESTIMATED
CENTRAL PRES 992 MB.  MAXIMUM SUSTAINED WIND 60 GUSTS TO 75 KT.
GIL STILL MAINTAINS NUMEROUS STRONG CONVECTION WITHIN 120 NM NW
...90 NM NE QUADRANTS AND 60 NM S SEMICIRCLE BUT HAS BECOME LESS
ORGANIZED AS IT BEGINS TO FEEL THE INCREASE
IN S WIND SHEAR.  FORECAST CALLS FOR SLOW WEAKENING AS GIL MOVES
INTO PROGRESSIVELY INCREASING SHEAR AND COOLER WATERS. SEE LATEST
NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTNT22
KNHC FOR ADDITIONAL DETAILS.

JUST E OF GIL...LOW PRES AT 13N120W 1009 MB CONTINUES TO PRODUCE
DIMINISHING CONVECTION...MOSTLY IN ITS S QUADRANT AS OUTFLOW FROM
KEEPS DISRUPTING UPPER LEVEL PATTERN OVER LOW PRES. ENVIRONMENTAL
CONDITIONS REMAIN MARGINALLY CONDUCIVE FOR DEVELOPMENT SO SYSTEM
HAS A MEDIUM...30 PERCENT...CHANCE OF STRENGTHENING.  MODEL 
GUIDANCE KEEPS CIRCULATION GOING FOR NEXT 48 HOURS...BUT MAINTAIN
WINDS BELOW TROPICAL STORM THRESHOLD. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH EXTENDS FROM 10N85W TO 08N93W TO 1009 MB LOW PRES 
AT 13N120W.  ITCZ  FROM 13N133W TO BEYOND 11N140W.  SCATTERED
MODERATE CONVECTION WITHIN 120 NM S OF AXIS E OF 88W AND ISOLATED
MODERATE WITHIN 150 NM S OF AXIS W OF 103W.

...DISCUSSION...                                       
SHARP UPPER LEVEL TROUGH IMPINGES IN NW CORNER OF BASIN AND
BRINGS LARGE REGION OF DRY STABLE AIR MASS INTO E PAC N OF 20N
W OF 120W.  UPPER LEVEL ANTICYCLONE OVER...JUST DOWNGRADED...
TROPICAL STORM GIL EXTEND RIDGE EASTWARD OVER SURFACE LOW PRES
1009 MB AT 13N130W AND BEYONDTO 13N110W.  PLENTY OF WARM TROPICAL
MOISTURE FOCUSES ALONG MONSOON TROUGH E OF 120W...BUT CONVECTION 
MAINLY NOTED IN PROXIMITY OF TROPICAL BOTH SYSTEMS.  

UPPER LEVEL CYCLONE AT 21N116W HAS TROUGH TO 15N108W TO 08N96W 
SPLITTING RIDGE AND ALLOWING SCATTERED MODERATE CONVECTION ALONG
MONSOON TROUGH E OF 88W. 

...ELSEWHERE AT THE LOWER LEVELS...

A SECOND LOW PRES IS CENTERED NEAR 12N138W 1009 MB. NUMEROUS 
MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 90 NM SW 
SEMICIRCLE. ALTHOUGH THE DISTURBANCE IS CURRENTLY POORLY 
ORGANIZED...THERE IS A CHANCE THAT THE LOW MAY DEVELOP INTO A 
TROPICAL CYCLONE DURING THE NEXT 48 HOURS...HOWEVER IT WILL 
LIKELY BE W OF THE DISCUSSION AREA.

A SURFACE RIDGE IS N OF HURRICANE GIL AND THE LOWS N OF 18N W OF 
110W. PRES GRADIENT BETWEEN THE RIDGE AND THE LOW PRES LOCATED 
NEAR 12N138W...WHICH IS EMBEDDED IN THE ITCZ...MAINTAINS AN AREA 
OF NE WINDS OF 20-25 KT FROM 12N TO 18N W OF 135W. MIXING NE AND 
SW SWELL IS RESULTING IN COMBINED SEAS OF 8-10 FT. THESE 
CONDITIONS ARE FORECAST TO REMAIN IN PLACE ACROSS THE TROPICAL 
WATERS OVER THE NEXT 36 TO 48 HOURS. THE AREA OF SEAS HIGHER 
THAN 8 FT WILL INCREASE IN ADVANCE OF TROPICAL CYCLONE GIL... 
PARTICULARLY BETWEEN 10N AND 20N W OF 130W. HOWEVER...THE AREA 
OF FRESH TO STRONG NE WINDS IS FORECAST TO MOVE WWD IN TANDEM 
WITH THE LOW PRES NEAR 12N138W.  

$$ 
WALLY BARNES