000
AXPZ20 KNHC 312219
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC WED JUL 31 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...
HURRICANE GIL AT 13.9N 120.6W AT 31/2100 UTC MOVING W-NW OR 285 
DEGREES AT 10 KT.  MAXIMUM SUSTAINED WIND 65 GUSTS TO 80 KT.
NUMEROUS STRONG WITHIN 120 NM OF N AND 75 NM S SEMICIRCLES.  
SCATTERED MODERATE ISOLATED STRONG ELSEWHERE WITHIN 150 NM OF 
CENTER.  GIL MOVE W-NW FOR THE NEXT FEW DAYS ALONG SOUTHERN
PERIPHERY OF LARGE UPPER LEVEL RIDGE WHICH PROVIDES FAVORABLE
CONDITIONS FOR INTENSIFICATION.  TRACK IS ALSO ACROSS WARM SEAS
SURFACE TEMPERATURES FOR THE NEXT 48 HOURS SO GIL IS FORECAST
INTENSIFY SLIGHTLY...AFTER WHICH IT ENTERS A REGION OF 
UNFAVORABLE UPPER WINDS AND COOLER SEA SURFACE TEMPERATURES 
WHICH ARE EXPECTED TO WEAKEN THE SYSTEM. SEE LATEST NHC FORECAST
/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTNT22 KNHC FOR 
ADDITIONAL DETAILS.

LOW PRES CENTER 1008 MB AT 12N112W MOVES W AT 15 KT WITH
SCATTERED CONVECTION WITHIN 120 NM OF CENTER.  LOW PRES FOLLOWS
THE WAKE OF HURRICANE GIL AND ITS DEVELOPMENT IS IN DOUBT DUE TO
ITS POSITION AND TRACK. NEVERTHELESS...THERE IS A 40 PERCENT
CHANCE THIS SYSTEM COULD BECOME A TROPICAL CYCLONE WITHIN NEXT
48 HOURS.  EVEN IF NOT...MARINE CONDITIONS COULD DETERIORATE
TEMPORARILY DUE TO SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION.  
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH AXIS FROM 09N84W TO 10N101W TO 1008 MB LOW PRES
12N112W.  ITCZ AXIS FROM 12N123W TO 1010 MB LOW PRES AT 10N130W
TO 09N140W.  SCATTERED MODERATE TO STRONG N OF 06N E OF 90W.
SCATTERED MODERATE ISOLATED STRONG WITHIN 240 NM N AND 60 NM
S OF AXIS FROM 126W TO 131W.  
   
...DISCUSSION...  
WELL DEFINED UPPER LEVEL CYCLONE AT 25N1389W BRINGS LARGE AREA
OF DRY STABLE AIR MASS INTO NW PART OF BASIN N OF 18N W OF 120W.
ASSOCIATED TROUGH ALOFT TO 15N140W INCREASES SW FLOW WHICH WILL
EVENTUALLY IMPACT HURRICANE GIL BY FRI INCREASING ITS SW SHEAR
AND LITERALLY DECOUPLING LOWER AND UPPER CENTERS...AFTER WHICH 
CYCLONE WEAKENS INTO OBLIVION.  

MEANTIME UPPER LEVEL RIDGE MAINTAINS GOOD OUTFLOW FEATURE OVER
GIL ALLOWING FOR FURTHER STRENGTHENING WITHIN NEXT TWO DAYS. 
WHILE SECOND SURFACE LOW PRES CENTER NOW AT 12N112W SHARE SAME
CONDITIONS ALOFT...OUTFLOW FROM GIL MAY CAUSE DISRUPTION IN ITS
DEVELOPMENT.  OVERALL REGION STILL CONTAINS ABUNDANT WARM
TROPICAL MOISTURE AND SEAS REMAIN WARM SO SHORT-TERM 
INTENSIFICATION CANNOT BE TOTALLY ELIMINATED. 

...AT THE LOWER LEVELS...
HEALTHY HIGH PRES CENTER 1030 MB AT 34N142W MAINTAINS STEADY 
FRESH NE TRADES OVER WESTERN BOUNDARIES OF BASIN FROM 12N-18N
W OF 130W WITH MIXING NE AND SE SWELL RESULTING IN COMBINED SEAS
TO 9 FT. CONDITIONS FORECAST TO REMAIN FOR NEXT 36 TO 48 HOURS.
THE AREA WILL SUBSIDE AS TROPICAL CYCLONE GIL ADVANCES W. 

$$
WALLY BARNES