000
AXPZ20 KNHC 172149
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI AUG 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH FROM 09N83W TO 10N92W THEN RESUMES FROM 15N96W TO LOW 
PRES 1009 MB AT 10N101W TO 09N110W.  AXIS RESUMES AGAIN FROM 
14N121W TO BEYOND 10N140W.  NUMEROUS MODERATE SCATTERED STRONG 
CONVECTION WITHIN 150 NM S OF AXIS E OF 91W AND WITHIN 60 NM 
BOTH SIDES OF AXIS FROM 94W TO 98W.  SCATTERED MODERATE ISOLATED 
STRONG CONVECTION WITHIN 120 NM S OF AXIS FROM 103W TO 130W.

...DISCUSSION...
BROAD MID TO UPPER LEVEL ANTICYCLONE OVER NORTHWESTERN MEXICO 
ADVECTS ABUNDANT MOISTURE INTO E PAC JUST E OF 120W N OF 13N BUT 
ALSO BRINGS MODERATE TO STRONG WIND SHEAR ALOFT OVER REMNANTS OF 
HECTOR.  SECOND MID TO UPPER LEVEL ANTICYCLONE...JUST OVER 
TROPICAL STORM HELENE IN SW BAY OF CAMPECHE...CONTRIBUTES 
SIMILAR ADVECTION OVER 1009 MB LOW PRES AT 10N101W.  WEAK UPPER 
LEVEL TROUGH FROM 19N105W TO 06N116W SPLIT ANTICYCLONES AND 
ALLOWS DIVERGENT FLOW ALOFT TO ENHANCE SCATTERED MODERATE 
CONVECTION OVER MONSOON TROUGH W OF 1009 MB LOW PRES.  AIR MASS 
REMAINS VERY DRY N OF MONSOON TROUGH W OF 120W AS SURFACE HIGH 
PRES PROMOTES MODERATE SUBSIDENCE. 

...ELSEWHERE AT THE LOWER LEVELS...
FRESH SW WINDS IN SE QUADRANT TO REMNANTS OF HECTOR FORCE 
EXISTING 8-9 FT SWELLS UNTO SOUTHERN PORTIONS OF GULF OF 
CALIFORNIA WITH POSSIBILITY OF FUNNELING GROWING WAVES FARTHER 
UP NORTH.  SCATTERED...BUT DIMINISHING...CONVECTION MAY PRODUCE 
TEMPORARY DETERIORATION OF MARINE CONDITIONS.  HEAVY RAINS STILL 
PROBABLE...PARTICULARLY OVER HIGH TERRAIN IN SONORA AND BAJA 
CALIFORNIA TONIGHT AND SAT.

LOW PRES 1009 MB AT 10N101W REMAINS UNDER OVERALL ADVERSE 
ENVIRONMENT WITH MODERATE TO STRONG WIND SHEAR THAT PRECLUDES 
DEVELOPMENT.  GLOBAL MODEL SOLUTIONS WEAKEN W DRIFTING SYSTEM 
ALTHOUGH KEEPS AREA PRESSURES LOWER THAN NORMAL. 

CROSS EQUATORIAL LONG PERIOD S SWELL PROPAGATING ALONG PAC COAST 
BRING SEAS TO 10 FT AS FAR N AS 18N IS EXPECTED TO SUBSIDE 
TONIGHT AND SAT.

$$
WALLY BARNES