000
AXPZ20 KNHC 111537
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI MAY 11 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 
1545 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 07N78W TO 11N100W TO 1007 MB LOW 
PRES AT 08.7N104.8W TO 10N110W TO 05N123W THEN ITCZ TO 03N140W. 
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 150 NM OF AXIS  
FROM 89W TO 117W AND E OF 80W.

ALOFT...
HEALTHY MID TO UPPER CYCLONE SPINNING NEAR 29N142W STARTED 
MAKING ITS TURN TO THE NE BARELY CLIPPING FAR NW CORNER OF BASIN 
LATER TODAY.  SECOND VIGOROUS CYCLONE OVER W TEXAS DRIFT NE 
WEAKENING ITS ATTENDANT LONGWAVE TROUGH.  TROUGH EXTEND FROM TIP 
OF BAJA CALIFORNIA PENINSULA TO 15N118W WITH VERY DRY SUBSIDING 
AIR MASS WITHIN 300 NM W OF AXIS.  BROAD RIDGE WITH CREST ALONG 
124W HOLDS ITS POSITION BETWEEN BOTH CYCLONES AND ADVECTS 
ABUNDANT MOISTURE INTO W COAST N OF 32N.  

STRING OF ANTICYCLONES ALONG 10N ADD A TOUCH OF DIVERGENT FLOW 
ALOFT OVER ITCZ/MONSOON TROUGH ENHANCING MODERATE TO STRONG 
CONVECTION WITHIN 150 NM OF AXIS.  ONE PARTICULAR ANTICYCLONE 
SITS RIGHT OVER DEVELOPING 1007 MB LOW PRES CENTER NEAR 
08.7N104.8W WHERE SST TOP 29 DEGREES CELSIUS...ALBEIT ONLY IN A 
SHALLOW TOP LAYER.  UNDER THIS FAVORABLE ENVIRONMENT...MODEL 
GUIDANCE INCREASE ORGANIZATION OF SYSTEM WITH DIFFERENT TRACKS 
AND INTENSITIES.  FORECAST LEANS TOWARD LESS AGGRESSIVE APPROACH 
THAN GFS...BUT DEFINITELY STRONGER THAN UKMET OR NOGAPS...MORE 
IN TUNE WITH CMC BRINGING SPINNING WINDS TO 30 KT WITHIN NEXT 48 
HRS BEFORE A QUICK DOWNTURN AFTER THE WEEKEND LIKELY DUE TO 
SHALLOWNESS OF WARM WATER LAYER AND INCREASING SW WIND SHEAR 
FROM UPSTREAM APPROACHING LONGWAVE TROUGH.

ELSEWHERE AT THE LOWER LEVELS...
HIGH PRES CENTER 1032 MB WELL N OF AREA EXTEND RIDGE TO 18N117W. 
RIDGE WEAKENED BY SURFACE TROUGH ALONG 138W N OF 25N DRIFTING W 
OUT OF BASIN LATER TODAY...BUT STRONG ENOUGH WITHIN 180 NM OF W 
COAST OF BAJA CALIFORNIA TO BRING MODERATE TO FRESH NW BREEZE 
LATE IN FORECAST PERIOD.   

MAIN SURFACE FEATURE IS DEVELOPING LOW PRES CENTER 1007 MB NEAR 
08.7N104.8W AS FAVORABLE ENVIRONMENT PRESENTLY PROMOTES 
SCATTERED MODERATE TO STRONG CONVECTION.  DRY SUBSIDING AIR MASS 
JUST W OF LOW PRES MAY CURTAIL INTENSIFICATION LATER IN FORECAST 
PERIOD.  WIDE SPECTRUM OF GUIDANCE SOLUTIONS ADDS UNCERTAINTY TO 
FORECAST AS STATISTICAL MODELS INCREASE WINDS DRAMATICALLY WHILE 
DYNAMICAL MODELS ARE MUCH TAMER.  TO ADD EVEN MORE DIFFERENCE TO 
THE POT...THE TRACKING VARIES AS MUCH AS THE INTENSITY BUT THE 
TIMING IS MORE IN SYNC AMONG GUIDANCE.  WHILE WINDS ARE EXPECTED 
TO APPROACH NEAR STORM FORCE...THE SHORT DURATION OF EPISODE MAY 
NOT BE ENOUGH TO BUILD SEAS ABOVE 10-11 FT.  

LONG PERIOD SWELLS UP TO 11 FT PRODUCED BY PREVIOUS GALE EVENT 
WELL N OF BASIN PRESENTLY AFFECT WATERS N OF 23N W OF 118W WITH  
SEAS EXPECTED TO SUBSIDE BELOW 8 FT BY SAT NIGHT. 

WEAK TROUGH MOVING THROUGH BAY OF CAMPECHE EXPECTED TO FORCE N 
WINDS ACROSS ISTHMUS INTO GULF OF TEHUANTEPEC BY THE END OF 
FORECAST PERIOD SUN. 

$$
WALLY BARNES