000
AXPZ20 KNHC 121545
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI OCT 12 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 
1500 UTC.

...SPECIAL FEATURES...

1008 MB LOW EMBEDDED IN THE MONSOON TROUGH NEAR 14N108W HAS 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 120 NM NW 
SEMICIRCLE. ENVIRONMENTAL CONDITIONS APPEAR MARGINALLY CONDUCIVE 
FOR DEVELOPMENT...BUT ARE EXPECTED TO BECOME MORE FAVORABLE THIS 
WEEKEND AS THE SURFACE LOW MIGRATES TOWARD AN AREA OF REDUCE 
SHEAR ALOFT. THERE IS A MEDIUM CHANCE THAT THE LOW WILL BECOME A 
TROPICAL CYCLONE WITHIN THE NEXT 48 HOURS AS IT MOVES WESTWARD.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 10N86W TO LOW PRES 1008 MB NEAR 14N108W TO 
11N130W. ITCZ FROM 11N130W TO 10N140W. NUMEROUS SCATTERED 
ISOLATED STRONG WITHIN 120 NM N AND 90 NM S OF MONSOON TROUGH 
AXIS BETWEEN 95W AND 100W.

...DISCUSSION...

A VIGOROUS MID TO UPPER LEVEL SHORT WAVE TROUGH NEAR 33N130W IS 
DIGGING SE TOWARD THE BASE OF A BROADER CUTOFF UPPER LOW 
MIGRATING THROUGH SOUTHERN CALIFORNIA INTO NEVADA. THE EMERGENCE 
OF THE SHORT WAVE TROUGH HAS JUMP STARTED A STALLING FRONT 
SLOWLY APPROACHING THE NW CORNER OF THE DISCUSSION AREA OVER THE 
PAST 24 HOURS. ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT SHOWING 
THE SHORT WAVE TROUGH STALLING AND BECOMING CUTOFF NEAR 24N123W 
BY EARLY SUN. EAST TO WEST ORIENTED SURFACE RIDGING ASSOCIATED 
WITH A 1021 MB HIGH PRES AREA NEAR 27N125W REMAINS INTACT ACROSS 
THE AREA AS THE FRONTAL BOUNDARY STALLS AND WEAKENS. THIS WILL 
LEAVE MAINLY MODERATE TO FRESH TRADE WINDS IN PLACE ACROSS THE 
AREA FROM 10N TO 20N W OF 125W. NW SWELL TO 9 FT CONTINUES TO 
PROPAGATE INTO THE SAME GENERALLY AREA...BUT SEAS LESS THAN 8 FT 
CAN BE EXPECTED OUTSIDE THE MAIN TRADE WIND BELT AS THE SWELL 
DECAYS OVER THE NEXT COUPLE OF DAYS. 

PERSISTENT STRONG HIGH PRES OVER THE GULF OF MEXICO CONTINUES TO 
ALLOW FRESH TO STRONG GAP WIND FLOW TO PULSE THROUGH THE GULF OF 
TEHUANTEPEC...PRIMARILY DURING OVERNIGHT AND EARLY MORNING 
PERIODS. ACTIVE CONVECTION HAS BEEN FLARING OFF SOUTHERN MEXICO 
WHERE SOMEWHAT ENHANCED SW FLOW INTO THE MONSOON TROUGH ON THE 
SE SIDE OF THE DEVELOPING LOW IS CONVERGING WITH THE NE TO E GAP 
WINDS.

HIGH PRES BUILDING ACROSS THE GREAT BASIN AND INTERMOUNTAIN WEST 
WILL ENHANCE WINDS SLIGHTLY IN THE GULF OF CALIFORNIA THIS 
WEEKEND...ALLOWING PERIODS OF 20 TO 25 KT NW FLOW.

$$
CHRISTENSEN