000
AXPZ20 KNHC 091601
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE OCT 09 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 
1530 UTC.

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

MONSOON TROUGH EXTENDS FROM 10N86W TO 10N100W TO 08N105W TO 
06N118W WHERE IT ENDS. IT RESUMES AT 11N123W TO 09N125W WHERE IT 
TRANSITIONS TO THE ITCZ AXIS TO 05N135W TO 05N140W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 90 NM EITHER SIDE OF 
AXIS BETWEEN 95W AND 120W.

...DISCUSSION...

THE REMNANT CIRCULATION OF WHAT WAS TROPICAL CYCLONE OLIVIA IS 
CENTERED NEAR 15N122W. RESIDUAL WEAK CONVECTION IS BEING SHEARED 
WELL TO THE NE OF THE CENTER...IN THE STRONG SW MID AND UPPER 
FLOW ON THE SE SIDE OF AN UPPER TROUGH FROM 30N125W TO 23N140W 
TO THE SE OF HAWAII. FRESH TO STRONG WINDS ARE NOTED ON THE 
NORTHERN PERIPHERY OF THE CENTER...BUT THIS WILL DIMINISH 
THROUGH TODAY AS THE THE REMNANT LOW OF OLIVIA WILL CONTINUE TO 
WEAKEN AND DISSIPATE IN THE NEXT 24 TO 48 HOURS. 

A SHORT WAVE TROUGH IS PIVOTING EASTWARD ALONG THE SOUTHERN 
EXTENT OF AN UPPER LOW CENTERED OVER NORTHERN CALIFORNIA. THIS 
WAS SUPPORTING A WEAK COLD FRONT AT THE SURFACE WHICH HAS SINCE 
STALLED ALONG 30N BETWEEN 130W AND 135W. A SECOND STRONGER UPPER 
LOW IS CENTERED FURTHER WEST WELL TO THE N OF HAWAII NEAR 
40N160W. THIS WILL SHIFT TO THE ENE OVER THE NEXT COUPLE OF 
DAYS...SQUEEZING A DEEP LAYER RIDGE IN PLACE ALONG ROUGHLY 140W. 
THE RIDGE WILL NONETHELESS CONTINUE TO SUPPORT A 1018 MB SURFACE 
HIGH CENTERED NEAR 27N128W. 

AN UPPER CYCLONE NEAR 16N102W IS MOVING WESTWARD OFF THE W 
CENTRAL COAST OF MEXICO...TO THE SOUTH OF AN UPPER RIDGE 
EXTENDING FROM CENTRAL MEXICO THROUGH AN UPPER ANTICYCLONE IS 
CENTERED NEAR 16N116W TO 10N135W. AN ASSOCIATED CLUSTER OF 
STRONG CONVECTION IS NOTED FROM 17N TO 19N BETWEEN 104W AND 
106W. 

AREAS OF CONVECTION PERSIST ALONG THE MONSOON TROUGH E OF 120W 
FED IN PART BY 15 TO 20 KT SW FLOW. 

GAP WINDS...NORTHERLY WINDS WILL PULSE AT 20-25 KT THROUGH AND 
DOWNSTREAM THE GULF OF TEHUANTEPEC REACHING NEAR 14N96W INTO
EARLY THIS EVENING....THEN GUIDANCE SUGGESTS WINDS WILL DIMINISH 
THROUGH TONIGHT BY WED NIGHT WINDS INCREASE AGAIN TO 20-25 KT 
THROUGH THE GULF OF TEHUANTEPEC.

GLOBAL MODELS CONTINUE TO SUGGEST THAT LOW PRES WILL FORM ALONG
THE EASTERN END OF THE MONSOON TROUGH BY WED NIGHT IN THE 
VICINITY OF 10N90W. THIS WILL OCCUR AS THE NORTHERLY DRAINAGE 
FLOW THROUGH THE GULF OF TEHUANTEPEC ENHANCES THE FLOW OVER THE 
N SEMICIRCLE OF THE LOW. LATEST GFS MODEL GUIDANCE HAVE BEEN LESS
AGGRESSIVE WITH WINDS RELATED TO THIS LOW VERSUS RUNS FROM 
PREVIOUS DAYS. THIS IS MORE IN LINE WITH THE OTHER MODELS...AND 
RAISES CONFIDENCE LEVEL WITH RESPECT TO WIND AND WAVE HEIGHT 
FORECASTS IN THE GRIDS. 

WAVEWATCH MODEL GUIDANCE HAS BEEN CONSISTENT IN FORECASTING
A LARGE NW SWELL WAVE TRAIN THAT ENCROACHES INTO THE FAR NW 
SECTION OF THE AREA BEGINNING ON WED AND LASTING THROUGH AT 
LEAST THE END OF THE WEEK. THIS IS RELATED TO THE COLD FRONTAL
SYSTEM THAT IS FORECAST TO PASS JUST TO THE N OF THE AREA 
BY THAT TIME. THE SWELLS ARE FORECAST TO PRODUCE SEAS OF UP
TO 10 OR 11 FT.
 
$$
AGUIRRE/CHRISTENSEN