000
AXPZ20 KNHC 201552
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU OCT 20 2011

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 
1315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS WAS ANALYZED FROM THE CENTRAL AMERICA 
COAST NEAR 14N89W TO 12N97W TO 1012 MB LOW NEAR 13N103W TO 
07N121W. ITCZ AXIS FROM 07N121W TO 09N140W. SCATTERED MODERATE 
WITHIN 120 NM N OF AXIS BETWEEN 97W AND 105W AND AGAIN BETWEEN 
112W AND 118W.

...DISCUSSION...

MAIN MARINE WEATHER FEATURE TODAY IS THE ON-GOING TEHUANTEPEC 
GAP WIND EVENT.  NO IN-SITU OBSERVATIONS HAVE BEEN AVAILABLE 
THIS MORNING...BUT IT IS LIKELY THAT THE WINDS ARE STILL PEAKING 
AT MINIMAL GALE FORCE.  THE FORCING SHOULD DIMINISH SLIGHTLY AS 
THE SURFACE HIGH ALONG THE MEXICAN GULF OF MEXICO COAST MOVES 
EASTWARD DURING THE NEXT TWO DAYS.  IT IS ANTICIPATED THAT THE 
TEHUANTEPEC EVENT WILL DROP BELOW GALE FORCE THIS AFTERNOON.  
HOWEVER...REINFORCING COLD AIR ADVECTION ACROSS THE GULF OF 
MEXICO AND THE CHIVELA PASS OF MEXICO ON SATURDAY WILL CONTINUE 
THE NORTHERLY WINDS IN THE GULF OF TEHUANTEPEC THROUGH THE 
WEEKEND AND POSSIBLE BACK UP TO GALE FORCE ON MONDAY.  PEAK 
SIGNIFICANT WAVE HEIGHTS ARE LIKELY AROUND 12 FEET THIS 
MORNING...WHICH WILL DIMINISH TO 8 TO 10 FEET BY SATURDAY.

A WEAK 1012 MB LOW CENTERED NEAR 13N103W ALONG THE MONSOON 
TROUGH HAS DEVELOPED THIS MORNING.  HOWEVER...DEEP CONVECTION IN 
ASSOCIATION WITH THIS LOW IS CURRENTLY MINIMAL.  MODERATE 
VERTICAL SHEAR OF 15-20 KT AS DIAGNOSED BY CIMSS ALONG WITH THE 
LACK OF SIGNIFICANT DEEP CONVECTION SUGGEST FURTHER DEVELOPMENT 
OF THE SYSTEM TO A TROPICAL CYCLONE IS NOT LIKELY IN THE 
SHORT-TERM.  THE GFS AND NOGAPS GLOBAL MODELS DO NOT REPRESENT 
THIS FEATURE...THOUGH THE ECWMF AND UKMET MODELS DO DIAGNOSE A 
WEAK LOW IN THE CORRECT LOCATION.  BY SATURDAY...ALL OF THE 
MODELS MAINTAIN A VERY WEAK BROAD LOW IN THE VICINITY OF 15N113W 
EITHER FROM THIS CURRENT LOW OR IN THE DEVELOPMENT OF A LOW ON 
THE WEST END OF THE MONSOON TROUGH.  NONE...THOUGH...SHOW ANY 
SIGNIFICANT TROPICAL CYCLONE DEVELOPMENT POTENTIAL THROUGH 
TUESDAY.

NO SIGNIFICANT COLD FRONT INCURSIONS ALONG THE NORTHERN BOUNDARY 
OF OUR AREA ARE EXPECTED THROUGH TUESDAY.  SOME LONG-PERIOD 
SWELL WITH WAVE HEIGHTS OF 8 TO 10 FEET SHOULD BEGIN REACHING 
OUR NW REGION BY MONDAY MORNING.

$$
LANDSEA