000
AXPZ20 KNHC 170952
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI OCT 17 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0800 UTC.

...ITCZ...
AXIS ALONG 12N89W TO 10N110W TO 09N120W TO 10N128W TO 09N140W. 
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION LIES N OF THE 
AXIS TO 13N E OF 98W.

...DISCUSSION...
THE 0312 UTC ASCAT PASS OVER THE GULF OF TEHUANTEPEC REVEALS 20 
TO 25 KT WINDS WITHIN 25 NM OF A LINE FROM 16N94.5W TO 14N95W.  
THE LOW TO MID LEVEL NORTHERLY FLOW IS EXPECTED TO CONTINUE FOR 
THE NEXT FEW DAYS...WEDGED BETWEEN THE SLOW MOVING BROAD LOW 
PRESSURE AREA ASSOCIATED WITH THE REMNANTS OF T.D. 16 AND HIGH 
PRESSURE BEHIND THE COLD FRONT CURRENTLY OVER CENTRAL MEXICO. IF 
THE GRADIENT BETWEEN THESE SYSTEMS BECOMES STRONGER THAN 
CURRENTLY FORECAST...THERE IS THE POTENTIAL FOR WINDS TO 
STRENGTHEN TO GALE FORCE...BUT AT THIS TIME...THE GUIDANCE IS IN 
AGREEMENT ON CONSISTENT 20 TO 30 KT WINDS IN THE GULF OF 
TEHUANTEPEC FOR AT LEAST THE NEXT 48 HOURS.

ANY INCREASE IN THE PRESSURE GRADIENT IN THE VICINITY OF THE 
GULF OF TEHUANTEPEC WOULD LIKELY BE DUE TO RE-DEVELOPMENT OF THE 
REMNANTS OF T.D. 16 IN THE EASTERN PACIFIC.  AT THIS TIME...THE 
FORECAST DOES NOT CALL FOR SIGNIFICANT STRENGTHENING DURING THE 
NEXT FEW DAYS AS THE LOW PRESSURE SYSTEM MOVES SLOWLY WEST AWAY 
FROM THE COAST.  THE SYSTEM IS EXPECTED TRACK UNDER A REGION OF 
UPPER LEVEL DIFFLUENCE...SO THE POTENTIAL EXISTS FOR DEEP 
CONVECTION AND SIGNIFICANT RAINFALL TO ACCOMPANY THIS BROAD AREA 
OF LOW PRESSURE.

THE UPPER LOW CURRENTLY NEAR 30N127W WILL BE PUSHED 
NORTHEASTWARD INTO CA AS A SHORTWAVE TROUGH MOVES INTO NORTHWEST 
WATERS AND RELOADS THE MEAN TROUGH ALONG A LINE FROM 30N124W TO 
22N1402 LATE FRI/EARLY SAT.  THE UPPER LOW IS EXPECTED TO EXIT 
FORECAST WATERS WITH LITTLE FANFARE.  AT THE SURFACE...HIGH 
PRESSURE WILL TO BUILD N OF 20N W OF 120W THROUGH THE PERIOD.

A WEAK SURFACE LOW EMBEDDED IN THE ITCZ NEAR 10N130W CURRENTLY 
SUPPORTS MINIMAL CONVECTION.  A QUIKSCAT PASS AT 0316 UTC 
CONFIRMS THE CLOSED CIRCULATION AT THE SURFACE...WITH STRONGEST 
WINDS WITHIN 120 NM OF THE NW QUADRANT IN THE 20 TO 25 KT 
RANGE.  THE FORECAST CALLS FOR THIS SYSTEM TO WEAKEN AS IT 
ENCOUNTERS INCREASING UPPER LEVEL SOUTH TO SOUTHWESTERLY WINDS 
ON THE LEADING EDGE OF THE AMPLIFYING MEAN UPPER TROUGH OVER 
NORTHWEST WATERS.  MID TO LOW LEVEL MOISTURE ASSOCIATED WITH 
THIS SYSTEM IS EXPECTED TO TRACK NORTHWESTWARD TOWARD THE MEAN 
TROUGH OVER THE NEXT FEW DAYS...BUT CONVECTION IS EXPECTED TO BE 
LIMITED AS THE LOW LEVEL SYSTEM TRACKS INTO THE EXPANDING HIGH 
PRESSURE TOWARD A REGION OF COOLER SEA SURFACE TEMPERATURES.

$$
SCHAUER CLARK