000
AXPZ20 KNHC 281519
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED OCT 28 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1430 UTC.

...ITCZ...

THE ITCZ IS CENTERED ALONG 8N77W 7N85W 12N107W 10N124W 8N140W. 
LARGE CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION 
ARE WITHIN 120/150 NM OF LINE FROM 6N79W TO 11N99W AND WITHIN 
90/120 NM EITHER SIDE OF THE ITCZ FROM 131W TO W OF 140W. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM E OF A 
SURFACE TROUGH THAT EXTENDS FROM 8N129W THROUGH A 1009 MB LOW 
NEAR 10N128W TO 12N126W. 

...DISCUSSION...
A DEEP LAYERED UPPER TROUGH EXTENDS FROM THE DESERT SW TO 22N E 
OF 125W SUPPORTING A COLD FRONT THAT EXTENDS FROM NEAR EL PASO 
TEXAS ACROSS NW MEXICO AND THE BAJA PENINSULA NEAR 29N114W TO 
28N116W THEN DISSIPATING TO 29N123W. A STRONG JET STREAM IS 
EMBEDDED AT THE BASE OF THE UPPER TROUGH WITH ESTIMATED WINDS OF 
90 TO 120 NM N OF A LINE FROM 32N123W TO INLAND OVER MEXICO NEAR 
27N110W AND STRONGER WINDS N OF 32N. AN UPPER LEVEL RIDGE IS 
WEST OF THIS TROUGH CENTERED NEAR 34N137W WHILE A 1033 MB 
SURFACE HIGH...CURRENTLY CENTERED NEAR 38N135W WILL SHIFT SE 
OVER THE NEXT 48 HOURS. THE COMBINATION OF LOW SURFACE PRESSURE 
OVER THE SOUTHERN PLAINS WITH THE SURFACE RIDGE OVER THE E 
PACIFIC WILL KEEP A TIGHT PRESSURE GRADIENT TO PRODUCE WINDS OF 
25 TO 30 KT N OF 27N MAINLY E OF 130W WITH GALE FORCE GUSTS 
POSSIBLE. SIMILAR WINDS ARE IN THE GULF OF CALIFORNIA N OF 28N. 
NLY SURFACE WINDS OF 25 TO 30 KT HAVE BEEN REPORTED ALONG THE 
COASTAL STATIONS OF CALIFORNIA WITH SEAS TO 19 FT. THESE STRONG 
WINDS AND HIGH SEAS WILL CONTINUE TO SPREAD S OVER THE NEXT 24 
HOURS AND BEGIN WEAKENING IN 24 TO 48 HOURS. THE FRONTAL 
BOUNDARY IS DISSIPATING OVER THE GULF OF MEXICO SO THE NEAR 20 
KT WINDS WILL REMAIN IN THE GULF OF TEHUANTEPEC FOR A FEW MORE 
HOURS. A BROAD AREA OF LOWER PRESSURE COVERS THE AREA N OF 8N 
BETWEEN 92W TO 108W WITH A PAIR OF SURFACE TROUGHS ANALYZED 
ALONG 96W AND 105W. AN UPPER RIDGE IS ANCHORED NEAR 12N105W 
PROVIDING DIFFLUENCE ALOFT TO ENHANCE SCATTERED MODERATE/STRONG 
CONVECTION WITHIN 75 NM OF LINE FROM 12N98W TO THE COAST OF 
MEXICO NEAR 17N101W WITH SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION WITHIN 75 NM OF LINE FROM 13N93W TO 15N97W. ALTHOUGH 
THE SYSTEM IS UNORGANIZED AT THIS TIME...MODELS INDICATE THE 
POTENTIAL FOR DEVELOPMENT AS THE LOW THAT WILL DEVELOP DRIFTS NE 
OVER THE NEXT FEW DAYS. A WEAK 1010 MB LOW IS EMBEDDED WITHIN 
THE ITCZ NEAR 11N115W BUT IS ONLY PRODUCING ISOLATED SHOWERS 
WITHIN 75 NM RADIUS OF THE LOW. 

$$
WALLACE