000
AXPZ20 KNHC 260929
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI OCT 26 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

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

MONSOON TROUGH EXTENDS FROM THE GULF OF FONSECA TO LOW PRES NEAR 
10.5N94W 1008 MB TO 11N110W TO 11N117W...WHERE IT TRANSITIONS TO 
ITCZ AND CONTINUES TO 10N130W AND TO BEYOND 08N140W. ISOLATED 
MODERATE CONVECTION IS FROM 09N TO 11N BETWEEN 89W AND 95W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION CAN BE FOUND FROM 
11N TO 13.5N BETWEEN 113W AND 120W. SCATTERED MODERATE 
CONVECTION IS NOTED WITHIN 90 NM S OF ITCZ AXIS BETWEEN 123W AND 
126W...AND N OF THE ITCZ AXIS BETWEEN 128W AND 133W. 

...DISCUSSION...

ALOFT...A TROUGH/RIDGE PATTERN DOMINATES THE MAJORITY OF THE 
FORECAST AREA. AN UPPER LEVEL TROUGH STRETCHES FROM 30N130W TO 
15N140W. E OF THE TROUGH...AN ANTICYCLONIC CIRCULATION IS 
CENTERED NEAR 19N116W. THE ANTICYCLONIC FLOW COVERS THE AREA S 
OF 28N E OF 133W. UPPER DIFFLUENCE ON THE SOUTHERN PERIPHERY OF 
THE RIDGE IS HELPING TO INDUCE SOME CONVECTIVE ACTIVITY ALONG 
THE MONSOON TROUGH/ITCZ PREVIOUSLY DESCRIBED. THE UPPER TROUGH 
WILL PUSH EASTWARD TO THE N CENTRAL PORTION OF THE AREA BY SAT 
SUPPRESSING THE BROAD ANTICYCLONIC FLOW TO THE S.

AT THE SURFACE...A NEARLY STATIONARY 1028 MB HIGH IS ANALYZED 
JUST N OF THE DISCUSSION AREA NEAR 34N133W WITH A RIDGE 
EXTENDING SE TO NEAR 17N115W. HIGH PRES GENERALLY COVERS THE 
WATERS N OF 15N W OF 115W. PRES GRADIENT BETWEEN THIS HIGH PRES 
AND A TROUGH OVER NW MEXICO IS SUPPORTING FRESH TO STRONG NW 
WINDS N OF 24N BETWEEN 115W AND 127W WITH A SMALL POCKET OF 
WINDS IN THE 25-30 KT RANGE JUST N OF THE AREA OFFSHORE THE 
SOUTHERN CALIFORNIA COAST BASED ON LATEST SCATTEROMETER DATA. 
SEAS WITHIN THIS AREA ARE IN THE RANGE OF 8-11 FT. THE HIGH IS 
FORECAST TO SLOWLY MOVE WWD DURING THE NEXT FEW DAYS WITH THESE 
FRESH NLY WINDS SHIFTING W AND IN TANDEM  WITH THE HIGH. AT THE 
SAME TIME...HIGH PRES OVER THE GREAT BASIN IS PRODUCING FRESH TO 
STRONG WINDS ACROSS THE NORTHERN AND CENTRAL SECTIONS OF THE 
GULF OF CALIFORNIA. SEAS WILL GRADUALLY BUILD TO 6-8 FT TODAY 
AND LIKELY PEAK NEAR 9 FT ACROSS N PORTIONS THIS EVENING. WINDS 
ARE FORECAST TO DIMINISH TO 20 KT OR LESS SAT EVENING.  

THE BROAD RIDGE IS ALSO PRODUCING FRESH NE TRADE WINDS N OF THE 
ITCZ W OF 125W...WITH SEAS OF 8-10 FT. THE AREA OF TRADES WILL 
SHRINK WWD TO ABOUT 135W IN 48 HOURS AS HIGH PRES TO THE N 
WEAKENS.  

HIGH PRES BUILDING ACROSS THE WESTERN PART OF THE GULF OF MEXICO 
WILL BRING A NEW GAP WIND EVENT ACROSS THE GULF OF TEHUANTEPEC 
TONIGHT. WINDS WILL INCREASE TO 20-30 KT BY LATE FRI NIGHT... 
AND LAST INTO SAT EVENING WITH SEAS BUILDING TO 8-11 FT WHILE 
SPREADING DOWNSTREAM FROM THE GULF.

GLOBAL MODELS CONTINUE TO FORECAST MULTIPLE WEAK CYCLONIC 
CIRCULATIONS ALONG THE MONSOON TROUGH SUCH AS THE ONE LOCATED 
NEAR 10.5N94W TO PERSIST WITH LITTLE OR NO INTENSIFICATION 
EXPECTED THROUGH SAT.

$$
GR/JA