000
AXPZ20 KNHC 192135
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE OCT 19 2010

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...
THE ITCZ AXIS IS ALONG 9N84W TO 08N100W TO 06N110W TO 09N125W TO 
09N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 
WITHIN 100 NM N OF AXIS BETWEEN 125W AND 135W...AND WITHIN 60 NM 
S OF AXIS BETWEEN 128W AND 132W. 

...DISCUSSION...
ALOFT...
A WELL-DEFINED MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION IS 
CENTERED NEAR THE CALIFORNIA/BAJA CALIFORNIA BORDER IN THE 
VICINITY OF 32N118W AND IS FORECAST BY THE COMPUTER MODELS TO 
MOVE NE ACROSS NORTHERN BAJA CALIFORNIA INTO ARIZONA TONIGHT 
THROUGH WED NIGHT. LOCALLY HEAVY RAIN AND TSTMS COULD BE 
ASSOCIATED WITH THE PASSAGE OF THIS LOW. CYCLONIC FLOW COVERS 
THE AREA N OF 25N BETWEEN BAJA CALIFORNIA AND 125W. A JET STREAM 
BRANCH WITH CORE WINDS OF 70-90 KT ROUNDS THE BASE OF THIS UPPER 
LEVEL LOW. SOUTHWESTERLY WINDS ARE LOCATED S OF THE JET TO 15N W 
OF 130W. THESE WINDS ARE ADVECTING A FAIR AMOUNT OF MID/UPPER 
LEVEL MOISTURE OVER THE NW PORTION OF THE AREA. A RIDGE COVERS 
ROUGHLY THE REGION S OF 20N BETWEEN 100W AND 132W. WATER VAPOR 
IMAGERY INDICATES A LARGE AREA OF MODERATE TO STRONG SUBSIDENCE 
WITHIN THE RIDGE. A DIFFLUENT PATTERN ALOFT ON THE WEST SIDE OF 
THE RIDGE IS HELPING TO INDUCE SOME CONVECTION ALONG THE ITCZ 
BETWEEN 125W AND 135W. ABUNDANT MID/UPPER MOISTURE IS ALSO SEEN 
OVER THE EASTERN PART OF THE AREA E OF 100W WHERE AN UPPER NE TO 
E FLOW PREVAILS.  

SURFACE...
SWLY FLOW IS EVIDENT E OF 95W IN THE ERN PORTION OF THE FORECAST 
AREA PER AN EARLIER ASCAT PASS AND SURFACE DATA. CURRENTLY...
WINDS ARE IN THE 10 TO 15 KT RANGE THERE...BUT ARE EXPECTED TO 
INCREASE TO 20 KT MAINLY FROM 03N TO 08N BETWEEN 79W AND 95W IN 
ABOUT 36 HOURS. A WEAK 1012 MB SURFACE LOW IS ALONG THE ITCZ 
AXIS NEAR 7N98W WITH A TROUGH EXTENDING NE FROM THE LOW TO 
10N96W. A FEW SHOWERS ARE NEAR THIS SYSTEM. OTHERWISE...A 1024 
MB HIGH LOCATED NEAR 31N135W EXTENDS A RIDGE OVER THE FORECAST 
WATERS COVERING MAINLY THE AREA N OF 15N AND W OF 110W. TRADE 
WINDS OF 20 KT AND SEAS TO 8 FT CAN BE FOUND S OF THE RIDGE FROM 
10N TO 18N W OF 130W. A RECENT ASCAT PASS CORROBORATED THESE 
WIND SPEEDS. THE TRADES ARE FORECAST TO DIMINISH BELOW 20 KT IN 
ABOUT 12 HOURS. 

A COLD FRONT WILL MOVE INTO THE FAR NW CORNER OF THE REGION LATE 
WED.  S TO SW WINDS OF 20 KT AND SEAS TO 8 FT ARE EXPECTED AHEAD 
OF THE FRONT. NW SWELL BEHIND THE FRONT WILL RAISE SEAS UP TO 12 
FT BY EARLY THU. CROSS EQUATORIAL SW SWELL WITH WAVE PERIODS 
BETWEEN 15 TO 16 SECONDS ARE BEGINNING TO SPREAD ACROSS THE 
SOUTH WATERS AND WILL REACH THE COASTS OF CENTRAL AMERICA AND 
MEXICO S OF 22N BY LATE WED. 

$$
GR