000
AXPZ20 KNHC 191538
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE OCT 19 2010

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 
1500 UTC.

...ITCZ...
THE ITCZ AXIS IS ALONG 7N98W TO 08N105W TO 09N118W TO 08N130W TO 
08N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 
FROM 08N TO 12N BETWEEN 127W AND 132W. 

...DISCUSSION...
ALOFT...
A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE AREA N OF 10N. A 
WELL-DEFINED MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED 
OFF THE SOUTHERN CALIFORNIA COAST IN THE VICINITY OF 32N120W AND 
IS MOVING S 10 TO 15 KT. CYCLONIC FLOW COVERS THE AREA N OF 25N 
BETWEEN BAJA CALIFORNIA AND 125W. A WESTERLY JET STREAM ALOFT 
ROUNDS THE BASE OF THE CYCLONIC CIRCULATION WITH WINDS OF 70-90 
KT COVERING THE AREA N OF 23N AND E OF 125W. SOUTHWESTERLY WINDS 
ARE LOCATED S OF THE JET TO 15N W OF 130W. THESE WINDS ARE 
ADVECTING A GOOD AMOUNT OF MID/UPPER LEVEL MOISTURE OVER THE NW 
PORTION OF THE AREA. A RIDGE COVERS ROUGHLY THE AREA S OF 20N 
BETWEEN 100W AND 132W. WATER VAPOR IMAGERY INDICATES A LARGE 
AREA OF SUBSIDENCE WITHIN THE RIDGE PARTICULARLY S OF ABOUT 20N 
TO THE EQUATOR BETWEEN 105W AND 130W. A DIFFLUENT PATTERN ALOFT 
BETWEEN THE RIDGE AND AN UPPER LEVEL LOW LOCATED NEAR 5N125W IS 
HELPING TO INDUCE SOME CONVECTION ALONG THE ITCZ W OF 118W. 
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. WINDS ARE IN THE 10 TO 15 KT 
RANGE. A WEAK 1011 MB SURFACE LOW IS ALONG THE ITCZ AXIS NEAR 
7N98W WITH A TROUGH EXTENDING NE FROM THE LOW TO 11N94W. A FEW 
SHOWERS ARE NEAR THE LOW PRES. ANOTHER WEAK 1011 MB SFC LOW IS 
NEAR 9N119W. ISOLATED MODERATE CONVECTION IS NEAR THIS SYSTEM. 
OTHERWISE...A BROAD HIGH PRES RIDGE DOMINATES THE N PORTION OF 
AREA MAINLY 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 12N TO 18N W OF 
133W. THESE WINDS ARE FORECAST TO DIMINISH BELOW 20 KT IN ABOUT 
12 HOURS. A COLD FRONT WILL MOVE INTO THE FAR NW CORNER OF THE 
AREA LATE WED. SW WINDS OF 20 KT AND SEAS TO 8 FT ARE EXPECTED 
AHEAD OF THE FRONT. NW SWELL BEHIND THE FRONT WILL RISE SEAS UP 
TO 12 FT BY EARLY THU. CROSS EQUATORIAL SW SWELL...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