000
AXPZ20 KNHC 182121
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON OCT 18 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 09N85W TO 09N110W TO 08N120W TO 09N130W 
TO 09N140W. SCATTERED MODERATE CONVECTION IS NEAR 9N123W. 

...DISCUSSION...
ALOFT...
A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE N WATERS. SWLY FLOW 
AHEAD OF A DEEP LAYER TROUGH LOCATED W OF AREA IS NOTED OVER THE 
NW PORTION OF THE REGION. THE WINDS SHIFT W AND INCREASE TO 
70-90 KT OVER THE NORTH-CENTRAL WATERS THEN TURN W TO NW OVER 
THE BAJA CALIFORNIA PENINSULA AND NW MEXICO. THESE WINDS ARE 
TRANSPORTING ABUNDANT MID/UPPER LEVEL MOISTURE ACROSS THE N 
PORTION OF THE FORECAST AREA PARTICULARLY N OF 20N. AN UPPER 
LEVEL TROUGH EXTENDS FROM EASTERN TEXAS TO NEAR ACAPULCO MEXICO. 
STRONG SUBSIDENCE IS ALONG THE TROUGH AXIS. AN ANTICYCLONIC 
CIRCULATION IS LOCATED NEAR 16N116W. A DIFFLUENT PATTERN ALOFT W 
OF THIS ANTICYCLONE IS HELPING TO INDUCE SOME CONVECTION ALONG 
THE ITCZ BETWEEN 120W AND 125W. MODERATE TO STRONG SUBSIDENCE IS 
NOTED ON THE EASTERN SIDE OF THIS SYSTEM TO NEAR 100W WHILE A 
GOOD AMOUNT OF 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...
A MONSOON TROUGH IS EVIDENT E OF 95W IN THE ERN PORTION OF THE 
DISCUSSION AREA. THE MOST RECENT ASCAT PASS SHOWED SW WINDS IN 
THE 10 TO 15 KT RANGE THERE. FURTHER W...A WEAK TROUGH EXTENDS 
FROM 15N138W TO 12N140W. SCATTERED MODERATE CONVECTION IS WITHIN 
60-80 NM EITHER SIDE OF THE TROUGH AXIS. OTHERWISE A BROAD HIGH 
PRES RIDGE DOMINATES THE N PORTION OF AREA MAINLY N OF 15N AND W 
OF 110W. THE COMBINATION OF THE TROUGH AND HIGH PRES TO THE 
NORTH IS PRODUCING AN AREA OF ELY WINDS OF 20 KT FROM 12N TO 18N 
W OF 131W. ANOTHER TROUGH ENTERS THE FORECAST REGION NEAR 
30N119W THEN CONTINUES SW TO NEAR 25N123W. SURFACE DATA AND AN 
EARLIER ASCAT PASS SHOWED SOME WIND BARBS OF 20 KT BEHIND THE 
TROUGH AXIS.

CROSS EQUATORIAL SW SWELL...WAVE PERIODS BETWEEN 14 TO 16 
SECONDS...WILL BEGIN TO SPREAD ACROSS THE SOUTH WATERS LATE 
TONIGHT. A NEW BATCH OF NW SWELL WILL REACH THE FAR NW CORNER 
LATE TUE.

GAP WINDS...
VISIBLE SATELLITE PICTURE SUGGESTS THAT SOME WINDS ARE STILL 
BLOWING ACROSS THE GULF OF TEHUANTEPEC WHERE A ROPE CLOUD IS 
NOTED. 
  
$$
GR