000
AXPZ20 KNHC 211547
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU OCT 21 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...

AXIS ALONG 08N83W TO 09N115W TO 09N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 90 NM OF LINE FROM 07N79W TO 11N89W. 
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF 
AXIS BETWEEN 133W AND 138W.

...DISCUSSION...

A DEEP LAYERED UPPER LEVEL TROUGH CLIPS THE NW PORTION OF THE 
DISCUSSION AREA WITH AXIS EXTENDING FROM 30N132W TO 25N140W THEN 
SW TO THE NEAR THE BIG ISLAND OF HAWAII. THE ASSOCIATED SURFACE 
COLD FRONT IS ANALYZED FROM 30N131W TO 25N140W WHERE IT 
CONTINUES STATIONARY W OF 140W. EARLIER MORNING ASCAT PASSES 
OVER THIS AREA DEPICT WINDS LESS THAN 20 KT S OF 30N ASSOCIATED 
WITH THE FRONT...HOWEVER...SEAS 8 TO 12 FT DUE TO NW SWELLS ARE 
LOCATED OVER THE NW CORNER OF THE FORECAST WATERS AREA. WITH THE 
FRONTAL BOUNDARY FORECAST TO MOVE QUICKLY EASTWARD AND GRADUALLY 
DISSIPATE...SEAS ARE EXPECTED TO SUBSIDE BELOW 10 FT BY LATE 
FRIDAY LEAVING 12 TO 14 SECOND NW SWELL NORTHWEST OF A LINE FROM 
30N116W TO 10N140W. 

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 14N113W WITH AN 
UPPER LEVEL RIDGE AXIS EXTENDING E-W ALONG 14N BETWEEN 97W AND 
138W. UPPER LEVEL DIFFLUENCE AND MOIST SOUTHWESTERLY FLOW ALOFT 
WITHIN THE WESTERN PERIPHERY OF THE RIDGE W OF 130W IS ENHANCING 
SCATTERED MODERATE CONVECTION ALONG THE ITCZ BETWEEN 133W AND 
138W WITH THE RESULTANT MOISTURE ADVECTED N THEN NE REMAINING S 
OF 23N AND W OF 130W. 

AN UPPER LEVEL TROUGH LOCATED WELL E OF THE AREA OVER THE 
FLORIDA PENINSULA AND W ATLC WATERS EXTENDS AN AXIS SW ACROSS 
THE SE GULF OF MEXICO AND YUCATAN PENINSULA TO A BASE OVER THE 
GULF OF TEHUANTEPEC. AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER 
THE WESTERN CARIBBEAN AND EXTENDS AN UPPER LEVEL RIDGE AXIS OVER 
HONDURAS AND NICARAGUA TO NEAR 14N94W. S OF THE E-W RIDGE AXIS 
ALONG 14N...SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN 
150 NM OF THE CENTRAL AMERICA COAST BETWEEN 77W AND 90W.

ELSEWHERE AT THE SURFACE...A 1021 MB HIGH IS CENTERED AT 26N131W 
WITH A RIDGE AXIS SE TO NEAR 19N111W. NE TRADES OF 15 TO 20 KT 
ARE NOTED S OF THE RIDGE AND N OF THE ITCZ WITHIN THE AREA FROM 
11N TO 17N W OF 118W. WITH THE SURFACE HIGH FORECAST TO REMAIN 
NEARLY STATIONARY AND STRENGTHEN SLIGHTLY OVER THE NEXT COUPLE 
OF DAYS...NE TRADES WILL INCREASE TO 20 KT THROUGH SAT MORNING 
FROM 11N TO 18N W OF 130W. SEAS ARE EXPECTED TO BUILD TO 9 FT IN 
NW SWELL.

AS THE FRONTAL TROUGH DISSIPATES AND HIGH PRESSURE 
RE-ESTABLISHES ITSELF OVER THE FORECAST WATERS N OF 18N...THIS 
WILL INDUCE A STRONGER PRESSURE GRADIENT ALONG THE BAJA 
CALIFORNIA COAST IN 36-48 HOURS WITH NW TO N WINDS TO 20 KT 
WITHIN 90 NM OF THE COAST N OF 28N. SEAS TO 8 FT IN NW SWELLS 
ARE FORECAST TO AFFECT THOSE WATERS.

FINALLY...SOUTHWESTERLY MONSOON FLOW OF 15 TO 20 KT OVER THE 
WATERS FROM 02N TO 08N BETWEEN 79W AND 90W IS FORECAST TO EXPAND 
WESTWARD TO 100W IN 24 HOURS WITH SEAS INCREASING TO 10 FT IN SW 
CROSS-EQUATORIAL SWELLS THAT WILL COVER MOST OF THE PACIFIC 
WATERS FROM THE EQUATOR TO 08N BETWEEN CENTRAL AMERICA AND 110W 
AS SUGGESTED BY WAVEWATCH III MODEL GUIDANCE.

$$
HUFFMAN