000
AXPZ20 KNHC 032146
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU DEC 03 2009

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 05N77W TO 05N90W TO 10N102W TO 09N107W TO 
11N120W TO 07N130W TO 08N133W TO 04N140W. SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION WITHIN 120 NM OF AXIS BETWEEN 120W 
AND 128W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 
160 NM EITHER SIDE OF AXIS BETWEEN 130W AND 135W.

...DISCUSSION...
SURFACE HIGH PRESSURE 1018 MB NEAR 29N130W REMAINS WEAK. DESPITE 
WEAKER HIGH PRESSURE TO THE NORTH...TWO LOW PRESSURE 
CIRCULATIONS...ONE NEAR 10N124W AND ONE NEAR 08N134W...HAVE KEPT 
THE PRESSURE LOW ENOUGH ALONG THE ITCZ TO MAINTAIN THE PRESSURE 
GRADIENT. AS A RESULT...THE AREA OF FRESH TRADES HAS NOT 
DECREASED IN AREAL EXTENT. WITH A SHORTWAVE TROUGH CURRENTLY 
NEAR 140W EXPECTED TO MOVE ACROSS THE N PORTION OF THE FORECAST 
AREA THROUGH SAT...THE SURFACE HIGH PRESSURE IN THE N PORTION OF 
THE AREA WILL CONTINUE TO REMAIN RELATIVELY WEAK. SURFACE LOW 
PRESSURE ANALYZED NEAR 14.5N140W...BASED ON 1840 UTC ASCAT 
PASS...IN RESPONSE TO AFOREMENTIONED SHORTWAVE TROUGH. 
CONVECTION AROUND THIS FEATURE HAS DECREASED AS THE AXIS OF THE 
UPPER TROUGH IS NOW EAST OF THE FEATURE...PUTTING IT ON THE 
SUBSIDENT SIDE. WITH THE LOSS OF UPPER LEVEL SUPPORT...THE 
SURFACE LOW WILL DISSIPATE TONIGHT. 

LONG PERIOD NW SWELL CONTINUES ACROSS MOST OF THE AREA W OF 
110W...MIXING WITH NE SWELL IN THE AREA OF TRADES.

NORTHERLY FLOW IS EXPECTED TO INCREASE TO 20-25 KT OVER THE GULF 
OF CALIFORNIA N OF 27N TONIGHT AS HIGH PRES BUILDS OVER THE 
GREAT BASIN.

GAP WINDS...
EXPECT ELY WINDS AT OR NEAR 20 KT TO PULSE UP AND DOWN THROUGH 
THE GULF OF PAPAGAYO AND THEN DOWNSTREAM TO NEAR 89W DURING THE 
NEXT FEW DAYS. THESE WINDS WILL BE STRONGEST IN THE MORNING 
HOURS WITH THE AID OF DRAINAGE FLOW. ALSO...A GALE FORCE WIND 
EVENT IS EXPECTED TO DEVELOP ACROSS THE GULF OF TEHUANTEPEC IN 
ABOUT 48 HOURS...SAT AFTERNOON...AS A STRONG HIGH PRES BUILDS 
SWD INTO THE FAR WRN GULF OF MEXICO AND ALONG THE EASTERN SLOPES 
OF THE SIERRA MADRE MOUNTAINS OF MEXICO IN THE WAKE OF A STRONG 
COLD FRONT FORECAST TO MOVE ACROSS THE ENTIRE GULF REGION ON SAT.

OF NOTE...THE MONTHLY DISTRIBUTION OF TEHUANTEPEC EVENTS SHOWS 
THAT THE LARGEST NUMBER OF GALE FORCE EVENTS OCCURS IN DECEMBER. 
STORM-FORCE EVENTS OCCUR MOST OFTEN IN JANUARY. GALE FORCE 
EVENTS HAVE OCCURRED AS EARLY AS SEPTEMBER AND AS LATE AS MAY. 
HOWEVER...ABOUT 84% OF ALL EVENTS TAKE PLACE BETWEEN NOVEMBER 
AND MARCH. 

$$

CHRISTENSEN/AL