000
AXPZ20 KNHC 131515
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN DEC 13 2009

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 INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W TO 
07N110W TO 07N140W. SCATTERED MODERATE CONVECTION IS WITHIN 75 
NM OF THE POINT 06N80W. SCATTERED MODERATE TO STRONG CONVECTION 
IS WITHIN THE AREA FROM 05N TO 09N WEST OF 124W.

...DISCUSSION...

MODERATE WESTERLIES ARE NORTH OF 20N. EMBEDDED SHORTWAVE IS OVER 
THE NORTHWEST PART OF THE AREA AND MOVING EAST 25 KNOTS AND WILL 
STRENGTHEN AS IT APPROACHES MEXICO MONDAY. NORTH OF 25N 
SCATTERED TO BROKEN MOSTLY HIGH CLOUDS ARE ASSOCIATED WITH THE 
MODERATE WESTERLIES. THE MOISTURE FOR THESE CLOUDS ORIGINATES 
FROM CONVECTION GENERATED BY A VIGOROUS SHORTWAVE LOCATED WEST 
OF THE AREA NEAR 150W. 

AN UPPER LEVEL TROUGH EXTENDS FROM SOUTH TEXAS ACROSS CENTRAL 
MEXICO TO THE ITCZ NEAR 113W. A NARROW AND DIMINISHING BAND OF 
UPPER LEVEL MOISTURE IS WITHIN 300 NM EAST AND SOUTHEAST OF THE 
TROUGH. THE HIGH CLOUDS THAT HAVE BEEN WITHIN THE BAND HAVE 
DIMINISHED.

OTHERWISE A BROAD RIDGE IS OVER THE AREA IN THE MIDDLE AND UPPER 
LEVELS. DRY MIDDLE AND UPPER LEVELS ARE WEST OF THE UPPER TROUGH 
FROM 14N TO 24N IMPLYING STRONG SUBSIDENCE IN THIS AREA. DRY 
MIDDLE AND UPPER LEVELS ARE ALSO NOTED SOUTH OF THE ITCZ ACROSS 
THE ENTIRE AREA AND MOST OF THE AREA EAST OF THE NARROW BAND OF 
UPPER MOISTURE MENTIONED ABOVE. THE EXCEPTION IS SOME LOCAL ITCZ 
CONVECTION WHICH ARE INTRODUCING SOME MIDDLE AND UPPER LEVEL 
MOISTURE IN THE OTHERWISE DRY AREA.

AT THE SURFACE WEAKENING COLD FRONT EXTENDS THROUGH 32N117W TO 
27N122W. OTHERWISE A WEAK RIDGE IS NORTH OF 13N WEST OF 110W. 
ELSEWHERE A BROAD TROUGH CENTERED ALONG THE ITCZ IS ANALYZED AT 
THE SURFACE.

MARINE CONDITIONS W OF 100W ARE BEING DOMINATED BY LARGE AND 
LONG PERIOD NW SWELL...WITH WAVE PERIODS OF 12 TO 16 SECONDS AND 
SIGNIFICANT WAVE HEIGHTS AS HIGH AS 13 FT. THIS SWELL EVENT WILL 
CONTINUE TO PROPAGATE SE AND GRADUALLY SUBSIDE. ALSO TRADE WINDS 
OF 20 TO 25 KNOTS ARE OVER A BROAD AREA WEST OF 115W FROM 08N TO 
19N.

GAP NE TO E WINDS OF 20 TO 25 KT ACROSS THE GULF OF PAPAGAYO 
REGION AS TRADE WINDS CROSS CENTRAL AMERICA FROM THE WESTERN 
CARIBBEAN.
  
GAP N WINDS OF 20 KT IN THE GULF OF TEHUANTEPEC REGION WILL 
DIMINISH MONDAY NIGHT.
  
$$
LL