000
AXPZ20 KNHC 231516
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE DEC 23 2008

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...04N77W TO 
07N110W TO 09N130W TO 08N140W. SCATTERED MODERATE CONVECTION IS 
WITHIN 60 NM OF THE POINT 07.5N114W. SCATTERED MODERATE 
CONVECTION IS WITHIN 90 NM OF THE POINT 07N122W. SCATTERED 
MODERATE CONVECTION IS WITHIN 45 NM EITHER SIDE OF THE AXIS FROM 
126W TO 132W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
IS WITHIN 90 NM OF THE POINT 10N134.5W.

OTHER CONVECTION NEAR THE ITCZ. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION IS WITHIN 75 NM OF THE POINT 13N127W.

...DISCUSSION...
THE SOUTHERN PORTION OF A STRONG MIDDLE LATITUDE TROUGH IS OVER 
THE NORTHEAST PART OF THE PACIFIC OCEAN AREA AND MEXICO NORTH OF 
21N WEST OF 100W. THIS FEATURE WILL REMAIN IN PLACE THROUGH AT 
LEAST 48 HOURS. SHORTWAVES WILL MOVE THROUGH THE BROADER FEATURE 
KEEPING THE OVERALL PATTERN IN PLACE. SURFACE COLD FRONT WILL 
ACCOMPANY THE SHORTWAVES. ONE FRONT IS ALONG THE LINE THROUGH 
32N112W TO 29N115W TO 27N124W. SOME MIDDLE AND UPPER LEVEL 
MOISTURE WITH BROKEN TO OVERCAST MIDDLE AND HIGH CLOUDS ARE 
ASSOCIATED WITH THE SHORTWAVE. THESE CLOUDS ARE OVER NORTHERN 
BAJA CALIFORNIAN AND NORTHWESTERN MEXICO INCLUDING THE STATES OF 
SONORA AND CHIHUAHUA NORTH OF ABOUT 29N. ANOTHER COLD FRONT IS 
FORECAST TO ENTER THE NORTHWEST PART OF THE PACIFIC OCEAN AREA 
TONIGHT. 

A LARGE DEEP LAYER CYCLONIC CIRCULATION CENTERED WEST OF THE 
AREA NEAR 20N142W IS ADVECTING DEEP LAYER MOISTURE FROM THE ITCZ 
NORTHWARD OVER THE AREA WEST OF 120W. MULTI LAYER BROKEN TO 
OVERCAST CLOUDS COVER THE AREA SOUTH OF 18N WEST OF 120W. SOME 
AREAS OF EMBEDDED CONVECTION ARE FORMING NORTH OF THE ITCZ IN 
THIS FLOW MOSTLY BETWEEN 124W AND 136W SOUTH OF 15N. THE 
CYCLONIC CIRCULATION IS FORECAST TO MOVE WEST SOUTHWEST ABOUT 10 
KNOTS AND WEAKEN SLIGHTLY. THIS WILL DIMINISH THE SOUTHERLY FLOW 
AND LEAVE BEHIND A BROAD TROUGH.

THE AREA SOUTH OF 20N EAST OF 120W IS COVERED BY WEAK 
ANTICYCLONIC FLOW. THE AREA EAST OF 105W IS DRY AND CLOUD FREE 
IN THE MIDDLE AND UPPER LEVELS WITH AREAS OF OVERCAST CLOUDS 
NEAR THE ITCZ IN THE LOWER LEVELS. NO SIGNIFICANT CONVECTION IS 
NOTED IN THE ITCZ EAST OF 112W AT THIS TIME.

OTHER THAN THE ABOVE MENTIONED COLD FRONT THE AREA NORTH OF 18N 
WEST OF 115W IS ANALYZED AS A WEAK SURFACE RIDGE. REMAINDER OF 
THE AREA IS ANALYZED AS A BROAD SURFACE TROUGH.

GAP WINDS ARE RAPIDLY ENDING IN THE GULF OF TEHUANTEPEC REGION 
AND WILL FALL TO LESS THAN 20 KNOTS TODAY. GAP WINDS IN THE GULF 
OF PAPAGAYO REGION WILL CONTINUE THROUGH AT LEAST 48 HOURS AND 
BE IN THE 20 TO 25 KNOT RANGE WITH SEAS ONLY TO 8 FEET BECAUSE 
OF THE LIMITED FETCH AND THE SOMEWHAT INTERMITTENT NATURE OF THE 
GAP WINDS.

$$
LL