000
AXPZ20 KNHC 311004
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON DEC 31 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.
 
...ITCZ...
INTERTROPICAL CONVERGENCE ZONE AXIS ALONG AXIS 7N. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 NM EITHER 
SIDE OF THE AXIS BETWEEN 90W AND 96W. SCATTERED MODERATE 
CONVECTION IS OBSERVED WITHIN 60 NM OF 7.5N 97W.

...DISCUSSION...
A LONGWAVE TROUGH CONTINUES TO DOMINATE CENTRAL N AMERICA WITH 
ITS AXIS N OF 20N ALONG 105W. A LONGWAVE RIDGE HAS BUILT IN OVER 
THE PAC N OF 30N ALONG 100W. AN UPPER LEVEL CYCLONE HAS CUT OFF 
AT 23N133W WITH A TROUGH SE ALONG 13N128W TO A BASE AT 7N119W. 
DRY UPPER AIR IS NOTED WITHIN THE TROUGH...N OF 22N BETWEEN 115W 
AND 85W AND WITHIN 480 NM OVER W SEMICIRCLE OF THE CUT OFF LOW. 
UPPER MOISTURE IS NOTED ELSEWHERE N OF 5N W OF 120W AND 
ELSEWHERE N OF 10N BETWEEN 120W AND 110W.

A TROPICAL ANTICYCLONE CONTINUES OVER THE CENTRAL CARIBBEAN WITH 
A RIDGE EXTENDING W TO A SHARP CREST AT 12N100W. CONVECTION 
ALONG THE E PAC ITCZ NEAR 85W IS ENHANCED WITH SOME OF THE 
DEBRIS MOISTURE SPREADING N ACROSS CENTRAL AMERICA E OF 87W. 
OTHERWISE THE UPPER LEVELS ARE DRY E OF 110W.

AT THE LOW LEVELS...HIGH PRES DOMINATES THE AREA N OF THE ITCZ W 
OF 110W WITH THE EASTERLY TRADES S OF THE RIDGE IN THE 20-25 KT 
RANGE AND EXPECTED TO DIMINISH TO ABOUT 20 KT AS THE RIDGE 
WEAKENS AND SHIFTS EASTWARD IN ADVANCE OF A COLD FRONT THAT WILL 
MOVE INTO THE NW WATERS MOVE TUE MORNING. THIS COLD FRONT IS 
ACCOMPANIED BY A FRESH NW SWELL TRAIN THAT WILL DRIVE SEAS TO 
ABOUT 16 FT IN THE AREA NEAR 30N140W SUNRISE THU.

GAP WINDS WILL SURGE TODAY TO ABOUT 20 KNOTS IN AND DOWNSTREAM 
OF THE GULF OF TEHUANTEPEC AND THE GULF OF PAPAGAYO...WITH SEAS 
TO MAX AT 7 FT. THE GRADIENT WILL TIGHTEN TO 20 TO 25 KT TONIGHT 
IN THE GULF OF TEHUANTEPEC AND GRADUALLY INCREASE TO GALE FORCE 
BY SUNRISE TUE. THESE NLY WINDS WILL CONTINUE TO INCREASE TO 
STORM FORCE BY SUNSET TUE AND FURTHER INCREASE TO MINIMAL 
HURRICANE FORCE TUE NIGHT WITH SEAS TO BUILDING TO ABOUT 24 FT 
NEAR 13N96W AT SUNSET WED. NE WINDS WILL ALSO FURTHER INCREASE 
TO 30 KT IN THE GULF OF PAPAGAYO...AND ALL PAC WATERS TO THE N 
OF 8N BETWEEN 85W AND 92W IN 48 HOURS...WITH MINIMAL GALE WINDS 
IN THE GULF OF PAPAGAYO SUNRISE THU. 

NW WINDS IN THE GULF OF CALIFORNIA WILL FLUCTUATE AROUND 20 KT 
TODAY THEN INCREASE BRIEFLY TO 20 TO 25 KT TUE THEN DIMINISH TO 
20 KT WED. SEAS MAX WILL MAX AT 6-7 FT IN THE CENTRAL EXPOSED 
WATERS.

$$
NELSON