000
AXPZ20 KNHC 170952
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI DEC 17 2010

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 EXTENDS ALONG 02N78W TO 
09N83W TO LOW PRES AT 07N90W...THEN THE AXIS CONTINUES TO SECOND 
LOW PRES AT 09N108W...CONTINUING W AGAIN TO BEYOND 09N140W. 
SCATTERED MODERATE CONVECTION IS NOTED WITHIN 60 NM OF 09N107W 
AND ISOLATED MODERATE WITHIN 180 NM OF 09N129W.

...DISCUSSION...

AN UPPER ANTICYCLONE IS CENTERED JUST W OF AREA AT 18N142W. AN 
UPPER TROUGH EXTENDS FROM 32N108W TO A BASE AT 12N113W. AN 
UPPER RIDGE EXTENDS W ACROSS THE TROPICS ALONG 09N TO THE E OF 
110W. UPPER MOISTURE IS SPILLING ACROSS THE SUBTROPICAL RIDGE AS 
FAR SE AS THE SOUTHERN TIP OF THE BAJA CALIFORNIA PENINSULA. 
FURTHER S...THE ITCZ IS UNDER THE UPPER RIDGE AND IS SUPPORTING 
THE CONVECTION WITHIN 180 NM OF 09N129W. THE UPPER LEVELS APPEAR 
MOIST FROM 08N TO 13N W OF 120W WHILE A BAND OF DRY UPPER AIR IS 
INDICATED WITHIN 240 NM OF LINE 18N113W TO 24N140W. UPPER 
MOISTURE...ORIGINATING FROM CONVECTION OVER COLOMBIA...IS 
SPREADING W OVER THE DEEP TROPICS E OF 83W. OTHERWISE THE UPPER 
LEVELS ARE DRY E OF 110W WITH THE UPPER DEBRIS MOISTURE 
ASSOCIATED WITH THE CONVECTION NEAR 09N107W QUICKLY EVAPORATING. 
A SURFACE COLD FRONT IS WASHING OUT FROM 32N122W TO 26N130W TO 
25N140W WITH SEAS TO 9 FT W OF THE FRONT IN NW SWELL.  

EXPECT THE UPPER ANTICYCLONE TO SHIFT E TO NEAR 25N125W IN ABOUT 
24 HOURS AND NEAR 22N108W IN 48 HOURS. THIS WILL ALLOW AN UPPER 
SHORTWAVE TO MOVE E INTO THE NW CORNER EARLY SAT AND CONTINUE E 
REACHING A POSITION FROM SOUTHERN CALIFORNIA TO 02N137W LATE 
SUN. THE ASSOCIATED SURFACE COLD FRONT WILL EXTEND FROM 30N135W 
TO 28N140W IN 24 HOURS AND AGAIN ACCOMPANIED BY A 20 KT WIND 
SHIFT AND SEAS 7 TO 10 FT IN NW SWELL. THE FRONT SHOULD REACH 
ALONG 30N130W TO 26N140W IN 48 HOURS WITH SEAS W OF THE FRONT 
BUILDING 8 TO 12 FT PRIMARILY IN THE NW SWELL.  

EXPECT THE SURFACE LOW NEAR 07N90W TO MEANDER IN THE SAME AREA 
THROUGH 48 HOURS WITH WINDS 15 TO 20 KT CONTINUING JUST SE OF 
THE CENTER. EXPECT THE LOW PRES NEAR 09N108W TO MOVE W AND 
GRADUALLY DISSIPATE THROUGH 48 HOURS WITH ENHANCED WINDS TO 20 
KT MAINLY OVER THE IMMEDIATE SE QUADRANT. THE ITCZ TROUGH ALONG 
ABOUT 130W SHOULD CONTINUE W...WITH NE TRADES W OF THE TROUGH 
AXIS IN THE 15 TO 20 KT RANGE.
 
GAP WINDS...NORTHERLY FLOW TO 20 KT IN AND JUST S OF THE GULF OF 
PANAMA IS EXPECTED TO DIMINISH EARLY TODAY. A COLD FRONT WILL 
MOVE SE THROUGH THE WESTERN GULF OF MEXICO SAT NIGHT WITH 
NORTHERLY WINDS AT 20 TO 25 KT SURGING THROUGH THE CHIVELAS PASS 
AND INTO THE GULF OF TEHUANTEPEC AROUND SUNRISE ON SUN...AND 
CONTINUING THROUGH WED.  

$$
NELSON