000
AXPZ20 KNHC 181519
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT DEC 18 2010

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.

...TROPICAL LOWS...

A WELL DEFINED SURFACE LOW PRES CENTERED AT 10N 110W IS 
ESTIMATED AT 1010 MB. OVERNIGHT ASCAT PASS INDICATES 20 KT WINDS 
OVER THE EASTERN SEMICIRCLE OF THE LOW WITH SEAS TO 8 FT. THE 
LOW IS EXPECTED TO MOVE TO NEAR 10N113W 1009 MB IN 24 
HOURS...AND NEAR 10N116W AT 1008 MB IN 48 HOURS WITH LITTLE 
CHANGE IN WINDS AND SEAS.  

ANOTHER PERSISTENT SURFACE LOW PRES IS CENTERED NEAR 07N88W AND 
ESTIMATED AT 1011 MB. SOUTHWESTERLY WINDS AT 15 TO 20 KT ARE 
WITHIN ABOUT 180 NM OVER THE SE QUADRANT WITH SEAS TO 8 FT. THE 
LOW IS EXPECTED TO MEANDER IN THE SAME AREA THROUGH 48 HOURS 
WITH LITTLE CHANGE IN WIND AN SEAS.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N77W TO LOW 
PRES NEAR 07N88W TO LOW PRES NEAR 10N110W TO 07N125W TO 12N136W 
TO 10N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION N OF 
01N E OF 82W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
WITHIN 120 NM OF 10N110W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION FROM 06N TO 11N W OF 137W.

...DISCUSSION...

SURFACE HIGH PRESSURE 1019 MB IS CENTERED NEAR 24N121W WITH 
RIDGE EXTENDING WEST TO PAST 23N140W AND SE TO 18N109W. A 
SURFACE COLD FRONT EXTENDS FROM 30N135W TO 28N140W WITH SW WINDS 
OF 20 TO 25 KT FOUND WITHIN 300 NM E OF THE FRONT AND SEAS TO 11 
FT IN NW SWELL WEST OF THE FRONT. SEVERAL SECONDARY SURGES WILL 
PUSH THE NORTHERN SEGMENT OF THE FRONT E TO THE NORTHERN BAJA 
CALIFORNIA PENINSULA AROUND THE MIDDLE OF NEXT WEEK FOLLOWED BY 
SEAS TO 14 FT IN NW SWELL.  

A LOW LEVEL TROUGH EXTENDS FROM 14N134W TO 10N130W WITH ACTIVE 
CONVECTION AND NE TRADES TO 20 KT WITHIN 240 NM W OF TROUGH. 
EXPECT THE TROUGH TO CONTINUE SHIFTING W OF 140W WITHIN 48 
HOURS. 
 
GAP WINDS...A WEAK COLD FRONT WILL MOVE SE THROUGH THE WESTERN 
GULF OF MEXICO TONIGHT WITH 20 TO 25 KT NORTHERLY WINDS SURGING 
THROUGH THE CHIVELA PASS AND INTO THE GULF OF TEHUANTEPEC LATE 
TONIGHT. GUIDANCE NOW SUGGESTS SOUTHERLY RETURN FLOW WILL 
QUICKLY BECOME ESTABLISHED OVER THE GULF OF MEXICO ON SUN 
DIMINISHING THE THE N WINDS IN THE GULF OF TEHUANTEPEC TO LESS 
THAN 20 KT SUN NIGHT.  

$$
AL