000
AXPZ20 KNHC 281533
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU OCT 28 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 1315 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 09N84W TO 
10N90W TO 09N100W TO LOW PRES 13N120W TO 08N140W. SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION WAS WITHIN 150 NM 
EITHER SIDE OF THE ITCZ AXIS BETWEEN 91W AND 96W. SCATTERED 
MODERATE WAS WITHIN 60 NM N OF THE ITCZ AXIS BETWEEN 120W AND 
123W AS WELL AS WITHIN 120 NM N OF THE ITCZ AXIS W OF 134W.

...DISCUSSION...

A HIGHLY AMPLIFIED NORTHERN STREAM PATTERN HAS BROUGHT A COLD 
FRONT INTO NW WATERS FROM 30N132W TO 26N140W. SCATTERED SHOWERS 
LIE OVER THE FAR NW CORNER OF THE FORECAST AREA BEHIND THE 
FRONT. WINDS ABOVE 20 KT ARE NOT EXPECTED WITH THIS FRONT...BUT 
IT HAS USHERED IN NW SWELL CURRENTLY TO 9 FT. THE FRONT WILL 
WEAKEN AS IT CONTINUES SOUTHEASTWARD OVER THE NEXT TWO DAYS AND 
SEAS WILL BUILD AS HIGH AS 15 FT BY FRI MORNING OVER N CENTRAL 
WATERS.

A 1012 MB SURFACE LOW IS EMBEDDED IN THE ITCZ NEAR 13N120W AND 
IS MOVING W AROUND 5 KT. SCATTERED MODERATE CONVECTION NEAR THE 
LOW IS SKEWED INTO ITS SW QUADRANT JUST N OF THE ITCZ. THE 0558 
UTC ASCAT PASS SHOWED NO HINT OF 20 KT WINDS ON THE WESTERN 
SEMICIRCLE OF THE LOW. THE FORECAST GUIDANCE AGREES ON WINDS TO 
20 KT ON THE EASTERN SIDE OF THE LOW THAT WILL MIGRATE N OF THE 
LOW FRI AND SAT AS IT PASSES S OF THE HIGH PRES RIDGE TO THE N. 
A 1016 MB HIGH CURRENTLY SITS NEAR 25N129W AND WILL BE SHOVED E 
BY THE COLD FRONT OVER NW WATERS DURING THE NEXT FEW DAYS. THE 
LOW CURRENTLY LIES IN AN AREA OF NW SWELL. SEAS IN THE 8 TO 10 
FT RANGE CAN BE FOUND N OF THE LOW TO 30N...BUT THIS SWELL WILL 
BE DECAYING THROUGH THE DAY TODAY AND FRI AS IT PROGRESSES TO 
THE S AND CLOSER TO THE LOW. 

UPPER LEVEL DIFFLUENCE BETWEEN AN ANTICYCLONE NEAR 16N93W AND AN 
INVERTED UPPER TROUGH ALONG 96W S OF 06N HAS ENHANCED THE 
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION SEEN NEAR THE 
ITCZ S OF TEHUANTEPEC. UPPER LEVEL DIFFLUENCE HAS ALSO ENHANCED 
THE SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION JUST S OF 
THE GULF OF PANAMA E OF 82W FROM 04N TO 07N. THE FORECAST 
GUIDANCE HAS SW WINDS TO 20 KT IN BOTH OF THESE AREAS THIS 
MORNING...BUT THERE ARE NO OBSERVATIONS TO SUPPORT WINDS THAT 
STRONG. THE MODELS ALSO DIMINISH WINDS BELOW 20 KT IN BOTH AREAS 
BY TOMORROW. THE HIGH SEAS FORECAST DOES NOT MENTION 20 KT WINDS 
IN THESE AREAS BECAUSE OF THE LACK OF CONFIRMATION...BUT THE 
WINDS AND SEAS COULD BE HIGH LOCALLY WITHIN THE ACTIVE 
THUNDERSTORM ACTIVITY.

GAP WINDS...
NORTHERLY WINDS ARE EXPECTED TO SURGE ACROSS THE ISTHMUS OF 
TEHUANTEPEC BEHIND A COLD FRONT THAT WILL RAPIDLY MOVE S ACROSS 
THE WESTERN GULF OF MEXICO TODAY. WINDS ARE EXPECTED TO REACH 
GALE FORCE AROUND SUNSET. WINDS WILL INCREASE TO 40 KT OVERNIGHT 
FRI NIGHT AND SEAS ARE EXPECTED TO BUILD AS HIGH AS 14 FT 
THROUGH SAT MORNING.

$$
SCHAUER