000
AXPZ20 KNHC 231549
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI DEC 23 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM 09N78W TO 06N94W. THE ITCZ 
AXIS EXTENDS FROM 06N94W TO 10N112W TO 09N125W TO BEYOND 
08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED 
WITHIN 90 NM OF AXIS W OF 125W. 

...DISCUSSION...

GULF OF CALIFORNIA...1043 MB HIGH PRESS OVER N CENTRAL NEVADA 
WITHIN AN AREA OF OVERALL HIGH PRESS IN THE GREAT BASIN IS 
PROMOTING STRONG NORTHERLY FLOW DOWN THE LENGTH OF THE GULF OF 
CALIFORNIA. AN EARLIER 0412 UTC ASCAT PASS INDICATED 30 KT FLOW 
OVER THE NORTHERN GULF OF CALIFORNIA AND GIVEN THE LOW BIAS OF 
ASCAT WINDS...IT IS LIKELY GALE FORCE WINDS ARE OCCURRING OVER 
THE N CENTRAL GULF OF CALIFORNIA. IN ADDITION...THE STRONG 
GRADIENT FLOW ACROSS THE GULF OF CALIFORNIA WILL SPILL OVER SOME 
OF THE GAPS ON THE BAJA PENINSULA...WITH CERTAIN AREAS OF WINDS 
TO 30 KT ALONG THE PACIFIC COAST OF BAJA THROUGH FRI. THE 
RIDGING OVER THE GREAT BASIN WILL WEAKEN SLIGHTLY AS A SHORT 
WAVE TROUGH MIGRATES N OF THE RIDGE THROUGH THE NORTHERN 
ROCKIES...ALLOWING WINDS OVER THE GULF OF CALIFORNIA TO START TO 
DIMINISH BY LATE SAT AND SUN. 

GULF OF TEHUANTEPEC...COLD AIR MOVING THROUGH THE GULF OF MEXICO 
IS PUSHING THROUGH THE CHIVELA PASS AND ENTERING THE GULF OF 
TEHUANTEPEC. AN EARLIER 0408 UTC PASS SHOWED 20 KT N FLOW IN THE 
GULF OF TEHUANTEPEC. A SHIP WITH CALL SIGN ABQH5 REPORTED NLY 
WINDS OF 26 KT IN THE GULF OF TEHUANTEPEC AT 1200 UTC. WINDS ARE 
FORECAST TO REACH GALE FORCE OVERNIGHT TONIGHT INTO SAT AS HIGH 
PRES BEGINS TO EMERGE IN THE SOUTHERN PLAINS...WHICH WILL 
INCREASE THE WINDS FUNNELING INTO THE GULF OF TEHUANTEPEC. THIS 
WILL DIMINISH SLIGHTLY THROUGH SAT AS THE COLD HIGH PRES TO THE 
NORTH WEAKENS AND MODIFIES. WINDS WILL INCREASE AGAIN 
SUN...POSSIBLY TO GALE FORCE...AS ANOTHER SURGE OF COLD AIR 
MOVES THROUGH THE WESTERN GULF OF MEXICO AND INTO THE 
TEHUANTEPEC AREA. 

GULF OF PAPAGAYO...FRESH TRADEWINDS OVER THE WESTERN CARIBBEAN 
WILL FUNNEL INTO THE GULF OF PAPAGAYO. WINDS WILL PEAK DURING 
THE EARLY MORNING HOURS WITH THE ADDITION OF NOCTURNALLY DRIVEN 
KATABATIC WINDS.

ELSEWHERE W OF 110W...A 06 UTC ASCAT PASS SHOWED A BROAD SWATH 
OF 20 TO 25 KT NE TRADE WINDS GENERALLY FROM 12N TO 23N W OF 
115W...S OF A 1030 MB SURFACE HIGH PRES CENTERED NEAR 40N130W. 
THE WEAK SURFACE TROUGH FROM 14N118W TO 08N121W EARLIER HAS 
BECOME DIFFUSE AND ALIGNED PARALLEL TO THE ITCZ WITH LITTLE 
DIFFERENTIATION IN THE WIND FIELD AHEAD OF AND BEHIND THE TROUGH 
AXIS. ALTIMETER PASSES OVER THE PAST 12 HOURS INDICATE SEAS TO 9 
FT IN THE AREA OF FRESH TRADE WINDS...PRIMARILY IN MIXED NW AND 
NE SWELL. THE UPPER PATTERN WILL BECOME MORE AMPLIFIED OVER THE 
NEXT 24 TO 48 HOURS...ALLOWING THE HIGH PRES N OF THE AREA TO 
BUILD. AS A RESULT TRADE WIND FLOW WILL INCREASE SLIGHTLY THIS 
WEEKEND WITH MIXED SEAS BUILDING TO 12-13 FT. MEANWHILE...TRADE 
WIND CONVERGENCE AT THE SURFACE ALONG WITH UPPER LEVEL DIVERGENT 
FLOW IS SUPPORTING SCATTERED CONVECTION ALONG THE ITCZ W OF 125W.

$$
COBB