000
AXPZ20 KNHC 091546
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI DEC 9 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 
1500 UTC.

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

THE MONSOON TROUGH EXTENDS FROM 10N84W TO 07N90W. THE ITCZ 
EXTENDS FROM 07N90W TO 07N110W TO 10N125W TO 07N140W. NUMEROUS 
MODERATE SCATTERED STRONG CONVECTION IS OCCURRING FROM 07N TO 
14N W OF 134W.

...DISCUSSION...

IN THE UPPER LEVELS...A SHARP TROUGH JUST WEST OF OUR AREA 
EXTENDING FROM 22N146W TO 05N142W IS PROVIDING LIFT FOR THE 
AFOREMENTIONED CONVECTION OCCURRING ALONG THE WESTERN PORTION OF 
THE ITCZ.  SOME CONTINUED DEEP CONVECTION SHOULD BE EXPECTED AS 
THE UPPER TROUGH AND ITCZ INTERACT DURING THE NEXT TWO DAYS.  
BUT THERE IS ALMOST NO POSSIBILITY FOR THIS TO BECOME A TROPICAL 
CYCLONE BECAUSE OF THE STRONG VERTICAL SHEAR AND LACK OF A 
SIGNIFICANT SURFACE DISTURBANCE.  ELSEWHERE...THE TROPICAL NE 
PACIFIC IS DOMINATED BY A LARGE ANTICYCLONE CENTERED NEAR 
14N111W...WHICH IS PROMOTING TYPICALLY SUBSIDENT AND DRY 
CONDITIONS AS WELL AS ADVECTING SOME OF THE UPPER LEVEL MOISTURE 
AND CLOUDINESS FROM THAT CONVECTION TOWARD NW MEXICO.

AT THE SURFACE...A HIGH CENTERED WELL NW OF OUR AREA ALONG WITH 
THE LOW PRESSURE ALONG THE ITCZ IS CAUSING A MODERATE PRESSURE 
GRADIENT AND THUS SOME FRESH NE TO E TRADEWINDS.  THESE SHOULD 
CONTINUE FOR THE NEXT COUPLE OF DAYS.

A GULF OF TEHUANTEPEC GAP WIND EVENT CONTINUES THIS MORNING 
...THOUGH NO OBSERVATIONS IN THE AREA HAVE BEEN AVAILABLE.  IT 
IS LIKELY THAT THE N TO NE WINDS WILL REMAIN BELOW GALE FORCE 
THROUGH SATURDAY MORNING.  HOWEVER...BY SATURDAY AFTERNOON THE 
SURFACE PRESSURE GRADIENT WILL AGAIN BECOME ACCENTUATED AND 
LIKELY CAUSE THE WINDS TO REACH MINIMAL GALE FORCE.  THE 
FORECAST IS BASED UPON A BLEND OF THE GFS...UKMET...AND ECMWF 
MODELS.  IT DOES APPEAR THAT THE WINDS WILL THEN REMAIN AT OR 
JUST BELOW GALE FORCE ALL THE WAY THROUGH WEDNESDAY.  

BOTH THE GULF OF CALIFORNIA AND THE GULF OF PAPAGAYO MAY BRIEFLY 
EXPERIENCE 20 KT SURFACE WINDS.  BUT SINCE THESE ARE NOT 
EXPECTED TO BE OF MORE THAN SIX HOUR DURATION NOR OF LARGE 
SPATIAL EXTENT...THESE ARE NOT INCLUDED IN THE HIGH SEAS 
FORECAST.

LONG-PERIOD NW SWELL JUST ENTERING THE NW CORNER OF OUR AREA 
WILL SPREAD SOUTHEASTWARD DURING THE NEXT COUPLE OF DAYS TO 
COVER ABOUT HALF OF OUR AREA.  HOWEVER...THESE WILL ONLY BE OF 
UP TO 10 FEET SIGNIFICANT WAVE HEIGHT.

$$
LANDSEA