000
AXPZ20 KNHC 161602
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI DEC 16 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...

MONSOON TROUGH AXIS CROSSES CENTRAL AMERICA AND ENTERS EPAC NEAR 
10N85W TO 08N91W TO 08N101W WHERE IT TRANSITIONS TO ITCZ... 
CONTINUING ON TO 08N132W TO BEYOND 07N140W. SCATTERED MODERATE 
CONVECTION NOTED S OF TROUGH AXIS...N OF 06N TO PANAMA AND E OF 
85W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 
90 NM OF AXIS W OF 130W. 

...DISCUSSION...

AN UPPER CYCLONE DRIFTING SLOWLY SE OVER THE SW U.S. AND EXTREME 
NW MEXICO WILL BECOME NEARLY STATIONARY AND DEEPEN THROUGH 
36-48 HRS BEFORE BEGINNING TO SHIFT SLOWLY E LATE SUN AND 
MONDAY. AN ASSOCIATED WEAK FRONTAL TROUGH CURRENTLY LIES FROM 
30N117W TO 26N120W TO 24N129W WITH NW TO N WINDS 20 TO 25 KT AND 
SEAS 8 TO 10 FT BEHIND FRONT. THIS FRONTAL TROUGH WILL CONTINUE 
SOUTHEASTWARD AND MOVE TO JUST OFFSHORE OF THE BAJA PENINSULA 
THROUGH SAT MORNING. SHOWERS AND NW WINDS TO 20 KT ASSOCIATED 
WITH THE CYCLONE WILL PRIMARILY IMPACT THE NORTHERN GULF OF 
CALIFORNIA AND BAJA CALIFORNIA NORTE...WITH WINDS EXPECTED TO 
DIMINISH BY SAT MORNING AFTER THE FRONTAL TROUGH AT THE SURFACE 
BEGINS ILL DEFINED.

A WEAK UPPER LOW LIES NEAR 27N137W. THIS LOW IS EXPECTED TO 
UNRAVEL WITH ITS REMAINS MOVING EASTWARD AS A WEAK DEEP LAYER 
TROUGH APPROACHES IT FROM THE W TONIGHT. WHAT REMAINS OF THE LOW 
WILL BECOME CAPTURED IN THE FLOW AROUND THE SOUTHERN EDGE OF THE 
DEEP UPPER LOW OVER THE SW U.S./NW MEXICO ON SAT. A DISSIPATING 
COLD FRONT ASSOCIATED WITH THE AFOREMENTIONED WEAKENING DEEP 
LAYER TROUGH WILL APPROACH NW WATERS SAT AND USHER IN A PULSE OF 
NW SWELL...WITH SEAS REACHING 10-12 FEET OVERNIGHT SAT NIGHT 
GENERALLY IN THE AREA N OF 20N W OF 130W. THE FRONT WILL WEAKEN 
THE SUBTROPICAL HIGH PRES OVER NW WATERS AND CAUSE TRADE WINDS 
TO SHRINK WESTWARD OVER THE NEXT 24-48 HOURS.

MOISTURE IS POOLED ALONG THE ITCZ/MONSOON TROUGH AXIS WITH 
PRECIPITABLE WATER VALUES HIGHEST ALONG THE EASTERN EDGE OF THE 
AXIS E OF 90W. UPPER LEVEL DIFFLUENCE ASSOCIATED WITH 
ANTICYCLONIC FLOW ALOFT ACROSS THIS AREA CONTINUES TO ENHANCE 
CONVECTION INVOF THE MONSOON TROUGH...OVER PANAMA...COSTA RICA 
AND THE GULF OF PANAMA. THESE CONDITIONS ARE NOT EXPECTED TO 
CHANGE MUCH OVER THE NEXT FEW DAYS.

GAP WINDS...
GULF OF TEHUANTEPEC...THE FORECAST GUIDANCE AGREES ON BRINGING N 
TO NE WINDS TO GALE FORCE IN THE GULF OF TEHUANTEPEC BY SAT 
NIGHT. WHILE THERE IS NO STRONG...PROGRESSIVE COLD FRONT 
EXPECTED TO SWEEP THROUGH THE GULF OF MEXICO TO INCREASE WINDS 
THROUGH THE ISTHMUS OF TEHUANTEPEC...THE BUILDING PRES GRADIENT 
BETWEEN HIGH PRES PASSING SE OVER THE SOUTHERN PLAINS AND LOWER 
MISSISSIPPI VALLEY AND LOWER PRES ALONG THE MONSOON TROUGH TO 
THE S WILL BE ENOUGH TO INITIATE GALE FORCE WINDS. LOOK FOR 
FRESH TO STRONG N WINDS BEGINNING TONIGHT TO PRECEDE THE GALE. 

GULF OF PAPAGAYO...THE BUILDING PRES GRADIENT OVER SOUTHERN 
MEXICO WILL EXTEND S TO THE GULF OF PAPAGAYO BY EARLY SAT 
MORNING WITH FRESH NE WINDS EXPECTED THERE...WITH LATEST MODEL 
GUIDANCE SUGGESTING A LARGE AND STRONG PLUME OF NELY WINDS TO 
DEVELOP BY SUN MORNING AND EXTEND N ALONG THE NICARAGUAN COAST 
TO THE GULF OF FONSECA. GIVEN THIS SCENARIO...SEAS COULD BUILD 
TO 10 FT DOWNWIND OF PAPAGAYO BY LATE SUN MORNING.

$$
STRIPLING