000
AXPZ20 KNHC 021524
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC WED JAN 02 2013

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 
1400 UTC.

...SPECIAL FEATURE...                                         
GULF OF TEHUANTEPEC STORM WARNING...A COLD AIR MASS WILL RACE 
THROUGH CHIVELA PASS LATER TODAY...BRINGING A STRONG BREEZE TO 
THE GULF OF TEHUANTEPEC BY AFTERNOON...GALE FORCE WINDS BY 
EVENING...AND STORM FORCE WINDS OVERNIGHT. SEAS WILL RAPIDLY 
BUILD FROM 10 FT TO 20 FT OVERNIGHT. SEA SURFACE TEMPERATURES 
WITHIN 100 NM OF THE COAST ARE 27 DEGREES CELSIUS OR WARMER. THE 
WARM OCEAN SHOULD HELP MIX THE STRONG WINDS WITHIN THE COLD AIR 
ALOFT DOWN TO THE SURFACE OVER THE GULF OF TEHUANTEPEC. NOCTURNAL 
DRAINAGE FLOW WILL ALSO ENHANCE THE WINDS OVERNIGHT. STORM FORCE 
WINDS ARE EXPECTED TO END AFTER SUNRISE FRI AND WINDS WILL 
GRADUALLY DIMINISH BELOW GALE FORCE JUST AFTER THE FORECAST 
PERIOD ENDS SAT MORNING AS THE DRIVING HIGH PRESSURE TO THE N 
SHIFTS EASTWARD...WEAKENING THE PRESSURE GRADIENT.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 07N77W TO 05N79W TO 
08N86W TO 04N101W. ITCZ AXIS WAS ANALYZED FROM 04N101W TO 
09N135W TO 08N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION WAS WITHIN 150 NM N OF THE AXIS BETWEEN 120W AND 130W 
WHILE SCATTERED MODERATE CONVECTION WAS TO THE W WITHIN 300 NM N 
AND 150 NM S OF THE AXIS BETWEEN 130W AND 138W.

...DISCUSSION...                                               
STRONGLY DIFFLUENT FLOW ALOFT IS ENHANCING LIFT NEAR THE ITCZ 
OVER WESTERN FORECAST WATERS WHERE PRECIPITABLE WATER VALUES ARE 
IN EXCESS OF 50 MILLIMETERS. CONVECTION IN PLACE HERE IS 
DESCRIBED IN THE SECTION ABOVE AND SCATTERED TO NUMEROUS SHOWERS 
AND MULTI-LAYERED CLOUDS EXTEND N OF THE AREA OF CONVECTION OVER 
MUCH OF THE FORECAST REGION W OF 125W. THE UPPER PATTERN IS 
BECOMING MORE PROGRESSIVE. THE AREA OF DIFFLUENCE ALOFT 
SUPPORTING THIS LIFT AND ENHANCING THE CONVECTION WILL BE 
SHIFTING EASTWARD ALONG THE ITCZ OVER THE NEXT DAY OR SO AS A 
RESULT. 

A 1024 MB SUBTROPICAL HIGH NEAR 35N131W IS DRIVING THE MODERATE 
TO FRESH TRADE WINDS FOUND PRIMARILY FROM 08N TO 20N W OF 115W. 
DECAYING LONG-PERIOD NW SWELL DOMINATES WESTERN WATERS WHERE IT 
IS MIXING WITH FRESH NE WIND WAVES ASSOCIATED WITH THE TRADE 
WINDS. A NEW BATH OF NW SWELL ASSOCIATED WITH A COLD FRONT 
APPROACHING THE AREA SAT MORNING HAS MOVED AHEAD OF THE FRONT 
AND IS BEGINNING TO PASS INTO NW WATERS. THIS NEW BATCH OF SWELL 
WILL NOT BE ENOUGH TO MAINTAIN THE CURRENT AREA OF SEAS OVER 8 
FT WHICH IS EXPECTED TO SHRINK AND REMAIN CONFINED W OF 120W 
THROUGH FRI BEFORE SUBSIDING BELOW 8 FT EARLY SAT. 

A NEGATIVELY TILTED UPPER TROUGH WILL APPROACH NW WATERS AT THE 
END OF THE FORECAST PERIOD SAT MORNING...SENDING A REASONABLY 
STRONG COLD FRONT AT THE SURFACE TOWARD THE FORECAST AREA. 
SOUTHERLY WINDS AHEAD OF THE FRONT WILL BECOME A FRESH BREEZE 
AND SEAS WILL BEGIN TO BUILD...BUT CONDITIONS ARE EXPECTED TO 
REMAIN BELOW ADVISORY CRITERIA THROUGH SUNRISE SAT.

GULF OF PAPAGAYO...STRONG TRADE WIND FLOW IN THE SW CARIBBEAN 
AND LOCAL OVERNIGHT DRAINAGE FLOW HAS BROUGHT A STRONG NE BREEZE 
TO THE GULF OF PAPAGAYO THIS MORNING. THE 0336 UTC ASCAT PASS 
CONFIRMED THESE CONDITIONS EVEN BEFORE THE PEAK DRAINAGE PERIOD. 
THESE WINDS AND SEAS WILL DIMINISH LATER TODAY...BUT PULSE UP TO 
25 KT AGAIN OVERNIGHT TONIGHT AND FRI NIGHT.
 
$$ 
SCHAUER