000
AXPZ20 KNHC 031533
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC FRI JAN 03 2014

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...THE ASCAT-B PASS FROM 0410 
UTC THIS MORNING HAD WINDS TO 45 KT IN THE GULF OF TEHUANTEPEC. 
GIVEN THE LOW BIAS IN THE ASCAT INSTRUMENTS AT THAT WIND SPEED 
AND THE TIME OF THE PASS PRIOR TO THE PERIOD OF PEAK NOCTURNAL 
DRAINAGE FLOW...THE STORM WARNING SEEMS TO BE ON TARGET. A 
SUBSEQUENT OSCAT PASS AT 0636 UTC SHOWED 45 KT BARBS AS FAR S AS 
13.8N 95.2W...APPROXIMATELY 140 NM S OF THE GULF OF TEHUANTEPEC. 
AT 1200 UTC SHIP SMGW REPORTED GALE CONDITIONS AND 9 FT SEAS 
NEAR 13.5N 94.4W...TO THE E OF THE SWATH OF STRONGEST WINDS. 
MODEL GUIDANCE SUGGESTS THAT STORM CONDITIONS WILL LINGER UNTIL 
THROUGH AFTERNOON. THIS SEEMS REASONABLE GIVEN THE STRENGTH OF 
THE COLD AIR ADVECTION. WINDS WILL GRADUALLY DIMINISH BELOW GALE 
FORCE AFTER SUNRISE SAT MORNING AS THE DRIVING HIGH PRESSURE TO 
THE N SHIFTS EASTWARD...WEAKENING THE PRESSURE GRADIENT. WINDS 
IN THE GULF OF TEHUANTEPEC WILL DIMINISH BELOW A STRONG BREEZE 
BY SUNSET SAT...BUT SEAS OVER 8 FT IN NE SWELL FROM THE EVENT 
WILL CONTINUE TO PROPAGATE WESTWARD...SPANNING FROM 02N TO 12N 
BETWEEN 100W AND 113W BY SUN MORNING.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 07N77W TO 05N80W TO 
05N102W. THE ITCZ AXIS WAS ANALYZED FROM 05N102W TO 09N135W TO 
10N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 210 NM N OF 
THE AXIS BETWEEN 116W AND 129W AND WITHIN 90 NM S OF THE AXIS 
BETWEEN 121W AND 127W. 

...DISCUSSION...                                                
A SOUTHERLY JET ALOFT LIES ON THE E SIDE OF AN UPPER TROUGH 
ALONG 135W. DIFFLUENT FLOW ALOFT IN THE REAR RIGHT QUADRANT OF 
THE JET IS ENHANCING LIFT NEAR THE ITCZ 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 BETWEEN 120W AND 
135W. THE AREA OF DIFFLUENCE ALOFT SUPPORTING THIS LIFT AND 
ENHANCING THE CONVECTION WILL BE SHIFTING NORTHEASTWARD OVER THE 
NEXT DAY OR SO AS THE UPPER PATTERN PROGRESSES. 

A NEGATIVELY TILTED UPPER TROUGH IS SLOWLY APPROACHING NW WATERS 
AND WILL SEND A REASONABLY STRONG COLD FRONT AT THE SURFACE INTO 
THE FORECAST AREA EARLY SUN. SOUTHERLY WINDS AHEAD OF THE FRONT 
WILL BECOME A FRESH TO STRONG BREEZE AND SEAS WILL BUILD TO OVER 
8 FT BEFORE SUNSET SAT...WITH SEAS BUILDING TO 10 FT BY SUN 
MORNING.

A 1022 MB SUBTROPICAL HIGH NEAR 37N131W IS DRIVING THE MAINLY 
MODERATE TRADE WINDS FOUND N OF THE ITCZ TO 25N W OF 115W. NW 
SWELL CONTINUES TO DOMINATE WESTERN WATERS WHERE IT IS MIXING 
WITH NE WIND WAVES ASSOCIATED WITH THE TRADE WINDS. A NEW BATCH 
OF NW SWELL ASSOCIATED WITH THE COLD FRONT APPROACHING THE AREA 
WILL NOT BE ENOUGH TO MAINTAIN THE CURRENT AREA OF SEAS OVER 8 
FT WHICH IS EXPECTED TO SHRINK AND REMAIN CONFINED W OF 123W 
THROUGH TODAY BEFORE SUBSIDING BELOW 8 FT EARLY SAT. 

GULF OF PAPAGAYO...THE BUILDING PRESSURE GRADIENT BETWEEN HIGH 
PRESSURE TO THE N BEHIND THE FRONT BRINGING STORM CONDITIONS TO 
THE GULF OF TEHUANTEPEC AND THE MONSOON TROUGH TO THE S IN 
ADDITION TO OVERNIGHT DRAINAGE FLOW HAS INDUCED A STRONG NE 
BREEZE IN THE GULF OF PAPAGAYO THIS MORNING. A SHIP REPORTED 26 
KT AND 8 FT SEAS AS FAR AS 210 NM DOWNWIND OF THE GULF AT 1200 
UTC THIS MORNING. THESE WINDS AND SEAS WILL DIMINISH LATER 
TODAY...BUT PULSE UP TO 25 KT AGAIN OVERNIGHT TONIGHT. BY SAT 
AFTERNOON...THE PRESSURE GRADIENT SHOULD RELAX ENOUGH TO KEEP 
WINDS BELOW A STRONG BREEZE IN THE GULF OF PAPAGAYO THROUGH THE 
END OF THE FORECAST PERIOD SUN MORNING.

$$ 
SCHAUER