000
AXPZ20 KNHC 011555
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC TUE JAN 01 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 
1430 UTC.

...SPECIAL FEATURE...                                         
GULF OF TEHUANTEPEC STORM WARNING...THE LAST SCATTEROMETER PASS 
IN THE GULF OF TEHUANTEPEC AT 0400 UTC SHOWED GALE TO NEAR GALE 
FORCE WINDS EXTENDING AS FAR AS 100 NM FROM THE COAST PRIOR TO 
THE PERIOD OF MAXIMUM NOCTURNAL DRAINAGE FLOW. AT 1000 
UTC...SHIP ZCDG4 REPORTED WINDS ABOVE GALE FORCE AND 10 FT SEAS 
IN THE GULF NEAR 15.5N 94.7W. THE GALE WARNING IN THE GULF OF 
TEHUANTEPEC WAS EXTENDED UNTIL AFTER SUNRISE THIS MORNING BASED 
ON THESE OBSERVATIONS. THE PRESSURE GRADIENT BETWEEN THE MONSOON 
TROUGH TO THE SOUTH AND RIDGING OVER NE MEXICO WILL WEAKEN TODAY 
WHEN LOW PRESSURE DEEPENS IN THE SW GULF OF MEXICO AND LIFTS 
NORTHWARD. THIS WILL BRING A BRIEF REPRIEVE FROM WARNING 
CONDITIONS BEFORE A STRONG COLD FRONT BARRELS THROUGH CHIVELA 
PASS AROUND MIDDAY THU. THE AFOREMENTIONED REPORT FROM SHIP 
ZCDG4 MEASURED THE SEA SURFACE TEMPERATURE AT 82 DEGREES 
FAHRENHEIT...28 DEGREES CELSIUS. THE WARM OCEAN SHOULD HELP MIX 
THE STRONG WINDS WITHIN THE COLD AIR ALOFT DOWN TO THE SURFACE 
OVER THE GULF OF TEHUANTEPEC. STORM FORCE WINDS ARE EXPECTED IN 
THE REGION STARTING THU NIGHT AND CONTINUING THROUGH AT LEAST 
THE END OF THE FORECAST PERIOD AROUND SUNRISE FRI.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS EXTENDS FROM 06N77W TO 08N85W TO 05N95W 
TO 05N100W. THE ITCZ AXIS EXTENDS FROM 05N100W TO 07N120W TO 
08N128W TO 06N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION LIES WITHIN 60 NM N AND 120 NM S OF THE AXIS E OF 80W 
TO THE COAST OF COLOMBIA. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION IS WITHIN 90 NM N OF THE AXIS BETWEEN 127W AND 
134W WHILE SCATTERED MODERATE CONVECTION IS JUST TO THE W 
BETWEEN 60 NM AND 270 NM N OF THE AXIS BETWEEN 134W AND 139W. 

...DISCUSSION...                                               
THE HIGHLY AMPLIFIED LONG-WAVE UPPER PATTERN OVER THE FORECAST 
AREA IS EXPECTED TO GRADUALLY BECOME MORE PROGRESSIVE OVER THE 
NEXT TWO DAYS. THE PATTERN CURRENTLY FEATURES A TROUGH ALONG 
105W...A RIDGE ALONG 125W...AND AN UPPER TROUGH W OF THE AREA 
CENTERED ALONG 145W. THE SOUTHERN STREAM SOUTHWESTERLY UPPER JET 
MAXIMA ON THE LEADING EDGE OF THESE TROUGHS ARE PUMPING TROPICAL 
MOISTURE NORTHWARD. A SURFACE REFLECTION OF THE EASTERN TROUGH 
LIES FROM CABO CORRIENTES MEXICO TO 13N110W. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION LIES WITHIN 120 NM E AND 60 NM W 
OF THE TROUGH. MOISTURE AHEAD OF THE WESTERN TROUGH IS IMPACTING 
THE AREA W OF 125W AND N OF THE ITCZ...WITH ENHANCED CONVECTION 
ALONG THE ITCZ HERE DESCRIBED IN THE SECTION ABOVE AND SCATTERED 
TO NUMEROUS SHOWERS AND MULTI-LAYERED CLOUDS OVER MUCH OF THE 
REMAINDER OF THAT REGION. THE PATTERN WILL SHIFT E BEGINNING THU 
AS THE EASTERN TROUGH PHASES WITH A NORTHERN STREAM TROUGH THAT 
WILL BRING THE COLD AIR MASS INTO THE GULF OF TEHUANTEPEC.

A 1025 MB SUBTROPICAL HIGH NEAR 34N131W IS DRIVING THE MODERATE 
TO FRESH TRADE WINDS FOUND PRIMARILY FROM 08N TO 23N 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. THE LEADING EDGE OF THIS BATCH OF NW SWELL HAS REACHED 
NEAR MANZANILLO MEXICO THIS MORNING AND IS EXPECTED TO PASS THE 
GALAPAGOS ISLANDS FRI MORNING. SEAS OVER 8 FT ASSOCIATED WITH 
THIS SWELL WILL SHRINK IN AREA AND REMAIN CONFINED W OF 119W 
THROUGH THE END OF THE FORECAST PERIOD FRI MORNING. 

GULF OF PAPAGAYO...SHIP OZHS2 REPORTED 18 KT WINDS AND 10 FT 
SEAS DOWNWIND OF THE GULF OF PAPAGAYO NEAR 10.7N 89.1W AT 1500 
UTC. SCATTEROMETER MISSED THIS AREA THIS MORNING...BUT THE 
COMBINED EFFECT OF STRONG TRADE WIND FLOW IN THE SW CARIBBEAN 
AND LOCAL OVERNIGHT DRAINAGE FLOW HAS LIKELY BROUGHT A STRONG NE 
BREEZE TO THE GULF THIS MORNING. THESE WINDS AND SEAS WILL 
DIMINISH LATER TODAY...BUT PULSE UP TO 25 KT AGAIN OVERNIGHT 
TONIGHT BEFORE DISSIPATING AROUND SUNRISE THU WHEN THE PRESSURE 
GRADIENT OVER THE AREA RELAXES. 

$$ 
SCHAUER