000
AXPZ20 KNHC 101543
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN FEB 10 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 
1530 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 04N88W TO 04N105W TO 
08N120W. THE ITCZ AXIS WAS ANALYZED FROM 08N120W TO 04N140W. NO 
SIGNIFICANT CONVECTION WAS NOTED.

...DISCUSSION...
A DEEP LAYER RIDGE IS BUILDING OVER THE FAR NE PACIFIC OFF THE 
OR/WA COAST...N OF A SHARP UPPER TROUGH EXTENDING FROM THE 
NORTHERN PLAINS THROUGH THE CENTRAL ROCKIES AND SOUTHERN 
CALIFORNIA TO ROUGHLY 35N130W. THIS BLOCKING PATTERN IS 
PREVENTING A VIGOROUS UPPER LOW NEAR 37N145W FROM PROGRESSING 
EASTWARD. THIS IS ALSO STALLING AN ASSOCIATED COLD FRONT PASSING 
E OF 142W WITH A TRAILING STATIONARY FRONT AND SHEAR LINE TO THE 
HAWAIIAN ISLANDS. 

THIS BASIC PATTERN REMAINS UNCHANGED THROUGH THE NEXT 48 
HOURS...WITH THE MAIN INFLUENCE ON MARINE WEATHER W OF 110W 
REMAINING THE DOMINATE RIDGE N OF THE AREA OVER THE NE PACIFIC. 
LATEST SCATTEROMETER AND ALTIMETER DATA INDICATE THAT GENERALLY 
MODERATE TO FRESH WINDS PREVAIL OVER THE AREA...EVEN IN THE 
TRADE BELT S OF 15N...ALTHOUGH WINDS TO 20 KT WERE NOTED ALONG 
THE COAST OF CENTRAL BAJA EARLIER. THE CONSENSUS OF WAVE MODEL 
INITIALIZATIONS INDICATES AN EARLIER TRAIN OF NW SWELL WITH 
HEIGHTS GREATER THAN 8 FT AND PERIODS AROUND 12 SECONDS COVERS 
MOST OF THE AREA N OF 10N W OF 110W. THE SWATH OF DATA FROM 
ALTIMETERS SHOWED SEAS OF 8 TO 11 FT ALONG 128W N OF 
20N...LIKELY TOO FAR EAST TO CAPTURE SOMEWHAT HIGHER VALUES 
PROPAGATING INTO THE AREA FROM THE NW IN REINFORCING PUSH OF NW 
SWELL. 

BY MID WEEK...THE RIDGE TO THE NORTH BUILDS AND SHIFTS 
SOUTH...ALLOWING TRADE WINDS BETWEEN ROUGHLY 10N AND 18N W OF 
120W TO INCREASE TO AS MUCH AS 20 TO 25 KT BY WED. NW SWELL WILL 
PERSIST BUT START TO MIX WITH EMERGENT SHORTER PERIOD NE SWELL 
OVER THE AREA OF THE STRONGER TRADE WINDS. 

GAP WINDS...
RIDGING OVER THE WESTERN ATLANTIC IS MAINTAINING ENOUGH OF A 
GRADIENT TO SUPPORT FRESH TO STRONG FLOW THROUGH THE GULF OF 
PAPAGAYO. THE STRONGER WINDS PULSE DURING THE OVERNIGHT AND 
EARLY MORNING HOURS WHEN DRAINAGE IS STRONGEST...THEN DIMINISH 
DURING LATE MORNING INTO THE EARLY EVENING. SEAS WILL BRIEFLY 
BUILD AS MUCH AS 8 FT DURING THE LATTER STAGES OF THESE STRONG 
PULSES. 

SIMILARLY MODERATE TO FRESH WINDS WILL CONTINUE INTO THE GULF OF 
PANAMA...EFFECTIVELY PUSHING THE MONSOON TROUGH FARTHER TO THE 
SOUTH TO NEAR 04N...OR ELIMINATING IT ALTOGETHER IN FAVOR OF A 
MORE CONFLUENT ITCZ PATTERN. GLOBAL MODELS INDICATE WINDS 
UPSTREAM IN THE SW CARIBBEAN WILL WEAKEN AND BACK MORE TO THE 
EAST OVER THE NEXT DAY OR SO...ALLOWING THE GAP WINDS IN THE 
GULF OF PANAMA TO DIMINISH.

LOOKING AHEAD...EXTENDED RANGE GUIDANCE INDICATES GAP WINDS 
THROUGH THE GULF OF TEHUANTEPEC WILL START TO INCREASE BY LATE 
FRI AS A STRONG COLD FRONT MOVES THROUGH THE WESTERN GULF OF 
MEXICO.

$$
CHRISTENSEN