000
AXPZ20 KNHC 111546
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON FEB 11 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 02N85W TO 05N110W. 
ITCZ AXIS WAS ANALYZED FROM 05N110W TO 07N128W THEN CONTINUES 
FROM 05N132W TO 03N140W. A TROUGH LIES ALONG 130W FROM 03N TO 
08N. THERE IS NO SIGNIFICANT DEEP CONVECTION NOTED OVER THE 
FORECAST AREA. 

...DISCUSSION...
A SHEAR UPPER TROUGH EXTENDS FROM AN UPPER LOW OVER THE CENTRAL 
ROCKIES ACROSS SOUTHERN CALIFORNIA...WESTWARD ALONG 28N THEN TO 
A STALLING AND WEAKENING CUT OFF UPPER LOW NEAR 32N143W. AN 
UPPER DISTURBANCE IS DIGGING INTO THE BASE OF THE TROUGH OVER 
THE SW UNITED STATES...SUPPORTING A 1013 MB SURFACE LOW OVER 
SOUTHERN ARIZONA AND MODERATE TO FRESH WESTERLY FLOW ACROSS THE 
NORTHERN PORTION OF THE GULF OF CALIFORNIA.

A SECOND WEAKER UPPER LOW IS RAPIDLY LOSING DEFINITION AND 
BECOMING ELONGATED AS IT MOVES INTO THE HIGHLY SHEARED UPPER 
TROUGH AXIS NEAR 27N125W. THE UPPER LOW NEAR 32N143W IS BLOCKED 
FROM MOVING EAST BY A DEEP LAYER RIDGE BUILDING N OF THE AREA. 
AN ASSOCIATED AND VERY WEAK 1022 MB SURFACE LOW IS ANALYZED NEAR 
31N142W. SCATTEROMETER DATA CONFIRM THAT THERE IS ENOUGH OF PRES 
GRADIENT TO SUPPORT STRONG FLOW NW OF THE DISCUSSION AREA 
BETWEEN THE LOW PRES AND A 1032 MB HIGH PRES FARTHER TO THE NE. 
THE MAIN IMPACT OF ALL OF THIS ON THE DISCUSSION AREA S OF 32N 
AND W OF 140W IS THE PREVALENCE OF NW SWELL ACROSS THE REGION. 
ALTIMETER DATA SHOW SEAS OF 8 FT OR GREATER PRIMARILY IN NW 
SWELL HAVE OVERTAKEN MOST OF THE AREA W OF 110W AND N OF 10N. 

BY MIDWEEK...THE DEEP LAYER LOW PRES TO THE WEST WILL WEAKEN AND 
THE RIDGING N OF THE AREA WILL BUILD. THIS WILL ALLOW TRADE WIND 
FLOW MAINLY FROM 10N TO 20N W OF 115W TO INCREASE TO 20 TO 25 KT 
IN PLACES. 

GAP WINDS...
GULF OF PAPAGAYO...THE INCREASED PRESSURE GRADIENT BETWEEN THE 
MONSOON TROUGH TO THE S AND RIDGING OVER THE NW CARIBBEAN HAS 
INCREASED THE NE TRADE WIND FLOW THROUGH CENTRAL AMERICA TO A 
FRESH TO STRONG BREEZE IN THE GULF OF PAPAGAYO. THESE WINDS WILL 
CONTINUE TO PULSE TO 25 KT THROUGH EARLY TUE...WITH THE 
STRONGEST WINDS EXPECTED IN THE EARLY MORNING HOURS WHEN 
DRAINAGE FLOW OFF THE LAND IS AT A MAXIMUM. SEAS WILL BRIEFLY 
BUILD TO AS MUCH AS 8 FT IN THE STRONGEST WINDS. RIDGING IN THE 
CARIBBEAN WILL WEAKEN TUE...SLACKENING THE PRESSURE GRADIENT AND 
DIMINISHING WINDS THROUGH CENTRAL AMERICA. 

LOOKING AHEAD...THE GFS HAS BACKED OFF CONSIDERABLY INTRODUCING 
STRONG GAP FLOW FRI THROUGH THE GULF OF TEHUANTEPEC AND IS MORE 
IN LINE WITH THE ECMWF SHOWING MAINLY MODERATE TO FRESH WINDS.

$$
CHRISTENSEN