000
AXPZ20 KNHC 140341
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU FEB 14 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM NEAR 01N87W TO 06N97W TO 
04.5N102W TO 06N106W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING 
ON TO 08N112W TO 05N123W TO BEYOND 05N140W. SCATTERED TO 
NUMEROUS MODERATE TO STRONG CONVECTION NOTED FROM 05N TO 14N W 
OF 129W. 

...DISCUSSION...
A STRONGLY TILTED MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE 
CENTRAL U.S. SW TO FAR W TEXAS...WITH A BROAD BASE THEN 
EXTENDING S INTO NRN MEXICO. SHORTWAVE ENERGY SWEEPING THROUGH 
THE BACKSIDE OF THE TROUGH IS EXPECTED TO SHIFT THE TROUGH 
FURTHER EAST TONIGHT AND THU AND GRADUALLY BE REPLACED BY UPPER 
LEVEL RIDGING ANCHORING OVER THE NW FORECAST WATERS. AT THE 
SURFACE...A STRONG PRESSURE GRADIENT BETWEEN A 1037 MB HIGH OVER 
THE NE PACIFIC AND TROUGHING OVER NORTHERN MAINLAND MEXICO IS 
DRIVING FRESH TO STRONG N-NW WINDS DOWN THE LENGTH OF THE GULF 
OF CALIFORNIA TO AS FAR SOUTH AS 18N BETWEEN 105W AND 109W...AND 
WAS CAPTURED BY AN AFTERNOON ASCAT PASS AROUND 1730 UTC SHOWING 
20-25 KT WINDS THROUGH CENTRAL AND S PORTIONS. THE LONG FETCH 
DOWN THE GULF HAS ALLOWED SEAS TO BUILD TO 9 FT...AND AS WINDS 
CONTINUE TONIGHT...WITH LIKELY BUILD 9-10 FT ACROSS S CENTRAL 
PORTIONS. THE 1037 MB HIGH CURRENTLY CENTERED NEAR 39N135W WILL 
REMAIN STATIONARY UNTIL THURSDAY WHEN IT IS FORECAST TO WEAKEN 
AND SHIFT NORTHEASTWARD. WINDS AND SEAS WILL DIMINISH IN THE 
GULF OF CALIFORNIA THURSDAY AFTERNOON AND NIGHT AS THE PRESSURE 
GRADIENT RELAXES...THEN BUILD IN ACROSS N PORTIONS OF THE GULF 
FRIDAY AS THE PRES GRADIENT INCREASES FROM THE NE.

A DEEP LAYERED CYCLONE IS CENTERED WEST OF THE AREA NEAR 24N144W 
AND IS EMBEDDED IN A HIGH AMPLITUDE MIDDLE TO UPPER TROUGH 
EXTENDING S-SW INTO THE DEEP TROPICS. A SURFACE TROUGH IS 
REFLECTED BELOW THE UPPER LOW AND REMAINS JUST W OF THE AREA. A 
SERIES OF LOW TO MIDDLE LEVEL PERTURBATIONS ALONG THE ITCZ WERE 
SHIFTING W BETWEEN 125W AND 140W. THE PRES GRADIENT BETWEEN THE 
STRONG NE PACIFIC RIDGE AND THE ITCZ THERE WAS GENERATING A 
LARGE AREA OF FRESH TO STRONG TRADE WINDS FROM 07N TO A LINE 
FROM 14N116W TO 21N140W...WITH THE ASSOCIATED LOW LEVEL 
CONVERGENCE INDUCING SCATTERED TO NUMEROUS SHOWERS AND 
THUNDERSTORMS FROM 05N TO 14NW OF 129W. THIS CONVECTION WAS 
BEING ENHANCED BY THE BROAD SCALE LIFT OCCURRING TO THE E AND SE 
OF THE UPPER TROUGH...AND SPREADING ABUNDANT HIGH CLOUDS 
NORTHEASTWARD. THESE MINOR WAVES ALONG THE ITCZ WILL CONTINUE TO 
SHIFT W DURING THE NEXT 48 HOURS AND INTERACT FAVORABLY WITH THE 
E MOVING UPPER TROUGH TO MAINTAIN VERY ACTIVE CONVECTION E OF 
THE UPPER TROUGH. GLOBAL MODELS SUGGEST THAT THE AREA OF STRONG 
TRADES WILL SHRINK IN COVERAGE AS THE NE PACIFIC HIGH SHIFTS NE. 
HOWEVER WINDS BETWEEN THE ITCZ AND 14N AND FROM 130W TO 140W ARE 
EXPECTED TO INCREASE TO 25-30 KT THURSDAY...AS SEAS BUILD TO 
10-14 FT.  

GAP WINDS...
GULF OF TEHUANTEPEC...NORTHERLY WINDS BEHIND A COLD FRONT MOVING 
THROUGH THE SW GULF OF MEXICO THU WILL SQUEEZE THROUGH THE 
CHIVELA PASS AND BEGIN TO GENERATE FRESH N WINDS IN THE GULF OF 
TEHUANTEPEC BY EARLY FRI MORNING. HIGH PRESSURE BUILDING ACROSS 
THE GULF OF MEXICO FRI NIGHT AND SAT WILL STRENGTHEN THE GAP 
WINDS THROUGH TEHUANTEPEC...WITH GALES EXPECTED BY LATE SAT 
AFTERNOON OR EVENING. 

$$
STRIPLING