000
AXPZ20 KNHC 132205
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED FEB 13 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 09N84W TO 05N91W TO 
05N107W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 
05N107W TO 05N140W. ISOLATED MODERATE CONVECTION IS WITHIN 150 
NM NORTH AND 90 NM SOUTH OF THE AXIS BETWEEN 119W AND 140W.

...DISCUSSION...
A STRONGLY TILTED MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE 
CENTRAL U.S. PLAINS THROUGH CENTRAL BAJA CALIFORNIA TO A BASE IN 
THE NE FORECAST WATERS NEAR 24N112W AND IS EXPECTED TO SHIFT 
FURTHER EAST THIS EVENING AND GRADUALLY BE REPLACED BY UPPER 
LEVEL RIDGING ANCHORED OVER THE NW FORECAST WATERS BETWEEN 120W 
AND 135W. AT THE SURFACE...THE STRONG PRESSURE GRADIENT BETWEEN 
THE NE PACIFIC RIDGE AND TROUGHING OVER NORTHERN MAINLAND MEXICO 
DUE TO THE COLD FRONT ASSOCIATED WITH THIS TROUGH ALOFT IS 
FORCING FRESH TO STRONG N-NW WINDS DOWN THE LENGTH OF THE GULF 
OF CALIFORNIA TO AS FAR SOUTH AS 18N BETWEEN 105W AND 109W. A 
RECENT AFTERNOON ASCAT PASS AROUND 1730 UTC CAPTURED THESE 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 1039 MB HIGH CURRENTLY CENTERED NEAR 38.5N135W WILL REMAIN 
STATIONARY UNTIL THURSDAY WHEN IT IS FORECAST TO WEAKEN AND 
SHIFT NORTHEASTWARD. WINDS AND SEAS WILL DIMINISH IN THE GULF OF 
CALIFORNIA BY THURSDAY AFTERNOON AS THE PRESSURE GRADIENT 
RELAXES...THEN BUILD IN ACROSS N PORTIONS OF THE GULF FRIDAY AS 
THE PRES GRADIENT INCREASES FROM THE E.

AN UPPER LEVEL LOW CENTERED WEST OF THE AREA NEAR 25N144.5W 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 THREE 
LOW TO MIDDLE LEVEL PERTURBATIONS ALONG THE ITCZ WERE SHIFTING W 
BETWEEN 126W 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. THESE MINOR WAVES ALONG THE ITCZ WILL CONTINUE TO SHIFT 
W DURING THE NEXT 48 HOURS...AND GLOBAL MODELS SUGGEST THAT THE 
AREA OF STRONG TRADES WILL SHRINK IN COVERAGE...BUT WINDS 
BETWEEN 130W AND 130W WILL INCREASE TO 20-30 KT...AND 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 GENERATE FRESH TO STRONG N WINDS IN THE GULF OF 
TEHUANTEPEC BY EARLY FRI MORNING. 

$$
STRIPLING