000
AXPZ20 KNHC 150337
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI FEB 15 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...
MONSOON TROUGH AXIS EXTENDS FROM 01N92W TO LOW PRES NEAR 
06N96.5W 1009 MB TO 04N102W...WHERE IT TRANSITIONS TO 
ITCZ...CONTINUING ON TO 08N113W TO 06N132W TO 06N132W TO 
04N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 04N 
TO 10N BETWEEN 129W AND 137W. ISOLATED TO SCATTERED MODERATE 
CONVECTION ALOFT WAS POSSIBLE...EMBEDDED IN THE DENSE HIGH 
CLOUDS FROM 10N TO 18N BETWEEN 126W AND 135W.

...DISCUSSION...
QUICKLY WEAKENING MID TO UPPER TROUGH EXTENDS FROM WEAK MID 
LEVEL CYCLONE NEAR 33N1135W S TO 15N138W. A SHARPLY NEGATIVELY 
TILTED UPPER TROUGH EXTENDS FROM THIS PORTION OF THE TROUGH SE 
TO THE EQUATOR ALONG 118W...WITH UPPER DIVERGENCE JUST E OF THIS 
TROUGH AIDING IN MAINTAINING SCATTERED MODERATE TO STRONG 
CONVECTION OCCURRING WITHIN A ZONE OF STRONG TRADEWINDS FROM 07N 
TO 15N W OF 123W. THE NORTHERN PORTION OF THE TROUGH IS SHIFTING 
E AND INDUCING MIDDLE TO UPPER CONVERGENCE NEAR THE ITCZ W OF 
136W AND HAS ACTED TO REDUCE CONVECTION THERE IN THE PAST 
SEVERAL HOURS. A SECOND UPPER TROUGH HAS MOVED SLOWLY S INTO THE 
NORTHERN PORTION OF THE AREA THIS AFTERNOON...AND BECOME NEARLY 
STATIONARY ALONG 33N BETWEEN 120W AND 130W. AN EXTREMELY BROAD 
UPPER DOMINATES ALL OF THE U.S. N OF 35N TONIGHT...WITH A MEAN 
AXIS S OF 40W ALONG 93-95W...EXTENDING S INTO THE GULF OF MEXICO 
N OF 22N. AN UPPER RIDGE EXTENDS FROM AN UPPER ANTICYCLONE AT 
14N113W TO A CREST AT 32N121W...AND HAS MERGED WITH A WEAK UPPER 
RIDGE EXTENDING E TO W ALONG 13N SPANNING THE FAR E PORTIONS AND 
INTO CENTRAL AMERICA.  

AT THE LOW LEVELS...A RIDGE EXTENDS FROM 1036 MB HIGH ACROSS THE 
NE PACIFIC THROUGH 30N130W TO 14N107W. NE TRADES ARE ENHANCED TO 
20 TO 25 KT S OF THE RIDGE FROM 07N TO 16N W OF 123W...WITH 
RECENT AFTERNOON SCATTEROMETER PASSES DEPICTING NE WINDS 25-30 
KT FROM 06.5N TO 10N BETWEEN 127W AND 140W...WHERE ALTIMETER 
PASSES VERIFY SEAS OF 9 TO 13 FT IN MIXING NE AND NW SWELL. THIS 
ENHANCED AREA OF TRADES WILL SHRINK OVER THE NEXT COUPLE OF DAYS 
AS THE RIDGE WEAKENS. NORTHERLY FLOW E OF THE SURFACE RIDGE HAS 
DIMINISHED THROUGH THE GULF OF CALIFORNIA BUT WILL RETURN THIS 
EVENING TO 20 TO 25 KT THROUGH MIDDLE PORTIONS OF THE GULF AND 
GRADUALLY SHIFT INTO N PORTIONS THROUGH SAT.      

GAP WINDS...
GULF OF TEHUANTEPEC...NORTHERLY WINDS BEHIND A COLD FRONT MOVING 
THROUGH THE SOUTHERN GULF OF MEXICO TODAY WILL SQUEEZE THROUGH 
THE CHIVELA PASS AND BEGIN TO GENERATE PULSING FRESH TO STRONG 
N WINDS IN THE GULF OF TEHUANTEPEC FROM AROUND SUNRISE FRI 
MORNING THROUGH FRI NIGHT. HIGH PRESSURE BUILDING ACROSS THE 
GULF OF MEXICO FRI NIGHT WILL STRENGTHEN THE GAP WINDS THROUGH 
TEHUANTEPEC...WITH NORTHERLY GALES EXPECTED BY SUNRISE SAT... 
STRENGTHENING TO STORM STRENGTH BY SAT EVENING...AND CONTINUING 
THROUGH SUNRISE ON SUN. 

$$
STRIPLING