000
AXPZ20 KNHC 082346
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE JAN 08 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 
2130 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 04N78W TO 09N85W TO 07N90W THEN ITCZ 
CONTINUES THROUGH 06N110W TO 09N140W. SCATTERED MODERATE WITHIN 
60-120 NM OF THE AXIS BETWEEN 110W AND 123W...AND FROM 09N TO 
13N W OF 135W.

...DISCUSSION...
HIGHLY AMPLIFIED PATTERN IN PLACE OVER THE DISCUSSION AREA WHICH 
FEATURES A CUT-OFF LOW SPINNING OVER N-CENTRAL MEXICO NEAR 
28N107W. THE UPPER LOW IS DIVING SSE AND WAS EMBEDDED WITHIN 
A LARGER LONGWAVE DEEP TROUGH WHICH COVERS THE EAST PACIFIC 
BETWEEN 100W AND 120W. AXIS OF SUBTROPICAL JET-STREAM WITH 
MAXIMUM WINDS OF 110-130 KT ROUNDS THE BASE OF THE LOW AND 
TROUGH SOUTH OF BAJA CALIFORNIA AND TURNS NNE ACROSS MAINLAND 
MEXICO INTO CENTRAL TEXAS. NEGATIVELY TILTED RIDGE EXTENDS FROM 
08N125W TO BEYOND 30N135W WITH A COUPLED NEGATIVELY TILTED 
TROUGH EXTENDING FROM JUST E OF THE HAWAIIAN ISLANDS TO 07N135W. 
STRONGLY DIFFLUENT UPPER FLOW WAS ENHANCING CONVECTION AND
THUNDERSTORMS ALONG AND WELL N OF THE ITCZ W OF 120W AND FANNING 
THE MID TO UPPER LEVEL MOISTURE NORTHEAST ACROSS THE AREA N OF 
10N W OF 120W...EXCEPT ACROSS THE FAR NE CORNER WHERE STRONG 
SUBSIDENCE WAS OCCURRING ON THE BACKSIDE OF THE TROUGH OVER THE 
EAST PACIFIC. AN UPPER-LEVEL TROUGH OVER THE WESTERN CARIBBEAN 
AND NORTHERN CENTRAL AMERICA EXTENDS INTO THE EPAC WATERS TO 
NEAR 5N90W. 

FRESH TO STRONG N-NE TRADES WINDS ASSOCIATED WITH A 1030 MB 
SUBTROPICAL HIGH CENTERED NEAR 34N132W PREVAIL ACROSS MOST OF 
THE AREA N OF THE ITCZ W OF 117W. AN 1818 UTC ASCAT PASS 
CONFIRMED THE PRESENCE OF THESE WINDS WITH AN AREA OF STEADY 
25...AND LOCALLY 30 KT WINDS FROM 10N TO 15N W OF 135W. AN 
ADDITIONAL AREA OF FRESH NW TO N WINDS ARE ALSO NOTED JUST OFF 
THE BAJA CALIFORNIA PENINSULA ROUGHLY FROM 23N TO 27N AND E OF 
116W. THE HIGH PRES WILL WEAKEN WED AS A COLD FRONT APPROACHES 
THE WEST COAST OF THE CONUS. EVEN STRONGER HIGH PRES WILL 
DEVELOP BEHIND THE COLD FRONT NEAR 40N142W BY THU MORNING. THIS 
WILL CREATE A VERY TIGHT PRES GRADIENT BETWEEN THE HIGH AND 
LOWER PRESSURE ALONG THE ITCZ...RESULTING IN A BROAD AREA OF 20 
TO 30 KT NE-E WINDS AND BUILDING SEAS 8 TO 14 FT W OF 120W THU 
THROUGH SAT. THIS VERY STRONG HIGH PRES...1040-1042 MB...WILL 
ALSO INDUCE GALE FORCE NW WINDS ALONG THE CALIFORNIA COAST THU 
AFTERNOON THROUGH EARLY SAT...GENERATING LARGE N-NW SWELL THAT 
WILL SPREAD SOUTHWARD W OF THE BAJA CALIFORNIA PENINSULA...WITH 
SEAS BUILDING TO 13-15 FT N OF 27N BY FRI.

GAP WINDS...
WINDS CONTINUE TO DIMINISH IN THE GULF OF TEHUANTEPEC. THE EDGE 
OF A 1638 UTC ASCAT PASS EDGED ABOUT 90 NM FROM THE GULF OF 
TEHUANTEPEC INDICATED WINDS HAVE DROPPED OFF TO LIGHT AND 
VARIABLE THERE...SUGGESTING THE GAP WIND EVENT MAY HAVE ENDED.  

FRESH WINDS EXPECTED TO PULSE DOWNSTREAM FROM THE GULF OF 
PAPAGAYO THROUGH THU AS WESTERN CARIBBEAN TRADES REMAIN NEAR 
GALE FORCE. STRONGEST WINDS WILL OCCUR LATE AT NIGHT AND EARLY 
MORNING HOURS WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE 
FLOW. 

A TIGHT PRES GRADIENT ACROSS NW MEXICO WILL SUPPORT FRESH TO
STRONG NW WINDS IN THE GULF OF CALIFORNIA THROUGH THIS EVENING.

$$
COBB