000
AXPZ20 KNHC 201619
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN JAN 20 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 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 08N75W TO 02N80W TO 08N84W TO 07N90W THEN 
ITCZ TO 06N109W TO 07N116W TO 06N126W TO 09N140W.  SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 180 NM OF AXIS FROM 
98W TO 110W.

...DISCUSSION...
SMALL AND WEAK MIDDLE TO UPPER LEVEL CYCLONE NEAR 31N120W 
SHIFTING SLOWLY E...WITH TROUGH S-SE TO 15N114W...AND BEGINNING 
TO LIFT NE OVER SHARP UPPER RIDGE TO E ALONG 95W. UPPER 
DIVERGENCE AT BASE OF TROUGH ACTING TO ENHANCE CONVECTION N OF 
ITCZ BETWEEN 100W AND 111W. SHARP SHORTWAVE RIDGE TO W OF TROUGH 
ALONG 126N AND N OF 18N.  

NEGATIVE TILE LONGWAVE DEEP LAYERED TROUGH EXTENDS FROM NE 
PACIFIC S-SE TO VIGOROUS VORTEX NEAR 25.5N142.5W...WITH TROUGH 
EXTENDING TO BROAD BASE NEAR 11N143W. SATELLITE DERIVED WINDS 
DEPICT 75-100 KT UPPER JET ACROSS SE SEMICIRCLE OF VORTEX. OLD 
COLD FRONTAL BOUNDARY LINGERS AHEAD OF THIS EWD DRIFTING 
LONGWAVE TROUGH...FROM 30N137W TO 20N137W TO 15N140W. BROAD ZONE 
OF UPPER DIVERGENCE E OF TROUGH...AND 136W...CONTINUES TO 
ENHANCE CONVECTION ALONG COLD FRONT...AND LIKELY INDUCING 
ISOLATED AREAS OF GALE FORCE WINDS NEAR DEEPER CONVECTION JUST 
AHEAD OF FRONT...OVERNIGHT THROUGH THIS MORNING. SE TO S WINDS 
20-30 KT PREVAIL WITHIN 300 NM E OF FRONT...WITH GALES OCCURRING 
N OF 30N AND OUT OF DISCUSSION AREA. SURFACE LOW GENERATED BELOW 
UPPER VORTEX NEAR 27N145W 1003 MB MOVING E...WITH TRAILING COLD 
FRONT W OF AREA. LONG WAVE TROUGH AND ATTENDANT SURFACE LOW WILL 
SHIFT GRADUALLY E NEXT 48 HOURS AND REMAIN NEGATIVELY TILTED FOR 
ACTIVE CONVECTION SE SEMICIRCLE...WITH COMPLEX SURFACE LOW 
SHIFTING SLOWLY E TO SE IN UNISON. SLIGHT CHANCE FOR GALES IN 
SMALL ISOLATED AREAS NEAR DEEPER CONVECTION ALONG FRONT...AND 
ALSO ACROSS NW QUAD OF LOW BY TUE. HIGH SEAS OF 10-16 FT WILL 
PERSIST ACROSS THIS NW PORTION OF THE AREA THROUGH TUE AS LARGE 
NW SWELL PROPAGATING THROUGH THE REGION PASSES THROUGH THIS AREA 
OF MIXED SWELL CREATED BY SURFACE LOW.

VERY LONG PERIOD NW SWELL IS CURRENTLY MOVING THROUGH W HALF OF 
DISCUSSION AREA...AND HAS BEGUN TO PEAK ACROSS BAJA CALIFORNIA 
NORTE. BUOY 46047 LOCATED 120 NM W OF SAN DIEGO REPORTED SWELL 
OF 10 FT AND 23 SECONDS LAST NIGHT THAT IS NOW REACHING BAJA 
CALIFORNIA. LONGER PERIOD FORERUNNERS ARE MOVING OFFSHORE OF 
MEXICO AND W PORTIONS OF CENTRAL AMERICA ATTM...AND WILL ALSO 
PEAK IN THE NEXT 48 HOURS. EXPOSED REEFS AND COASTS WITH NW 
EXPOSURE WILL SEE VERY SIGNIFICANT WAVE ENERGY...AND PRODUCE 
VERY STRONG AND POWERFUL SURF...WIDESPREAD RIP CURRENTS...AND 
COASTAL EROSION DURING HIGH TIDES. 

ELSEWHERE AT THE LOW LEVELS...
CONTINUED NORTHEASTERLY WINDS IN SW GULF OF MEXICO ARE MOVING 
ACROSS CHIVELA PASS AND BRINGING GALE FORCE N-NE WINDS INTO GULF 
OF TEHUANTEPEC. WINDS ARE EXPECTED TO DIMINISH THROUGH 
TEHUANTEPEC NEXT 24 HOURS...TO MINIMAL GALES...AND PERSIST 
THROUGH MON NIGHT. NEXT BLAST OF COLD AIR IN GULF OF MEXICO 
INCREASES WINDS AGAIN LATE IN FORECAST PERIOD. 

CURRENT GALE FORCE WINDS OVER SW CARIBBEAN REINFORCE FRESH TO 
STRONG NE WINDS ALONG GULFS OF PAPAGAYO AND FONSECA THROUGH 
FORECAST PERIOD WITH STRONGEST WINDS NOTED IN EARLY MORNINGS AS 
DOWNSLOPE DRAINAGE WINDS ADD STRENGTH TO WIND FIELD. STRONG NE 
WINDS ACROSS SW CARIBBEAN ALSO CONTRIBUTES TO FRESH N BREEZE 
OVER GULF OF PANAMA THROUGH LATE MON.

$$
STRIPLING