000
AXPZ20 KNHC 240952
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU JAN 24 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0930 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH EXTENDS FROM 09N84W TO 06N91W THEN ITCZ AXIS TO 04N100W 
TO 07N109W TO 05N120W.  NO SIGNIFICANT CONVECTION.

...DISCUSSION...
SHARP UPPER LEVEL TROUGH EXTEND FROM 32N129W TO 13N135W WITH 
VERY DRY SUBSIDING AIR MASS W OF AXIS WHILE ABUNDANT TROPICAL 
MOISTURE ADVECTS N ON E SIDE N OF 20N ALL THE WAY TO MEXICO.  
MID TO UPPER LEVEL DOWNSTREAM RIDGE CREATES REGION OF DIVERGENT 
FLOW ALOFT ENHANCING CONVECTION ALONG AND WITHIN 180 NM E OF 
WEAK SURFACE TROUGH EXTENDING FROMM 1014 MB LOW PRES AT 30N124W 
TO 18N128W.  SECOND AND BROADER UPPER LEVEL TROUGH ALONG 87W S 
OF NICARAGUA MAINTAIN DRY REGION E OF 99W.  

...ELSEWHERE AT THE LOWER LEVELS...
GULF OF TEHUANTEPEC WINDS CONTINUE JUST AT GALE FORCE THRESHOLD 
AND EXPECTED TO DIMINISH BELOW LATE SAT AS 1026 MB HIGH PRES 
OVER NE GULF OF MEXICO DRIFTS E INTO SW N ATLC AND WIND SOURCE 
SHIFT MORE SE EFFECTIVELY CUTTING OFF FUNNELING EFFECT.  

GULFS OF PAPAGAYO AND PANAMA GAP WINDS CONTINUE TO PULSE THROUGH 
SAT AS DOWNSLOPE DRAINAGE NIGHT AND EARLY MORNING AIR ENHANCE NE 
WIND FIELD WHILE AFTERNOON SEABREEZE COUNTERS IT AND DIMINISHES 
RESULTANT WIND.  SEAS BUILD TO 10 FT AS WINDS REACH 20-25 KT 
THEN SUBSIDE IN THE DAYTIME TO BELOW 8 FT.  

ELSEWHERE...LARGE VERY LONG PERIOD NW SWELL CAUSED BY PREVIOUS 
LOW PRES CENTER PROPAGATE ACROSS E PAC TO 100W AND CROSS INTO S 
PAC W OF 98W.  SEAS CONTINUE TO SUBSIDE AS WINDS DIMINISH IN 
RESPONSE TO WEAKENING AND EVENTUAL DISSIPATION OF LOW PRES INTO
AN OPEN SURFACE TROUGH AS IT MOVE N OF BASIN.  HIGH PRES CENTER 
1026 MB REPLACES TROUGH BY LATE SAT THEN STRENGTHENS BEYOND 
FORECAST PERIOD.

$$
WALLY BARNES