000
AXPZ20 KNHC 190946
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT JAN 19 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 FROM 09N83W TO 07N89W THEN ITCZ TO 05N98W TO 
09N122W TO 08N140W.  SCATTERED MODERATE CONVECTION WITHIN 120 NM 
OF AXIS FROM 116W TO 119W.

...DISCUSSION...
NEGATIVELY TILTED UPPER LEVEL TROUGH FROM 36N130W TO 32N129W TO 
DEVELOPING WEAK UPPER LEVEL CYCLONE NEAR 28N128W BRINGING MINOR 
INSTABILITY TO REGION.  MODEL GUIDANCE DRIFTS CYCLONE ALONG 30N 
INTO NORTHERN BAJA CALIFORNIA WITH SCATTERED MODERATE CONVECTION 
MAINLY IN ITS EASTERN SEMICIRCLE DUE TO DIVERGENT FLOW ALOFT. 
MID/UPPER LEVEL RIDGE E OF CYCLONE BRING ABUNDANT MOISTURE 
STREAMING ACROSS NRN AND CENTRAL MEXICO AND FURTHER NE INTO SW 
CONUS.  LONGWAVE UPPER LEVEL TROUGH W OF AREA AT 149W HAS SERIES 
OF SHORTWAVES ROTATING ITS BASE SUPPORTING ADVANCING COLD FRONT 
JUST W OF AREA NEAR 143W N OF 20N.

MUCH STRONGER DEEP LAYER CYCLONE MOVES INTO BASIN SUN DRAGGING 
VIGOROUS SURFACE LOW PRES 1003 MB ACROSS 26N140W WITH ATTENDANT 
COLD FRONT.  LOW PRES 1005 MB MOVES SE TO 27N140W WITH NEAR GALE 
FORCE WINDS IN NE QUADRANT AND SEAS ABOVE 20 FT LATE IN FORECAST 
PERIOD.  SCATTERED MODERATE CONVECTION ALONG AND WITHIN 240 NM E 
OF FRONT.  BROAD MID/UPPER LEVEL ANTICYCLONE CREST S OF 10N W OF 
95W PROMPTS DIFFLUENT FLOW ALOFT WITH AFOREMENTIONED TROUGH AND
ENHANCE BROKEN MULTILAYERED CLOUDS AND SCATTERED MODERATE 
CONVECTION FROM 10N TO 13N BETWEEN 105W AND 112W.

ELSEWHERE AT THE SURFACE...VERY TIGHT PRES GRADIENT ACROSS 
CENTRAL AND SRN MEXICO BRINGS STRONG WIND THROUGH CHIVELA PASS 
BECOMING STORM FORCE WIND IN GULF OF TEHUANTEPEC...OBSERVED TO 
50 KT AND AS EVIDENCED BY EARLIER OSCAT PASS.  MODEL GUIDANCE 
EXTEND STORM FORCE CONDITIONS THROUGH TONIGHT INTO EARLY SAT 
DIMINISHING TO GALE THROUGH SUN THEN TO VERY STRONG TO NEAR-GALE 
CONDITIONS BEYOND TUE.  

GULF OF PAPAGAYO ALSO HAVE STRONG PERSISTENT NE WINDS THROUGH 
MON THAT EXTEND FAR DOWNWIND FROM SOURCE REGIONS RESULTING IN 
VERY LARGE AREA OF NE SWELL THROUGH TONIGHT EXTENDING FROM 05N 
TO 14N E OF 113W.  STRONG N TO NE BREEZE SURGE THROUGH GULF OF 
PANAMA CONTINUE WITH LITTLE CHANGE INTO EARLY NEXT WEEK.

LARGE VERY LONG PERIOD NW SWELLS ENCROACH INTO E PAC W OF 110W 
THROUGH FORECAST PERIOD.  SWELLS SPREAD SE WITH LITTLE CHANGE IN 
WAVE PERIOD IMPACTING MAINLY BAJA CALIFORNIA PENINSULA WITH 
LARGE WAVE HEIGHTS AND BEACH EROSION.

$$
WALLY BARNES