000
AXPZ20 KNHC 160336
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT FEB 16 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...
THE MONSOON TROUGH AXIS IS NOT DISCERNIBLE ON THE 0000 UTC MAP. 
THE ITCZ EXTENDS FROM 08N98W TO 06N108W TO 08N122W TO 03N136W TO 
03N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...
THE HIGH PRES RIDGE ACROSS THE NE PACIFIC CONTINUES TO WEAKEN 
THIS EVENING...CENTERED ON A 1032 MB HIGH NEAR 36N138W AND 
EXTENDING A RIDGE AXIS SE THROUGH 30N130W TO 23N114W. THE 
PRESSURE GRADIENT BETWEEN THIS RIDGE AND THE ITCZ CONTINUES TO 
SUPPORT A BROAD AREA OF 20-25 KT TRADE WINDS N OF THE ITCZ FROM 
N OF 05N TO LINE FROM 22N140W TO 17N129W AND FROM 07N TO 15N 
BETWEEN 124W AND 139W...WHERE SEAS ARE RUNNING 8 TO 12 FT IN 
MIXED NE AND NW SWELL. THE HIGH WILL WEAKEN FURTHER AS IT SHIFTS 
SOUTHWESTWARD...EVENTUALLY MERGING WITH HIGH PRESSURE BEHIND A 
COLD FRONT FORECAST TO MOVE N OF AREA OVERNIGHT. THIS WILL 
WEAKEN THE RIDGING OVER THE FORECAST WATERS AND CAUSE THE AREA 
OF STRONG TRADES TO GRADUALLY SHIFT WESTWARD AND DIMINISH TO A 
FRESH TO STRONG NE BREEZE THROUGH SUN MORNING. 

A WEAKENING UPPER TROUGH REMAINS NEARLY STATIONARY OVER THE NW 
CORNER OF FORECAST AREA...WHILE A BROAD AND ENERGETIC UPPER 
TROUGH SHIFTING SE ACROSS THE HAWAIIAN ISLANDS APPROACHES SW 
PORTIONS OF THE LOCAL AREA. UPPER RIDGING S OF 22N AND W OF 125W 
DOMINATES SE PORTIONS. A BROAD 80-110 KT UPPER JET IS ON THE E 
SIDE OF THE TROUGHS AND RIDES OVER THE RIDGE FROM 17N130W 
THROUGH 24N120W THEN EASTWARD ACROSS BAJA CALIFORNIA AND THE N 
HALF OF MEXICO. THESE STRONG WINDS ARE TRANSPORTING ABUNDANT MID 
TO UPPER LEVEL MOISTURE FROM THE ITCZ NEAR 130W ACROSS BAJA 
CALIFORNIA PENINSULA AND N MEXICO AND ACROSS N PORTIONS OF THE 
GULF OF MEXICO.  

GAP WINDS...
GULF OF CALIFORNIA...THE STRONG PRESSURE GRADIENT BETWEEN THE NE 
PACIFIC RIDGE AND TROUGHING OVER NORTHERN MAINLAND MEXICO IS 
RESULTING IN FRESH TO STRONG N-NW WINDS ACROSS THE NORTH AND 
CENTRAL PORTIONS OF THE GULF. THE PRES GRADIENT IS FORECAST TO 
REMAIN STRONG EVEN AS THE SUBTROPICAL RIDGE WEAKENS. A FRESH TO 
STRONG BREEZE IS FORECAST TO CONTINUE UNTIL LATE SAT MORNING 
WITH WINDS OF 20 KT OR LESS SAT EVENING. 

GULF OF TEHUANTEPEC...ATTENTION REMAINS FOCUSED ON THE NEXT GULF 
OF TEHUANTEPEC STRONG GAP WIND EVENT...FORECAST TO BE THE SECOND 
STORM FORCE WIND EVENT THIS YEAR. A REINFORCING COLD FRONT WILL 
QUICKLY MOVE ACROSS THE GULF OF MEXICO OVERNIGHT TONIGHT 
FOLLOWED BY STRONG NLY WINDS. THESE WINDS WILL FUNNEL THROUGH 
THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC...AND WILL QUICKLY 
INCREASE TO GALE FORCE BY SAT AFTERNOON THEN TO STORM FORCE BY 
SAT EVENING. THE STORM FORCE WINDS AREA EXPECTED TO PERSIST 
THROUGH SUN MORNING BEFORE DIMINISHING TO GALE...WITH GALES 
PERSISTING THROUGH SUN EVENING. A GALE WARNING IS IN EFFECT 
BEGINNING AT 16/1800 UTC FOLLOWED BY STORM WARNING AT 17/0000 
UTC. WAVEWATCH MODEL GUIDANCE SUGGESTS THAT SEAS WILL BUILD TO 
15-24 FT IN ASSOCIATION WITH THESE STRONG WINDS LATE SAT NIGHT 
THROUGH EARLY SUN.

GULF OF PAPAGAYO...STRENGTHENING HIGH PRESSURE OVER THE GULF OF 
MEXICO AND NW CARIBBEAN WILL INCREASE THE PRESSURE GRADIENT 
BETWEEN THIS RIDGING AND LOWER PRESSURE TO THE SW ALONG THE ITCZ 
TO YIELD FRESH TO STRONG NE WINDS IN THE GULF OF PAPAGAYO SAT 
NIGHT THROUGH EARLY SUN...INCREASING TO 25-30 KT BY SUNRISE 
SUN.  

$$
STRIPLING