East Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 151543
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI FEB 15 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...
THE MONSOON TROUGH AXIS IS NO DISCERNIBLE ON THE 1200 UTC MAP. 
THE ITCZ EXTENDS FROM A 1009 MB LOW PRES 09N97W TO 06N108W TO 
08N118W TO 04N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...
THE 1032 MB SUBTROPICAL HIGH NEAR 41N134W EXTENDS A RIDGE AXIS 
SOUTHWARD THROUGH 30N135W TO 19N110W. THE PRESSURE GRADIENT 
BETWEEN THIS RIDGE AND THE ITCZ IS STILL STRONG ENOUGH TO 
SUPPORT 20-30 KT WINDS N OF THE ITCZ MAINLY FROM 04N TO 15N W OF 
130W AND FROM 07N TO 13N BETWEEN 115W AND 130W. THE SUBTROPICAL 
HIGH WILL WEAKEN AS IT SHIFTS SOUTHWESTWARD...EVENTUALLY MERGING 
WITH HIGH PRESSURE BEHIND A COLD FRONT FORECAST TO MOVE N OF 
AREA OVERNIGHT TONIGHT. THIS WILL WEAKEN THE RIDGING OVER THE 
FORECAST WATERS AND CAUSE TRADES TO GRADUALLY SHIFT WESTWARD AND 
DIMINISH TO A FRESH TO STRONG NE BREEZE THROUGH SUN MORNING. 

AN UPPER TROUGH LIES OVER THE NW CORNER OF FORECAST AREA. A 
110-130 KT UPPER JET IS ON THE E SIDE OF THE TROUGH FROM 19N134W 
THROUGH 30N124W THEN EAST-SOUTHEASTWARD INTO NW MEXICO. THESE 
STRONG WINDS ARE TRANSPORTING ABUNDANT MID TO UPPER LEVEL 
MOISTURE FROM THE ITCZ NEAR 130W ALL THE WAY NE INTO THE BAJA 
CALIFORNIA PENINSULA AND NW MEXICO.  

GAP WINDS...
GULF OF CALIFORNIA...THE STRONG PRESSURE GRADIENT BETWEEN THE 
SUBTROPICAL RIDGE AND TROUGHING OVER NORTHERN MAINLAND MEXICO IS 
RESULTING IN FRESH TO STRONG N-NW WINDS ACROSS THE CENTRAL 
PORTION 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 WIND EVENT...FORECAST TO BE THE SECOND STORM 
FORCE GAP 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. THIS EVENT IS EXPECTED TO PERSIST THROUGH SUN 
MORNING. A GALE WARNING IS IN EFFECT BEGINNING AT 16/1800 UTC 
FOLLOWED BY STORM WARNING AT 17/0000 UTC. SEAS ARE EXPECTED TO 
BUILD IN EXCESS OF 15-20 FT IN ASSOCIATION WITH THESE STRONG 
WINDS BY 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 BY 
EARLY SUN MORNING.  

$$
GR