000
AXPZ20 KNHC 180343
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON FEB 18 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 
0300 UTC.

...SPECIAL FEATURE...
STRONG NORTH TO NORTHEAST WINDS ACROSS THE SOUTHEAST GULF OF 
MEXICO AND WESTERN CARIBBEAN PERSIST THIS EVENING...BEHIND A 
STRONG COLD FRONT IN THE WESTERN CARIBBEAN. STORM FORCE WINDS  
THROUGH THE GULF OF TEHUANTEPEC HAVE DIMINISHED BELOW STORM 
FORCE THIS AFTERNOON...AND ARE ESTIMATED TO BLOWING 30 TO 35 KT 
THROUGH AND DOWNSTREAM OF TEHUANTEPEC THIS EVENING...TO NEAR 
97W. THIS "NORTERO" ACROSS CENTRAL AMERICA IS ALSO DRIVING WINDS 
TO NEAR 30 KT THROUGH AND DOWNSTREAM OF THE GULF OF PAPAGAYO... 
WERE A 1716 UTC OSCAT PASS SHOWED 25-30 KT NE WINDS THIS 
AFTERNOON. GLOBAL MODELS GUIDANCE IS IN GENERAL AGREEMENT THAT 
THIS STRONG COLD NORTHERLY FLOW WILL INDUCE GALES TONIGHT 
THROUGH THE GULF OF PAPAGAYO AND DOWNSTREAM TO NEAR 
90W...STARTING AROUND 0600 UTC...A VERY UNUSUAL EVENT. THESE 
GALES ARE LIKELY TO LAST UNTIL THE MORNING HOURS...BEFORE 
ABATING BELOW GALE FORCE BY MID MORNING. MINIMAL GALES WILL 
PERSIST OVERNIGHT THROUGH THE GULF OF TEHUANTEPEC...AND ABATE 
BELOW GALE FORCE AROUND SUNRISE. A VERY LARGE AREA OF CONFUSED 
AND HIGH SEAS WILL BE GENERATED BY THIS BROAD SCALE REGIONAL 
EVENT...WITH SEAS 8 TO 12 FT IN A MIX OF N AND NE SWELL...FROM 
04N TO 14N E OF 108W...WHICH WILL IMPACT THE N AND NE COASTS OF 
THE GALAPAGOS ISLANDS DURING THE DAY MONDAY.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
NO MONSOON TROUGH DISCERNIBLE FOR 00Z ANALYSIS. ITCZ EXTENDS 
FROM 06N87W TO 02N97W TO 07N116W TO 06N140W. SCATTERED TO 
LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION NOTED WITHIN 210 
NM N AND 90 NM S OF ITCZ W OF 131W.

...DISCUSSION...
A COMPLEX SERIES OF UPPER LEVEL TROUGHS AND SHORTWAVES ACROSS 
THE CENTRAL AND NE PACIFIC THE PAST FEW DAYS HAS MERGED INTO A 
LONGWAVE TROUGH EXTENDING FROM THE NW U.S. SOUTHWESTWARD ACROSS 
THE NW CORNER OF THE DISCUSSION AREA TO AND ELONGATED WEAKENING 
VORTEX IN THE BASE OF THIS TROUGH JUST OFF THE N COAST OF THE 
BIG ISLAND OF HAWAII. BROAD SCALE RIDGING PREVAILS ACROSS MOST 
OF THE REMAINDER OF THE DISCUSSION AREA SOUTHEAST OF THIS 
FEATURE...EXCEPT FOR AN EQUATORIAL UPPER TROUGH FROM 14N114W TO 
02N110W. A BROAD ZONE OF WEST TO SOUTHWEST FLOW OVER THE RIDGE 
EXTENDS FROM S OF THE HAWAIIAN ISLANDS INTO BAJA CALIFORNIA AND 
N MEXICO...WITH JET CORE OF 75-110 KT CURRENTLY ENTERING FAR 
BAJA CALIFORNIA NORTE...EXTREME NW MEXICO AND INTO THE DESERT SW 
OF THE U.S. 

AT THE SURFACE...THE E PACIFIC HIGH PRES RIDGE HAS REORGANIZED 
OVER THE E CENTRAL PACIFIC WELL N OF THE HAWAIIANS ISLANDS 
EXTENDING SE TO NEAR 23N116W. THE PRESSURE GRADIENT BETWEEN THE 
RIDGE AND THE ITCZ IS MAINTAINING FRESH TO STRONG NE TRADEWINDS 
ACROSS SW PORTIONS OF THE AREA...WITH ASSOCIATED LOW LEVEL 
CONVERGENCE INDUCING AN AREA OF MODERATE TO STRONG CONVECTION 
DESCRIBED ABOVE. DIFFLUENT UPPER LEVEL FLOW ACROSS THIS AREA 
AIDING IN THE DEEP CONVECTION HAS CREATED A LARGER SEAM IN THE 
UPPER FLOW...INDUCING STRONG UPPER DIVERGENCE ACROSS THIS AREA.

ELSEWHERE...PULSES OF NWLY SWELL CONTINUE TO PROPAGATE INTO THE 
REGIONAL WATERS...AND WILL MAINTAIN SEAS 8 FT AND HIGHER ACROSS 
THE THIRD OF THE AREA THROUGH TUE.

$$
STRIPLING