000
AXPZ20 KNHC 180941
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURES...

FOR THE GULF OF TEHUANTEPEC...A 03 UTC ASCAT PASS INDICATED 
WINDS JUST BELOW GALE FORCE. GIVEN ADDITIONAL OVERNIGHT DRAINAGE 
EFFECTS...WINDS MAY STILL REACH GALE FORCE IN THE NEAR SHORE 
WATERS THROUGH EARLY MORNING AND THEREFORE THE GALE WARNING 
REMAINS IN EFFECT THROUGH 12 UTC. ALTHOUGH GRADUALLY 
WEAKENING...THE PRES AND TEMPERATURE GRADIENT BETWEEN THE GULF 
OF MEXICO AND GULF OF TEHUANTEPEC WILL REMAIN STRONG ENOUGH TO 
SUPPORT STRONG GAP WINDS THROUGH LATE MORNING. WINDS WILL 
DIMINISH INTO THE AFTERNOON AS THE AIRMASS N OF THE AREA 
MODIFIES AND THE STRONG HIGH PRES CONTINUES TO SHIFT 
EAST...EASING THE PRES GRADIENT. WITH WINDS DIMINISHING...SEAS 
WILL SUBSIDE ACCORDINGLY TO BELOW 6 FT WITHIN 300 NM DOWNSTREAM 
OF THE AREA...WITH LARGER NE TO E DOWNSTREAM SWELL MIXING WITH E 
SWELL ORIGINATING OUT OF THE GULF OF PAPAGAYO.

FOR THE GULF OF PAPAGAYO...EARLIER DATA AT THE EDGE OF AN 17 UTC 
OSCAT PASS HINTED THAT WINDS HAD ALREADY REACHING GALE FORCE 
WITHIN THE PLUME 150 NM WSW OF THE GULF OF PAPAGAYO 
AREA...ALTHOUGH THE DATA WERE AMBIGUOUS. THE SURGE OF NORTHERLY 
WINDS BEHIND A STRONG COLD FRONT MOVING DEEP INTO THE SW 
CARIBBEAN HAVE ONLY RECENTLY REACHED THE LATITUDE OF 
PAPAGAYO...SUGGESTING THAT GAP WINDS ARE ONLY RECENTLY STARTING 
TO INCREASE. LATEST REPORTS FROM LIBERIA COSTA 
RICA...MRLB...ALSO SHOW INCREASED FLOW ONLY STARTING AROUND 05 
UTC AND WINDS TO GALE FORCE IN THE PAPAGAYO AREA ARE ASSUMED TO 
HAVE INITIATED BY 06 UTC. WW3 AND ECMWF INDICATE A LARGE 
DOWNSTREAM PLUME OF EASTERLY SWELL WITH SEAS UP TO 11 FT TODAY 
WILL PERSIST THROUGH LATE TUE AS FAR AS 1000 NM 
DOWNSTREAM...MIXING IN PART WITH NE TO E SWELL LINGERING FROM 
THE STORM AND GALE FORCE WINDS IN THE GULF OF TEHUANTEPEC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
NO MONSOON TROUGH DISCERNIBLE FOR 06Z ANALYSIS. ITCZ EXTENDS 
FROM 03N93W TO 07N135W TO BEYOND 07N140W. SCATTERED MODERATE 
CONVECTION NOTED WITHIN 120 NM N ITCZ W OF 135W.

...DISCUSSION...

A STRONG UPPER DISTURBANCE IS PUSHING THROUGH THE NE PACIFIC N 
OF THE AREA...COMING INTO PHASE AND REINFORCING A STALLED 
ELONGATED TROUGH EXTENDING FROM SOUTHERN CALIFORNIA TO A UPPER 
LOW ABOUT 480 NM NE OF THE BIG ISLAND OF HAWAII NEAR 24N148W. 
THIS UPPER DISTURBANCE WILL DIG ACROSS SOUTHERN CALIFORNIA 
THROUGH MID WEEK...SUPPORTING A COLD FRONT PASSAGE ACROSS 
NORTHERN BAJA AND THE NORTHERN PORTION OF THE GULF OF 
CALIFORNIA. EXPECT MODERATE TO FRESH SW TO W FLOW OFF THE COAST 
OF NORTHERN BAJA AND THE NORTHERN GULF OF CALIFORNIA TUE INTO 
WED.

THE UPPER LOW OFF THE BIG ISLAND WILL BECOME CUTOFF 
FROM THE TROUGH...AND REMAIN ANCHORED S OF A DEEP LAYER RIDGE 
ALONG 150W WELL N OF HAWAII. THE ASSOCIATED 1037 MB SURFACE HIGH 
WILL CONTINUE TO MAINTAIN FRESH TO STRONG TRADES W OF 125W N OF 
THE ITCZ THROUGH MID WEEK. FARTHER SOUTH...A SPLIT FLOW UPPER 
PATTERN IS EVIDENT ABOVE THE ITCZ W OF 130W. MOISTURE LEVELS 
REMAIN HIGH IN THIS AREA...AND THE COMBINATION OF LOW LEVEL 
CONVERGENCE ALONG THE ITCZ AND UPPER DIFFLUENT FLOW IS RESULTING 
IN SCATTERED CONVECTION WITHIN 120 NM N OF THE ITCZ W OF 135W. 
GLOBAL MODELS INDICATED A LOW AMPLITUDE SURFACE TROUGH FORMING 
IN THIS AREA WITHIN 24 HOURS...FURTHER ENHANCING TRADE WIND 
FLOW. 

PULSES OF NW SWELL CONTINUE TO PROPAGATE INTO THE REGIONAL 
WATERS...AND WILL MAINTAIN SEAS 8 FT AND HIGHER MAINLY W OF 110W 
OF THE AREA THROUGH TUE...MIXING WITH FRESH NE SWELL IN THE AREA 
OF STRONG TRADES W OF 125W. 

$$
CHRISTENSEN