000
AXPZ20 KNHC 212205
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
2205 UTC SAT DEC 21 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...SPECIAL FEATURES...

GULF OF TEHUANTEPEC...THE NEXT GAP WIND EVENT IS EXPECTED TO 
BEGIN MON MORNING WITH N WINDS OF 20-30 KT...AND QUICKLY  
INCREASING TO GALE FORCE DURING THE AFTERNOON HOURS WITH AN 
EXPECTED RANGE OF 30-40 KT. WITH VERY STRONG HIGH PRES RIDGING 
BUILDING SWD BEHIND A COLD FRONT THAT WILL MOVE ACROSS THE 
WESTERN GULF OF MEXICO LATE SUN INTO MON...THE PRES GRADIENT 
OVER SOUTHEASTERN MEXICO AND THE ISTHMUS OF TEHUANTEPEC WILL 
TIGHTEN CONSIDERABLY ALLOWING FOR THE STRONG NLY FLOW TO FUNNEL 
THROUGH THE CHIVELA PASS AND OUT ACROSS THE GULF. LATEST 30M AND 
925 MB WIND GUIDANCE FROM GFS DEPICTS THIS NEXT EVENT TO PEAK AT 
ABOUT 45 KT MON NIGHT INTO TUE. CANNOT RULE OUT POSSIBLE BRIEF 
GUSTS TO 50 KT. SEAS IN THE GULF WILL RAPIDLY BUILD TO 12 FT MON 
AFTERNOON...TO 10-17 FT MON NIGHT AND TO EVEN HIGHER VALUES OF 
16-20 FT ON TUE. WITH THE FANNING OUT OF THE WINDS AWAY FROM THE 
GULF MON THROUGH TUE...EXPECT WINDS OF FRESH INTENSITY TO SPREAD 
TO NEAR 105W WITH SEAS TO 8 FT...AND SEAS TO 10 FT TO REACH NEAR 
100W.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

THE MONSOON TROUGH AXIS EXTENDS FROM 10N85W TO 08N91W TO 07N100W 
TO 08N109W...WHERE LOW LEVEL WINDS SUGGEST A TRANSITION TO ITCZ 
WHICH EXTENDS TO 08N116W TO 08N128W AND TO BEYOND 10N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS FROM 08N-
11N W OF 135W. SCATTERED MODERATE CONVECTION IS SEEN WITHIN 120 
NM S OF THE ITCZ BETWEEN 120W-124W.

...DISCUSSION... 

AN UPPER LEVEL ANTICYCLONE IS NOTED AT 30N129W WITH A RIDGE 
CREST TO WELL N OF THE DISCUSSION AREA. TO ITS E...BROAD UPPER 
TROUGHING COVERS THE AREA N OF 19N. A JET STREAM BRANCH EXTENDS 
FROM 17N140W E TO 17N127W THEN ENE TO 18N115W TO 21N110W AND TO 
ACROSS CENTRAL MEXICO. A SHORTWAVE TROUGH IS EMBEDDED WITHIN  
JET STREAM ASSOCIATED WLY FLOW ROUGHLY FROM 19N119W SE TO 
10N114W. OVERCAST TO BROKEN TO MULTILAYERED CLOUDS ARE WITHIN 
480 NM S OF THE JET STREAM W OF 132W. BROKEN TO SCATTERED MAINLY 
HIGH LEVEL CLOUDS ARE WITHIN 360 NM S OF THE JET STREAM E OF 
119W. SCATTERED TSTMS HAVE DEVELOPED TO THE E OF THE SHORTWAVE 
TROUGH WITHIN 45 NM OF 14N116W. WIDELY SCATTERED SHOWERS AND 
ISOLATED TSTMS ARE POSSIBLE UNDERNEATH THE AREA OF CLOUDINESS 
ASSOCIATED WITH THE JET STREAM BRANCH OUTSIDE CONVECTION RELATED 
TO THE ITCZ AS DESCRIBED ABOVE. SATELLITE WATER VAPOR IMAGERY 
SHOWS VERY DRY AIR COVERING THE AREA N OF 19N E OF ABOUT 135W. 
AS A RESULT...BROKEN TO SCATTERED STRATOCUMLUS CLOUDS MOVING SSW 
WITH POSSIBLE ISOLATED SHOWERS. 

AT THE SURFACE...HIGH PRES OF 1031 MB IS CENTERED N OF THE AREA 
NEAR 39N140W WITH RIDGE EXTENDING SEWD THROUGH 32N133W AND TO 
NEAR 22N118W. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER 
PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING A SMALL AREA 
OF FRESH TO STRONG TRADES FROM 12N TO 17N W OF 132W. THE 1031 MB 
HIGH WILL SLOWLY SHIFT E THROUGH MON WITH ONLY SLIGHT WEAKENING 
ALLOWING FOR THE AREA OF FRESH TO STRONG TRADES TO ONLY SHRINK A 
LITTLE FROM E TO W.

LONG PERIOD NW SWELLS...WITH WAVE PERIODS BETWEEN 19-21 SEC 
ALONG THE LEADING EDGE...ARE MOVING ACROSS THE FAR NW PORTION OF 
THE FORECAST AREA. THESE SWELL WILL CONTINUE TO PROPAGATE SEWD  
COVERING MUCH OF THE FORECAST AREA W OF 110W BY MON MORNING. 
GUIDANCE SUGGESTS THAT THE LEADING EDGE OF THIS SWELLS TRAIN 
WILL CROSS THE EQUATOR W OF ABOUT 116W BY MON. 

GULF OF PAPAGAYO...NE WINDS FOR THE TIME BEING HAVE DIMINISHED 
TO 15-20 KT. HOWEVER...BY LATE TONIGHT THEY ARE EXPECTED TO 
BEGINNING PULSING AGAIN REACHING TO 20-25 KT BY DAYBREAK ON SUN 
AS NOCTURNAL DRAINAGE FLOW KICKS IN. THE WINDS ARE FORECAST TO 
DIMINISH AGAIN DURING MON AFTERNOON...AND MAYBE PULSE BRIEFLY 
EARLY ON MON BEFORE DIMINISHING AGAIN IN THE AFTERNOON. SHUTTING 
DOWN 

GULF OF CALIFORNIA...HIGH PRES WILL BUILD ACROSS THE GREAT BASIN 
REGION THROUGH MON WHILE INTENSIFYING. THE PRES GRADIENT BETWEEN 
THE HIGH PRES AND TROUGHING OVER MEXICO WILL STRENGTHEN WINDS 
OVER THE CENTRAL AND NRN GULF OF CALIFORNIA BY LATE SUN NIGHT 
WITH NW FLOW OF 20-25 KT. BY MON AFTERNOON...THESE WINDS ARE 
FORECAST TO ENCOMPASS JUST ABOUT THE ENTIRE GULF WITH SEAS 
BUILDING TO AROUND 6 FT. 
 
$$
AGUIRRE