000
AXPZ20 KNHC 192202
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT MAR 19 2016

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...                                   
A RATHER STRONG COLD FRONT FOR THIS TIME IN MARCH IS CURRENTLY
MOVING SSE THROUGH THE SW GULF OF MEXICO. THE FRONT WILL PASS E
OF THE CHIVELA EARLY ON SUN. NWP MODELS DEPICT VERY STRONG HIGH
PRES SURGING S ALONG THE SIERRA MADRE ORIENTAL MOUNTAINS OF
EASTERN MEXICO IN THE WAKE OF THE FRONT THROUGH MON. THE
RESULTING TIGHT PRES GRADIENT OVER SOUTHEASTERN MEXICO IS
FORECAST TO INDUCE A GULF OF TEHUANTEPEC GALE WIND EVENT TO
BEGIN AROUND 18Z SUN AS N-NE WINDS OF 30-35 KT. WITH THE PRES
GRADIENT CONTINUING TO TIGHTEN THROUGH SUN NIGHT AND INTO
MON MORNING...THE GALE FORCE WINDS WILL RESPOND BY INCREASING
QUICKLY TO 45 KT WITH SEAS BUILDING FROM 8-10 FT SUN AFTERNOON
TO 11-17 FT BY LATE SUN NIGHT. WINDS STAY AT THE RANGE OF 30-45 KT 
INTO MON AFTERNOON WITH SEAS BUILDING FURTHER TO 12-19 FT. A
LARGE SWATH OF N-NE 20-30 KT WINDS WILL SPREAD S AND SW FROM
THE GULF TO ENCOMPASS AN AREA ELSEWHERE WITHIN 90 NM EITHER SIDE
OF A LINE FROM 16N95W TO 14N95.5W TO 12N97W LATE SUN NIGHT...
AND ELSEWHERE WITHIN 90 NM EITHER SIDE OF A LINE FROM 16N95W TO
15N95W TO 11.5N97W TO 10.5N99W BY MON AFTERNOON. SEAS WITHIN THE 
ELSEWHERE AREA WILL BE IN THE RANGE OF 9-13 FT LATE SUN
NIGHT...AND REACH A HIGHER RANGE OF 10-15 FT BY MON AFTERNOON.
THE PARENT HIGH CENTER OF THE TIGHT PRES GRADIENT IS FORECAST BY
THE NWP MODELS TO SHIFT EASTWARD AND WEAKEN ALONG THE FAR
NORTHERN GULF TUE. THIS WILL ALLOW FOR THE CULPRIT TIGHT PRES
GRADIENT TO SLACKEN...AND FOR THE GALE FORCE WINDS TO DROP BELOW
GALE FORCE INTENSITY. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO
HEADERS MIAHSFEP2/FZPN03 KNHC FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...          
THE ITCZ AXIS EXTENDS FROM 06N84W TO 06N95W TO 06N105W TO 04N118W TO
03N130W TO 04N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WITHIN 60 NM OF THE AXIS BETWEEN 116W-120W AND ALSO BETWEEN 
134W-137W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE
AXIS BETWEEN 84W-92W. IN ADDITION...SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS NOTED JUST E OF THE ITCZ FROM 05N-07.5N 
BETWEEN 83W-84W.

...DISCUSSION...                                             
WATER VAPOR IMAGERY SHOWS A LARGE DEEP LAYER CYCLONIC VORTEX WELL TO
THE NW OF THE DISCUSSION AREA NEAR 48N148W WITH AN ASSOCIATED 
TROUGH EXTENDING SEWD TO THE FAR NW PART OF THE AREA. THE TROUGH
SUPPORTS A COLD FRONT THAT IS FAST APPROACHING THE NW CORNER OF
THE AREA AS SEEN IN THE LATEST VIS IMAGERY.REMNANTS FROM A
PREVIOUS SHORTWAVE TROUGH ARE ANALYZED AS A STATIONARY FRONT
THAT EXTENDS FROM A WEAK 1014 MB LOW AT 32N135W SW TO 26N140W.
THE STATIONARY FRONT IS FORECAST TO WEAKEN THROUGH EARLY
SUN AS THE AFOREMENTIONED COLD FRONT MERGES WITH IT. S-SW WINDS
OF 20-25 KT WITH SEAS OF 10-12 FT IN NW SWELL WITHIN 60 NM E OF
THE STATIONARY FRONT ARE FORECAST TO SHIFT N OF THE AREA
TONIGHT.

LATEST NWP MODELS CONTINUE TO SUGGEST THAT A MAJORITY OF WINDS
GREATER THAN THE 20 KT THRESHOLD FOR HIGH SEAS INCLUSION TO
REMAIN N OF 30N AND THE PRIMARY IMPACT ACROSS THE DISCUSSION
WATERS BEING THE NEW PULSE OF NORTHWESTERLY SWELL THAT
ACCOMPANIES THE FRONT. EXISTING NW SWELL OF 8-12 FT ASSOCIATED
WITH THE STATIONARY FRONT WILL PROPAGATE SSE AND GRADUALLY BEGIN
TO SUBSIDE THROUGH SUN...HOWEVER THE APPROACHING COLD FRONT WILL
ONCE AGAIN BUILD SEAS INTO A 12-17 FT RANGE NW OF A LINE FROM 
32N133W TO 15N140W BY EARLY SUN EVENING. THESE SEAS ARE 
ONLY FORECAST TO SUBSIDE SLIGHTLY EARLY ON MON AS THEY SPREAD
SE...THEN SUBSIDE FURTHER ON MON AFTERNOON. SEAS OF 8-11 FT 
PRIMARILY IN A NW SWELL ARE FORECAST TO SPREAD SSE TO A LINE
FROM NEAR 32N120W TO 18N129W TO 07N119W TO 02N125W TO 02N140W 
BY EARLY MON EVENING.

ELSEWHERE AT THE SURFACE...A 1021 MB HIGH IS ANALYZED AT
28.5N126W WITH A RIDGE AXIS EXTENDING SE TO NEAR 16N116. THE
OVERALL PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES TO THE S
WITHIN THE ITCZ REGION IS SUPPORTING MODERATE TO OCCASIONAL
FRESH NE TRADES S OF 18N AND W OF 120W...WITH SEAS RANGING 5-8
FT.

OTHER GAP WINDS... 
A GULF OF PAPAGAYO GAP WIND EVENT WITH 20-25 KT NE WINDS IS
SUGGESTED BY THE LATEST NWP MODELS TO BRIEFLY TAKE PLACE MON
MORNING WITH SEAS OF ABOUT 6-7 FT.

$$
AGUIRRE