000
AXPZ20 KNHC 161018 RRA
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI NOV 16 2012

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.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 09N73W TO 10N85W TO 06N104W...WHERE IT 
TRANSITIONS TO ITCZ..CONTINUING ON TO 08N119W TO 09N130W TO 
BEYOND 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
NOTED WITHIN 90 NM N OF AXIS BETWEEN 106W AND 114W.

...DISCUSSION...
ALOFT...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE FORECAST 
REGION. A PAIR OF UPPER ANTICYCLONES WITH MEAN CENTER NEAR 
15N111W EXTENDS A RIDGE TO THE N-NE ACROSS BAJA CALIFORNIA AND 
NW MEXICO INTO THE SW CONUS. THE ANTICYCLONIC FLOW COVERS 
ROUGHLY THE AREA BETWEEN 98W AND 120W. BROAD UPPER LEVEL CYCLONE 
TO THE S OF ANTICYCLONE PAST SEVERAL DAYS HAS BECOME ELONGATED 
AS IT HAS SHIFTED SLOWLY SW...AND NOW FORMS A TUTT FROM A 
CYCLONE NEAR 03N115W TO 05N108W TO 10N96W...WHERE IT HAS LINKED 
WITH BASE OF BROAD UPPER TROUGH ACROSS MOST OF THE EASTERN U.S. 
AND GULF OF MEXICO. A DEEP LAYERED CYCLONE NEAR 35N130W HAS 
BEGUN TO SHIFT NE AND WEAKEN...AND SUPPORTS A 1005 MB SURFACE 
LOW NEARLY DIRECTLY BELOW. THE CYCLONE IS FINALLY MOVING NE AND 
WILL LIFT OUT OF THE TROUGH AXIS AND INTO CENTRAL CALIFORNIA BY 
THIS AFTERNOON. A NEW SHORTWAVE IS MOVING INTO THE BACK SIDE OF 
THE BROAD TROUGH AND FORMING A NEW AND SHARPER UPPER TROUGH AXIS 
THROUGH 35N134W TO 21N143W. STRONG SWLY FLOW IS NOTED THROUGH 
THE BASE OF THE TROUGH AND OVER THE RIDGE...WITH A WIND MAXIMA 
OF 80-110 KT FROM 135W TO NEAR THE RIDGE CREST ALONG 108W. 

AT THE SURFACE...A 1022 MB HIGH PRESSURE IS CENTERED NEAR 
28N119W...AND CONTINUES TO WEAKEN AS IT IS NUDGED NE BY BROAD 
UPPER TROUGH. THE DEEP LAYERED LOW DESCRIBED ABOVE SUPPORTS TWO 
COLD FRONTAL BOUNDARIES...THE PRIMARY FRONT ENTERS THE FORECAST  
REGION NEAR 30N124.5W THEN CONTINUES S AND SW TO 20N134W. A 
SECONDARY FRONTAL BOUNDARY EXTENDED FROM 30N129W TO 23N140W. SW 
WINDS 20-25 KT WERE FOUND N OF 28N BETWEEN THE TWO FRONTS...WITH 
SEAS TO 10 FT IN NW SWELL. THESE FRONTS WILL BE DRAGGED NE AND E 
DURING THE NEXT FEW DAYS AND WEAKEN CONSIDERABLY AS THEY ARE 
STRUNG OUT MOVING OVER THE UPPER RIDGE. CYCLONIC FLOW AT 20 KT 
OR LESS WILL CONTINUE ACROSS NW PORTIONS THROUGH TONIGHT AS THE 
SURFACE LOW SHIFTS NE...WITH SEAS BUILDING 10-14 FT IN NW SWELL. 
THESE FRONTS WILL GRADUALLY DISSIPATE DURING THE NEXT 48 HOURS 
AS THE REMNANTS SHIFT INLAND ACROSS SOUTHERN CALIFORNIA AND BAJA 
CALIFORNIA NORTE. HIGH PRES WILL BUILD INTO FAR NW PORTIONS BY 
LATE SAT BRINGING SOME INCREASE IN THE TRADE WINDS TO SW 
PORTIONS AS THE PRES GRADIENT INCREASES N OF THE ITCZ. 

LONG PERIOD NW SWELL ASSOCIATED WITH THE LOW PRESSURE SYSTEM IS 
PUSHING ACROSS THE NW PART OF THE REGION WITH COMBINED SEAS TO 
14 FT. THIS SWELL EVENT WILL PROPAGATE S AND E ACROSS THE 
REGIONAL WATERS OVER THE NEXT COUPLE OF DAYS WITH SEAS SUBSIDING 
TO 8-9 FT W OF LINE FROM 30N124W TO 20N130W TO 12N140W BY SAT 
EVENING. 

GAP WINDS...
AN 0402 ASCAT PASS REVEALED WINDS AROUND 25 KT ACROSS THE GULF 
OF TEHUANTEPEC...A DECREASE FROM THE PAST 24 HOURS. WINDS ACROSS 
THE GULF OF MEXICO THAT HAS BEEN FORCING GALE FORCE WINDS 
THROUGH THE GULF OF TEHUANTEPEC HAVE BEGUN TO VEER MORE E-NE 
OVERNIGHT. NOCTURNAL DRAINAGE FLOW IS EXPECTED TO ENHANCE THE 
WINDS FLOWING FROM THE CHIVELAS PASS THROUGH THE GULF OF 
TEHUANTEPEC AND RAISE WINDS ONCE AGAIN TO GALE FORCE UNTIL 
SUNRISE...WHEN WINDS WILL LIKELY DECREASE TO 20-30 KT DURING THE 
DAY. THIS PULSING WIND PATTERN IS EXPECTED TO CONTINUE FOR THE 
NEXT FEW DAYS...WITH WINDS REACHING GAEL FORCE AT NIGHT 
GENERALLY FROM AROUND 0600 TO 1200 UTC. 

WINDS ACROSS THE FAR WESTERN CARIBBEAN HAVE BECOME NORTHERLY 
OVERNIGHT...WITH LESS WIND NOT FUNNELING THROUGH THE GAP IN 
TOPOGRAPHY OVER NICARAGUA AND EXITING INTO THE EASTERN PACIFIC 
WATERS. PULSING OF NOCTURNAL WINDS IS THUS ONLY EXPECTED TO 
REACH AROUND 20 KT DURING THE NEXT FEW DAYS...AND SEAS THROUGH 
AND DOWNWIND OF THE GULF OF PAPAGAYO WILL REMAIN AROUND 6-7 FT. 

$$
STRIPLING