000
AXPZ20 KNHC 080402
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU NOV 08 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0345 UTC.

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

THE MONSOON TROUGH EXTENDS W ACROSS THE SOUTHWESTERN CARIBBEAN 
ALONG 11N...THEN TURNS ABRUPTLY SW ACROSS THE PANAMA AND COSTA 
RICA BORDER TO THE PACIFIC COAST AT 09N84W...THEN SW TO 
06N93W...THEN TURNS W TO 08N97W WHERE LOW LEVEL WINDS INDICATE A 
TRANSITION TO AN ITCZ WHICH CONTINUES W THROUGH 09N103W TO 
BEYOND 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
NOTED FROM 07N TO 13N BETWEEN 102W AND 110W AND WITHIN 120 NM OF 
09.5N116W. ISOLATED MODERATE CONVECTION IS OBSERVED ELSEWHERE 
FROM 05N TO 15N BETWEEN 80W AND 117W.

...DISCUSSION...

AN UPPER TROUGH EXTENDS S INTO THE DISCUSSION AREA FROM 32N124W 
TO A BASE OVER THE DEEP TROPICS AT 10N122W. AT THE LOW LEVELS A 
SURFACE TROUGH EXTENDS FROM 32N124W TO 27N127W WITH 
BROKEN-OVERCAST STRATOCUMULUS OBSERVED WITHIN 150 NM W OF THE 
TROUGH AXIS. SCATTERED MODERATE CONVECTION WITH FREQUENT 
LIGHTNING STRIKES DETECTED IS NOTED WITHIN 30 NM EITHER SIDE OF 
A LINE FROM 30N119.5W TO 25N119W. 

AN UPPER LEVEL ANTICYCLONE IS AT 12N95W WITH AN 
UPPER RIDGE EXTENDING NW ACROSS WESTERN OLD MEXICO TO A CREST 
OVER ARIZONA AT 35N110W. A MOISTURE PLUME IS OBSERVED FROM 
20N-32N BETWEEN 118W-104W...AND IS ADVECTED NE AND E ACROSS THE 
RIDGE AXIS AND ACROSS NORTHERN OLD MEXICO. UPPER DIFFLUENCE IS 
NOTED FURTHER S AND IS ROUGHLY IN PHASE WITH THE CONVECTION N OF 
THE MONSOON TROUGH AND ITCZ AS PREVIOUSLY DESCRIBED. THE 
RESULTANT DEBRIS MOISTURE IS ADVECTED N AND NE IN THE UPPER 
ANTICYCLONIC FLOW...BUT EVAPORATES OVER CENTRAL AMERICA IN VERY 
DRY UPPER AIR ALOFT.

THE UPPER TROUGH WILL PROGRESS E ACROSS THE WESTERN SEABOARD OF 
THE CONUS. THE SURFACE TROUGH WILL SHIFT E ACROSS THE NE PORTION 
OF THE AREA ACCOMPANIED BY ONLY A 5-10 KT SW-W-NW WIND SHIFT. 
ANOTHER UPPER CYCLONE IS CURRENTLY W OF THE AREA AT 
26N145W...AND WILL GET PICKED UP BY A SECONDARY UPPER SHORTWAVE 
TROUGH THAT WILL SWING SE INTO THE NW CORNER OF THE DISCUSSION 
AREA ON THU...AND CONTINUE E ACROSS THE N-CENTRAL PORTION ON 
FRI. A SURFACE RIDGE WILL BUILD E ACROSS THE NORTHERN WATERS  
BEGINNING LATE TONIGHT...RESULTING IN NE LOW WINDS INCREASING TO 
20-25 KT AND SEAS 7-10 FT DEVELOPING OVER THE WATERS N OF 28N W 
OF 133W ON THU AND SPREADING SE TO COVER THE WATERS W OF A LINE 
FROM 30N120W TO 24N140W ON FRI. THE INCREASING PRESSURE GRADIENT 
WILL ARRIVE THE W COAST OF THE BAJA PENINSULA IN THE FORM OF NW 
15-20 KT WINDS LATE FRI NIGHT...WITH SEAS OF 6-8 FT IN NW SWELL 
ARRIVING ON SAT NIGHT. THESE CONDITIONS WILL SPREAD S ALONG THE 
ENTIRE W COAST OF BAJA BY MIDDAY SUN.  

GAP WINDS...THE MINIMAL GALE WINDS IN/DOWNSTREAM OF THE GULF OF 
TEHUANTEPEC ARE EXPECTED TO INCREASE 30-40 KT LATE TONIGHT 
THROUGH THU WITH SEAS BUILDING TO 14 FT. THE GALE CONDITIONS ARE 
EXPECTED TO PERSIST THROUGH SUNRISE FRI MORNING...THEN DIMINISH 
WITH ONE LAST SURGE MAXING AT 30 KT LATE FRI NIGHT INTO EARLY 
SAT MORNING. EXPECT THE NE WINDS IN AND DOWNSTREAM OF THE GULF 
OF PAPAGAYO TO PULSE THROUGH SUN AFTERNOON. THE RESULTANT NE 
SWELL WILL PROPAGATE W TO ALONG 94W...MERGING WITH THE SWELL 
ORIGINATING FROM THE NORTHERLY WINDS SURGING THROUGH THE GULF OF 
TEHUANTEPEC. BEST GUESS FOR NOW IS THE NEXT GALE EVENT SETTING 
UP FOR MON NIGHT IN THE GULF OF TEHUANTEPEC. 

CROSS EQUATORIAL SOUTHERLY SWELL...RESULTING IN SEAS TO 8 FT... 
ARE NOTED ACROSS THE DEEP TROPICS S OF 07N TO THE W OF 97W. THE 
AREA OF SOUTHERLY SWELLS IS EXPECTED TO SHRINK TO ONLY BETWEEN 
97W-117W BETWEEN 03N-07N ON THU AND SUBSIDE BELOW 8 FT ON FRI. 
NOTE THAT SOME THIS SWELL WILL MIX WITH THE SHORTER PERIOD NE 
SWELL PROPAGATING SW AND W FROM THE GULF OF TEHUANTEPEC GALE 
EVENT RESULTING IN AN AREA OF MIXED NE AND SW SWELL WITH SEAS OF 
8-10 FT THU AND FRI.

$$
NELSON