000
AXPZ20 KNHC 282205
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN OCT 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...SPECIAL FEATURE...

A 1006 MB LOW PRES LOCATED NEAR 13N111W IS EMBEDDED WITHIN THE 
MONSOON TROUGH. EARLIER DEEP CONVECTION HAS RECENTLY WEAKENED
...HOWEVER LATEST SATELLITE IMAGERY SHOWS RATHER DISORGANIZED
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 90 NM OF
LOW IN THE SE QUADRANT. THE LATEST VISIBLE SATELLITE IMAGERY
SHOWS LOW CLOUDS TURNING CYCLONICALLY INTO THE LOW FROM THE NE
AND NW QUADRANTS. THE OBSERVED CONVECTION IS TO THE SE OF THESE
CLOUDS. THE LOW REMAINS UNDER AN UPPER LEVEL ANTICYCLONE...WHICH 
FAVORS SOME SLOW DEVELOPMENT THROUGH THE NEXT 48 HRS WITH A 
MEDIUM CHANCE OF IT INTENSIFYING INTO A TROPICAL CYCLONE WITHIN 
THE NEXT 48 HRS.

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

MONSOON TROUGH EXTENDS FROM 07N79W NW ALONG THE PACIFIC COAST OF 
COSTA RICA AND PANAMA TO 11N92W TO LOW PRES NEAR 11N102W 1007 MB 
TO LOW PRES NEAR 13N111W 1006 MB TO LOW PRES NEAR 11N122W 1007 MB
TO 07N140W. SCATTERED TO STRONG CONVECTION IS ALONG AND WITHIN
120 NM S OF THE TROUGH BETWEEN 96W-102W. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION EXISTS FROM 08N-13N BETWEEN 
119W-124W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF 
THE TROUGH BETWEEN 77W-81W.

...DISCUSSION...

ALOFT...AN UPPER TROUGH EXTENDS FROM FAR NW MEXICO AND NORTHERN
BAJA CALIFORNIA SW TO NEAR 26N122W. W OF IT...BROAD MID/UPPER 
LEVEL ANTICYCLONIC FLOW IS PRESENT EXCEPT W OF 138W WHERE A VERY
SHARP SHORTWAVE TROUGH IS NOTED. ELSEWHERE BROAD MID/UPPER LEVEL
CONTINUES OVER THE MAJORITY OF THE DISCUSSION AREA ASSOCIATED
WITH A MID/UPPER LEVEL ANTICYCLONE AT 11N108W. A VERY PRONOUNCED
DIFFLUENT PATTERN ALOFT TO SW OF THE ANTICYCLONE IS HELPING FIRE
UP THE CONVECTION ASSOCIATED WITH THE LOW PRES NEAR 13N111W AND 
THE MONSOON TROUGH. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE
SUBSIDENCE WITH A RESULTANT VERY DRY AND STABLE AIR MASS OVER
MOST OF THE NORTHERN PORTIONS OF THE AREA N OF ABOUT 19N. THE
VISIBLE IMAGERY REVEALS BROKEN TO OVERCAST PATCHES OF 
STRATOCUMULUS CLOUDS MOVING SSW WITH POSSIBLE ISOLATED SHOWERS 
TO THE N OF 17N AND W OF 124W.

AT THE SURFACE...A 1022 MB HIGH PRES CENTER IS ANALYZED AT 
32N134W WITH A RIDGE EXTENDING SE TO NEAR 23N121W. HIGH PRES 
COVERS THE AREA N OF 21N W OF 122W. NE TRADE WINDS ARE RATHER 
LIGHT TO THE S AND SW OF THE RIDGE WITH SPEEDS OF 10-15 KT 
ACCORDING TO THE ASCAT PASS FROM THIS AFTERNOON. HOWEVER...SEAS 
OF 8 FT IN MIXED NE AND NW SWELL STILL LINGER OVER THE AREA N OF 
10N W OF 134W. N TO NE WINDS OF 20-25 KT N OF 28N BETWEEN 
124W-128W ARE DIMINISHING TO 15-20 KT AS THE HIGH CENTER OF 1022 
MB SHIFTS NE. LINGERING NE AND NW SWELLS ARE PRODUCING SEAS OF 
UP TO 8 FT N OF 28N BETWEEN 124W-128W...BUT ARE EXPECTED TO 
SUBSIDE TO LESS THAN 8 FT DURING MON.  NW SWELLS WILL MIX WITH 
NE SWELLS FROM 20N-26N W OF 130W AND W OF LINE FROM 20N130W TO 
10N140W IN 24 HRS WITH SEAS OF 8 FT. THESE CONDITIONS THEN 
SUBSIDE TO LESS THAN 8 FT IN 48 HRS AS THE SWELLS DIMINISH.

SCATTERED MODERATE CONVECTION ALONG THE MONSOON TROUGH W OF 130W 
HAS LARGELY DIMINISHED AS THE TRADE WIND FLOW SUBSIDED...BUT 
CONTINUES TO BE EVIDENT FARTHER E ASSOCIATED WITH A 1007 MB
LOW PRES NEAR 11N122W...AS WELL AS WITH THE LOW MENTIONED UNDER 
SPECIAL FEATURE. 

GAP WINDS...
A COLD FRONT OVER THE FAR SE PART OF THE SW GULF OF MEXICO IS 
FOLLOWED BY A COOLER AND DRIER AIRMASS. THIS DENSER AIR HAS
MIXED DOWNWARD BRINGING N-NE WINDS OF 20-30 KT THROUGH THE GULF 
OF TEHUANTEPEC WITH SEAS OF 8-11 FT. THE ASCAT PASS FROM NEAR
1630 UTC THIS AFTERNOON CONFIRMED THESE WINDS. WITH THE TIGHT
PRES GRADIENT IN PLACE OVER SE MEXICO...THESE WIND CONDITIONS
ARE FORECAST LAST THROUGH MON...THEN DIMINISH TO 20-25 KT ON
TUE AS THE GRADIENT SLACKENS. SEAS SUBSIDE TO 8 FT BY TUE
AFTERNOON.

$$
AGUIRRE