000
AXPZ20 KNHC 061536
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU DEC 06 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

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

THE MONSOON TROUGH IS ALONG 08N78W TO 07N95W. THE INTERTROPICAL 
CONVERGENCE ZONE AXIS EXTENDS FROM 07N95W TO 08N122W TO 07N140W. 
WIDELY SCATTERED MODERATE CONVECTION IS FROM 06N TO 15N BETWEEN 
103W AND 122W. SCATTERED MODERATE CONVECTION IS FROM 04N TO 08N 
BETWEEN 127W AND 133W...AND FROM 05N TO 08N W OF 136W.

...DISCUSSION...

ALOFT...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES MOST OF THE 
REGIONAL WATERS. AN UPPER-LEVEL TROUGH EXTENDS FROM 27N122W TO 
15N127W THEN CONTINUES SE TO NEAR 07N118W. BROAD RIDGING COVERS 
THE AREA TO THE E OF THE TROUGH EASTWARD TO ACROSS CENTRAL 
AMERICA AND NORTHERN SOUTH AMERICA. DIFFLUENT FLOW IS EVIDENT E 
OF THE TROUGH ON WATER VAPOR IMAGERY AND CONTINUES TO ENHANCE 
CONVECTION ALONG AND NORTH OF THE ITCZ AXIS. THIS AREA SPREADS 
NORTHWARD TO 25N AS AN AREA OF INCREASED MULTILAYERED CLOUDS 
WITH LIKELY EMBEDDED ISOLATED SHOWERS. WATER VAPOR IMAGERY ALSO 
INDICATES MODERATE TO STRONG SUBSIDENCE MAINTAINING DRY AND 
STABLE CONDITIONS ACROSS MOST OF THE AREA N OF 09N W OF THE 
UPPER LEVEL TROUGH. SOME MID/UPPER LEVEL MOISTURE IS CURRENTLY 
REACHING THE FAR NW CORNER OF THE FORECAST REGION AHEAD OF 
ANOTHER UPPER LEVEL CYCLONE FORECAST TO DROP SE INTO THE 
DISCUSSION AREA ON FRIDAY...BUT THE ASSOCIATED SURFACE FRONTAL 
SYSTEM SHOULD REMAIN NW OF THE DISCUSSION AREA.

AT THE SURFACE...A 1025 MB HIGH IS CENTERED NEAR 29N136W WITH A 
RIDGE EXTENDING SE TO NEAR 18N114W. EARLIER SCATTEROMETER DATA 
INDICATED 20 TO 25 KT TRADE WINDS ON THE SOUTHERN PERIPHERY OF 
THE RIDGE...PARTICULARLY FROM 07N TO 20N W OF 126W. SEA HEIGHTS 
WITHIN THE AREA OF THE TRADES ARE 8 TO 10 FT IN MIXED SHORT 
PERIOD NE AND LONG PERIOD NW SWELL. MODERATE TO FRESH NORTHERLY 
WINDS ARE NOTED BETWEEN THE RIDGE AND THE SEMI-PERMANENT TROUGH 
ACROSS WESTERN MEXICO. THE SURFACE HIGH IS FORECAST TO WEAKEN 
SLIGHTLY TODAY AND MERGE WITH A STRONGER RIDGE POSITIONED TO THE 
NORTH ALONG 40N. AS A RESULT...THE AREA OF TRADES WILL ERODE 
FROM THE SE AND BECOME A SMALLER AREA OVER WEST-CENTRAL PORTIONS 
OF THE DISCUSSION AREA BY EARLY SATURDAY. ALSO...THE PRESSURE 
GRADIENT WILL TIGHTEN NE OF THE SURFACE RIDGE AXIS GENERATING 
INCREASED WINDS OFF THE NORTHERN COAST OF BAJA CALIFORNIA WITH 
SEAS BUILDING TO 9 FT IN NW SWELL. 

GAP WINDS...
N TO NE WINDS AT 20 TO 30 KT ARE SURGING THROUGH THE CHIVELA 
PASS INTO AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC. THESE WINDS 
WILL BE RATHER SHORT-LIVED AS MODEL GUIDANCE SUGGESTS THE WIND 
FIELD WILL DECREASE IN SPEED TO 20-25 KT LATER THIS MORNING AND 
TO 20 KT OR LESS BY THIS EVENING.

WINDS WILL CONTINUE TO PULSE IN THE GULF OF PAPAGAYO TO 20 KT 
DURING LATE NIGHT AND EARLY MORNING HOURS THEN DIMINISH BELOW 15 
KT IN THE AFTERNOON THROUGH SAT.  

$$
HUFFMAN