000
AXPZ20 KNHC 251011
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE DEC 25 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 
0945 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 07N78W TO 09N85W TO 06N94W WHERE 
LOW LEVEL WINDS SUGGEST IT TRANSITIONS TO THE ITCZ TO 09N107W TO 
08N122W TO 09N127W TO 06N140W. NUMEROUS STRONG CONVECTION IS
ALONG AND WITHIN 30 NM OF THE TROUGH BETWEEN 78W-90W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N OF THE  
ITCZ BETWEEN 126W-129W...AND ALSO FROM 09N TO 11N BETWEEN 
120W-122W. SCATTERED MODERATE CONVECTION IS WITHIN 30 NM OF THE
ITCZ BETWEEN 129W-136W.

...DISCUSSION...

A LONGWAVE TROUGH EXTENDS FROM THE CENTRAL U.S. PORTIONS SSW TO 
CENTRAL MEXICO...AND SW TO 22N126W TO A DEVELOPING UPPER LOW AT 
16N135W AND S TO NEAR 02N135W. A LARGE UPPER RIDGE OVER THE FAR 
NE PORTION IS AMPLIFYING WHILE IT SLIDES EASTWARD IN RESPONSE TO 
A RATHER VIGOROUS UPPER TROUGH WELL N OF THE AREA ALONG 135W. 
BROAD MID/UPPER LEVEL RIDGING COVERS THE AREA TO THE W AND NW OF 
THE LONGWAVE TROUGH. FAST UPPER LEVEL WSW WINDS BETWEEN IT AND 
THE UPPER TROUGH TO THE N ARE ADVECTING EXTENSIVE UPPER LEVEL 
MOISTURE IN THE FORM OF MOSTLY OVERCAST MID AND UPPER LEVEL 
CLOUDS E AND NE AROUND THE NRN CREST OF THE RIDGE. THIS MOISTURE 
HAS A TRAJECTORY THAT CARRIES IT TOWARDS CALIFORNIA AND THE U.S. 
W COAST. MODERATE SUBSIDENCE IN THE UPPER LEVELS BETWEEN OVER 
MUCH OF THE AREA WHERE THE RIDGE IS IN PLACE IS ALLOWING FOR DRY 
AND STABLE ATMOSPHERIC CONDITIONS THERE WITH JUST PATCHES OF 
STRATOCUMULUS CLOUDS MOVING WESTWARD WITH POSSIBLE ISOLATED 
SHOWERS. AT THE SURFACE...THE SOUTHERN PORTION OF A COLD FRONT 
SUPPORTED BY THE UPPER TROUGH IS ANALYZED JUST TO THE NW OF THE 
DISCUSSION AREA...WHILE A 1026 MB HIGH CENTER IS AT 28N136W WITH 
A RIDGE SE TO NEAR 21N115W.  

CONVECTION REMAINS ACTIVE ALONG THE ITCZ BETWEEN 126W-129W AHEAD
OF THE UPPER LOW AND TROUGH WHERE DIVERGENCE IS PRESENT. THE 
UPPER TROUGH N OF THE AREA WILL MOVE INLAND THE U.S. W COAST WED 
WITH THE UPPER LOW AT 16N135W LIFTING NE AND BECOMING DIFFUSE. 
THE UPPER FLOW PATTERN THAN BECOMES GENERALLY MORE ZONAL ACROSS 
THE NRN AND CENTRAL PORTIONS THROUGH MID-WEEK. WITH THIS TAKING 
PLACE...THE SURFACE HIGH OF 1026 MB DISSIPATES AS THE COLD FRONT 
JUST NW OF THE AREA QUICKLY MOVES E TO INLAND SRN CALIFORNIA 
WHILE WEAKENING. BEFORE MOVING INLAND THIS FRONT WILL USHER IN 
NW WINDS OF 20 TO 25 KT OVER THE EXTREME NE PORTION BY LATE WED.

THE OVERNIGHT ASCAT PASSES FROM 0536 UTC AND 0718 UTC REVEALED
FRESH TO STRONG TRADES S OF THE SURFACE HIGH PRES RIDGE...FROM 
ABOUT 07N TO 20N W OF 120W. JASON ALTIMETRY DATA FROM THE PAST 
18 HOURS CONFIRM GLOBAL WAVE MODEL INITIALIZATIONS SHOWING A 
BROAD AREA OF SEAS FROM 9 TO 11 FT WITHIN THIS AREA OF TRADES.
THIS AREA OF TRADES IS FORECAST TO SHRINK SLIGHTLY OVER THE NEXT 
24-48 HRS.

STRONGER HIGH PRES IS FORECAST TO BUILD ESE ACROSS MUCH OF THE 
AREA ON WED KICKING UP THE TRADE WINDS FROM 08N TO 20N W OF 
124W. GLOBAL WAVE MODEL GUIDANCES SUGGEST THAT NW SWELLS WILL
PUSHING INTO THE NW PART OF THE AREA ON WED.

GULF OF TEHUANTEPEC...A BRIEF GAP EVENT IS IN STORE THE GULF
OF TEHUANTEPEC LATER THIS WEEK AS A COLD FRONT PUSHES THROUGH 
THE GULF OF MEXICO. THE FRONT WILL BE FOLLOWED BY A SURGE OF 
COLDER AND DRIER AIR DOWN THE COAST OF MEXICO...FUNNELING 
THROUGH THE CHIVELA PASS AND THROUGH THE ISTHMUS OF TEHUANTEPEC 
BEGINNING EARLY WED EVENING. A GALE WARNING HAS BEEN POSTED FOR 
THE GULF OF TEHUANTEPEC STARTING 27/00 UTC...AND FORECAST TO 
LAST FOR 6 HRS.
 
$$
AGUIRRE