820 
fxus65 kvef 022357 
afdvef 


Area forecast discussion 
National Weather Service Las Vegas Nevada 
355 PM PST Tuesday Dec 2 2008 


Synopsis...a dry cold front will push down through southern Nevada 
and northwest Arizona bringing gusty north winds overnight and 
slightly cooler air to the region Wednesday. A dry weather pattern 
will remain over the region the rest of the week with temperatures 
around 5 degrees above normal. A low pressure system off the 
Southern California coast could move inland late in the weekend. 
&& 


Short term...the main feature of interest is a cold front currently 
sweeping down through south central Nevada that is associated with a 
shortwave trough heading across Utah toward The Four Corners region. 
The front will push through southern Nevada early this evening as 
the upper low quickly tracks southeast and into New Mexico early 
Wednesday. Upstream wind sensors indicate showed wind gusts across 
central Nye County generally between 25 and 35 miles per hour. Also...west 
winds across the western Mohave desert were gusting 35-40 miles per hour. It 
still appears gusts generally 20-30 miles per hour will occur over southern 
Nevada this evening. The latest NAM appears to have a pretty good 
handle on the winds and it shows speeds quickly decreasing between 
12z and 18z Wednesday morning. Of course...cooler air will accompany 
the north winds but temperatures over the southern half of the area may not 
be a whole lot cooler Wednesday than today for sites that did not 
mix well due to lack of heating from cloud cover earlier. Aside from 
that...there will be little in the way of sensible weather concerns 
Wednesday through Friday. The one thing to watch is a Pacific low 
currently near 45n/140w which is forecast to dig and become a cutoff 
low well off the Southern California coast by Thursday afternoon. It 
is forecast to remain parked offshore through Friday but could 
become a concern later in the weekend. 


Long term...grid work for the afternoon package was based on a 
diluted version of the European model (ecmwf) which has been showing better run to 
run consistency with an upper low off the coast than the GFS. 


The ec with decent initial 12z GFS support has the low centered 
about 300 or so miles west of Point Conception Saturday morning. It 
is forecast to approach the coast on Saturday and move inland 
Sunday...generally right along the southern regions of the County Warning Area. The 
12z European model (ecmwf) is not quite as wet as the 00z run from yesterday as it 
develops a weak tropical moisture tap. However will have to watch 
this one closely and begin ramping up pop/quantitative precipitation forecast potential for the 
weekend if models continue to show a consistent tap and the low does 
indeed track across the area as currently forecast. Once that 
system passes to the east...a shortwave is forecast to move out of 
southwestern Canada and through Utah. This could bring an increase 
in north wind on Monday as it pushes a cold front through the area. 
&& 


Aviation...for McCarran...generally variable winds under 6kts 
expected through early this evening with a few lingering high clouds 
at or above 20kft. A surface cold front is expected to pass through the Las 
Vegas Valley this evening. Timing for a stronger push of north winds 
appears to be between 03 and 06z with speeds 10-15kts and gusts as 
high as 25kts possible. North winds around 10kts will linger into 
the early daylight hours on Wednesday then becoming light in the 
afternoon. 


For the rest of southern Nevada...northwest Arizona...and southeast 
California...southwest winds generally under 10 kts expected through 
early evening across the south except over western San Bernardino 
County where west winds will gust to 35kts at times. Northwest winds 
10-20 kts with gusts to 35 kts will continue over the north through 
the evening behind a surface cold front. This front is expected to 
pass through the rest of the County Warning Area overnight but wind speeds should 
decrease as it moves further to the south. Cloud cover to be limited 
to mainly a few high cirrus along the southern regions. 
&& 


Vef watches/warnings/advisories... 
Nevada...none. 
Arizona...none. 
California...none. 
&& 


$$ 


Adair/Salmen 


Http://weather.Gov/lasvegas