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Area forecast discussion 
National Weather Service Las Vegas Nevada 
920 am PST Wednesday Nov 19 2008 


Synopsis...our strong ridge of high pressure will continue to 
weaken today but not before bringing one more day of near record 
high temperatures to southern Nevada and the Colorado River valley. 
The ridge will weaken further as a storm system passes by to our 
north Thursday. Even though temperatures will cool they will remain 
above normal through the end of the week. A pattern change is likely 
by the middle of next week...with temperatures falling closer to 
normal and the chances of rain and mountain snow increasing. 
&& 


Update...weather remains quiet and no major update will be needed 
this morning. The 12z sounding indicates that temperatures aloft at 
850mb and 700mb have cooled about 3 degrees on average...so daytime 
maximum temperatures may be slightly lower than previously expected...but still 
well above normal...slightly below record. 
-Kennedy- 
&& 


Previous discussion...from 310 am PST Wednesday Nov 19 2008. 
Short term...satellite shows clear skies over the forecast area 
this morning with temperatures running a few degrees cooler than 
yesterday morning. Models consistent indicating strong ridge will 
continue to flatten/weaken today as a strong shortwave trough 
quickly moves east along the northern Nevada border Thursday. An 
area of high clouds over the Pacific northwest will shift across the 
Great Basin tonight and Thursday ahead of the shortwave trough. More 
high clouds will start to stream overhead Friday associated with a 
weak southern stream disturbance over the subtropical eastern 
Pacific. Las Vegas and Needles will once again threaten records 
today so will continue with appropriate headlines. Temperatures will 
fall Thursday and Friday but still be some 4 degrees above normal in 
the north and up to 8 degrees above normal in the Mojave Desert. 


Long term...decent model agreement for the weekend with high 
pressure over the western Continental U.S. And a weak upper low sliding through 
the southern regions of the County Warning Area. At best...a modest increase in high 
level moisture possible as the upper low moves through and then 
potentially a small decrease in temperatures by Sunday as the surface flow 
turns northerly. After Sunday...a developing trough in the eastern 
Pacific will eventually lead to a weather change across the region. 
Models provide a wide variety of solutions in strength...track and 
timing of the numerous weather features so confidence in any one 
solution remains very low. Maintained the climopop idea of the 
previous package with no additional clarification to dictate an 
increase or decrease. Temperatures were only adjusted slightly but 
maintained above normal conditions. Winds in general are expected to 
turn southerly as the system approaches but this could be closer to 
Tuesday or Wednesday. Cloud cover should increase overall across the 
area and partly cloudy conditions are not out of the question. 
&& 


Aviation...for McCarran...light diurnal winds are expected through 
Friday morning. Clear skies through tonight with increasing cirrus 
at or above 25kft Thursday. 


For the rest of southern Nevada...northwest Arizona...and southeast 
California...winds will generally remain under 10kts through 
Thursday. A few clouds at or above 25k feet expected today with scattered 
high level cirrus Thursday. 
&& 


Climate...Las Vegas and Needles may continue to flirt with record 
highs today. The existing records are as follows... 


Location Wednesday 11/19 
-------- --------- 
Las Vegas Nevada /klas/ 78 /1976/ 
Needles California /keed/ 84 /2007/ 
&& 


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


$$ 


Pierce/Salmen 


Http://weather.Gov/lasvegas