096 
fxus65 kvef 232131 
afdvef 


Area forecast discussion...updated 
National Weather Service Las Vegas Nevada 
230 PM PDT Wednesday Jul 23 2008 


Synopsis...high pressure will continue to produce hot and dry 
conditions across the region over the next couple of days. 
Thunderstorms return to Mohave County Friday with storm chances 
expanding further west and north over the weekend. 
&& 


Short term...high pressure extends from the central rockies to the 
Desert Southwest and is producing hot and dry conditions over the 
forecast area. This is expected to hold true through Thursday before 
a return of easterlies brings an increase in moisture to the region. 
Models indicate that conditions will become more favorable for 
thunderstorm development across Mohave County late Friday and into 
Saturday. Both the GFS and European model (ecmwf) now forecast the high pressure area 
over the central rockies to shift east into the Southern Plains late 
Saturday. This would allow the remant moisture from Hurricane Dolly 
to begin advecting northward around the western extension of the 
high and into eastern Arizona and New Mexico...leaving the County Warning Area on 
the western fringes of the more moist and unstable air. Adjusted 
probability of precipitation down in response...especially over the northwestern County Warning Area. 
Temperatures are expected to remain at or slightly above normal 
through Saturday over much of the area with a downward trend over 
the southeast where the greatest amount of cloud cover expected. 


Long term...the biggest issue concerning the extended forecast 
continues to be just how much moisture works into the area from what 
will eventually become the remnants of Hurricane Dolly. See the 
latest track from TPC concerning Dolly for specific details in the 
short range...but afterwards what eventually becomes the remnant low 
that was Dolly heads west-northwest across northern Mexico before 
recurving more towards the northwest towards southern Arizona by 
Saturday afternoon. One concern is just how fast this moisture from 
Dolly will work into the area if this system slows down enough. The 
European model (ecmwf) continues to be the most aggressive at bringing in deeper 
moisture the fastest into the County warning forecast area while other models are slower. 
For now even by Sunday the European model (ecmwf) is not bringing deeper moisture 
further west than a 29 Palms to Pioche line. The operational GFS is 
progging negative vorticity advection as well as Li/S of +3 to +6 across the area on Sunday 
afternoon...suggesting we may see some sort of subsidence across the 
area before the deeper moisture arrives. Thus I did tone down probability of precipitation 
up in the northwest County warning forecast area for then. The remnant moisture from Dolly 
should eventually get ejected into our County warning forecast area due to the southeast 
flow around an upper ridge centered over North Texas but the latest 
models hint it may just take some time for this moisture to come in. 
With this in mind I did not change much beyond Monday as future 
model runs will likely have a better grasp of the situation. Temperatures 
will be highly dependant on cloud cover and convection. 
&& 


Aviation...for McCarran...generally light southerly winds are 
expected tonight into tomorrow...though a brief period of easterly 
winds at 5-10 kts are possible between 18z and 20z Thursday. A mainly 
clear sky is expected tonight into tomorrow. 


For the rest of southern Nevada...northwest Arizona...and southeast 
California...VFR conditions are expected across the area once again 
tonight into tomorrow. Generally light winds...though a few gusts 
around 15 kts are possible. With abundant dry air in place...a 
mainly clear sky is expected. 
&& 


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


$$ 


Salmen/stachelski 


Http://weather.Gov/lasvegas