240 
fxus65 krev 061029 aaa 
afdrev 


Area forecast discussion 
National Weather Service Reno Nevada 
329 am PDT sun Jul 6 2008 


Update... 
krgx radar indicated increase in echoes over Pershing and 
Churchill counties since 2 am...associated with weak shortwave 
passing across western Nevada that is most evident on the water vapor 
satellite loop. The 06z GFS indicated a local instability maximum on 
the modified totals data between 12z-18z in this area which may 
support isolated lightning strikes. Will add isolated am showers/thunderstorms 
in the west-central Nevada basin and range for the scheduled morning 
forecast issuance. Mjd 


&& 


Previous discussion... /issued 255 am PDT sun Jul 6 2008/ 


Short term... 
ridge off the West Coast is expected to strengthen through Monday 
then expand into the western US...resulting in a continued warming 
trend with maximum temperatures reaching or exceeding 100 degrees. Record 
highs are most reachable on Monday or Tuesday...see the public 
information statement /pnsrev/ for details on record high temperatures 
in locations across the region for the next few days. 


Haze and smoke made a return to the Reno-Tahoe zones Sat evening 
due to west-northwest winds from the surface to the mixed layer. Winds today 
will be lighter which may inhibit dispersion of existing smoke 
this morning...but transport winds over the smoke plumes of the most 
active fires this afternoon will not favor much additional smoke 
pouring into northestern California or western Nevada...especially by late afternoon when 
the transport winds shift to the northeast. Areas of existing haze 
and smoke may linger through tonight over northestern California and northwest surface winds 
could bring one more push toward portions of the Reno-Tahoe 
region...but concentration of smoke should be lower than Saturday. 
Overall clearing is expected for Monday-Tuesday as prevailing winds 
become northeast. 


The combination of daytime heating and increased 500 mb moisture 
with the prevailing northeast wind flow on Monday-Tuesday will allow for 
more afternoon-evening cumulus formation near the Sierra crest. Local 
orographic lift may even allow for some vertical cloud growth into 
isolated cumulonimbus towers...but if any thunderstorms manage to form they would 
quickly be pushed west of the crest. Away from the Sierra 
crest...capping inversion above the cloud layer will inhibit thunderstorm 
formation through Tuesday. Mjd 


Long term...Wednesday through Saturday... 
no significant changes planned to going extended forecast this 
period. Operational GFS is now a little less aggressive with trough by 
the end of the period as opposed to European model (ecmwf). Ensembles tending to 
support GFS a bit more than European model (ecmwf). Oddly...GFS is trying to develop 
more convection by the end of the extended period over the far southern 
County Warning Area while European model (ecmwf) is producing its convection east of the County Warning Area. Given a 
Flat Ridge over the region with a weak trough trying to work east 
across the top of ridge would tend to favor a dry forecast with only 
ghost probability of precipitation across the southern and eastern County Warning Area by the end of the period. This 
is something of a compromise solution and feel this is the best 
course at this time. Mex guidance from GFS has bumped temperatures back up again 
for Thursday after dropping them 24 hours ago. Since only minor 
modifications were made yesterday will not make sig changes to temperatures 
at this time. Still some records possible for the early portion of the 
extended with highest readings expected Wednesday/Thursday then slight 
cooling for Friday and Saturday. This is currently handled with pns 
and headlined in zones. Mlf 


Aviation... 
once again VFR conditions should prevail through the forecast period 
but with late afternoon winds increasing from the west think some 
smoke will be pulled back into the Tahoe basin and just east of the 
Sierra impacting ktrk/ktvl and krno. Do not think visibilities will drop 
much below 5 miles though...and the drop should last no more than 4 
hours in the early evening. Afternoon winds for krno likely will 
gusts to around 20 kts again today...then drop off in the 
evening. No problems noted for klol vicinity. Mlf 


&& 


Rev watches/warnings/advisories... 
Nevada...none. 
California...none. 
&& 


$$ 


Http://weather.Gov/Reno