061 
fxus65 krev 150954 
afdrev 


Area forecast discussion 
National Weather Service Reno Nevada 
250 am PDT Monday Mar 15 2010 


Short term... 


Upper ridge continues to push into the Great Basin...with some 
extremely dry air aloft. Slide Mountain dew point still sitting 
around -35f. To put that in perspective...even at 32 degrees at the 
top of slide...that relative humidity is only 3-4 percent. Expecting 
700mb temperatures to increase today to 2-3c...with high temperatures hitting the 
low 60s today across the lower valleys and low 50s in the Sierra 
valleys. Should see several degrees warmer on Tuesday...as we get 
increased southwest flow. 


A shortwave trough will pass to the north of our area on 
Tuesday...moving into the Pacific northwest by Tuesday night. This will help to 
flatten out the ridge and increase the southwest wind flow aloft. 
Models have indicated some meager instability over the last several 
runs..lifted index 0 to -1c. Could see some isolated showers on Wednesday 
afternoon...but with limited moisture and dry boundary layer...may not 
see much more than virga. Even the sref is starting to hint at the 
Wednesday convection. Did bump up probability of precipitation and add a slight chance of showers 
to the forecast for Tahoe and Mono. If this was April...would be 
thinking more along the lines of thunderstorms with those lifted 
indices...but for now will thunder out of the forecast. Hoon 


Long term...Thursday through Sunday... 


Few changes. Shortwave still prognosticated to be passing southward through the 
Great Basin with models continuing to indicate enough instability and light quantitative precipitation forecast 
signatures to warrant the slight chance of showers mainly southern/eastern zones. 
Activity may begin as far north as eastern Pershing/Churchill counties 
in the morning but quickly move to southern counties of Mono/Mineral as dry 
northerly flow on systems back side pushes instability southward. Otherwise much 
drier air pushing across region Thursday night-Friday with air mass unlikely to recover 
much over the weekend. Just as dewpoints show some slight moderation 
Sat night...a dry southwesterly flow sets up ahead of next Pacific trough on sun. 


Models continue to show trough late weekend into early next week. The 
European model (ecmwf) was a bit slower with main syst passage now late Sun night-Monday 
which was in line with the deterministic GFS. Although the GFS was a 
bit flatter and north with track. The Canadian was closer to the 
European model (ecmwf) tonight. Bottom line...another day or two is going to be needed 
to better pinpoint impacts and timing. Forecast will continue to reflect low 
probability of precipitation across the north beginning Sun night with increasing winds Sun afternoon-Sun 
night. Temperatures will remain above normal with 50s Sierra to 60s lower valleys 
common. Hohmann 
&& 


Aviation... 
VFR conds all sites. No issues. Hohmann 
&& 




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


$$ 


Http://weather.Gov/Reno