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Area forecast discussion...amended fire weather discussion 
National Weather Service Elko Nevada 
348 am PDT Sat Sep 6 2008 


Synopsis...high pressure will dominate the weather through early 
next week...producing warm daytime temperatures and sunny skies. 
The next chance for thunderstorms will be Tuesday over higher 
elevations of central Nevada. A cold front Wednesday will bring 
slightly cooler temperatures for the second half of the week. 
&& 


Short term...today through Sunday. Satellite shows scattered to broken cirrus 
streaming over northeast Nevada this morning...associated with 100kt 
jet over southern Idaho. Jet will move off to the east today...taking 
the cirrus with it. After several days..NW flow at 500mb finally 
weakens today as high pressure builds in from the eastern Pacific. 
Weak ridge will be over the forecast area Sunday. Afternoon lifted indice's... 
combined with precipitable waters around a quarter inch...will be insufficient for 
any convection. Afternoon highs today will be a degree or two 
higher than yesterday...and Sunday will be 2 to 3 degrees warmer 
again. Rea 


Long term...Sunday night through Friday. Period starts with a ridge 
of high pressure off the Pacific coast...and a broad trough over the 
central United States. In between these two large features...several 
small disturbances will be located in the western United 
States...including two weak upper-level circulations over northern 
and Southern California. With a weak southerly flow trying to 
develop over central and southern Nevada...expect a very modest flow 
of monsoonal moisture to begin creeping northward. However...this 
looks very minimal...and in fact appears to be diminished in 
tonights models compared to last nights...so thus feel safe that only 
some cumulus build-ups will affect central Nevada on Monday. With 
very warm middle-level temperatures...expected middle to upper 80s in most 
valleys with low 90s in the warmest locales. 


Tuesday...these weak features try to coalesce into a broad trough 
across the western US. European model (ecmwf) tries to rotate the circulation from 
Southern California northeastward into central Nevada...while GFS 
holds it back. The progress of that modest disturbance may mean the 
difference between whether any isolated thunderstorms manage to 
develop Tuesday afternoon across east-central Nevada...where the 
greatest instability and moisture could combine. Compared to last 
night...the potential for storms looks a bit lower on tonights 
models...so I nudged probability of precipitation back ever so slightly as well as 
diminishing the coverage of thunderstorms and rain in the grids ever so slightly. 
Temperatures will cool just slightly compared to Monday...with most 
valleys again in the middle 80s. 


Wednesday...the flow aloft begins to be influenced by a much more 
potent shortwave trough diving southward across the Canadian rockies 
into the northwestern United States. The European model (ecmwf) has come into better 
agreement with the GFS in regards to this feature...and both models 
now show a weaker trough which stays further northeast. This will 
cause winds aloft to turn northwesterly...and any lingering 
monsoonal moisture should be scoured out. Along with the drier 
air...the incoming air mass will also turn cooler...and the higher 
valleys will fail to exceed 80 degrees. 


Thursday and Friday...the eastern Pacific Ridge builds eastward into 
the West Coast...and dry weather should prevail. Temperatures will 
start rebounding by Friday as the ridge rebuilds and middle-level 
temperatures warm. Rcm && 


Aviation...light northwest flow aloft will produce mostly clear 
skies and relatively light winds through Saturday. Will see a slight 
increase in moisture and instability across central Nevada beginning 
on Sunday which may result in afternoon cumulus cloud build-ups 
over central Nevada...however do not believe there is enough 
moisture for thunderstorm development. Rcm 
&& 


Fire weather...high pressure will control the weather into early 
next week. Middle-level moisture will begin returning to central 
Nevada Monday...and may be sufficient Tuesday...with increasing 
afternoon instability and a weak cold front approaching from the 
west...for lal 2 isolated dry thunderstorms. Tuesday may also 
breezy with low afternoon surface humidities...which could 
potentially reach red flag criteria. 


Middle-level moisture should linger Wednesday in central Nevada 
as the trough associated with the cold front moves through...but 
slightly lower afternoon surface temperatures may limit instability. 
Gusty winds and low surface humidities will be possible again 
Wednesday. 


Temperatures will cool an additional 2 or 3 degrees Thursday as drier 
air moves back into the state. Rea 
&& 


Lkn watches/warnings/advisories...none. 


$$