Weather

983 
fxus65 kslc 110337 
afdslc 


Area forecast discussion 
National Weather Service Salt Lake City Utah 
937 PM MDT Friday Oct 10 2008 


Synopsis...a cold upper disturbance moving through the Pacific 
northwest will continue to form a deep low over the Great Basin 
today. This low will move little through Saturday then slowly lift 
out Monday with high pressure returning for early next week. 




&& 


Discussion...the cold upper trough is making its way into the 
forecast area this evening...and snow has already begun to fall in 
southwest Wyoming. Much colder air has already pushed in behind 
the associated surface front that is moving slowly near a kbjn- 
kcdc-kvel line. This resulted in a few record low maximum temperatures over 
northern Utah...and could also result in below freezing mins as 
low as the Cache Valley. 


With the trough moving into the area and closing off tomorrow 
morning...precipitation will become more widespread. In valley 
locations...the precipitation will begin as rain before switching over to 
snow in the late afternoon/early evening as the low continues 
east...bringing still colder air into the region. Snow will 
continue through Saturday night before tapering off Sunday. 


Right now...it looks like warning amounts are most likely in the 
northern mountains and mountain valleys as well as southwest 
Wyoming...while advisory amounts will be more likely in valley 
locations as well as the central mountains. However...because 
this storm is occurring early enough in the season that many 
trees have not yet lost their leaves and the snow is expected to 
be heavy and wet...there is a greater possibility of branches 
breaking and causing power outages in the urban corridor. Because 
of this...winter storm warnings may be warranted in valley 
locations though accumulations will not technically reach 
criteria. Additionally...gsl temperatures are quite warm...around 
17c...and with the next push of cold air there is a definite 
possibility of lake enhanced snow late Saturday into 
Sunday...resulting in locally higher amounts of snowfall. Minimum 
temperatures Sunday night/Monday morning should be below freezing 
for all but far southern Utah. 


The trough is expected to exit the state Monday...allowing for 
warmer and drier air to move into the region. Temperatures should 
return to more seasonable values by midweek. 


Current forecast looks to be on track. No updates expected this evening. 


&& 


Aviation...winds at the slc terminal will remain from the northwest 
through tomorrow morning with a 10 percent chance of the typical 
southeast drainage winds developing between 09z and 10z. 
However...if the drainage wind does develop...it will only remain 
for a few hours. VFR conditions should prevail overnight...though 
conditions will deteriorate during the morning hours...with rain 
beginning by late morning. 


&& 


Fire weather...the last afternoon fire weather planning forecast 
for the season will be produced Saturday October 11 2008. The 
early morning forecast will continue to be issued through the end 
of the month. 


&& 


Slc watches/warnings/advisories... 
Utah...Winter Storm Warning until 6 PM Sunday for utz007. 


Winter Storm Watch from noon Saturday to 6 PM Sunday for utz006- 
utz008>010-utz517. 


Winter Storm Watch from 3 PM Saturday to 6 PM Sunday for utz001>004- 
utz015. 


Wyoming...Winter Storm Warning until 6 PM Sunday for wyz021. 




&& 


$$ 


Traphagan 


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