Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 172104

Area Forecast Discussion
National Weather Service Salt Lake City UT
304 PM MDT Tue Oct 17 2017

.SYNOPSIS...A warming trend will continue through the middle portion
of the week. A weak storm system is forecast to cross the area
Friday, bringing cooler temperatures and mountain showers.


.SHORT TERM...Mostly benign westerly flow aloft will continue
through early Friday, bringing generally quiet weather conditions
to Utah and southwest Wyoming. A ridge axis currently overhead per
latest water vapor imagery will slide east of the area tonight,
while a very weak shortwave currently in western Nevada will push
through central Utah. The only effect of this wave will be a few
mid level clouds in central/southern Utah tonight.

A stronger shortwave trough is forecasted to lift northeastward
from Las Vegas area across central and eastern Utah late tomorrow
into Thursday. A few models are wringing out light precip over the
central Utah mountains from this disturbance. Given the very dry
low-level profiles, it will be tough to get anything other than
sprinkles outside of the high terrain. Otherwise, Wednesday will
be another pleasant day for most areas with temperatures 5-10
degrees above normal.

Southwest flow aloft increases over the Great Basin Thursday in
advance of a developing longwave trough stretching from NorCal to
the Pacific NW. Stronger mixing should allow for the warmest
temperatures of the week, with most Utah valleys reaching the 70s
or around 10 degrees above normal.

The trough pushes inland Thursday, reaching Utah by mid-day
Friday and pushing a cold front through northern Utah and
southwest Wyoming during the day. Breezy conditions can be
expected by Friday afternoon, especially over the western deserts.
Models are in general agreement with keeping the core of cold air
at 500MB to our north, with a shallower front from the surface to
around 700MB that pushes through all of our area except far
southern Utah by Friday night. As has been the trend with recent
troughs, this system will be lacking moisture, and thus the best
chance of light precip will be over the higher terrain from around
Utah County northward, particularly over the Uintas. Snow levels
will approach valley floors, but not expecting to see anything in
the Wasatch Front given the mostly dry nature of the system. The
most noticeable aspect will be a ~20 degree drop in temperatures
from Thursday`s highs to Saturday`s highs.

.LONG TERM...Temperatures quickly rebound across the area Sunday
as a dry northwest flow aloft sets in and heights build in the
wake of Saturday`s trough passage.

Looking ahead to next week, global models are in agreement in
building a strong ridge over the Western US. This ridge is quite
persistent and actually strengthens further into the week. This
will likely bring an extended period of warmer-than-normal
temperatures and dry conditions for our area.


.AVIATION...The dry/stable westerly flow aloft across northern Utah
will maintain VFR conditions under mostly clear skies through the
TAF period. Light west-northwest winds will turn to the southeast
around 04z this evening.





Van Cleave/Conger

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