Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 250346

Area Forecast Discussion
National Weather Service Salt Lake City UT
946 PM MDT Thu Sep 24 2020

.SYNOPSIS...A dry cold front will move south across northern and
central tonight through Friday. A second reinforcing frontal
boundary along with cooler temperatures will follow for Friday
night. Cooler temperatures will continue through the weekend.
High pressure aloft will strengthen over the West Coast and
western Great Basin, resulting in above normal temperatures and
dry conditions into next week.


.SHORT TERM (Through 12z Sunday)...The strong mid-latitude
westerlies across the Pacific Northwest/northern Rockies will
usher in a series of embedded shortwaves through Saturday.
These dynamic features will generally focus the strongest
dynamic/thermal support for lift well north of Utah the next
couple of days.

The one notable change from these passing shortwaves will be to
nudge somewhat cooler air south across northern/central Utah.
The first cold front to work south through the area moved into
northern Utah late this afternoon, and has reached the KOGD area
at mid-evening. This front should accelerate south later tonight
as the next shortwave embedded in the zonal flow to the north
moves east across Idaho. Subsequent embedded shortwaves will
serve to reinforce the cooler air already in place and bring
temperatures back to near seasonal levels this weekend.

.LONG TERM (After 12Z Sunday)...The cooling trend observed in the
short term period will continue through Sunday as a trough sliding
into the central United States brings N/NE flow and a mostly dry
front through the state. There still remains a good deal of spread
with regard to the precise position of the trough and associated
front, and this is a situation where small changes in the location
of the system will cause noticeable differences in the amount of
cooling the area sees. Because of this, confidence in the
temperature forecast on Sunday is a bit lower than usual.

Behind this system, strong ridging is anticipated to build over the
Great Basin through day seven. This will result in a steady warming
trend in temperatures through at least the middle of the upcoming
week, bringing temperatures back above seasonal normals once again.
Under the influence of the ridge, conditions will remain dry with
light winds.


.AVIATION...The SLC terminal will see VFR conditions through the
TAF period. Southeast winds will takes a turn back to the north
and become gusty for a short period of time between 06Z and 09Z,
then gradually return to the southeast again by around 11Z-13Z.


.FIRE WEATHER...Noting critical fire weather conditions developing
across the northeast this afternoon in advance of a dry frontal
boundary that will work into far northern Utah later this evening.
Areas that remain south of this boundary, and the upper elevation
zones, are expected to see minimal recovery to RH tonight, with a
a further increase to winds Friday. Although a slight increasing
trend in Min RH is expected across the northern zones for Friday,
it will be marginal for the time being and have opted to upgrade
eastern Utah and the central/southern Mountains to Red Flag
Warnings this afternoon. A secondary reinforcement from a weak
wave grazing northern utah will push the boundary a bit further
south for Saturday, but with this will come a further increase in
RH and a net decrease in winds as the flow aloft trends lighter.

Near seasonal temperatures will be in place for the remainder of
the weekend into early next week, and no critical conditions are
foreseen at this time. High pressure will build into the district
mid/late next week allowing yet another warming trend to occur.


UT...Red Flag Warning from noon Friday to midnight MDT Friday night
     for UTZ484-488-489-493-494-496-498.

     Red Flag Warning until 9 PM MDT Friday for UTZ479>483.

WY...Red Flag Warning until 7 PM MDT Friday for WYZ277.




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