Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 240236

Area Forecast Discussion
National Weather Service Salt Lake City UT
836 PM MDT Tue Jul 23 2019

A broad area of high pressure aloft will remain centered near the
four corners through Wednesday, then slowly shift south over
Arizona late in the week. Showers and storms will becoming more
likely with the potential for locally heavy rainfall through the
end of the week.


.SHORT TERM (Through 00z Saturday)...
Scattered thunderstorms across southern and central Utah earlier
this afternoon have largely diminished into scattered showers with
some isolated lightning strikes near the Nevada border. These
scattered showers will continue to spread north across northern
Utah late this evening and overnight as a shortwave moving through
Nevada grazes the NW corner of Utah overnight. Given the sparse
lightning activity has gone ahead and dropped the Red Flag
Warnings early this evening. While will see another warm night
tonight given the warm airmass and abundant cloud cover,
temperatures will moderate to normal mid-summer conditions on
Wednesday, the Heat Advisories have also been expired.

The orientation of the high will begin to shift/suppress
south/west into Arizona Wednesday, this as a northern branch
trough translates across the northern Rockies region. With this
shift flow aloft will veer more westerly for Wednesday, then
eventually northwesterly by the evening further pooling the sub-
trop moisture over central and especially southeastern Utah. PWAT
values up to 1.4" coupled with another 24 hours worth of
moistening at lower levels will promote a locally heavy rain
threat and increased flash flood potential for
Wednesday...greatest from roughly Capitol Reef N.P. south across
the Grand Staircase/Escalante region, more isolated points west
towards the Zion/Dixie region.

With this veering of flow aloft, northern UT/sw Wyoming should
trend largely dry Thursday, while central/southern portions will
remain well entrenched in the moisture and associated convective
and locally heavy rain potential. The high does look to attempt
to bulge north least temporarily as trajectories will
once again favor passage of return flow waves into the overnight

.LONG TERM (After 00Z Saturday)...
The ridge over the area is expected to flatten again Friday night
into Saturday in response to a trough moving over the top of it.
As the trough exits, the ridge axis is expected to rebuild over
Nevada Saturday night into Sunday. This will act to shift the flow
aloft to a more northwesterly direction, drawing drier air into
Utah and southwest Wyoming through the upcoming weekend. As a
result, the area will see decreasing coverage of POPs as
temperatures warm, jumping back above climo by Monday.

Another approaching trough is expected to slide the ridge axis back
over the Four Corners region by Tuesday morning, bring the flow
aloft back to a more moist southwesterly direction. Have indicated
an increasing trend in POPs for day seven.


Northwest winds should prevail at the KSLC terminal over
the next few hours before shifting to the southeast between 05-07Z.
There is a 30% chance that the scattered showers currently south of
the terminal cause the southerly wind shift to occur earlier.
Regardless, once the south winds take over, they should prevail
through the night until a lake breeze develops tomorrow. Gusty,
erratic winds are possible again tomorrow afternoon as scattered
showers and thunderstorms develop in the vicinity of the terminal.




SHORT TERM...Church/Merrill
LONG TERM...Traphagan/Webber

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