Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 252048

Area Forecast Discussion
National Weather Service SALT LAKE CITY UT
Issued by National Weather Service GRAND JUNCTION CO
248 PM MDT Wed Apr 25 2018

.SYNOPSIS...High pressure will bring gradually warming
temperatures and dry conditions through the end of the week.
Southwest flow will increase across the region Friday into
Saturday, with very warm temperatures and storms possible over
higher terrain. Cooler and unsettled weather returns Sunday into
next week as the next Pacific storm system works slowly east
across the Great Basin and northern Rockies.


.SHORT TERM (Through 00z Sunday)...A few high clouds are seen
drifting over the region in westerly flow with dry conditions. The
flow shifts to northwest this evening and overnight as a shortwave
trough moves across the northern Rockies, through Wyoming and
down the Front Range. Some breezy conditions may accompany the
trough passage. The ridge of high pressure to the west will slide
over the region by Thursday leading to much warmer temperatures.
The warmest temperatures of the week will occur on Friday and
Saturday as southwest flow increases ahead of an upper level
trough moves into the Pacific Northwest as a closed low. H7 temps
are expected to climb into the 8C to 10C+ range resulting in well
above normal temperatures and some lower valleys rising into the
80s and even low 90s across southwest Utah. This warmer southwest
air will also help increase afternoon mixing, with H7 winds in the
25 to 35 kt range. Mid and high level moisture will also be
increasing with the low levels remaining dry, leading to the
potential development of afternoon thunderstorms both Friday and
Saturday afternoon, favoring the higher terrain. Expect gusty
outflow winds and lightning to be the primary threats with storms.

.LONG TERM (After 00z Sunday)...The models are not in great
agreement with how to handle the upper level closed low over the
Pacific Northwest Sunday into next week. The GFS shifts the low
into Montana by Monday, with several pieces of energy rotating
around the periphery of the closed low and tracking through the
Great Basin and over Utah Sunday through Wednesday. The EC on the
other hand, keeps the upper low situated over the northern
Rockies with showers favoring the central and north Sunday through
Tuesday. A piece of energy dives down through the Great Basin on
the western side of the low and splits as it moves into SW Utah,
resulting in more active and widespread showers and thunderstorms
on Wednesday. Regardless of the differences in timing of these
waves and the placement of the low, the weather looks to remain
cooler and unsettled Sunday through Wednesday at least. So, went
with a broadbrush approach and kept precipitation focused along
the higher terrain with some lower chances in the valleys through
the period. Really no areas to focus on for better storm chances
until models come into better agreement with these details.


.AVIATION...VFR conditions will prevail at the KSLC terminal
through the valid TAF period with light northwest winds prevailing
through 02Z before switching to southeast overnight. Some high
cirrus clouds this afternoon will give way to clearing skies





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