557
FXUS65 KSLC 150927
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
327 AM MDT Mon Oct 15 2018
.SYNOPSIS...A much cooler air mass will remain in place today.
The area will then see a steady warming trend through midweek. A
weak upper-level system will move into the southeast corner of
Utah midweek.
&&
.SHORT TERM (Through 00Z Thursday)...An elongating positively
tilted mid level trough extends from the Great Lakes region
southwestward through the central Rockies and into the southern
Great Basin early this morning. A shortwave trough digging down
the back side of this larger scale feature is currently closing
off over southern Nevada, and is forecast to cut off from the mean
flow later today as it becomes established over Arizona. Meanwhile
an amplified upper ridge is centered just off the Pacific
Northwest coast, and is forecast to build slowly inland over the
next couple of days, setting up a large scale rex block pattern
over the Interior West. As the upper low forecast to develop over
Arizona slowly drifts northward, moisture associated with this
feature will spread into southern and central Utah beginning late
Tuesday, and continuing into Wednesday, bringing a chance of
valley rain and mountain snow showers. Meanwhile the building
ridge will bring a warming trend to the north through midweek.
In the near term, clear skies and a cold airmass is allowing for
the first hard freeze of the season for most valleys excluding the
lower elevations of southern Utah. Gusty gap winds across
Washington County have begun to taper off a bit and are generally
below advisory criteria. As such went ahead and cancelled the
going Wind Advisory for Washington County while maintaining the
Hard Freeze Warning for most northern and central valleys still in
their growing season.
.LONG TERM (After 00Z Thursday)...No major changes in the evolution
of the Rex Block pattern with today's long term forecast period. A
weakening upper level low will be over Utah Wednesday evening and
then gradually eject into the Plains. Another upper level low will
begin to develop near San Diego Friday and then gradually move
northeastward into southern Nevada by Monday morning.
Expect showers to gradually shift eastward across eastern Utah later
Wednesday into Thursday. While the second upper level low
develops...dry and warming conditions can be expected across much of
Utah. The next threat for precipitation will be confined to
southwestern Utah Sunday...likely expanding north and east by
Monday.
&&
.AVIATION...Expect light and variable to light north winds to
continue at the SLC terminal into the morning...with a stronger
northerly wind developing between 16-17Z.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Hard Freeze Warning until 9 AM MDT this morning for UTZ002>004-
011>016.
WY...None.
&&
$$
Seaman/Kruse
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