Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 281056

Area Forecast Discussion
National Weather Service Salt Lake City UT
456 AM MDT Thu Sep 28 2023

.SYNOPSIS...Slightly cooler temperatures will settle into northern
Utah today behind a cold front. Winds increase tomorrow into
Saturday ahead of a more substantial cool-season system which will
move through late Saturday into early next week, bringing widespread
precipitation and a more marked cooldown.


.SHORT TERM (THROUGH 12Z SATURDAY)...A southwesterly flow aloft
remains in place across Utah today. A shortwave disturbance which
lifted across MT overnight has pushed a shallow cold front into
northern Utah. This front is currently located from near Delta to
the western Uintas. Another weak disturbance is noted over NorCal
this morning which will graze northern Utah later today. This
disturbance will help strengthen the cold front a little more, but
overall it should weaken before it really gets into southern Utah.

Cooler temperatures are expected today across northern Utah behind
the front. Looking at a 5-10F drop from yesterday`s highs, which
will put it closer to climatological normals. Southern Utah will
largely remain warm and locally breezy ahead of the front, so little
change there.

Tomorrow, the next storm system will be making its way onto the West
Coast. This will allow southerly winds to increase across much of
the area. Breezy to locally windy (but sub-advisory) conditions are
expected, given 25-35kt of H7 flow and a strengthening surface
pressure gradient owing to pressure falls over east-central NV. This
will also allow temperatures to trend slightly warmer again across
northern Utah.

.LONG TERM (After 12Z Saturday)...The extended period begins with a
trough digging into the Great Basin area. This trough will then
cutoff from the main low resulting in a cutoff low sitting over the
Utah area through early next week. This low will leave behind cooler
than normal temperatures as it progresses slowly out of the area.
The low is expected to leave the area by the middle of next week.

Starting on Saturday, this will continue to strengthen. Out ahead of
this system, winds will be approaching advisory level strength as
700mb flow will be around 30kts to 35kts. Wind gusts will be between
35mph and 50mph with the strongest gusts occurring in western and
Southern Utah. Temperatures will remain 5F to 10F above normal ahead
of this low.

Precipitation is expected to begin late Saturday night into Sunday
morning as the moisture is pulled from the Pacific into the area.
Current guidance has the best chance of precipitation occurring late
Saturday night through early Monday morning. Between Monday and
Tuesday higher terrain locations will still see scattered showers as
the low will be weakening and moving off to the northeast. Snow
levels during Saturday will stay around 10kft and slowly drop
through the day Sunday, to about 9500ft, and by the time late
Sunday/early Monday morning rolls around, snow levels will be around
8500ft across the CWA. QPF totals are expected to be between
.2" and .5" across the CWA while snow totals above 8500ft will
generally be less than an inch with isolated areas seeing up to a
couple of inches.

As the low sits over the area, temperatures for Sunday through
Tuesday will be between 7F and 15F below normal. This means for most
valleys, high temperatures will be in the low to mid 60s. While
areas of Lower Washington County will see highs in the low to mid
70s. Heading towards the latter half of next week, temperatures will
slowly creep back up towards normal after the low moves through.


.AVIATION...KSLC...VFR conditions expected. Light winds are expected
until northwest winds kick in between 17Z and 19Z. Between now and
then, predominant light northwest flow is expected with light
southerly winds occurring at times. There is a 40% chance that winds
will stay southerly until the northwest wind change. Regardless of
direction, winds will be light.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions and light and
diurnal winds are expected through the TAF period. Gusty southwest
winds, up to 25mph, will be possible across eastern and southern


.FIRE WEATHER...A dry cold front will bring cooler temperatures to
northern Utah today while southern Utah remains warm with locally
breezy south winds. South winds increase areawide tomorrow ahead of
the next storm system. These winds will become even stronger for
Saturday, with isolated hazardous fire weather conditions where
fuels are critically dry. Precipitation will fill in by late
Saturday, continuing at times through Sunday with rain in the
valleys and snow at the higher elevations (generally above 8000-8500
feet) as cold air works its way in on Sunday. Wetting rains are
expected for a large portion of the area with this storm.





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