Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 241552
Area Forecast Discussion
National Weather Service Salt Lake City UT
852 AM MST Fri Feb 24 2017
.SYNOPSIS...A cold upper trough over the area this morning will
shift east this afternoon. The next system will cross the area
Saturday afternoon and night, with yet another cold storm on tap
for the first part of next week.
Water Vapor Satellite a closed low over north central Wyoming.
400-200mb MDCARS wind observations place a 130-160kt westerly jet
from Arizona into Oklahoma. GOES/SLC 12Z RAOB/HRRR indicate that
precipitable water values vary from 0.05"-0.10" mountains to
Going forecast in good shape, just a few tweaks.
Cold advection is maximized right now (-16C KSLC RAOB) with the
cold pool (-36C) overhead. KSLC RAOB shows instability with steep
lapse rates. As a result with morning warming expect showers to
increase in coverage.
The Great Salt Lake may enhance showers. With a lake temperatures
of 42F, adjusted BUFKIT forecast soundings suggest Lake Induced
CAPE of 500-800 j/kg with an equilibrium level between 15-20kft,
plenty of added instability to intensify showers.
Road temperatures are currently in the 20s, meaning that they will
be snow covered especially under showers. As the day progresses
they should warm near freezing to mitigate some of the impacts.
Heavier showers will also restrict visibilities abruptly. Showers
will diminish late today with warming aloft and as heights rise.
The western portion of the cold upper trof remains over UT early
this morning with a cold moist and unstable west- northwest flow
Snow showers continue early this morning up and down the I-15
corridor as well as over the mtns from east of Cedar City nwd.
Expect these to persist into late morning then begin to dissipate
as the upstream short wave ridge begins to move in with rising
heights and an increasingly stable airmass spreading in thru the
aftn. The airmass is cold and snow will stick to roads thru about
mid morning before they start to run wet. Existing winter weather
highlights will remain in place.
The short wave ridge only brings a brief break tonight into Sat
morning before the next shearing positive tilt trof sags south
thru the area. This brings a threat of light snow first to the
north Sat aftn then shifting swd Sat night lingering across far
srn UT on Sun. Don`t expect much accumulation anywhere but local
travel impacts could still occur overnight as the airmass is cold
and snow will stick to roads again. Precip should stay as rain
below about 3500 ft down south. The flow begins to back around to
swly and warms somewhat Sun night ahead of the next cold trof.
The next trough pushes into the CWA in earnest through the day
Monday, with the best chance of valley precipitation from 12Z
Monday through 00Z Tuesday. Low level cold advection continues
into Monday night, with 700mb temps dropping to near -16C at the
Utah/Idaho border. Combined with lingering moisture and persistent
westerly flow, snowfall will likely continue in the mountains
through much of Tuesday.
The trough exits the area late Tuesday, leading to a significant
drying trend heading into Wednesday. The ridge that follows looks
to be fairly flat, with the ridge axis well west of Utah,
creating a relatively stable northwesterly flow over the CWA
through at least Thursday. This flat ridge makes the warming trend
relatively slow at first, though it could accelerate heading into
Friday as a shortwave off the Pacific shifts the ridge axis
eastward. Bottom line, the latter half of the upcoming work week
looks to be fairly quiet weather-wise, with temperatures
eventually rising to near average for early March.
VFR conditions will generally prevail at the SLC terminal through
the TAF period. However, periodic snow showers through 19Z will
briefly lower conditions to MVFR with a 20 percent chance of IFR
which if occurs will be less than 15 min in duration. After 19Z
snow showers will decrease. Winds will be west northwest through
UT...Winter Weather Advisory until 4 PM MST this afternoon for
Winter Weather Advisory until noon MST today for UTZ001>003-006.
WY...Winter Weather Advisory until noon MST today for WYZ021.
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