Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 181007
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
407 AM MDT Wed Apr 18 2018

.SYNOPSIS...High pressure will prevail across the region today
but will breakdown Thursday as an upper level closed low moves
towards southern Utah. This low will track across southern Utah
Thursday night and across eastern Utah Friday. High pressure
returns for the weekend.


&&

.SHORT TERM (Through 00Z Sunday)...Ridge over the area overnight
with clear skies prevailing in most areas. Looks like hard freeze
warning is panning out in the Cache Valley, northern portions of
the Great Salt Lake Desert, and near Green River early this
morning with areas of upper 20s already. Mostly sunny skies will
prevail today with strong warming trend expected. There are some
high level clouds seen on satellite imagery moving into west
central Utah which will move east and north through this morning.
However, they will remain thin so temperatures should reach their
forecast highs, but if clouds thicken early than expected,
temperatures could hold down a few degrees from there projected
highs.

The surface gradient becomes favorable for enhanced canyon winds
tonight in the favored locations along the central and northern
Wasatch Front. Generally, winds will be 10-20 mph with gusts into
the 20s at the mouths of the canyons from Parleys Canyon to
Brigham City.

The closed low will track across southern Nevada late tonight and
into Utah by mid morning. Temperatures at 700mb will lower to
near
-5 to -6 degrees C, which should place the snow line between 5000
 ft and 7000 feet over southwest valleys, excluding Dixie Thursday
 night into Friday. Little if any accumulation expected in the
 valleys, but several inches are possible in the mountains. The EC
 is a little weaker with the closed low and farther south, which
 if correct will have less precip across the southwest valleys.
 Had to take this into consideration, so lowered PoPs some for
 Thursday night. The eastern portions of the CWA will have a
 chance of precipitation from midnight Thursday night through Friday
 evening as the low tracks eastward.

Some wrap around moisture will move northward along the backside
of the Wasatch Mountains Friday but will struggle to move westward
to the Wasatch Front as winds be easterly so downsloping will
occur causing the air mass to dry as it descends.

The ridge rebuilds Saturday with a warming trend to ensue.


.LONG TERM (After 00z Sunday)...Notable shift of the northern branch
amplitude anticipated during the long term period, as the mean storm
track will be taking a marked shift north vs. the last few weeks. As
a whole the pattern through the term will remain quite benign with
temps on average running about 10 degrees above climo on a daily
basis.

Do have to note a weak shearing wave that globals continue to
suggest will clip far northern portions of the area Monday, but also
see a lot of variance within individual ensemble members regarding
timing/amplitude of the weak feature. Opted to maintain largely
slight chance PoPs focused over the northern mtns and the UT/ID
border region through Monday night, but do not foresee significant
changes to sensible weather regarding this wave passage.

&&

.AVIATION...Operational weather concerns will remain minimal at the
KSLC terminal through the valid TAF period. Southeast surface winds
currently in place are expected to switch to the northwest between
20-22z. VFR conditions will be maintained.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Hard Freeze Warning until 9 AM MDT this morning for UTZ001-002-
     005-013.

WY...None.
&&

$$

SHORT TERM...Struthwolf
LONG TERM...Merrill
AVIATION...Merrill

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php


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