Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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512
FXUS65 KSLC 241546
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
946 AM MDT Fri Mar 24 2017

.SYNOPSIS...High pressure will build into the area today. This will
be followed by a Pacific weather disturbance late tonight through
Saturday, and another storm system during the first half of next
week.

&&

.DISCUSSION...Short wave ridging is in place across the area this
morning, with the axis bisecting the forecast area from SW-NE per
morning H5 analysis. Stability beneath this ridge has cleared all
cloud cover, with the last lingering stratus over the NE thinning
over the last few hours. The only update this morning was to
update sky cover to clear/sunny for all areas this morning.

Upstream the next pacific trough is already pushing into the
NorCal coast, and is primed to translate east across the eastern
Great Basin late tonight/tomorrow. In advance of this, the
aforementioned ridge axis will continue to shift east today
allowing a mild southwesterly flow aloft to develop from west to
east this afternoon. Temps remain primed to warm fairly rapidly
today as modest mixing coupled with H7 temps climbing from -6C to
+1C by 00z this afternoon will drive temps back up to about 5
degrees above climo. No other updates made or planned this
morning.

PREVIOUS DISCUSSION...The upstream trough will continue carving
south as it makes its way inland and becomes a somewhat split
trough as it crosses Utah tomorrow. However, it will be
accompanied by a plume of moisture, bringing PWATs up to 0.4-0.6
inches, and will maintain enough energy to produce fairly
widespread precipitation across the forecast area late tonight
through tomorrow. Although the associated cold front is not
particularly strong owing to the splitting nature of the trough,
cold advection behind the trough axis will bring 700mb
temperatures as low as -7 to -8C across northern Utah tomorrow
night. As such, snow levels are expected to fall to near
6500-7000ft across much of the area, and potentially down to
around 5000 feet across northern Utah towards the tail end of the
storm tomorrow night.

Another shortwave ridge will build into the area for Sunday but
temperature will not have the opportunity to warm much above normal
with the next storm quickly approaching.

The next Pacific storm system is expected to cross the forecast
area on Monday. EC/GFS now show this system moving across Utah and
southwest Wyoming as an open wave before diving southeast and
closing off around the Four Corners Tuesday morning. The system is
progged to bring a decent cold front through, with temperatures
just a bit cooler in the GFS compared to the EC given a more
southerly track. Precip along the boundary should be valley
rain/mountain snow, but 700 mb temps could potentially support
snow to northern Utah valley floors with any precip continuing
into Tuesday morning. Previous model runs have shown warmer
temperatures and thus higher snow levels, so have held off on a
mention of snow along the Wasatch Front and Cache Valley at this
time.

High pressure is expected to briefly return late Tuesday into
Wednesday behind the exiting system, resulting in a lull (if not a
break) in precipitation. However, EC/GFS continue to show a Pacific
Northwest storm system diving southeast into the Great Basin
Thursday. Both show the system closing off as it moves into the
Desert Southwest Friday morning but diverge with the track it takes
afterward. GFS ultimately moves the system into northern Mexico and
Texas by Saturday night/Sunday, which would limit the potential for
precip over the forecast area after Friday. However, the latest
ECMWF tracks the system along the UT/AZ border through Sunday
morning, resulting in a longer period of precipitation. For now,
have kept chance POPs in through much of day seven.


&&

.AVIATION...VFR conditions expected to prevail at the SLC terminal
through the day with increasing high clouds from the north and west.
Southerly winds are expected to persist through the afternoon, but
there is a 20 percent chance of a late shift to the northwest
between 21Z and 23Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

DISCUSSION/AVIATION...Merrill/Dewey
PREVIOUS DISCUSSION...Cheng/Traphagan

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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