Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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182
FXUS65 KSLC 241047
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
447 AM MDT TUE MAY 24 2016

.SYNOPSIS...A series of weak weather disturbances will continue
to cross Utah through late week, keeping unsettled conditions over
the area.

&&

.SHORT TERM (Through 12Z Friday)...The current large-scale pattern
depicts a mean longwave trough remaining in place over the western
CONUS. A closed low is located over southern Saskatchewan while a
couple of shortwave disturbances are evident over central California
and off the northern California coast. Southwesterly flow remains in
place over much of Utah, but the winds will increase as the leading
shortwave disturbance lifts across the state this afternoon/evening.

The shortwave disturbance will provide some additional forcing over
the typical diurnal convection. Expect showers/thunderstorms to
increase in coverage a bit over yesterday. Models continue to trend
with the idea that enough moisture will spread into the area to
allow for showers to develop over portions of southern Utah today.
However, with the boundary layer still quite dry there with
dewpoints currently in the teens and 20s, gusty microburst winds
will likely occur with showers.

The second of the aforementioned shortwave disturbances will develop
into a closed low and track across northern Arizona late tomorrow
into Thursday morning. Meanwhile, the Saskatchewan closed low is
progged to elongate as a weak disturbance rotates around it and
grazes northern Utah tomorrow afternoon. This northern feature will
help drive scattered showers for northern Utah tomorrow afternoon
while portions of southern Utah could see a few showers developing
by tomorrow evening with the closed low.

With the passage of the second shortwave disturbance, the mean
trough axis will start shifting east of Utah on Thursday.
Northwesterly flow will develop behind a weak boundary and
precipitation should become a bit more widespread over the forecast
area. However, temperatures will see only minor day-to-day changes
today through Thursday.

.LONG TERM (After 18Z Friday)...Shortwave ridging builds over the
Rockies on Friday afternoon, with Utah/Wyoming/Colorado generally
between storm systems. This will allow for warmer and somewhat more
stable conditions for Friday, though enough moisture looks to linger
under the ridge to allow for convection initiating off the terrain
Friday afternoon.

The bulk of the next upper level trough remains north of the
forecast area Saturday, but models have come into better agreement
about bringing the surface cold front into the northern portions of
the CWA through the day Saturday. This front looks to be accompanied
by decent low level moisture, so have increased POPs for Saturday
afternoon across the north, and they will likely need to be raised
even more if models stand firm with the cold frontal timing. Sunday
is a little less certain, but looks somewhat similar to Saturday,
with the surface front hanging out across northern Utah and the bulk
of the upper low spinning off to the northwest.

The fate of this upper low becomes much less confident past Sunday,
with a fairly major divergence of model guidance; some push the
storm off to the east, while other models retrograde it a bit to the
west. Have kept the forecast temperatures and POPs generally close
to climatological normals in days 6 and 7 until models come into
better agreement.

&&

.AVIATION...There is a 20 percent chance of showers or thunderstorms
at the SLC terminal today, with a most likely impact of gusty
erratic winds. Away from storms, the wind forecast is still somewhat
lower confidence. The most likely scenario is that southerly winds
will increase around 16-18Z, but will eventually switch to northwest
winds between 20Z and 22Z. That said, there is a 30 percent chance
that winds will remain southerly through the entire day.

&&

.SLC Watches/Warnings/Advisories...
UT...None.
WY...None.
&&

$$

Cheng/Schoening

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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