Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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599
FXUS65 KSLC 242129
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
329 PM 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 06z Saturday)...Afternoon water vapor and H5
analysis depict three upper level circulations embedded in the
mean long wave trough over the western conus. The one located on
the eastern periphery over southern Nevada will continue to weaken
as it lifts northeast across the area tonight, the next upstream
off the central Cali coast has closed and will continue to deepen.
The third over northern Cali should largely dissolve as it wraps
into the latter over the next 12 hours.

SPC mesoanalysis places a core of 500+ J/KG MUCAPE over the
northern third of the area attm. Relatively steep lapse rates
coupled with a half inch of PWAT remain in place this afternoon as
well. Weak forcing along the northeastern periphery of the
aforementioned short wave coupled with diurnal destabilization
have aided scattered showers and storms across the north, focused
over the northwest where mid level convergence is most pronounced.
Only Isolated convective showers have formed over the southern
mtns where a more stable environment exists. Anticipate similar
coverage to hold through much of the evening before largely
dissipating. This said, a subtle deformation sagging into the
north will likely retain scattered showers across the north
through the night as the upper wave progresses through central
UT.

The closed circulation now off the Cali coast will progress east
southeast into SoCal tomorrow, then Arizona tomorrow night,
gradually filling as it translates. With modest moisture
remaining in place, and convergent mid level flow draped across
the north, expecting similar areal coverage of showers and storms
tomorrow. Steeper mid level lapse rates across the south should
allow for some deeper convection however, with thunderstorms more
likely over the terrain.

Though largely diurnal in nature, areal coverage of nocturnal precip
should remain isolated Wed night due to aforementioned convergence
over the north and weak forcing along the northern periphery of
the low across the south.

Flow aloft will trend northwesterly Thursday through Friday and
remain cyclonic in nature. This coupled with the maintenance of
modest moisture and diurnal destabilization will continue to yield
daily convection, though focus may begin shifting south and along
the I-15 corridor. Those details remain to be seen and have
maintained generally isolated coverage valleys and scattered
coverage mtns.

Temps will remain at or slightly below climo each day within this
cool pattern, but a slow warm up looks to be realized by the
weekend.

.LONG TERM (After 06Z Saturday)...The next Pacific Northwest storm
system is progged to graze the UT/ID border as it moves by during
the day Saturday. Despite this, it is expected to move a weak
frontal boundary into northern Utah Saturday afternoon and evening,
which could act as a focus for afternoon convection. By Sunday, the
area will be under a somewhat unstable southwest flow between
systems, with some moisture lingering over northern and central
Utah, allowing for a few showers and thunderstorms.

For early next week, a weakening Pacific storm system is progged to
track onshore Sunday night/early Monday. Both the EC and GFS tend to
keep the center of this system over northern Mexico/southern Arizona
as it moves by, but the EC brings it through a bit faster, on Monday
instead of Monday night/Tuesday. Regardless, this would keep
conditions somewhat unsettled over much of the forecast area,
allowing for isolated convection, primarily over the higher terrain.
Another Pacific Northwest system is then expected to graze northern
Utah on Tuesday, bringing another relatively weak frontal boundary
through. Latest EC brings the system a bit closer to Utah compared
to the GFS, and thus indicates a bit more shower activity. Have kept
POPs near or slightly above climo for now. Despite the passing
fronts, temperatures are generally expected to remain right around
seasonal norms through the extended portion of the forecast
period.

&&

.AVIATION...Scattered thunderstorms expected near the SLC
terminal through the early evening hours. This will impact the wind
direction. While a southwest direction is favored with storm motion,
northwest is also possible though less favored. Cigs should remain
above 7000k feet. Expecting a diurnal wind shift to the southeast
between 03z and 04z. For Wednesday, expecting a northwest wind shift
but a later onset between 21z and 22z.

&&

.FIRE WEATHER...A semi active period areawide will continue.
Current activity is focused over the northern half of the
district where scattered showers and isolated storms exist this
afternoon. Isolated convection has formed across the south. These
trends will largely continue each afternoon and evening for the
next few days...though coverage of precip potential will gradually
expand across the southern terrain. Yet another storm system will
approach northern Utah this weekend...this maintaining scattered
storm potential across the north and isolated terrain based
potential across the south.

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

$$

Merrill/Traphagan/Dewey

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