Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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417
FXUS65 KSLC 250356
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
956 PM MDT TUE MAY 24 2016

.SYNOPSIS...The elongated upper level trough to the west of Utah
will shift slowly into the state by Thursday. Unsettled conditions
associated with this trough will persist through the end of the
week.

&&

.SHORT TERM (Through 06z Saturday)...Scattered convection that
covered much of northern and central Utah this afternoon has
dissipated with the loss of heating this evening. Can not rule
out the possibility that some convective precip will return later
tonight through early Wednesday.

One apparent shortwave rounding the base of the coastal California
upper low will lift northeast into Southwest Utah by around
midnight. This feature will continue northeast through central
and northeast Utah overnight. Southern Utah looks a bit too dry
and stable to support precip from this weak dynamic feature.
Conditions able to support some form of convection will improve
across central Utah...and continue across northeast Utah and
southwest Wyoming.

A second area to watch will be near the Idaho border. Animation of
water vapor imagery shows a deformation axis stretching from
southern Montana southwest back towards the upper low off the
California coast. This deformation has concentrated moisture
across far northern Utah where it should remain through Wednesday
morning. Lingering showers near the Idaho border overnight could
gain a little better organization by early Wednesday if the
vorticity max depicted in the GFS/NAM does in fact ripple east
across the Utah/Idaho border region. Some evidence for the
existence of this feature does exist in the water vapor imagery
over far north-central Nevada/extreme southwest Idaho. Will
maintain the chance category Pops in the current forecast
package.

Diurnal convection should once again form up wednesday afternoon,
with the greatest concentration across the north where the
moisture and instability remain somewhat more favorable. Southern
Utah may become more involved Wednesday night/Thursday as the
coastal California low tracks east in Arizona. This low should
bring some improvement to the moisture profile along with
sufficient dynamic lift to support some convective precip.

The rather weak flow regime setting up for Friday will allow some
moisture to linger across the state. Differential heating will
allow for terrain-based convection to kick off during the
afternoon...then dissipate fairly quickly with the loss of
heating Friday evening.

.PREVIOUS 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...VFR conditions with light south-southeast winds will
exist at the KSLC terminal through at least 09z. A weak
disturbance moving north from southern Utah could bring isolated
showers back to the terminal area for late tonight. A second
system near the Idaho border could keep showers going through the
14z to 15z. Ceilings in any precip will generally remain in the
8 to 10 kft range.

&&

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

$$

SHORT TERM/AVIATION...Conger
LONG TERM...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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