Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 240233
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
833 PM MDT Tue Apr 23 2019

.SYNOPSIS...High pressure aloft will expand east across the Great
Basin through Wednesday. A series of weather disturbances will
move over the top of the ridge and impact mainly northern and
western Utah during the latter half of the week.

&&

.DISCUSSION...
Quiet weather with high pressure dominating surface and aloft. A
few locations favored in northwest/north flow are gusting a bit as
a result of the pressure gradient ahead of the building high.

Just a quick update to tweak the hourly diurnal curves with the
latest observations and model data.

&&

.PREVIOUS DISCUSSION...
Inferring flow aloft based on infrared satellite imagery reveals
that a shortwave ridge axis has shifted into northern Utah /
southwest WY this afternoon. As expected based on high-res models,
convective activity this afternoon has been limited to just a few
cumulus buildups along and in the lee of higher terrain. Synoptic
subsidence and unfavorable thermal profiles have otherwise
limited development.

A warming trend is expected for the remainder of the workweek as
temperatures aloft climb and a mean ridge axis persists over the
Great Basin. SLC is currently forecast to flirt with the warmest
highs yet this year in the mid to upper 70s, while St George and
Utah`s Dixie should reach into the low 90s. Snowmelt will
continue, though overnight lows should remain cool enough to allow
for a bit of a thaw freeze cycle for most elevations which would
help temper snowmelt pace through Thursday.

Models are indicating an increasing trend in convective potential
each afternoon through Friday afternoon for most of the forecast
area except perhaps the far southern areas. Looking at BUFR
soundings, convective parameters are certainly more favorable with
each day. While models are likely suffering from convective
feedback in the QPF fields, convective indicies agree with the
increasing chances of showers/thunderstorms. Forecast precipitable
water climbs appreciably Thursday night, which should lead to a
warm night and potentially elevated snowmelt. Friday looks to be
the warmest day of the week, breezy, and the day of the workweek
with the best chance of showers/thunderstorms. All these factors
should lead to increased snowmelt that day as well which is worth
keeping an eye on. The flow aloft buckles by late Friday, pushing
a surface cool front into northern Utah / southwest Wyoming and
perhaps providing another ingredient for afternoon convection.

As the ridge flattens further with the northern branch trough
moving south, the flow aloft becomes more cyclonic in nature with
a baroclinic zone pushing into northern Utah Saturday. This front
does not have a lot of moisture associated with it, outside of
some scattered showers tied to the terrain mostly and seems to be
fairly quick in progression as it exits the area to the southeast
by Sunday.

The previously  mentioned closed low off the Southern California
coast begins to head inland late in the weekend and the flow across
the area turns more southwesterly. Compared to previous forecast
model runs the past few days, the closed low is now advertised to
become absorbed into the larger trough feature earlier on. This
should lend to more showery conditions and better instability Monday
and Tuesday across mainly central and southern Utah, so potential
for thunderstorms exists. Available moisture will be plentiful with
the trough swinging through southern Utah into southwestern
Colorado. Temperatures from Sunday into early next week will be
cooler than the most recent few days we are seeing now, however
still remain at or near seasonal normal.

&&

.AVIATION...
VFR conditions are expected to prevail for the KSLC terminal
through the valid TAF period. Northwest winds in place are
expected to shift to the southeast between 03z and 04z this
evening with mostly clear skies.

&&

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

$$

PUBLIC...10/Van Cleave/Dewey
AVIATION...10

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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