Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 122143
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
343 PM MDT Sat Aug 12 2017

.SYNOPSIS...Moisture will remain in place across Utah today. A
drier airmass will start working into the area from the west
Sunday. A cold front will move into northern Utah Monday then
gradually across the state through midweek.

&&

.SHORT TERM (THROUGH 00Z Tue)...A low amplitude mid level ridge
remains centered over UT this afternoon downstream of a short wave
trof moving into the western Great Basin.

Deep moisture plus some modest jet support brought scattered to
numerous tstms to most of central and southern UT this aftn with a
few cells becoming strong and a number of them generating heavy
rainfall.

The upstream wave will cross the CWA overnight keeping the threat
of convection going tonight. The focus looks to shift northward
during the night with storms lasting into early Sunday over the
nern 1/2 of the CWA.

Drier westerlies are forecast for tomorrow behind this wave but
there should be enough lingering moisture for tstm development
over the mtns and east.

The flow quickly backs around to swly again by Mon as a deeper
trof moves into the PacNW states and nrn Rockies. This flow
continues to bring drier air into the CWA and expect a continued
downward trend to the convection.

This trof is fairly deep and is forecast to send a fairly strong
cold front (for this time of year) into the nrn CWA late Mon with
a band of convective showers along it. South winds ahead of this
front could approach advisory levels across the wrn valleys.

.LONG TERM (After 00Z Tuesday)...The upper level trough digging
southward through the Great Basin will bring a cold front through
northwest Utah late Monday into early Tuesday. Global models are
advertising this cold front to push through Utah from the
northwest with a good amount of moisture associated with it,
pointing to better chances for northern Utah including the Wasatch
Front to see rain showers through Tuesday morning. Timing of this
front differs slightly between models, the GFS and NAM
specifically, from Monday afternoon through midnight Tuesday.
Temperatures associated with this look to be much cooler than we
have been used to. Lowered daytime highs on Tuesday to the low
80s, which happened to be towards the middle ground of guidance.

As the trough swings through Utah, a secondary wave enters Utah
and southwest Wyoming on Wednesday with another push of moisture
for most of Utah, although a less than favorable precipitation
producer, chances are less. By Thursday a much drier air mass
filters in further limiting instability and convection over most
of Utah.

Models are in pretty decent agreement through Friday before the
GFS remains mostly zonal in flow pattern and the ECMWF introduces
the ridge poking in from the southeast. Both models hint at
another surge of moisture from the south, but timing and just how
far north that push makes its way into Utah is not clear.

&&

.AVIATION...Northwest winds in place at the KSLC terminal this
afternoon and are expected to shift back to the southeast between
01z and 03z this evening. Isolated showers and thunderstorms
developing across northern Utah this afternoon and evening have a
20 percent chance of generating erratic outflow winds to the
terminal through 03z.

&&

.FIRE WEATHER...Moisture in place this afternoon will linger
tonight along with scattered showers and thunderstorms, gradually
diminishing overnight. A drier airmass will begin to spread into
western Utah Sunday with a continued drying trend Monday. A cold
front will begin to move into northwest Utah Monday afternoon and
gradually push through the entire district by Tuesday night. Winds
ahead of the front will become gusty on Monday and combined with
falling RH, could bring critical fire weather conditions to the
west central and southwestern valleys where fuels are cured. The
cold front will bring a cooler airmass to the district with higher
RH and could be accompanied by a band of showers across the
north, and a few thunderstorms across the northeast Tuesday
afternoon.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Fire Weather Watch from Monday afternoon through Monday evening
     for UTZ497.

WY...None.
&&

$$

SHORT TERM/FIRE WEATHER...Wilensky
LONG TERM/AVIATION...Dewey

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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