065
FXUS65 KSLC 271019
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
419 AM MDT Thu Jun 27 2024

.SYNOPSIS...A trough will graze northern Utah through early
Friday, bringing the potential for strong thunderstorms over
eastern Utah and less warm temperatures for northern Utah. Dry
conditions will return Friday through the weekend with warming
temperatures and increasing winds, bringing the potential for
critical fire weather conditions.

&&

.SHORT TERM (Through 12Z/6AM Saturday)...A Pacific Northwest
trough is making its way into Idaho this morning, with this system
moving into the central United States by Friday. As it continues
its eastward trek, it will graze northern Utah during the day into
early tomorrow. A switch to westerly flow will bring drying to
western portions of the area today as deeper moisture remains in
place over eastern Utah. The position of the trough and
positioning of the associated jet will increase instability,
promoting the development of thunderstorms, and also increase
shear, with the HRRR indicating 25-35kts of shear widespread over
the forecast area by the afternoon. The cold front associated with
the passing trough is expected to move into central Utah by the
early evening, with this boundary acting as a potential focus for
convection for areas along and north of it that have not yet
experienced drying. These conditions look to be ripe for the
development of strong to severe thunderstorms this afternoon,
primarily for areas east of I-15, with gusty winds being the
primary threat. With the deep moisture in place, the potential for
heavy rain remains. Despite increased steering flow, will still
see the potential for flash flooding, especially for burn scars in
eastern Utah and the southeast Utah national parks.

Drying will spread across the area by Friday with the exit of the
trough and the building of high pressure over the area. Minimum RH
values in the 10-15% range are anticipated by the afternoon over
southwest Utah, with winds remaining elevated. Thus, the valleys
of southern Utah should see at least isolated critical fire
weather conditions, though winds look marginal for a more
widespread event.

.LONG TERM (After 12Z/6AM Saturday)...A period of shortwave ridging
across the region on Saturday and Sunday will result in clear, dry,
and hot conditions. Temperatures Saturday and Sunday will be the
hottest temperatures throughout the long term period with highs in
the mid to upper 90s across most valleys and 100-105 across far
southern Utah.

A trough will be approaching from the PNW on Sunday. Ahead of the
trough, southwesterly flow aloft will increase. Daytime heating will
create a well mixed boundary layer that will result in gusty
southwesterly winds 25-35 mph for much of the CWA. RH 10-15% Sunday
afternoon will bring an increased risk of fire weather for the
western half of the CWA. High pressure centered over Texas will
advect higher moisture content towards the four corners that will
result in an RH gradient from west to east with RH values closer to
20% across the eastern half of the CWA. Given the higher moisture
content further east and weak ascent ahead of the approaching
trough, some isolated diurnal convection is possible in the eastern
portion of the CWA. Inverted V sounding profiles suggest that any
storms that do develop will be high based with the potential for
microbursts.

By Monday afternoon the axis of the trough will be moving through
Utah. Winds will once again increase during the afternoon with
widespread gusts 25-30 mph. Additionally, more isolated storms are
possible across the eastern portion of the region with another
microburst threat. Across northern and central Utah cooler air will
move in and allow highs to remain near or slightly above normal
through the remainder of the period as the jet stream resides nearby
keeping a gradient of cooler air aloft close enough to prevent
temperatures from climbing too much during the day. Temperatures
stay a few degrees hotter than normal across southern Utah.
Northwest flow aloft will keep dry air in place throughout most of
next week which will aid in more efficient nighttime cooling with
lows getting below 70 for areas outside of far southern Utah.

&&

.AVIATION...KSLC...VFR conditions will persist for KSLC terminal
through the period. Early morning showers near and south of the
terminal will create gusty southerly outflow winds at times, but
these will dissipate through the morning. Afternoon convection will
mostly stay south of the terminal, but there remains a 40% chance of
a strong to severe thunderstorm impacting the terminal with high
cloud tops, gusty winds, hail, heavy rain.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will persist
for the airspace. Showery activity in the morning will dissipate and
give way to widespread afternoon convection for the southern two
thirds of the airspace. These storms have the potential to be severe
with high cloud tops, gusty outflow winds, hail, frequent lightning
and heavy downpours.


&&

.FIRE WEATHER...As a Pacific Northwest trough grazes northern Utah
through early Friday, drier air will move in from west to east.
Significant moisture will remain in place over eastern Utah today
and will combine with heightened instability in associated with
the trough to result in scattered to numerous showers and
thunderstorms, with many capable of producing strong, gusty winds
this afternoon into the early evening. The potential for heavy
rain will also exist. The drying will continue in earnest late
Thursday into Friday, eliminating the threat of convection but as
winds increase, particularly through the weekend, this will bring
the potential for critical fire weather conditions. Another trough
moving by is expected to increase moisture over the area for the
beginning of the work week.

&&

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

$$

SHORT TERM/FIRE WEATHER...Traphagan
LONG TERM/AVIATION...Mahan

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