873
FXUS65 KSLC 091029
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
429 AM MDT Thu May 9 2024

.SYNOPSIS...A downslope windstorm will impact portions of northern
Utah today through tonight and into Friday afternoon. The low
responsible for this windstorm will remain parked across the
Great Basin heading into the upcoming weekend, resulting in
unsettled conditions with afternoon showers and thunderstorms.

&&

.SHORT TERM (Through 12Z/6AM Saturday)...A positively tilted upper
trough extends from the central Plains upstream into the Great
Basin early this morning. A low within this base of this trough is
in the process of becoming cut off from the main belt of
westerlies, and will gradually retrograde across central Utah and
eventually Nevada through the short term period.

As this low becomes cut off over the region, a favorable window
for downslope winds across the Wasatch Front from I-80 northward,
as well as the eastern Cache Valley will become established today,
and continue through tonight and into the day Friday. Currently
the flow aloft is northeasterly across northern Utah/southwest
Wyoming, however a shortwave trough crossing central Wyoming will
translate westward across northern Utah this morning. In its wake,
the low level flow will veer and strengthen, enhancing cold
advection n the wake of this wave. This should result in the
onset of easterly downslope winds across favored areas along the
Wasatch Front by early afternoon before peaking toward midnight,
and remaining elevated into the morning hours Friday. Guidance
supports advisory level winds across much of the prone area during
this timeframe. The exception is the Farmington/Centerville
hotspot where just over half of the hi-res guidance brings peak
gusts near or just above 60 mph this evening. This may manifest
itself in warning level winds being isolated to the Park Lane area
in Davis County. Given concerns regarding the areal extend and
magnitude of the peak winds, have held onto the High Wind Watch
for the northern Wasatch Front to allow for another cycle of hi-
res guidance, as the potential remains for a warning level event,
while the most likely outcome seems to be a high end advisory with
a couple of pockets of 60+ mph gusts.

As the upper low spins overhead, the cold pool aloft combined with
daytime heating, and ascent from shortwave features rotating
around the mean circulation will support daily convection both
today and again Friday afternoon/evening. This convection will be
greatest in areal coverage across central and southern Utah.

Despite the upper low spinning overhead, the unseasonably cool
airmass currently in place will modify through the short term
period. Temperatures across the northern valleys which remained
confined to the low 50s Wednesday will trend roughly 10F warmer
today, while the warming trend across southern Utah is more muted,
and closer to 5F. This warming trend will continue into Friday,
particularly across northern Utah where max temps will approach
but fall just shy of climo. Southern Utah will see only a slight
warming trend given the expected coverage of showers and
thunderstorms.

.LONG TERM (After 12Z/6AM Saturday)...The upcoming weekend is
shaping up to be quite a nice one, despite the fact that an area of
low pressure will sit overhead. This low is not a particularly deep
one and is merely the remnants of what`s left of the storm system
that`s been impacting much of the west for what seems like far too
long. Thankfully, we do note a ridge of high pressure over the
Pacific Northwest over the weekend which will eventually kick this
low on its way out of here. Really, there is little in the way of
weather impacts for much of this entire long term period. That`s not
to say there are none. We do, in fact, still have a source of lift
through the weekend to initiate showers and thunderstorms. Favored
areas both afternoons/evenings this weekend will be in the higher
terrains of central and southern Utah. For the rest of the region,
warming temperatures! High temperatures will be back to normals or
even a bit above by Sunday.

By Monday, our flow pattern turns back from the northwest and stays
that way through at least into Tuesday. Monday and Tuesday
afternoons thusly each have some breezy winds across eastern Utah
and southwest Wyoming, but nothing of much significance or impact.
Also on Monday, we`ll be watching for a potential shortwave
progression through northern Utah and southwest Wyoming. If it gains
a little more dynamic support, thunderstorm development will become
more widespread across these areas.

By mid-week, some more questions arise if we will remain under a
northwest regime or begin to switch more westerly. This will depend
on placement of potential cut-off low development to our southwest.
That stated, neither solution brings any precipitation into the
forecast.

&&

.AVIATION...KSLC...VFR conditions are forecast throughout the
forecast period while generally high based clouds are expected.
Light northerly winds will give way to easterly flow by the
afternoon with occasional strong gusts.

.REST OF UTAH AND SOUTHWEST WYOMING...Periods of MVFR conditions are
forecast across southwest Wyoming due to snow showers this morning.
This activity should wane and give way to mid level cloud decks for
the remainder of the day and increasing easterly winds and breezy
conditions expected.

Increasing easterly winds are also anticipated across LGU and OGD
this afternoon with VFR conditions at these locations. This
afternoon, showers and thunderstorms may impact HCR and PVU
terminals, reducing visibility, bringing lightning and stronger wind
gusts. A nearby thunderstorm may also impact CDC terminal this
afternoon with gusty outflow winds and lightning. SGU and BCE
terminals can expect VFR conditions with high based clouds or nearly
clear skies.


&&

.FIRE WEATHER...A low pressure system developing across the Great
Basin today will stall over the region through Saturday. Northern
Utah will remain on the northern side of this low resulting in a
favorable setup for gusty easterly winds. These winds will become
strong at times today through Friday along the eastern benches of
the Wasatch Front north of I-80, as well as the Cache Valley.

Moisture associated with this low will allow for showers and
thunderstorms each afternoon through Saturday. These storms will
initially develop over the higher terrain midday, then spread
into the adjacent valleys by mid to late afternoon. This moisture
will also keep daytime RH elevated and allow for excellent
overnight recovery.

Despite the low overhead, the unseasonably cool airmass
currently in place across the region will gradually warm through
the weekend. This warming trend will be most notable across
northern Utah where temperatures will return to near normal by
Friday, while southern Utah will experience a more gradual
warming trend. By Monday temperatures across the region will
run nearly 10 degrees above normal.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory until 10 AM MDT Friday for UTZ103-105-107.

     Wind Advisory until 6 PM MDT this evening for UTZ104.

     High Wind Watch from this evening through Friday morning for
     UTZ104.

WY...None.
&&

$$

Seaman/NDeSmet

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