156
FXUS65 KSLC 272104
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
304 PM MDT Thu Jun 27 2024

.SYNOPSIS...A trough will graze northern Utah through early
Friday, bringing strong thunderstorms and isolated flash flooding
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)...Early Thursday afternoon,
record amounts of atmospheric moisture was in place for the time
of year with PWATs in the 225-250% of normal range, mainly along
and south of the Unitas and east of I-15, very similar to what was
observed last Friday, June 21. Additionally, a trough and embedded
shortwave was propagating eastward across the Northern Rockies.
This was supplying 35-45kts of bulk shear across a broad swath of
the area, with the exception of SW and NW Utah. Finally, SBCAPE
values on the order of 1500-2500J/kg was in place. With all of
these ingredients interacting with one another, widespread showers
and thunderstorms, many severe with very heavy rain, were ongoing
from the Unitas southward and along/east of I-15. Millard/Juab
counties northward through the Wasatch Front have lower
probabilities for severe thunderstorms, but enough of a chance to
where we can`t rule out impactful thunderstorms across these
areas either, but probabilities are higher over aforementioned
eastern areas. A Severe Thunderstorm Watch is in effect until 9PM
MDT for much of eastern Utah. See spc.noaa.gov for more details.

This evening, CAMs suggest thunderstorms will gradually wind down,
and largely have diminished by midnight tonight, although a few
showers may linger overnight across central Utah. The severe
weather threat is expected to largely have come to an end around
9PM. The threat for damaging winds, large hail and heavy rain
leading to flash flooding will continue. Primary threat area this
evening will be east of I-15 and along/south of I-70.

Much quieter conditions are in store for Friday, with isolated,
largely disorganized afternoon and early evening showers and
thunderstorms, confined to largely the Swell. Temperatures will
cool to near normal over northern and central Utah behind today`s
trough, but remain 5-10F above normal across southern Utah.


.LONG TERM (After 12Z/6AM Saturday), Issued 419 AM MDT...
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...Northwesterly winds are likely to continue
through the afternoon/evening. However, there is a 30% chance that
outflow originating from storms in Utah County force winds to
southerly after 23z at KSLC. Showers over the terminal are unlikely
this afternoon/evening, but there is a 20% chance of an isolated
storm moving off the Oquirrh Mtns with gusty winds, lightning, and
small hail.

.REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers and
thunderstorms will continue to increase in coverage through the
afternoon, mainly south of KENV-KSLC-KEVW. The strongest storms are
expected across eastern UT. KCDC and KSGU could see an isolated
thunderstorm or two. Main threats include gusty and erratic outflow
winds around 30-50kts, lightning, and hail. Storms will largely
begin to diminish after 03z, with some showers lingering in central
Utah through around 08z. Regarding winds not near thunderstorms,
southwesterly flow will dominate ahead of a front pushing into
northern UT early this evening, transitioning winds to northerly.

&&

.FIRE WEATHER...As a Pacific Northwest trough grazes northern Utah
through early Friday, drier air will move in from west to east.
Until then, significant moisture will remain in place over eastern
Utah through this evening and will combine with the trough to
result in scattered to numerous showers and thunderstorms, with
many capable of producing strong, gusty winds into early this
evening. The potential for heavy rain and a few instances of flash
flooding will also exist. The drying will continue in earnest
late beginning Friday, eliminating the threat of convection but as
winds increase, particularly through the weekend, this will bring
the potential for critical fire weather conditions. The best
potential for critical fire weather conditions on Friday will be
across south-central Utah. On Saturday, the combination of low
humidity and breezy winds shifts to southwest Utah. Finally, by
Sunday, the best chance for critical fire weather conditions due
to wind and low relative humidity will be across most locations
beneath 7,000 feet, with the driest and breeziest conditions
across the west desert. Here, minimum humidity is expected to drop
down to 5 to 15 percent with afternoon gusts into the 25-35 mph
range. Another trough moving by is expected to modestly increase
moisture over the area for the beginning of the work week.

&&

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

$$

ADeSmet/Cunningham

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