406
FXUS65 KSLC 181023
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
423 AM MDT Tue Jun 18 2024

.SYNOPSIS...A much cooler day will be experienced on Tuesday
across the region behind a strong cold front. Temperatures will
return to normal by Wednesday then back above normal through the
weekend when another period of very hot temperatures build into
the area. Before then, anomalous moisture will build into eastern
Utah late Thursday through Friday, bringing showers and
thunderstorms.

&&

.SHORT TERM (Through 12Z/6AM Thursday)...Much cooler temperatures
have built into Utah and SW Wyoming behind an unseasonably strong
cold front that blasted through the area on Monday. Near freezing
to below freezing temperatures are in place across portions of the
Wasatch Back as well as the Bear River Valley and outlying
portions of the Cache this morning. One pocket of gusty winds
remains in place across SW Utah early this morning, thanks to the
presence of a strong pressure and thermal gradient. NE gusts
remain around 45 mph near the mouth of Black Ridge Canyon, with
isolated stronger gusts. These winds will begin to back off
shortly after sunrise. Meanwhile, tranquil conditions will be in
place through midweek across the area. Under building mid-level
heights, Wednesday`s temperatures will rebound to near seasonal
normals for mid-June after an unseasonably cool day on Tuesday.

.LONG TERM (After 12z/6AM Wednesday)...Ensemble guidance remains in
great agreement on a trough remaining upstream of the forecast area
through at least early Friday with a ridge building into the area
Friday through the weekend. Past Sunday, models diverge a bit as
there is some uncertainty on the depth of a trough progged to move
through southern Canada. The depth of this trough will ultimately
influence the temperature trends (mainly in the northern area)
through next week.

A trough upstream of the area during the latter portion of the week
will continue to promote warm and dry southwesterly flow over the
forecast area, allowing temperatures to warm back to above normal
levels. To the east of the area over the southern Plains, an wave
propagating to the west will interact with the upstream trough and
bring an increase in lower level flow as well as initiating a
moisture flux into the eastern Great Basin region. Increased flow in
the lower levels will bring increasing surface winds during the
afternoon on Thursday. The increase in flow will bring concerns of
elevated fire weather conditions in eastern Utah before the near
surface moisture arrives. At this time, no fire weather headlines
have been issued as fuels are not currently over their critical
thresholds in the zones of concern.

Moisture continues to work into the area through the evening hours
on Thursday, while the aforementioned trough begins shifting over
the region. Isolated showers and thunderstorms over eastern Utah
will be possible, and will carry the threat of dry lightning as the
lower level moisture lags. Should expect to see an increase in
shower activity through the overnight hours as upper level support
for lift increases. Going into Friday, upper support and increasing
moisture in the lower levels will act to destabilize the environment
and bring an increasing threat of strong thunderstorms and flash
flooding (model PWAT anomalies continue to push 200-250% of normal
over eastern Utah). Will need to continue to assess the threat of
flash flooding on Friday afternoon as models maintain abnormally
moist conditions over eastern Utah. The one concern with this is
whether or not the added dynamics from the trough will bring too
much cloud cover to destabilize the environment to the potential
that the models are suggesting. In general, if you`re planning a
slot canyon trip, you might want to hold off until late in the
weekend.

A stout ridge builds back over the region late in the weekend, which
will help to reinforce hot conditions areawide as well as provide a
drier environment. Confidence is increasing that the Wasatch Front
will be pushing temperatures to near 100 degrees and into the mid-
to upper-100s for lower elevations in southern Utah by Sunday. Will
need to continue to assess the need for heat related headlines by
Sunday as overnight lows will provide minimal recovery from the
heat. Thankfully for the northern portions of Utah and southwest
Wyoming, the heat looks to be fairly short lived as an active storm
track resumes to the north of the area, which should tamper down the
strength of the high. There is still uncertainty on how much the
high will be repressed by the northern stream, but in general we
should expect a gradual cooling trend into the middle portion of the
week across the northern half of the area. For the southern area,
heat looks to be maintained unless we can develop a deeper trough
into the CONUS (supported by ~30% of ensemble members).

&&

.AVIATION...KSLC...VFR conditions will prevail over the KSLC
terminal through the valid TAF period. Winds will become light and
variable, with periods of prevailing southerlies, through the early
to mid-morning hours. A return to northerly flow is expected after
17Z.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions under high
level cloud cover will prevail through the day. Winds will prevail
out of a predominant northerly direction across the region, with
strong winds in lower Washington County decreasing in speed through
the morning hours.

&&

.FIRE WEATHER...Dry and steadily warming temperatures are expected
for the next couple of days after the passage of an unseasonably
strong cold front on Monday. Temperatures on Tuesday will range
from 5F to 15F below normal across central and southern Utah,
to as much as 20F below normal across northern Utah. Temperatures
will return to normal by Wednesday and back to 5F to 15F above
normal by Thursday, with poor overnight recovery most areas. A
few pockets of critical fire weather conditions will develop
across wind-prone areas of southern Utah on Thursday due to the
combination of gusty southwest winds and low humidity between 8
and 15 percent.

A surge of moisture will then begin to work into eastern Utah from
the southeast by late on Thursday, with a significant increase in
moisture expected to move into areas generally along and east of
I-15 for Friday. On the leading edge of this moisture surge from
late Thursday into early Friday, isolated dry lightning will be
possible. Widespread showers with isolated thunderstorms are then
expected across eastern Utah on Friday, with widespread 50% and
above chances for wetting rains. Dry conditions are then expected
to quickly build back into the area for next weekend, with isolated
thunderstorms possible for eastern areas on Saturday. Hot and dry
conditions will be the rule for Sunday across the state, with
many northern valley locations approaching or exceeding 100F.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Freeze Warning until 9 AM MDT this morning for UTZ107-108.

     High Wind Warning until 8 AM MDT this morning for UTZ123.

WY...None.
&&

$$

ADeSmet/Webber

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