161
FXUS65 KSLC 101016
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
416 AM MDT Mon Jun 10 2024

.SYNOPSIS...A weak cold front will bring a brief cooldown across the
northern half of the region today, though temperatures will remain
above normal. Strengthening high pressure will then build in by the
middle of the week, resulting in temperatures well above seasonal
normal once again.

&&

.SHORT TERM (THROUGH 12Z WEDNESDAY)...High pressure is situated over
Colorado this morning as a split storm system moves into the Western
CONUS. The northern branch trough is continuing to track east across
Idaho early this morning while the southern branch wave has pinched
off into a closed low off the SoCal coast (and will factor into our
weather later this week). The cold front associated with the Idaho
trough has moved into northern Utah and currently extends from
western Juab County through the Salt Lake Valley. A few weak showers
continue to linger along the Idaho border. Meanwhile, another weak
disturbance is noted lifting across southeast Utah. This has
produced quite a bit of weak radar returns, but so far, no
measurable precipitation has been reported by any surface obs. As
such, these are likely just virga or sprinkles at best.

Temperatures will cool across a good portion of the area today due
to the cold front, most notably across the north. Many northern Utah
locales will see a 5-10 degree drop in afternoon maxes today
compared to yesterday. Still, given the abnormally hot temperatures
of late, this is still 5-10 degrees above climatological normals.
The airmass will also continue to gradually trend drier today.
However, models are still showing a pocket of up to around 0.85
inches of PWAT today. This pocket of moisture coincides with the
area of highest SBCAPE values this afternoon, which is a corridor
from the west deserts through Utah County. While isolated and
generally weak showers and thunderstorms are still possible over
many higher terrain areas today, focus will be placed on this
corridor where a couple of stronger cells may be possible later this
afternoon.

As high pressure starts to build back into the area on Tuesday, a
warming trend will return. While not quite back into headline
criteria inducing heat just yet, afternoon maxes will be generally 6-
12 degrees above climatology across the state, with triple digits in
the lower valleys of far southern Utah and 90s across a good portion
of the remaining valley areas.

.LONG TERM (After 12Z/6AM Wednesday)...A strengthening, but shallow,
ridge will dominate on Wednesday and Thursday, resulting in the two
hottest days of the next seven. KSLC could even see its first 100
degree day, with a roughly 40% chance on both Wednesday and
Thursday. As far as heat headlines go, an Excessive Heat Watch has
been issued for Lake Powell/Glen Canyon on Wednesday/Thursday due to
wide coverage of "Major" HeatRisk across the zone.

Luckily, the heat will not last long as a closed low situated off
the coast of SoCal begins to shift inland, reaching southern/eastern
UT by Friday. Highs on Friday will thus decrease by around 5-15
degrees across the area with the greatest decrease across eastern
areas along the track of the low. Scattered high-based convection is
also looking more likely along and east of the central spine of Utah
mountains during the afternoon.

Heading into the weekend, uncertainty in the longwave pattern
increases. Ensemble guidance favors some sort of trough moving into
the PacNW early in the weekend, though there is plenty of
disagreement in how it evolves across the Intermountain West.
Roughly 59% of ensemble members favor a deeper trough resulting in a
greater cooldown over Utah, while the other 41% of members suggest
the trough remains fairly zonal and far to our north. To quantify
this uncertainty further, the 25th-75th percentiles for 700-mb
temperatures range from +4C to +13C...dropping from +17C on Thursday.

&&

.AVIATION...KSLC...Northwesterly winds will continue through the
day, with some gusts to 20kts possible after 18z. Winds may
transition back to light and southeasterly as early as 05z this
evening, becoming variable at times after 03z.

.REST OF UTAH AND SOUTHWEST WYOMING...Isolated showers and
thunderstorms are likely to develop after 19z across a line roughly
from just south of KENV to just south of KPVU. These showers will be
capable of producing gusty outflow winds, including at KPVU.
Generally, winds will favor northwesterly across the northern two
thirds of UT behind a weak boundary, with areas south favoring
westerly to southwesterly winds during the afternoon.

&&

.FIRE WEATHER...A cold front which will weaken and stall over
central Utah today will result in cooler temperatures today, most
notably across the north. Although the airmass is gradually trending
drier, some isolated showers and thunderstorms can still be
expected, mainly over the higher terrain. Temperatures will start
trending warmer again tomorrow, then become hot Wednesday into
Thursday as high pressure builds over the area. The next storm
system looks to eject across southern and eastern Utah Friday into
Saturday, bringing increased moisture and cooler temperatures
heading into the weekend. However, as southerly flow increases on
Thursday ahead of this system, marginal/isolated critical fire
weather conditions are possible across portions of southern Utah
Thursday afternoon and evening.

&&

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

$$

Cheng/Cunningham

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