927
FXUS65 KSLC 162217
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
417 PM MDT Wed Jul 16 2025

.SYNOPSIS...Moisture begins to increase substantially across
southern and central Utah through the next 24-48 hours, bringing
and increasing threat of heavy rainfall across the area. Moisture
begins to wane as we head into the latter half of the weekend and
into early next week.

&&

.SHORT TERM (Through 12Z/6AM Friday)...Lower level moisture will
steadily increase across the southern half of Utah through the
remainder of the afternoon while the northern area remains largely
dry through the rest of today. With moisture increasing across the
southern area, will likely see increased likelihood of locally
heavy rainfall through the remainder of the daytime hours. The
closer to the UT/AZ border the greater the chance for heavy
rainfall. By sunset, would anticipate these storms to decrease in
activity and subside before midnight.

Moisture is expected to increase through the overnight hours
across southern Utah, setting the stage for a potentially wet
afternoon on Thursday. Current satellite observations show a stout
near surface circulation over southern AZ which appears to be tied
to a mid-level low. This disturbance will decrease in structure,
transitioning from a weak closed low to an inverted trough,
favoring an area of mid-level convergence that is expected to push
into northern AZ/ southern UT through the morning on Thursday.
While this increase in forcing may act as a significant trigger
for heavy precipitation across southern Utah, we may end up with
too much initial forcing during the early morning hours and see
more of a cloud shield/ widespread light stratiform precipitation.
If we end up with this cloud shield, potential for heavy rainfall
will be significantly inhibited. As such, have left the Flash
Flood Potential across southern Utah as "Possible" due to the lack
in confidence of a heavy rainfall threat. If anywhere is on the
border of becoming "Probable" (category 3 of 4) it would likely
arise in southwestern Utah... specifically Zion National Park,
western Grand Staircase-Escalante NM, and Snow Canyon SP. Will
need to assess the trends in the strength of the mid-level
disturbance through the overnight/ early morning hours to
determine whether or not these locations will see a increased
threat of heavy rainfall and flash flooding tomorrow.

Moisture continues to increase northward through the day on
Thursday and into Friday night, allowing coverage of showers and
thunderstorms to expand into central Utah. A majority of the
activity is expected to decrease after sunset across southern and
central Utah, however, the aforementioned mid-level disturbance
could keep enough energy in the system to keep at least rain
showers going through the overnight hours across portions of
central and southern Utah.

.LONG TERM (After 12Z/6AM Friday), Issued 402 AM MDT...
An upper cutoff low is forecast
to move north slowly over the Baja Peninsula, eventually ending up
over southern CA before eventually phasing into the mean flow by the
end of the weekend. This low will result in a period of unsettled
weather beginning Thursday resulting in widespread precipitation
across southern UT, perhaps extending further into northern UT
Friday and Saturday

Moisture return continues through the long term period as the
aforementioned upper low churns to our southwest. PWATs have
increased somewhat, generally ranging from 0.7" to 0.9" of water.
Some locally higher amounts are evident across the GFS, EURO, NAM,
and RRFS, although inconsistency is high at this time. Guidance
Guidance continues to trend more robust moisture further north
resulting in some higher rainfall totals and higher PoPs appearing
possible across northern UT as well with the Uintas appearing to be
an area of interest. With this setup, some locally heavy rainfall
amounts appear possible with an emphasis on southern UT and perhaps
the Uintas. Details remain inconsistent at best with where this
rainfall will occur, though it bears watching.

The aforementioned upper low looks to phase into the mean flow late
in the period as a trough moves in from the Pacific Northwest around
Monday. Guidance has somewhat flipped with what may occur over our
area with this trough as it now puts the trough axis directly over
our area which would limit ascent across the area. This would not be
favorable for rain as limited ascent would likely keep precipitation
limited to the higher terrain despite ample moisture remaining over
the area from the now dissipated upper low. Naturally, guidance
remains inconsistent at this timeframe and things may chance in
upcoming forecasts.

&&

.AVIATION...KSLC...VFR conditions persist through the end of the
TAF period. Typical breezy northwesterly winds continue through
around 03z before transitioning southeasterly thereafter. A brief
period of gusty southerly winds is expected between 15-19z Thursday,
before winds transition to their typical northwesterly breeze after
19z. Generally dry conditions are expected on Thursday, but can`t
rule out an afternoon convective build-up on the Oquirrhs impacting
the terminal between 20-00z, though chances remain less than 30%.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected
across regional terminals today. KBCE will continue to see impacts
from afternoon showers and thunderstorms through around 04z, with
lightning and gusty and erratic outflow winds being the main threat.
A moisture surge from the south will lead to more widespread showers
and thunderstorms on Thursday afternoon, mainly across the southern
portion of the airspace. These storms will be capable of producing
heavy rain that may lead to CIGS/VIS dipping into MVFR categories
roughly between 19-02z.

&&

.FIRE WEATHER...An impulse of monsoonal moisture will begin pushing into Utah
overnight tonight, spreading over central Utah through tomorrow
afternoon, then throughout the remainder of Utah through Friday.
As such, will see increasing chances for showers and thunderstorms
with higher potential to produce wetting rains as the lower level
moisture increases. By Thursday afternoon, chances for wetting
rain will increase to around 25-35 percent across a majority of
the high terrain east of I-15 while areas to the west will
struggle to achieve heavier precipitation. CWR will decrease
significantly (to less than 15%) north of the I-70 corridor and
east of Boulder Mountain/ Capitol Reef. As lower level moisture
spreads farther north on Friday, we`ll begin to see higher CWR
values expanding north of the I-70 corridor into the northern
Fishlake NF, Manti-La Sal NF, and the eastern portion of the
Uinta-Wasatch-Cahce NF. Similar to the Dixie NF and southern
Fishlake NF on Thursday, CWR values will be roughly between 25-35%
at most. Moisture will begin to gradually decrease by Saturday,
waning more significantly by Sunday forward. Should see CWR
decreasing Saturday forward across the entirety of Utah.

Aside from the precipitation potential, the increase in moisture
will help to bring increases in afternoon humidity as well as
overnight humidity recoveries... especially across southern Utah
on Thursday, then into central and northern Utah Friday and
Saturday. While moisture trends begin increasing across
central and northern Utah on Friday and Saturday, we should
see an opposite trend (drying) in southern Utah these days.



&&

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

$$

SHORT TERM...Webber
LONG TERM...Worster
AVIATION...Whitlam
FIRE WEATHER...Webber

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity