Deer Valley

000
FXUS65 KSLC 210415
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1015 PM MDT Tue Oct 20 2026

.KEY MESSAGES...

- Widespread precipitation returns Wednesday morning across
  southern Utah, with coverage expanding northward through Friday.
  Many areas will see precipitation accumulations between 0.5-2" 
  through this period, with local totals in excess of 3" possible.

- The heavy rain will bring a threat of flash flooding to southern
  and central Utah, and there is a Slight Risk of Excessive
  Rainfall across southern Utah Wednesday and across southern
  through east-central Utah Thursday.

- A few strong to severe thunderstorms may be capable of producing
  gusty winds and hail across southern Utah on Wednesday and
  statewide on Thursday, with a 2% chance of a tornado. A Marginal
  Risk for severe thunderstorms is in place on Wednesday across
  far southern Utah, southern through west-central Utah on 
  Thursday.

- The late week storm will also bring accumulating snowfall to the
  high terrain across northern and central Utah on Friday, with 2-6"
  possible mainly above 9000 feet. Locally higher amounts are 
  possible in favored locations. 

&&

.DISCUSSION...The large-scale pattern this evening consists of a
closed low spinning off the central California coast while Utah
remains under a southerly flow ahead of it. An upper jet rounding
the base of the low and punching through Arizona this evening is
helping to spread tropical moisture northward. Across Utah, PWATs
currently range from 0.6-0.9 inches, which is already close to the
99th percentile of climatology. Increased moisture advection will
only push these values higher over the next couple of days.

As the jet arrives over Utah, increasing upper diffluence may 
lead to some isolated shower activity tonight, mainly over 
northwest Utah. As the deeper moisture arrives after 10z, expect 
precipitation activity to start increasing across southern Utah. 
This precipitation will become more widespread across southern 
and central Utah through the day Wednesday. Models indicate a 
brief decrease in precipitation Wednesday night before increasing 
again areawide for Thursday. Areas of moderate to heavy 
precipitation is expected Wednesday and Thursday, and will be 
aided in part by potentially strong to severe convection as 
suggested by hi-res models. If instability does not become 
inhibited too much by cloud cover, there will be plenty of shear 
(40-55+ kt of 0-6km shear) and low-level helicity to work with 
across southern Utah on Wednesday and across a significant portion
of the forecast area on Thursday for a few of the stronger storms
to produce strong winds, hail, and even an outside chance of a 
tornado. There is currently a Marginal Risk for Severe Storms 
across southern Utah on Wednesday and across southern through 
weest-central Utah on Thursday. Additionally, with the heavy rain,
there is also a Slight Risk of Excessive Rainfall across southern
Utah on Wednesday and across southern through east-central Utah 
on Thursday. Also on Thursday, a Marginal Risk for Excessive 
Rainfall extends through the remainder of Utah. A Flood Watch is 
in effect across southern through east-central Utah Wednesday 
through Thursday as a result. Latest NBM continues to indicate 
widespread 1 to greater than 2.5 inches of QPF across southern 
through east-central Utah Wednesday through Thursday, with 75th 
percentile amounts exceeding 3 inches near Brian Head and Boulder 
Mountain. 

On Friday, the upper low is expected to lift across northern Utah
while a trailing wave rotating around the low swings across the
desert southwest. The track of the low across northern Utah will
keep precipitation confined more to the north on Friday, while
cooler air arrives into the area (H7 temperatures down to around 
-3C Friday through Saturday night). This will bring snow levels as
low as 7000-7500 feet, with accumulating snow of around 2-6
inches forecast above around 9000 feet, mainly across the 
Wasatch and Uinta Mountains. 

The trailing wave swinging around Arizona now looks to redevelop
into a closed low which will then linger over the area. As such,
there is now increasing likelihood for cool and unsettled weather
to remain in place through the weekend. Thereafter, high pressure
looks to build into the area early next week.

&&

.AVIATION...
KSLC...The SLC terminal will see VFR conditions through the 
overnight hours. Winds are expected to remain southerly tonight and 
through the day tomorrow, becoming occasionally gusty during the 
afternoon. There is a 30 percent chance that showers will impact the 
terminal during the late afternoon and early evening, with the most 
likely impact being gusty and erratic winds.  

REST OF UTAH AND SOUTHWEST WYOMING...The airspace will see VFR 
conditions through the evening with increasing clouds over southern 
Utah overnight. Showers and thunderstorms will increase in coverage 
over southern Utah throughout the morning, spreading into some 
northern portions of the airspace during the afternoon. Any storms 
that develop will have the potential of producing gusty and erratic 
winds, lightning, and brief mountain obscurations. 


&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch from 6 AM MDT Wednesday through Thursday evening for 
     UTZ117-123>131.

     Flood Watch from Wednesday afternoon through Thursday evening 
     for UTZ120-121.

WY...None.
&&

$$

PUBLIC...Cheng
AVIATION...Traphagan

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