Stockton, Utah Weather Forecast Discussion

487
FXUS65 KSLC 230941
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
341 AM MDT Tue Sep 23 2025
.SYNOPSIS...After a cooler start to the day areawide, temperatures
are expected to gradually warm through mid-week as high pressure
develops over the region. Dry conditions also prevail through this
period, before chances for wet weather returns to southern Utah by
Thursday.
&&
.SHORT TERM (Through 12Z/6 AM Thursday)...Temperatures early this
morning are running several degrees below those observed 24 hours
ago. Greatest 24 hour change is noted across northeastern Utah and
southwest Wyoming, where most locations have seen a 10-15 degree
drop in temperatures during this period. Some locations across the
Wasatch Back are even hovering just above freezing, generally in
the mid-30s range. Also noted this morning includes increased
canyon winds for wind-prone canyons of Weber and Davis Counties
and lower Washington County courtesy of north to northeast flow
aloft behind an exiting trough. These winds are expected to
develop once again tomorrow morning, though at a higher magnitude
for Weber and Davis County canyons as upper-level flow shifts
easterly, favorable for winds in the 30-40 mph range.
An omega blocking pattern is expected to develop today into
Wednesday, with an area of high pressure located across the
western US and a closed low meandering off the coast off the
southern California. This brief ridging overhead will promote a
gradual warming trend through Wednesday, with continued dry
conditions across the region.
.LONG TERM (After 12Z Thursday)...As a quasi-omega block pattern
begins to break down Thursday morning, moisture advection ahead of a
cut-off upper level low will begin to shift into southwestern Utah,
potentially supplemented by tropical moisture streaming northward
from Tropical Storm Narda. By 00Z Friday, precipitable water values
will average between the 90th and 97th percentile across
southwestern Utah. This, coupled with synoptic scale lift will
support convective development. Looking at the ensemble members, the
median 50% of members support SBCAPE values around 200-400 J/kg,
combined with deep layer shear around 10 to 15kts. These values
aren`t the most conducive to develop convection strong enough for
isolated flash flooding. Looking at the initial Convective Allowing
Models (CAMs) that extend this far into the future shows little
coverage of convection until the late evening Thursday to Thursday
night. Given the significance of the moisture advection, will hold
on to an isolated threat of flash flooding.
By Friday, the ensemble suite has become more consistent with the
center of the upper level low, largely somewhere between San
Bernadino County and San Diego.  This location is largely
responsible for the shift in the majority of the guidance toward
much more isolated convection Friday afternoon and evening. That
said, around 30% of ensemble members continue to show the upper
level low closer to Vegas or even St. George, retaining higher
moisture and thus higher instability. This cluster of ensemble
members is heavily represented by the GEPS and ENS...with only a few
outlier members of the GEFS.  So, while an unlikely solution, this
higher threat flash flood scenario remains a possibility.
By Saturday, as the next upper level trough begins to approach the
Pacific coast, the upper level low will finally make progress
eastward. Around 40% of ensemble members suggest support for more
widespread convection and isolated flash flooding will return to
southern Utah by Saturday afternoon.
The forecast is more nebulous by Sunday, with 50% of ensemble
members suggesting the upper level low will transition to an open
shortwave trough and bring a more state-wide threat of convection to
the region by Sunday afternoon, whereas the other 50% of members
continue to indicate a cut-off upper level low will be crossing
Arizona, with convection more localized to southern Utah.
Predictability at this point is lower than average.
&&
&&
.AVIATION...KSLC...VFR conditions prevail at the terminal through
the period, with continued dry conditions under mostly clear
skies. Northerly winds are likely to continue through the
remainder of the morning, though have a 20% chance of switching
southeasterly if terrain-driven winds can overtake the northerly
pressure gradient in place. Otherwise, generally light northwesterly
winds are expected through this afternoon.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions continue for
all regional terminals through the period, with mostly clear skies
expected across a majority of the airspace. Generally light north
to easterly winds are expected through the remainder of today,
except KEVW and KLGU where enhanced easterly winds are possible
this afternoon and evening.
&&
.FIRE WEATHER...Below-normal temperatures are expected this morning,
especially across northeastern Utah, as cool, northerly to
easterly flow prevails behind an exiting weather system. This flow
pattern will support the development of increased morning canyon
winds this morning and Wednesday morning, especially across lower
Washington County and canyons prone to easterly downslope winds
across northern Utah.
High pressure quickly builds in across the region through the
remainder of today and into Wednesday, which will support
continued dry conditions areawide and gradual warming through
this period. An area of low pressure nudges into the Desert
Southwest on Thursday into the weekend, resulting in a push of
moisture into southern Utah. Chances for widely scattered showers
and thunderstorms emerge across southwest Utah on Thursday,
spreading into the remainder of southern Utah into the weekend.
These storms will be capable of producing heavy rainfall in
addition to gusty outflow winds.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
Whitlam/Kruse
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

NWS SLC Office Area Forecast Discussion