421
FXUS65 KSLC 290922
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
322 AM MDT Sun Jun 29 2025

.SYNOPSIS...Mostly dry and increasingly hot conditions are
expected to continue into early next week, with moisture
increasing for the middle of the week.

&&

.SHORT TERM (Through 12z Tuesday)...Early morning satellite and H5
analysis depict minimal change to long wave pattern across the
western CONUS, though a slight uptick in heights has occurred
across the far south. Net result is weak zonal flow across the
bulk of the region, especially the northern 2/3rds. Today`s
sensible weather looks to be a rinse and repeat vs. Saturday, with
hot/dry conditions remaining the norm (roughly +5 degrees above
climo), and very isolated convective development along and
downstream of mountainous areas of central/northern Utah. Given
the extremely dry low levels, any convective development would
lean heavily on the dry side with isolated outflows and possibly
a lightning strike or two, but a few drops can`t be ruled out.

The high pressure across the desert southwest will begin to
amplify slightly for Monday owing to a slight uptick in temps
pushing toward +10 degrees above norm. Said, sensible conditions,
including the isolated convective potential during peak heating,
will remain near status-quo for the time being.

.LONG TERM (After 12z Tuesday)...Long term starts with the
forecast region placed within increasing deep southerly flow as a
ridge remains centered near the Four Corners region and a trough
begins to move ashore along the California coast. Strong positive H7
anomalies will in turn drive a continuation of above normal
temperatures, while the southerly flow begins to provide an
improving conduit for increasing moisture advection. While mostly
midlevel, this will contribute to PWATs pushing into the 100-150% of
normal range, in turn leading to an increase in isolated to
scattered diurnal convection. Generally anticipate most convection
to fire off of the high terrain and subsequently drift NNE given the
deep flow, and with the activity more mid/high based in nature, an
attendant gusty outflow wind threat is noted for what does develop.

Wednesday and Thursday will see the trough continue to advance
inland, with a secondary trough then beginning to deepen/translate
into the PacNW. Moisture advection will be maximized these days,
with PWAT values pushing more into the 150-200% of normal range.
This will result in diurnal convection becoming a bit more
widespread, especially given the extra energy from the initial
trough starting to eject through overhead. Any stronger more
organized activity would be capable of frequent lightning, gusty
outflow winds, and locally moderate to heavy rain (most impactful to
rain sensitive basins/areas). As such, those planning recreation or
outdoor events through the middle of the week should remain weather
aware. Temperatures will trend downward through this time, pushing
back to near to slightly above normal values for Thursday`s high
marks.

Guidance continues to diverge a bit on how the pattern evolves into
Friday. The general consensus is that the initial trough will be
translating out of the area, with more west/southwesterly flow from
the secondary trough yielding a less favorable path for moisture
transport. While this would result in decreasing moisture overall,
many models do still maintain sufficient moisture to result in some
isolated to scattered diurnal convective development once again. If
the initial trough and better pool of moisture can eject a bit
quicker, could see convective chances trend downward, or the
opposite if it trends slower/has longer residence time. Right now it
seems around 25% of ensemble members favor wetter, around 15% drier,
and the remainder somewhere in the middle. Given festivities
surrounding the Independence Day holiday, those planning on hosting
or attending events will probably want to keep an eye out for how
the forecast ultimately trends.

The secondary trough will remain more or less in place in some
fashion, but the fairly weak nature and limited moisture flow will
yield decreasing precipitation chances moving into the weekend.
Temperatures will also trend upward slightly.

&&

.AVIATION...KSLC...Light northwesterly winds in place still have
the potential of periodically switching to the south, namely
between 10-13z, but speeds are expected to remain 5kts or less.
Northwesterly winds are expected to increase above 7kts between
18-20z and remain in place for the remainder of the afternoon.
VFR conditions will prevail, with any cumulus development
remaining well removed to the east/south/west during the peak
heating hours today.


.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail
across the airspace outside of areas downstream of large wildfires
in the south. For those isolated areas (e.g. BCE) overnight
stability will again allow for smoke to drive localized IFR
conditions. High pressure continues to dominate the area with weak
gradients allowing terrain-driven and thermally-driven flows to
dominate, with a slight increase in afternoon cumulus buildups
over the higher terrain today in comparison to Saturday (mostly
east of I-15).

&&

.FIRE WEATHER...Primary note through Tuesday will be a continuation of
very dry conditions under warming trend temperatures pushing +10
degrees above norm by that time. There remains just enough
moisture over northern and central Utah to spark isolated high-
based storms during the peak heating hours, but they will remain
far from the norm, and focused over the mountain spines and just
downstream. These isolated cells will have the ability to produce
brief gusty outflow winds, and a lightning strike or two. This
will largely be rinse/repeat through Tuesday.

As has been mentioned, mid and upper level moisture will be on the rise
Wednesday across much of the district, shifting slightly further east
Thursday as a drier airmass encroaches on the region from the west. The
available moisture will be enough for isolated pockets of wetting rains,
but in large the development will promote more of an enhanced gusty
outflow potential, and pockets of lightning. Will be keeping tabs on
anticipated coverage over the next few days, especially given antecedent
conditions leading up.

&&

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

$$

Merrill/Warthen

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