863
FXUS65 KSLC 010910
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
310 AM MDT Tue Jul 1 2025

.SYNOPSIS...A very hot day is expected today with an increasing
threat of thunderstorms through Thursday. Drier air will likely
begin to impact the region Friday into the weekend.

&&

.DISCUSSION...Early morning upper air and satellite analysis
indicates the 4-Corners ridge remains in place, while the upper
level low off the California Coast has made some slow progress
eastward over the last 24 hours. Mesoanalysis indicates
precipitable water values have increased from 0.40-0.60" 24 hours
ago to fairly universal 0.60" across the state. An upper level
trough remains stretched near and southwest of the Gulf of Alaska.

Mid-level moisture advection will continue through the day today
in a monsoon-like pattern. By 00Z Wednesday,expect precipitable
water values to be approaching or exceeding the 90th percentile
across Utah. HREF mean SBCAPE values are expected to range from
400-600 J/kg across southern and eastern Utah, with slightly lower
values across western and northern utah. Deep layer shear is
generally less than 15kts. Conceptually, this will support
convection initially developing in the two primary genesis
locations, across eastern Nevada and along the higher terrain of
Utah...eventually shifting into adjacent valleys.

Looking at the CAMS, this is largely the trend across most
members. While moisture will continue to increase and deepen
through the column today, microbursts will again be a threat.
There were 4 reports of wind gusts at or above 58 mph Monday
afternoon and evening. Expect at least a few reports greater than
58 mph again today.

Expect today to be the hottest day of the next several, with
temperatures near the century mark across the Wasatch Front. Heat
advisories are now in effect for the Wasatch Front and Tooele
Valleys for this afternoon and evening. Be heat safe today and
consider altering outdoor plans to avoid the heat of the day and
drink plenty of water no matter where in the state you are
recreating!

By Wednesday, the upper level low will gradually shift inland
across central and southern California. Precipitable water values
will be at or above 1" across much of the region (around 90-95th
percentile or so). HREF mean SBCAPE values will tick up a bit with
deeper moisture profiles to around 500-650 J/kg. Deep layer shear
across southern and eastern Utah will remain at or below 15 kts
(supporting slow storm motions), with 15-25kts of deep layer shear
across western and northern Utah. The highest threat with the
storms across southern and eastern Utah will be heavy rain and
isolated flash flooding, whereas any thunderstorms that develop
across western and northern Utah may have transitory periods of
organization with small hail, gusty winds and heavy rain.

A trough approaching the West Coast will finally eject the remnant
open wave associated with the upper level low across Utah Thursday
afternoon and evening. Depending on the exact speed of this
system, net drying could be ongoing by Thursday afternoon. Expect
another round of thunderstorms Thursday afternoon and evening,
though if the dry air advection is faster than expected, this may
reduce the coverage and threat of isolated flash flooding.

The upstream trough will approach the region Friday. Ensemble
members have quite the spread with this system...with some members
bringing another round of widespread precipitation through the
state Friday afternoon and evening (about 30% of members) and
another grouping of members (around 70%) bringing dry, southwest
flow with near critical to critical fire weather conditions. If
you have plans on the 4th of July, continue to monitor forecasts.

&&

.AVIATION...KSLC...Predominantly VFR conditions are expected to
continue throughout the TAF period. High-based thunderstorms
capable of producing gusty and erratic outflow winds are expected
to develop early this afternoon. There is a 30% chance for storms
to impact the terminal between roughly 20-00z, with potential to
produce outflow gusts between 30-40 kts. Otherwise, winds remain
generally light this morning out of the southeast, becoming more
southerly after 15z.

.REST OF UTAH AND SOUTHWEST WYOMING...A monsoonal moisture push
into the region will lead to more widespread thunderstorm coverage
today. Impacts to flight categories are not likely given the
high-based nature of these storms. However, storms that develop
this afternoon will be capable of producing gusty and erratic
outflow winds between 30-40 kts if they move into the vicinity of
any regional terminals. Otherwise, VFR conditions to prevail with
increasing mid-to-high level clouds through the remainder of the
TAF period. Only exception remains KBCE where periods of MVFR/IFR
conditions are possible through roughly 15z from VIS restrictions
due to smoke from nearby wildfires.

&&

.FIRE WEATHER...As a slow moving upper level low continues to
impact Utah, more widespread convection is expected across the
region, especially across central and southern Utah this
afternoon. While thunderstorms will trend dry, especially during
the afternoon period, with very dry fuels and hot and dry
antecedent weather, expect conditions to support an increased
threat of lightning based fire starts. Red Flag Warnings for
lightning after a hot/dry period remain in effect for the central
and southern mountains this afternoon and evening.

As moisture continues to increase from the mid to low levels
tonight into Wednesday, convection will become more widespread
across much of the region. Thunderstorms will trend wet with a
higher threat of heavy rain and isolated flash flooding. As the
upper level low finally crosses the region Thursday, additional
thunderstorms are expected across the region.

Guidance varies with the threat of convection across portions of
northern Utah Friday afternoon and evening, with western and
southern Utah seeing increased dry southwesterly winds. This may
bring another round of critical fire weather conditions, this time
related to low humidities and gusty winds for western and
southern Utah.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Heat Advisory from noon today to midnight MDT tonight for
     UTZ102>106.

     Red Flag Warning from noon today to 9 PM MDT this evening for
     UTZ488-493-496.

WY...None.
&&

$$

Kruse/Whitlam

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