158
FXUS65 KSLC 030900
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
300 AM MDT Mon Jun 3 2024

.SYNOPSIS...A passing cold front will bring showers and
thunderstorms to southwest Wyoming and northern Utah today. High
pressure will build over the region beginning Tuesday, bringing
dry and increasingly hot conditions through the end of the work
week.

&&

.SHORT TERM (Through 12Z Wednesday)...Seeing increasing high and
mid-level clouds over northwest Utah this morning as a trough
makes its way onshore over the Pacific Northwest. The main trough
is expected to remain north of the area as it continues east, but
an associated cold front will makes its way through northern Utah
and southwest Wyoming during the day today. The associated upper
jet is expected to graze northern Utah during this time, providing
some more favorable instability. As a result, anticipating the
development of an area of showers with some embedded thunderstorms
for northern portions of the forecast area from about midday
through the early evening, with the best coverage occurring for
areas closer to the Utah/Idaho border. Associated cooling will be
modest, about 5F for northern Utah compared to yesterday, bringing
maxes back down to around seasonal normals as dry and unseasonably
warm conditions continue over southern Utah.

The system is on track to move east of the area by Tuesday morning
as the associated cold front fizzles and moves south out of Utah.
This will allow a broad Pacific ridge to spread eastward into Utah
and southwest Wyoming, bringing dry conditions and increasingly
hot conditions, described further in the long term discussion.

.LONG TERM (After 12Z Wednesday)...Wednesday will be the first
day in what will be several consecutive days of much warmer than
normal temperatures. This will be as a powerful ridge slides inland
from the eastern Pacific and builds into the western U.S. Southwest
Wyoming and northern Utah will have the biggest increase in
temperatures from Tuesday, with valley highs in the mid to upper
80s. Temperatures will get into the 90s for most southern Utah
valleys, while lower Washington County will get into the 100s.

Temperatures will warm further Thursday. There is good model
agreement on the ridge axis positioned over Utah, extending far to
the north. Valley high temperatures throughout northern Utah will
range from the low 90s near the Idaho border to the mid 90s for the
urban corridor. Mid to upper 90s are likely for many central
valleys, and 100s are likely around Lake Powell and again for lower
Washington County. An Excessive Heat Watch is in effect starting
Thursday for both Lake Powell and lower Washington County. Along
with the day temperatures, minimal cooling will happen overnight for
those locations, with low temperatures in the low to mid 70s.

The ridge axis will be nearly over Utah or slightly downstream
Friday. Models are in general agreement on weak shortwave energy
tracking into Utah within anticyclonic flow as the axis tracks east.
Shortwave energy along with warming of the day will bring more
clouds. Isolated showers and thunderstorms will almost exclusively
stay around terrain with weak forcing, little moisture, and minimal
wind shear. For temperatures, nearly identical numbers to Thursday
are likely. Forecast highs and lows each day are almost all less 5F
from record highs and lows throughout southwest Wyoming and Utah.
The Excessive Heat Watch for those aforementioned locations is in
effect through Friday.

There is a bit more uncertainty into the weekend on details with the
ridge. Most likely, it will stay in place, but not be as strong as
late in the week. There is general agreement on shortwave energy
rotating into Utah with isolated to scattered showers and
thunderstorms, primarily near higher terrain.

&&

.AVIATION...KSLC...Overcast conditions are likely by 17Z as a cold
front and light rain build into northern Utah. Winds will transition
to northwest around 17Z. Isolated showers from roughly 17-21Z will
be capable of gusty, erratic outflow winds. Light rain is likely
from roughly 21-00Z. VFR conditions will prevail, but ceilings will
likely lower into MVFR range at times. Winds will transition to
southeast around 00Z. Isolated showers will last through around 03Z.

.REST OF UTAH AND SOUTHWEST WYOMING...A cold front with light rain
will track into northwest Utah late in the morning. Overcast
conditions, likely into MVFR range, and light rain is likely for
much of northern Utah from roughly 20-00Z. Isolated showers will
last through roughly 03Z, with clouds decreasing through the night.
The front will push into southern Utah in the evening, bringing more
clouds, but minimal precipitation.

&&

.FIRE WEATHER...A Pacific Northwest storm system will bring a cold
front across northern Utah during the day today, with good
coverage of showers along with a few thunderstorms, primarily
during the afternoon and early evening. The best chance of wetting
rainfall will be for areas north of I-80. As the system exits the
area, a Pacific ridge will build over the area through the work
week, resulting in dry and increasingly hot conditions.
Uncertainty increases as the weekend approaches, with a chance of
a dry lightning threat due to increasing mid-level moisture.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Excessive Heat Watch from Thursday morning through Friday
     evening for UTZ123-131.

WY...None.
&&

$$

SHORT TERM/FIRE WEATHER...Traphagan
LONG TERM/AVIATION...Wilson

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