Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 261005

Area Forecast Discussion
National Weather Service Salt Lake City UT
405 AM MDT Sun May 26 2024

.SYNOPSIS...High pressure will gradually work its way into the
area through the first half of the upcoming week. A substantial
warming and drying trend will accompany this high, pushing
temperatures 5 to 10 degrees above normal by Tuesday. A mostly
dry cold front will push through the region late Wednesday
through Thursday.


.SHORT TERM (Through 12Z/6AM Tuesday)...The shortwave trough which
brought widespread showers and thunderstorms to much of the
forecast area Saturday is moving into the central High Plains
early this morning, leaving a stable and relatively cool airmass
across the eastern Great Basin and Colorado Plateau region.
Gradually rising heights and resulting warming aloft, coupled
with airmass modification from a late May sun angle, will allow
temperatures to rebound 5 to 8 degrees this afternoon. Despite
this temps will remain slightly below climo, reaching the low 70s
along the Wasatch Front and approaching 90 near St George.

Mid level ridging will amplify across the Great Basin region on
Memorial Day, allowing for an additional 5-8F degrees of warming
and pushing temperatures a little above climo Monday afternoon.
Upper 70s to low 80s will be common across northern and western
valleys, while St George reaches the mid 90s.

As the ridge axis shifts slightly east Monday afternoon, a weak
shortwave trough crossing the Sierra Crest/Western Great Basin
will spread just enough moisture into the area to support isolated
high based convection the higher terrain late Monday afternoon.
This threat will be greatest across the central and southern Utah
terrain. Given the deeply mixed boundary layer in place any precip
would be minimal, and the main threat would be microbust wind and
a few lightning strikes.

.LONG TERM (After 12Z/6AM Tuesday)...On Tuesday, deterministic and
ensemble model solutions are well-clustered in their respective
output, all showing the presence of modest deep-layer southwest flow
across the region in the wake of a departing ridge, and downstream
of an area of low pressure approaching the British Colombian
coastline. Such a configuration is favorable for warm temperatures
across the region, and that is indeed expected to be the case, with
the warmest day of the year so far in store for Tuesday. Highs will
surge into the upper 90s across Lower Washington County, and into
the mid to upper 80s across the Wasatch Front. Modest moisture
advection will combine with the influence of the approaching low to
promote an isolated shower or thunderstorm or two, mainly across
high terrain areas of northern Utah and SW Wyoming during the
afternoon and early evening. Gusty microburst winds appear to be the
main threat.

Over the past several days worth of forecasts, the greatest source
of uncertainty has been around the strength, track and timing
evolution of the British Colombian low. While there still remain
some lingering differences, model solution space appears to be
converging on a solution that drops this low across the Northern
Rockies in the Wednesday to Thursday timeframe, with the most likely
solution suggesting the low and associated cold front will graze
northern Utah and SW Wyoming in the process. There is a seasonably
strong tight height and baroclinic zone associated with this low, so
main impacts with it appear to be gusty westerly winds, especially
on Wednesday and Thursday, when wind-prone locations such as SW
Wyoming are in line for gusts in the 30-40 mph range during the
afternoon and early evening hours. Additionally, a few showers and
thunderstorms will once again develop, namely over higher terrain
areas of northern Utah and SW Wyoming once again. After another warm
day on Wednesday, temperatures will cool a few degrees in the wake
of the front across northern areas Thursday and Friday. The above
represents the current most likely solution. It`s worth mentioning
that there remain some members that do not budge the ridge all all,
and such an outcome would imply a continuation of warm and dry
conditions through the week. Meanwhile, other members on the
opposite end of the distribution drop a stronger low across Utah,
suggesting greater coverage of cooler, unsettled conditions.
Nonetheless, there is quite good consensus in the idea of a ridge
building back across the area next weekend, with some modest
strength and positioning differences.


.AVIATION...KSLC...VFR conditions expected through the period with
occasional mid clouds early this morning, and a few afternoon
cumulus building off of the terrain. In terms of winds, morning
drainage (SSE) winds expected to become NW between 16Z and 18Z
before returning to southerly between 04-05Z this evening.

anticipated through the period, with isolated valley fog possible
for those areas that receive late-evening rain and have since
cleared up in the presence of light winds. Otherwise, mid cloud deck
is expected to diminish this morning with a few cumulus building off
of the terrain this afternoon.


.FIRE WEATHER...In the wake of Saturday`s storm system, high
pressure will build into the region today, and further strengthen
through the early portion of the upcoming week. This will result
in a considerable warming and drying trend beginning today, and
continuing through Tuesday. By Tuesday afternoon summer like
conditions can be expected with max temperatures will run 5 to 10
degrees above normal, and afternoon humidity falling below 15
percent across much of the state.

This warm and very dry airmass will remain in place through much
of Wednesday, as gusty southwest winds develop ahead of an
approaching cold front. These winds will likely gust in excess of
25 mph Wednesday afternoon over much of the region south of I-80.
The combination of warm temperatures, very low humidity and gusty
winds would meet critical fire weather conditions if fuels were
sufficiently dry.

A mostly dry cold front is forecast to push into northern Utah
late Wednesday, then continue through central and eventually
southern Utah Thursday. Currently little if any precipitation is
expected with this front, with the main impacts being gusty
northerly winds behind the front along with a cooling trend.





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