FXUS65 KSLC 152131

Area Forecast Discussion
National Weather Service Salt Lake City UT
331 PM MDT Sat Jun 15 2024

.SYNOPSIS...Gusty southerly winds will bring critical fire weather
conditions to portions of southern Utah through Monday. A strong
cold front will cross the area Monday afternoon into Monday night,
bringing an atypically cold airmass to Utah. Temperatures will
rebound through midweek, with another round of potential critical
fire weather conditions Thursday into Friday across southern Utah.


.SHORT TERM (Through 00Z Wednesday)...A mainly dry cold front
crossed northern and parts of central Utah this morning, bringing
a slightly cooler airmass to the region this afternoon...and
relatively gusty northerly winds. Afternoon upper air and
satellite analysis indicates another shortwave trough rounding the
base of the longwave trough across the Pacific Northwest into
Montana. This shortwave trough will eventually eject into southern
Canada this evening. The associated weak cold front may slide
into far northern Utah this evening into tonight, bringing an
increase to the gusty northwesterly winds across the area.

The longwave trough will gradually shift south and east as the
next shortwave trough digs southeastward across the Pacific
Northwest Sunday into Monday. This will be the impetus for
increasing southwesterly flow across southern Utah bringing
critical fire weather conditions to areas with critical fuels
through Monday evening. A weakening, somewhat stationary boundary
across central Utah will keep northerly flow across the northern
half of Utah Sunday into early Monday.

The airmass associated with the shortwave trough is anomalously
cold, with 700mb temperatures near the 0.5 to 1 percentile for
this time of year over the Pacific Northwest. While this airmass
will modify to a degree over the Great Basin, 700mb temperatures
will be nearing the minimum in the climatology for the EPS for the
time of year as the cold front crosses Utah Monday. The best
forcing/moisture for precipitation will stay north of the region
Monday afternoon and evening as the trough gradually shifts across
the northern Rockies, however a portion of the ensemble systems
indicate some threat for convection Monday afternoon and evening,
mainly north of SLC.

As this anomalously strong cold front crosses northern Utah Monday
afternoon, strong and gusty post-frontal winds will be possible.
Right now, guidance has a low (10% or so) chance of wind gusts in
the wind advisory range (45 mph or higher) behind the cold front.
Conceptually, this seems to be low and will need to continue to
monitor for potential wind advisories in future shifts.

With a strong cold front and abrupt wind shift, Red Flag Warnings
were extended across the zones with critical fuels to better time
with the front.

With such a cold airmass in place behind the front Monday night
into Tuesday morning, patchy frost will be possible for outlying
areas of the Cache, Wasatch Back and other normally cold high
valleys of northern Utah. There is about a 10 percent chance of
temperatures less than 32 degrees for outlying areas of the Cache
and closer to 30% for the normally cold Rush Valley. Temperatures
Tuesday afternoon will average 5 to 15 degrees below normal across
northern and central Utah, closer to 5 degrees below normal
across southern Utah.

.LONG TERM (After 00Z Wednesday), Issued 413 AM MDT... For the
remainder of the workweek, heights will rebound quickly over the
Central Rockies as the mean trough axis retrogrades back to the
West Coast. By late in the workweek, increased mid-level moisture
will advect in just to our east, supporting some threat of
showers/thunderstorms over eastern Utah. That said, unless the
trough position sets up farther west than currently placed in
ensemble means, our area is likely to remain on the hot/dry/breezy
side of the trough, meaning that those conditions are expected to
return by the end of the week.


.AVIATION...KSLC...VFR conditions and prevailing northwest winds
are expected at the terminal through the valid TAF period. A
secondary boundary crossing the terminal between 03-05z will
maintain the northerly winds tonight, but a 40% chance exists that
a period of light and variable winds will occur between 09-13z
Sunday morning.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected
across the airspace through the valid TAF period. Moderately
gusty southwesterly winds are expected during the
afternoon/evening hours in the southern portions of the airspace ,
while modest northerly surface winds are expected to dominate in
the northern portions.


.FIRE WEATHER...Winds have already increased across the Grand
Staircase this afternoon, with gusts over 40 mph and humidities
near 8% being reported at Telegraph Flat. Near critical fire
weather conditions are being reported across zone 497. Poor
overnight recoveries are expected tonight across southern
Utah...with winds increasing further by late Sunday morning.
Critical fire weather conditions are expected across fire weather
zones 496 below 7000 feet, 495, 497 and 498 Sunday afternoon and
evening. Another night of poor RH recoveries is expected Sunday
night into Monday morning. As a strong cold front crosses into
northern Utah Monday afternoon, winds will increase further across
the critical zones. This abrupt wind shift to the northwest will
reach zones 495 and 496 Monday evening, 497 and 498 Monday evening
into the first half of Monday night.

A somewhat cooler airmass will build in behind this front for
Tuesday. By Thursday, winds will increase ahead of the next system
and the potential will increase for another round of critical
fire weather conditions Thursday afternoon and evening and again
Friday afternoon and evening in areas of critical fuels across
southern Utah.


UT...Red Flag Warning from noon Sunday to 9 PM MDT Monday for UTZ495-

     Red Flag Warning until 3 AM MDT Tuesday for UTZ498.

     Red Flag Warning from noon Sunday to midnight MDT Monday night
     for UTZ497.



Kruse/Merrill/Van Cleave

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