NWS Salt Lake City, UT wrote its last area forecast discussion before the first event at Jun 13, 2:45 PM MST, 1 hour 35 minutes earlier.
Area forecast discussion, Jun 13, 2:45 PM MST, 1 hour 35 minutes before
Area Forecast Discussion
National Weather Service Salt Lake City UT
345 PM MDT Mon Jun 13 2022
.SYNOPSIS...A cold front will continue southeast across the area
through tonight, bringing much cooler temperatures to the area
along with some precipitation for primarily northern Utah and
strong and gusty winds to southern Utah into this evening. High
pressure will return by midweek, bringing a warming and drying
trend. A strong low pressure system will begin to approach the
area by late week into the upcoming weekend, bringing an increased
potential for unsettled conditions.
&&
.SHORT TERM (Through 12Z/6AM Wednesday)...Early afternoon analysis
depicts a closed low across the Idaho panhandle with a mid-level
trough and associated jet streak extending SW back into northern
Utah. As of 3PM MDT, a surface cold front extends NE to SW from
roughly Vernal to Green River to just NW of Cedar City. With low
to mid-level frontogenesis waning, the front is becoming
increasingly frontolytic this afternoon, and therefore the
organized, banded precipitation structure is also diminishing.
However, the prospects for continue through this evening,
especially across portions of northern and central UT and SW
Wyoming. A trailing shortwave currently noted across northern NV
is forecast to slide eastward across northern UT tonight,
providing some forcing for ascent. 3PM MDT mesoanalysis products
indicate increasing SB and MLCAPE values of 500-1000J/kg owing to
surface heating behind the departing boundary. Bulk shear values
of 50-60kt are more than sufficient to support organized
thunderstorm activity. One limiting factor is deep-layer moisture,
however just enough moisture is available to support shower and
thunderstorm activity. Indeed, CAMs support additional
shower/thunderstorm development through the evening along the axis
of surface convergence along central and souther Utah, and in
advance of the incoming shortwave across northern UT. Stronger
thunderstorms will be capable of small hail and frequent lightning.
Gusty thunderstorm outflow winds can't be ruled out with any
convection either.
CAMs are in good agreement in their collective depiction of
propagating showers/thunderstorms eastward across northern and
central Utah through the evening and early overnight hours before
diminishing. A few CAMs depict a brief window of lake enhancement
SSE of the GSL overnight towards sunrise, and this makes sense as
lake-induced CAPE of over 1000J/kg is realized overnight, with
sfc-700mb delta-ts approaching 30C.
Gusty SW-WSW winds in the well-mixed pre-frontal boundary layer
will continue across southern Utah and the eastern valleys, with
gusts as high as 50-55 mph through sunset before winds either
begin to diminish to turn westerly/northwesterly behind the
weakening cold front.
There is a high likelihood of low temperatures reaching 28F
tonight and Tuesday night across the Bear River Valley. Have
strayed from issuing a Hard Freeze Warning tonight as these
temperatures are forecast to be realized for 1 hour or less.
However, steps should be taken to protect sensitive vegetation
here. In the Panguitch area, we're forecasting lows of 27-28F
tonight as well, but again for a brief window near sunrise.
Cool, dry conditions will be in place across the region on
Tuesday, with high temperatures forecast to range from around
10-15 degrees below seasonal normals across northern and central
Utah to near seasonal normals across southern Utah. There is a
slight (<20%) chance for an isolated shower or thunderstorm near
the ID/UT border in the late afternoon/evening.
.LONG TERM (After 12Z/6AM Wednesday)...An area of low pressure
will be situated well to our north and east Wednesday while an
area of weak high pressure builds over Utah and southwest Wyoming.
Temperatures for Wednesday remain forecast into the mid to upper
70s across northern Utah, a good 10 degrees below seasonal normal
in the mid 80s. Temperatures Thursday and Friday will
substantially increase, above seasonal normal in fact, as high
pressure builds across the region.
Focus then shifts Friday through the weekend as monsoonal moisture
remains in the forecast ahead of the arrival of a broad upper level
low pressure trough and subsequent cold front. Deterministic GFS and
GEFS IVT moisture indicate approx 250-500 kg / ms of moisture across
the region. From Friday afternoon through through Sunday evening, PW
values are noted at 150% to 200% above normal. Additional moisture
from a potential tropical disturbance in the Eastern Pacific may
bring additional moisture the region as well, though confidence is
low in this scenario at this time. All ensemble forecasts remain in
agreement regarding a deepening low pressure trough Friday into
Saturday off the west coast and are generally in agreement regarding
the progression and strength of the aforementioned low pressure
trough. That said, about 1/3 of the GEFS ensembles support a closed
low with the European cluster split between a closed low and
remaining a trough. Focus of the rain and thunderstorms remain in
southern and eastern Utah, as well as southwest Wyoming. In addition
to the rain impacts, a 50 knot 700 mb low level jet arrives Friday
morning and is not forecast to exit the region until the arrival of
a cold front Sunday evening. As a result, strong winds are forecast
across the west desert and in portions of northern and central Utah
Friday and Saturday afternoon. Shift of tails continue to indicate
an anomalously windy Saturday with a broad area of southerly
winds of 20 to 30 mph with stronger gusts. Wind advisories may be
required across the west desert if trends continue.
By early next week, most ensemble solutions indicate seasonal
temperatures and weak high pressure, allowing for dry conditions.
&&
.AVIATION...KSLC...VFR conditions are expected to begin the TAF
period. In the early evening hours, around 07Z, CIGS will begin to
drop to around 5kft and remain until ~14Z. Showers and thunderstorms
are expected to develop west and south of KSLC and by 01Z should be
in the vicinity. In addition to these storms, there is an increasing
likelihood that gusty northwest winds will begin to occur this
evening around 01Z and last for a few hours. There is a high chance
that winds will stay out of the north overnight however, there is a
slight chance that winds will go southerly between 10Z and 16Z. If
this happens, winds will then go northwesterly after 16Z.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected
for all terminals for the majority of the TAF period. Southern
locations, especially KBCE and KCDC, will have chances for scattered
showers and thunderstorms through the evening hours. CIGS are
expected to stay around 8kft when precipitation is near, could go
lower as storms move over ahead. A cold front will reach the
southern sites between 04Z and 06Z and bring gusty northwesterly
winds. For northern locations, scattered showers and thunderstorms
will continue to develop in western Utah and move across the state
creating the potential for MVFR conditions when passing over any TAF
site. These storms will diminish and create VFR conditions for all
TAF sites by 14Z. Winds will shift to be out of the west and
northwest for most northern TAF sites around 16Z.
&&
.FIRE WEATHER...An unseasonably strong cold front has moved into
central Utah this afternoon, and will make its way across the
remainder of the state through early tomorrow morning. Areas
behind the front will see significantly cooler temperatures, with
some areas seeing highs today 30F or more below values observed
yesterday. Some showers and isolated storms will continue through
this evening before diminishing. Strong, gusty winds will continue
into early this evening across southern Utah as well as portions
of eastern Utah, with gusts to 55 mph possible. This will combine
with the continued dry conditions to result in widespread critical
fire weather conditions. Behind the front, cool and dry
conditions will prevail across the district Tuesday, with a couple
of pockets of marginally critical fire weather conditions
possible across south-central Utah.
High pressure ridging will return on Wednesday and Thursday,
resulting in quickly rebounding temperatures back to near seasonal
normals on Wednesday and to 10 to 15 degrees above seasonal
normals by Thursday.
On Friday, a strong area of low pressure will begin to approach
the California and Oregon coastline, pushing the ridge off to the
east. This will force strong southerly flow to develop across the
area. Widespread hot, and windy conditions are likely as a
result. The strong southerly flow will also bring an increase in
moisture with it, and as a result humidities are also forecast to
begin rising on Friday, with western Utah most likely to remain
drier. On Saturday, windy conditions are expected, especially
across western Utah. In addition, showers and thunderstorms are
expected to become more numerous, with gusty outflow winds,
lightning and locally heavy rainfall possible. The western fringes
of the moisture shield may experience some dry thunderstorms
along with dry, windy conditions. At this time, the moisture is
expected to begin to move eastward on Sunday, with showers and
thunderstorms chances more likely across eastern Utah. Moisture is
then expected to move eastward by Monday. There remains some
uncertainty regarding the timing, location and amounts of
precipitation, but do know that confidence is increasing regarding
a potential high impact event Friday-Sunday.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Red Flag Warning until 10 PM MDT this evening for UTZ489-494-495-
497-498.
Wind Advisory until 9 PM MDT this evening for UTZ114-120-121-
127>131.
WY...None.
&&
ADeSmet/NDeSmet/Warthen/Cunningham/Cecava
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