Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 241031
Area Forecast Discussion
National Weather Service Salt Lake City UT
431 AM MDT Sat Sep 24 2016
.SYNOPSIS...The storm system which impacted the region over the
past couple of days will move east of the region this morning.
High pressure will bring a drier and more stable airmass for the
weekend through the first part of next week. A storm system is
expected to bring moisture back to the forecast area by midweek.
.SHORT TERM (Through 12Z Tuesday)...The upper low which has
impacted the region over the past couple of days is currently
lifting northeast across south central Wyoming, and will continue
to move away from the forecast area through the day. Isentropic
ascent resulting from moist warm advection along the back side of
this low continues to produce areas of valley rain with snow above
roughly 7000 feet. As the parent low continues east this region of
forcing will slowly diminish as the morning progresses. Went with
likely to categorical POPs in the northern mountains through the
morning with chance in the valleys anticipating a downward trend
over the next couple of hours, however will need to monitor radar
and surface observations closely, and may need to bump valley POPs
for the morning hours.
Mid level ridging will begin to build into the Great Basin
beginning this afternoon, then expand eastward across the forecast
area through the remainder of the short term period. As this ridge
begins building into the region late today through tonight,
lingering boundary layer moisture coupled with clear skies may
result in fog across areas such as the Cache Valley and Wasatch
Back tonight, and have added this overnight through sunday
morning. Additionally could see areas of frost in these
outlying/sheltered locations as well. Additionally, a northerly
gradient coupled with modest cold advection within northeast low
level flow will result in gusty winds through the gaps/canyons of
Washington county, although anticipate these will remain below
advisory level. Otherwise with the building ridge expect a warming
and drying trend into early next week.
.LONG TERM (After 12Z Tuesday)...The global models are in agreement
that in some form or other the closed low over the desert southwest
will bring moisture into the CWA beginning over the higher terrain
of southwest Utah late Tuesday. After this time the spread of
moisture northward across the CWA is different between the GFS and
EC despite them being similar in having the remnants of the low open
up an move across the CWA Wednesday night into Thursday. Have leaned
toward the GFS solution with more widespread QPF.
IN the wake of this feature lifting northeast there should be less
activity but believe moisture never really clears the area so have
kept a chance, mainly over the mountains, in for Thursday night and
Friday. Since there are very little dynamics associated with the
southwest flow have gone without thunderstorms during the 06-18Z
time frame for both Thursday and Friday and only isolated
thunderstorms in the afternoons and evenings.
Temperatures are expected to be a few degrees above normal through
the early part of this extended period as 700mb temps rise to 8-10
degrees C Tuesday and Wednesday and then cool a couple of degrees
Friday and Saturday as the 700mb temps drop to 6-8 degrees C.
.AVIATION...Light rain is expected to continue at the
SLC terminal through about 13Z but there is a 20 percent chance of
intermittent rain lasting through 15Z. CIGS will remain below 7K FT
AGL through about 18Z but could linger until 20-21Z. Winds will
shift from southeast to northwest about 17-18Z.
.FIRE WEATHER...A storm system exiting the region to the east will
continue to bring areas of valley rain and mountain snow to
northern Utah this morning, before conditions begin to dry out by
afternoon. Meanwhile the south will remain generally dry. High
pressure is expected to begin building into the region later this
afternoon, and strengthen through the remainder of the weekend
into early next week. This will result in a warming and drying
trend regionwide. Southerly flow is expected to bring moisture
back northward during the middle portion of the week.
UT...Winter Weather Advisory until 10 AM MDT this morning for
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