Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 212209
Area Forecast Discussion
National Weather Service Salt Lake City UT
409 PM MDT SUN AUG 21 2016
.SYNOPSIS...Moisture will spread northward across much of forecast
area tonight and Monday, then remain in place on Tuesday.
Meanwhile, an upper level disturbance will drift slowly across
the region. Drier air will spread over Utah on Wednesday.
.SHORT TERM (THROUGH 06Z WEDNESDAY)...Upper level ridge over the
Great Basin will shift east into the central plains as an upper
level trough moves through the Northern Intermountain region early
this week. Deep moisture has spread into the southern third of
Utah today and isolated storms have developed on modest
instability. A weak wave associated with a circulation evident in
water vapor imagery near the Arizona-California border lifts into
southern Utah tonight and may keep showers going there through the
Flow aloft backs to the southwest and allows deep moisture to spread
north through much of the state on Monday. With increased
instability slow storm motion there will be the potential for
locally heavy rain across portions of central and southern Utah.
Along the leading edge of the moisture surge an isolated dry
thunderstorm will be possible. The deep moisture will linger through
Tuesday with the potential for locally heavy rain once again.
Increased cloud cover and decreasing mid level temperatures will
allow temperatures to cool a bit on Monday and Tuesday.
.LONG TERM... (AFTER 06Z WEDNESDAY)...A few showers will still be
possible over southeast Utah early Wednesday morning as the upper
level disturbance, over the Four Corners area early in the
period, continues eastward. Some residual moisture, precipitable
water values near .75", left for some isolated convection,
primarily over the higher terrain of southern and eastern Utah, Wednesday
afternoon and evening. With cooler temperatures aloft, will see
high temperatures a few degrees below seasonal norms.
Models in good agreement in digging a trough southward into
California on Thursday, with upper level disturbances ejecting
northeast from trough into Great Basin Thursday and Friday. With
southerly flow developing, moisture will spread into southern Utah
on Thursday and across bulk of forecast area by Friday. With
upward lift from system and adequate moisture with precipitable
water values around .75", will go with a slight chance to chance
for showers and thunderstorms over southern Utah on Thursday and
over much of forecast area Friday. Trough will slide eastward
across Great Basin on Saturday, continuing potential for
convection across Utah.
In the wake of the trough, drier air will overspread forecast area
.AVIATION...Northwesterly winds at the SLC terminal are expected to
shift to the southeast between 03-04Z. Otherwise, mostly clear skies
.FIRE WEATHER...Upper level ridge over the Great Basin will shift
east into the central plains as an upper level trough moves through
the Northern Intermountain region early this week. Deep moisture
has expanded north into the southern third of Utah this afternoon
and isolated convection has developed across this area. Storms will
stay active into the evening and then showers will likely persist
through the night as a disturbance lifts north out of Arizona. Deep
moisture spreads north through much of the state on Monday and
expect scattered storms across central and southern Utah and in the
Uintas, with isolated storms in the northwest portions of the
state. A few storms in the northwest may produce dry lightning on
Monday afternoon and evening, although coverage is not expected to
be significant. Storms across southern Utah will have the
potential to produce locally heavy rainfall on both Monday and
Tuesday. A drying trend then spreads across the state on
Otherwise, expect better RH recover tonight and minimum relative
humidity values will be up quite a bit tomorrow across southern Utah
with plenty of cloud cover and increased thunderstorm coverage.
Relative humidity values will dip quite a bit during the middle of
the week as drier air spreads back into the region.
WY...Red Flag Warning in effect from noon to 9 PM MDT Monday
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