Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 231241 CCA
Area Forecast Discussion...Corrected
National Weather Service Salt Lake City UT
642 AM MDT SAT JUL 23 2016
.SYNOPSIS...The west to southwest flow across thee Great Basin
will spread increasingly drier air across Utah and southwest
Wyoming today. Strengthening high pressure aloft across the
region beginning Sunday will lead to very warm and generally
dry conditions across Utah next week.
.SHORT TERM (UNTIL 06Z WEDNESDAY)...The upper level trough
currently over the northern Rockies will exit east into the northern
plains states by this afternoon. A rather dry west-southwest flow
trailing this feature will spread significantly drier air into Utah,
nudging the moisture plume across southern and eastern Utah into the
four corners region by this evening.
The latest MSAS data places the surface cold front over central
Utah just north of the I-70 corridor. The front will continue to
drift south this morning, then stall as the supporting upper
trough exits into the northern plains. Could see some convection
develop along this boundary this afternoon as it encounters the
moisture plume over southern/eastern Utah.
The west-to-east ridge axis across the southern CONUS should
effectively cut-off the deep layer moisture pooled over southern
Arizona/northwest Mexico early next week. The latest versions of
the GFS and ECMWF do hint at some moisture working into extreme
southern Utah early next week. Can not rule out isolated terrain-
based convection across the south Monday/Tuesday, though doubt any
of this activity will generate significant precip either day.
Temperatures will remain quite warm and getting warmer during the
first half of the week.
.LONG TERM (AFTER 06Z WEDNESDAY)...Upper level ridge situated over
the southern plains retrogrades to the west by middle of next week.
The GFS...ECMWF and GEFS ensemble guidance all support idea that
center of upper level high shifts well west of the Four Corners.
This places Utah and southwest Wyoming under a dry west to northwest
flow for the middle and latter portion of next week. This will keep
dry weather in place during the period.
The main story in the medium range will be the potential for a
prolonged period of hot temperatures. With the upper level ridge
holding steady over the Great Basin we could see 700 hPa
temperatures around +16C to +18C across northern Utah with around
+20C across southern Utah. this could allow for a multiple day
stretch with temperatures of 100+ degrees along the central and
southern Wasatch Front with 105+ in Utah`s Dixie. This combined with
a stretch of very warm nights could set the stage for some heat
impacts next week.
.FIRE WEATHER...Upper level ridge in place of the plains with a
weak trough moving through the northern intermountain region this
morning. Weak cold front currently draped across central Utah. This
front will drift slowly south through southern Utah today and
tonight ushering much drier air into the state. However...enough
moisture will remain in place today and Sunday across southern and
eastern Utah to bring the potential for isolated convection over the
higher terrain. Relative humidity readings will remain critically
low through the weekend. Locally gusty southwest winds will be
possible today across south central Utah. However...winds are not
expected to exceed Red Flag criteria. Winds will become primarily
terrain driven Sunday through early next week. A stretch of hot and
dry conditions with low relative humidity values can be expected for
the early to middle portion of next week.
.AVIATION...The dry and stable air mass trailing yesterdays cold
front will maintain VFR conditions under clear skies today. Light
west-northwest winds early this morning will increase for late
this morning through early this evening.
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