Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 212151
Area Forecast Discussion
National Weather Service Salt Lake City UT
351 PM MDT Fri Oct 21 2016
.SYNOPSIS...High pressure is shifting east today with a
southwesterly flow developing for the weekend. Moisture will begin
to spread into the region Sunday and will continue to increase
through Monday. Drier conditions will return for the middle of the
.SHORT TERM (Thru 00z Tuesday)...The mid level ridge axis has
shifted east of UT this afternoon with skies remaining clear
across the CWA. The developing southwest flow aloft has mixed down
into some of the swrn valleys with temps rising into the 70s.
Elsewhere temps remain stuck in the 60s.
Swly flow increases tomorrow and these winds should surface in
more areas in the aftn bringing better mixing and warmer surface
temps even tho 700mb temps stay steady.
Latest models still bring moisture into the CWA from the southwest
on Sunday increasing thru Mon as a low amplitude short wave lifts
across the Great Basin in the swly flow.
Clouds increase Sun with a chance of showers beginning late in
the day over swrn UT. The heaviest precip looks to be over the
mtns and east on Mon into Mon night.
The new 12z GFS was generating even more qpf than the 06z run
with now close to two inches of rain by Tue aftn along portions
of the Wasatch Plateau and over the Book Cliffs. If this indeed
occurs it could bring a threat of local flooding to portions of
Carbon and Emery counties but we will need to monitor model trends
for the next day or so to see if this trend persists.
Have gone ahead and raised pops for much of the CWA starting Sun
night thru Mon as widespread rain looks likely even if the
amounts do not end up being that large.
.LONG TERM (After 00z Tuesday)...Under southwest flow aloft,
sufficient moisture advection across the Eastern half of Utah
continues into Tuesday of next week. Long term forecast models
continue to show widespread precipitation across the state into
late Monday and early Tuesday. Subtle differences in the models
in regards to precip amounts, but consensus on favorable areas
east of I-15 to receive the higher amounts of rain. Mid-level
temperatures cool near +2C, so precip should remain in the form of
rain during this event.
As the upper level low breaks down across the Pacific Northwest by
late Tuesday, weak ridging will build across the western states by
Wednesday as surface temperatures rebound and warm.
Differences in the global models present themselves by Thursday
with the next trough feature diving south from the Gulf of
Alaska and becoming positioned over the Eastern Pacific. Another
southwest flow pattern will advect moisture into the Great Basin
once again, and another chance for precip looks favorable by next
weekend for portions of the CWA.
.AVIATION...VFR conditions will prevail at SLC terminal through the
TAF period. Diurnal wind shift to the south by 03z under clear skies.
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