Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 222218
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
318 PM MST Wed Nov 22 2017

.SYNOPSIS...High pressure will  remain in place through the rest
of the week. A fast moving storm system is possible Monday into
Tuesday.

&&

.SHORT TERM (Through 00z Sunday)...Expansive mid level ridging
continues to dominate the intermountain region today, with a deep
trough off the PacNW aiding further amplification. H7 temps
continue to warm and will so through this evening, with values
expected to punch up to +4-5 C across northern Utah, and up to +9
C down towards Utah`s Dixie. These are some of the warmest H7
temps ever for this time of the year.

Previously forecasted several record breaking temps across the
area for this afternoon, and some have already come to fruition.
KSLC has maxed out at 68 degrees thus far (likely as high as it
will get), breaking the record of 66 degrees set in 1926. On
average, temps areawide are running some 20 degrees above normal.
Minimal change in the long wave pattern over the next 24 hours
will have minimal change on these conditions being maintained
through Thanksgiving.

Friday morning will still see a shallow boundary sagging into the
UT/ID border region, with a shallow frontal feature tracking south
across northern Utah. Outside of increased clouds in the north and
a net cooling of 5 degrees or so, not expecting much sensible
weather change from this.

Mid level ridging will rebound again for the weekend, with warming
trend temps likely pushing 20 degrees above climo by Sat
afternoon.

.LONG TERM (After 00Z Sunday)...Warm advection and a tightening
surface gradient ahead of an approaching cold front will keep
overnight temperatures well above seasonal norms across the region.
Sunday afternoon could see statewide record temps, with gusty winds
and cloud cover increasing rapidly ahead of the encroaching
baroclinic zone.

Though previous global model runs were rather in sync with frontal
timing, the latest runs show a bit of a departure from each other,
with the GFS quickening and the EC slowing. Ensemble models align
more closely with the deepening, amplifying EC solution. As such,
expecting the impressive H7 baroclinic zone to careen into NW Utah
early Monday morning, bringing a quick bout of precipitation and
very cold temps to the forecast area. GFS PWAT values max out around
0.5 inches and rather short-lived, leaving low confidence for snow
accumulation amounts at this point. Temps will be cold enough for
any snowfall to reach valley floors in the northern/central areas.

Still need to keep an eye on the possibility of lake enhanced or
Lake Effect snow Monday night south and southeast of the GSL.
Downslope winds will likely be quite strong across the central
mountains and into Washington County Monday night.

Tuesday`s cold temps should warm rapidly in the mountains by
Wednesday with valley inversions slowing the warmup under the
building mid-week ridge.

&&

.AVIATION...Winds at the SLC terminal are expected to switch to the
southeast around 02-04Z, though periods of light and variable winds
are also possible before 02Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

Merrill/Verzella/Schoening

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php



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