Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 182213

Area Forecast Discussion
National Weather Service Salt Lake City UT
313 PM MST Sat Nov 18 2017

.SYNOPSIS...High pressure will build across the region through
Sunday. A weak weather disturbance will graze northern Utah
on Monday, followed by strong high pressure returning by midweek.


.SHORT TERM (Through 00Z Wednesday)...High pressure firmly in
place over the forecast area this afternoon behind the storm
system that moved through yesterday. Behind yesterday`s front,
temperatures remain on the cool side with most locations seeing
maxes around 5F below seasonal normals under mostly clear skies.

The ridge will remain in place tomorrow, allowing for a warming
trend across the area. However, temperatures will be slow to warm
in some valley locations with inversions developing. In those
areas with inversions, maxes will still be near or slightly above
seasonal normals, while other locations will see temperatures up
to 5F above climo.

The ridge is progged to weaken Sunday night into Monday as a weak
trough moves over the top of the ridge, bringing some moisture and
instability into far northern Utah. This could produce a bit of
valley rain/mountain snow, primarily over the higher terrain and
with a better chance for locations close to the Utah/Idaho border.
Overall dynamics are not impressive, however, and have trended
POPs downward overall. The passage of this system cold help with
mixing, though, and the warming trend over the area is expected to
continue as it moves through.

High pressure is expected to rebound beginning Tuesday, allowing
for decreasing clouds and a continued warming trend.

.LONG TERM (After 00Z Wednesday)...Global models and GFS ensemble
members are in very good agreement with respect to the large-scale
pattern Wednesday through Thursday. High pressure over the
southwestern CONUS will keep dry and stable conditions and a mild
airmass in place. As typical this time of year, cool spots will be
common in some of the lower valleys where mixing will be poor,
otherwise temperatures are forecast to be around 10-20 degrees above
normal areawide.

The pattern is progged to flatten on Friday, sending a weak
shortwave trough to graze far northern Utah. Little in the way of
precipitation is expected with this trough, and any moisture should
remain confined to the far north. A weak cold front will also be
associated with this trough, but the airmass behind it is not
expected to be very cold, as neither the GFS nor EC bring 700mb
temperatures lower than -3c to the Idaho border.

High pressure will return for the weekend. The GFS wants to develop
fairly widespread precipitation across northern Utah on Saturday in
an overrunning situation, but this seems quite overdone and have
left this out of the day 7 forecast for now.


.AVIATION...Light and variable or light northwesterly winds are
expected at the SLC terminal from 22Z to 02Z, with winds eventually
increasing from the southeast around 02-05Z.




SHORT TERM...Traphagan

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