Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 260347

Area Forecast Discussion
National Weather Service Salt Lake City UT
947 PM MDT Sun Jun 25 2017

.SYNOPSIS...High pressure aloft will shift east early Monday,
allowing a mild southwesterly flow to develop across the region
by Monday afternoon. A cooling trend will begin on Tuesday and
continue through midweek. High pressure aloft will return for
the end of the week.


.SHORT TERM (Through 12Z Wednesday)...Moisture along the
weakening deformation axis across southwest Utah generated plenty
of convective cloud cover, but little in the way of even virga
this afternoon/early this evening. Recent satellite imagery has
most of the cloud cover thinning out over Utah, with areas of
colder topped clouds still hanging on to west over Nevada.

A shortwave ejecting north-northeast out of the eastern Pacific
upper low centered around 37/130 is generating fairly strong lift
across southern Oregon, with loosely organized convection across
northwest Nevada this evening. This feature will take a turn more
to the east later tonight, with the southern end of the shortwave
dragging mid-level moisture into northern/western Utah Monday
morning. Looking at an increase in high-based convective clouds
along the passing shortwave, with little more than isolated virga
during the morning.

The previously mentioned eastern Pacific low will follow as an
open wave across northern Utah Monday night. This feature will
offer a little better dynamic and thermal support for lift, though
with still limited moisture would not expected much more than
isolated showers/storms overnight.

Cooler near 700mb temps trailing the Monday night wave, especially
across the north, will bring temps down to around seasonal norms
Tuesday/Tuesday night. Drier air moving into the area, especially
across southern Utah, will limit any lingering convective precip
to the far northern and northeast mountains during the afternoon
and early evening hours.

.LONG TERM (After 12Z Wednesday)....Weak waves will continue to
impact primarily northern Utah Wednesday into Thursday, keeping a
threat of convection over the higher terrain. This will also allow
temperatures to stay near to just slightly above seasonal normals.

EC/GFS then indicate high pressure building over the forecast area
Friday through the first part of the weekend, resulting in a drying
trend with a slight warming trend in temperatures. EC indicates some
modest cooling by day seven with the arrival of a Pacific storm
system, but the GFS keeps the trough onshore and keeps the ridge in
place through the end of the forecast period. Have introduced some
isolated POPs for next Sunday and lowered temperatures slightly to
account for the EC solution.


.AVIATION...Strong high pressure aloft over Utah will maintain VFR
conditions under clear skies overnight. Moisture working into the
region from the west will bring scattered to broken clouds
generally based above 12 kft Monday. Winds will come around to
south-southeast around 04z. Southerly winds will increase a bit
Monday morning, then make the turn back to the northwest around


.FIRE WEATHER...High pressure aloft remains centered across the
Desert Southwest this afternoon. Mid level moisture embedded
within this high will maintain a threat of isolated thunderstorms
across the southern mountains through this evening. This high is
forecast to move east Monday, allowing southwesterly flow to
overspread much of western Utah, resulting in Red Flag conditions
Monday afternoon across much of central and southwest Utah. In
addition, a warming trend is expected across the north while
conditions in the south remain hot and dry. There is also
a threat for isolated high based showers and thunderstorms
across northern Utah late Monday afternoon and Monday evening
with activity spreading out of northeast Nevada. Held off on
issuing a Fire Weather Watch given a high degree of uncertainty
regarding whether this convection will indeed develop and spread
into northwest Utah, as many convective allowing models remain dry
across this area Monday afternoon. A dry cold front is expected
to sweep through northern Utah Tuesday, followed by a dry westerly
flow for much of the remainder of the week.


UT...Red Flag Warning from noon to 10 PM MDT Monday for UTZ492-493-




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