Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 140958

Area Forecast Discussion
National Weather Service Salt Lake City UT
358 AM MDT Fri Aug 14 2020

.SYNOPSIS...With a ridge of high pressure building over the Great
Basin, temperatures will warm significantly heading into the
weekend. The hot weather will continue into early next week, with
readings up to 10 to 15 degrees above normal. Aside from some
isolated thunderstorm activity over the mountains, dry weather
will prevail.


.SHORT TERM (Through 12Z Monday)...In the wake of a trough of low
pressure existing the Northern Rockies, somewhat cooler air aloft
has filtered into the northern portions of the forecast area this
morning. Thus, high temperatures look to be a degree or two
cooler today than yesterday. Hot readings will already be in play
across southern Utah. With some residual moisture, there could be
some isolated thunderstorm activity over the higher terrain of
southern Utah today, though given minimal air mass destabilization
and lack of any forcing mechanism, coverage will be extremely

The ridge of high pressure over the Desert Southwest will build
over the Great Basin heading into the weekend, then remain in
place into next week.  Given warming temperatures aloft, 700MB
readings of 17 to 20 degrees C by Sunday, hot temperatures will
occur, with near to record high temperatures likely by Sunday.
The existing Excessive Heat Warning for portions of southern Utah
looks good.  The Excessive Heat Watch for portions of northern
and central Utah will likely need to be transitioned to Heat
Advisories and/or Excessive Heat Warnings. With a west to
northwest flow aloft, a dry air mass will be in place Saturday and
Sunday. As such, have pulled any chances for showers and
thunderstorms for the two days.

.LONG TERM (After 12Z Monday)...High confidence in a high amplitude
ridge bringing record challenging heat during the early part of next
week remains consistent. Ensemble guidance continues to be in great
agreement of a significant ridge building over the region through
the latter part of the weekend and prevailing through the week
ahead. Unfortunately, with the high centered over the UT/AZ/NV
border region, any subtropical mid-level moisture getting absorbed
into the mean flow will be well west of the region to start, keeping
a dry forecast in the running through at least Tuesday. Temperatures
along the Wasatch Front will be pushing into the triple digit realm
by Sunday, and will likely continue through at least Tuesday. For
Utah`s Dixie, blended model guidance has continued to favor
temperatures exceeding the 110F mark through Wednesday. With that
being said, various excessive heat warnings and advisories are
currently in effect across much of Utah through 12AM Thursday.

Deterministic guidance continues to support increasing mid and upper
level moisture over the eastern Great Basin through the extended
forecast period, however, there still remains a fair amount of
uncertainty revolving around the probability of generating
precipitation with moisture wrapping around the ridge. As has been
the case over the past few days, the GFS continues to favor more
convective activity over the forecast area than the ECMWF. Aside
from Thursday afternoon/ evening, the ECMWF maintains a dry
forecast. The GFS, on the other hand, favors daily convection over
portions of Utah Wednesday forward, with increasing coverage through
Friday. Any convection that may develop in this pattern will be high
based and produce little to no rainfall, with most activity being
confined to the terrain. Model trends over the past couple of days
have continually been delaying the onset of convective activity, so
this will have to be monitored in the coming days as uncertainty
still remains fairly high.


.AVIATION...VFR conditions are expected to prevail under clear skies
through the valid TAF period. Light southerly drainage winds will
persist over the airfield through the morning hours, before
returning to a northerly lake breeze around 17Z.


.FIRE WEATHER...With the broad upper level trough exiting
the northern Rockies, breezy conditions will still be possible
over northeast Utah today, though wind speeds should remain
below critical fire weather condition thresholds.

A ridge of high pressure over the Desert Southwest will build
over the Great Basin heading into the weekend, then hold in place.
With the ridge, temperatures will turn hot, running 10 to 15
degrees above normal through the weekend and into next week. A
very dry air mass will prevail, with low daytime minimum relative
humidities and poor relative humidity recoveries at night. Enough
residual moisture will remain in place for isolated thunderstorms
over the higher terrain of southern Utah today, though any
coverage will be extremely limited. With some moisture return,
elevated convection will be possible next Wednesday through
Friday, though little in the way of rainfall is expected. With any
thunderstorms that do develop, the primary hazards will be gusty
and erratic winds, along with lightning strikes potentially
producing ignitions.


UT...Excessive Heat Warning until midnight MDT Wednesday night for

     Excessive Heat Watch from Sunday afternoon through Wednesday
     evening for UTZ001>005-011>016-020.

WY...Red Flag Warning remains in effect until 8 PM MDT this evening
     for WYZ277.



SHORT TERM...Barjenbruch
LONG TERM...Webber
FIRE WEATHER...Barjenbruch

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