Severe Thunderstorm Warning 44, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
403 PM MDT Wed Sep 11 2019

.SYNOPSIS...Fall-like temperatures will remain in the area through
Thursday. Drier and warmer conditions will return to the area
late in the week and continue through the upcoming weekend.

&&

.SHORT TERM (Through 00Z Sunday)...Afternoon satellite analysis is
pretty impressive as we zoom out and look across Montana, Wyoming,
Colorado and Utah. The large, broad trough is moving slowly
through the Rockies this afternoon. The slow transition from
negative tilting to positive tilting has made for a slow and
persistent showery day across the northern half of Utah. Showers
have been stratiform most of the time with isolated thunderstorms
that have resulted in ponding of water on roadways and poor
drainage areas of the metro area here in Salt Lake City.
Elsewhere, minor issues of debris flow in the Cottonwood Canyons
have closed roads for periods of time today.

Temperatures have remained on the cool side today, only reaching
into the upper 50Fs and low 60Fs. Widespread precipitation from
Payson to Ogden and points east and west have measured close to
half an inch and over 1.5 inches of rain in the last 24-48 hours.

The trough continues to move the best lift to the east while
filling in subsident air behind it. Riding along the cold front
and where the jet is maximized is where the remaining instability
lives. Persistent afternoon showers with isolated storms will be
possible for another few hours before the environment becomes
over-saturated and overturned. Not impressively high precipitable
water values, just over 0.5 to 0.6 inches, the airmass is cold
enough and unstable enough to continue squeezing out moisture from
around midnight through the present time.

Expecting Thursday through Saturday to be much more mild with a
drying and warming trend taking place. Zonal flow behind the
departing trough will help moderate temperatures a bit back into
the upper 70Fs and low 80Fs. The flow begins to shift as another
trough is on tap for late weekend.

.LONG TERM (After 00Z Sunday)...The ridge over the forecast area is
expected to shift east on Sunday as a broad trough approaches the
Pacific Northwest coast. Global models indicate that this system
will dive south into northern California on Monday before tracking
east across the area through day seven. The various models and
associated ensembles disagree on timing but all bring it through
Utah and southwest Wyoming in some form. The arrival of the trough
would bring noticeable cooling of temperatures as well as another
period of precip, at least for northern portions of the forecast
area. Ahead of the system, breezy southwest flow should slowly draw
moisture northward to start the week. Have stuck close to model
blend ideas for POPs for the end of the long term period, indicating
increasing coverage as the trough approaches.

&&

.AVIATION...The SLC terminal will see VFR conditions through the
evening with decreasing clouds. Southeast winds are expected to
prevail through the overnight hours, but there is a 30 percent
chance that nearby showers will result in some erratic winds before
00Z.

&&

.FIRE WEATHER...The airmass over Utah is cold with elevated
moisture today. The cold system is expected to exit to the east
tonight with building heights filling in behind. The airmass will
see a drying trend starting Thursday and continue through the
weekend under mostly light winds and warm temperatures. Next week
another Pacific Northwest trough will drop south through the Great
Basin creating breezy southwest winds and another round of cooler
temperatures.

&&

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

SHORT TERM/FIRE WEATHER...Dewey
LONG TERM/AVIATION...Traphagan

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

Hazardous Weather Outlook
National Weather Service Salt Lake City UT
625 AM MDT Wed Sep 11 2019

UTZ001>016-019>021-517-518-WYZ021-121200-
Cache Valley/Utah Portion-Northern Wasatch Front-
Salt Lake and Tooele Valleys-Southern Wasatch Front-
Great Salt Lake Desert and Mountains-Wasatch Mountain Valleys-
Wasatch Mountains I-80 North-Wasatch Mountains South of I-80-
Western Uinta Mountains-Wasatch Plateau/Book Cliffs-
Western Uinta Basin-Castle Country-San Rafael Swell-
Sanpete/Sevier Valleys-West Central Utah-Southwest Utah-
Utahs Dixie and Zion National Park-South Central Utah-
Glen Canyon Recreation Area/Lake Powell-Central Mountains-
Southern Mountains-Southwest Wyoming-
625 AM MDT Wed Sep 11 2019

This Hazardous Weather Outlook is for the western two thirds of
Utah and southwest Wyoming.

.DAY ONE...Today and Tonight

The cool early fall storm that entered western Utah last night
will continue east through the state today. Showers, along with a
few thunderstorms will concentrate on central and northern Utah
through around mid-afternoon. Brief heavy rains are possible with
some of the stronger showers and storms this morning.

Temperatures will be cold enough across the higher northern
mountains for snow today. Accumulations will be minimal with 2
inches or less expected.

Showers and thunderstorms will linger over northeast Utah and
southwest Wyoming early this evening, followed by clearing skies
across the outlook area later tonight. Fog will develop across
some of the higher northern and central valleys late tonight.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Warmer and drier conditions will exist across the outlook area
Thursday through at least early Monday. A new storm system will
exit the Pacific Northwest Monday and bring a chance for showers
and thunderstorms back into the area by Tuesday.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to standard operating procedures.

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

For information on potential road travel impacts visit...
http://www.udottraffic.utah.gov/roadweatherforecast.aspx