Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 212122

Area Forecast Discussion
National Weather Service Salt Lake City UT
322 PM MDT Sun Oct 21 2018

.SYNOPSIS...A slow moving low pressure system will cross the
region through Tuesday bringing unsettled weather. Drier
conditions will return for the middle to latter part of the week.


.SHORT TERM (Through 00Z Thursday)...Afternoon satellite imagery
and objective analysis show a mean upper circulation center
located along the California coast, with several shortwave
features rotating around this parent low. One such wave is
currently lifting through eastern Nevada and west central Utah,
while an upstream wave is noted approaching the southern
California coast.

The lead shortwave currently lifting through the forecast area is
helping to maintain a broken band of showers and isolated
thunderstorms across central and southern Utah. Satellite and
radar trends, as well as lightning data, indicate this convection
has been weakening over the past few hours as it moves into a more
stable environment, as well as loses dynamic support as the
ejecting shortwave weakens. Anticipate showers will eventually
make it into northern Utah but with reduced coverage from what was
observed earlier, and have maintained chance PoPs across areas
south of I-80, with slight chances further north.

The upstream wave approaching the California coast is forecast to
rotate inland this evening, and take a similar track to todays
wave as it lifts northeast through the southern and eastern Great
Basin. As such anticipate another round of convection to develop
and spread into southwest Utah late tonight, then lift northward
across central and eventually northern Utah during the day Monday.

As this secondary wave moves inland, the parent upper low is
forecast to drift inland and weaken, eventually evolving into an
open wave as it moves into the Great Basin Monday, then slowly
crosses the forecast area Tuesday. This will maintain a chance for
showers and thunderstorms across most of the forecast area through
Tuesday evening, before the airmass begins to dry late Tuesday
into Wendesday in response to building mid level heights. As such
have maintained PoPs through Tuesday before going with a drying
trend for Wednesday.

Temperatures are expected to trend slightly downward through the
short term period, but remain a few degrees above climo. With the
warm airmass in place snow levels are expected to remain at or
above 10 kft across the forecast area through the short term

.LONG TERM (After 00Z Thursday)...Upper level ridging will build
into the state Thursday bringing at least a temporary end to the
active pattern across the region as of late. Northwest flow may
allow a few weak disturbances to clip the far northern portion of
the state...but the remainder of the state is expected to remain dry
and relatively warm for late October. The next significant system
expected to impact the state is expected early next week.


.AVIATION...VFR conditions will prevail through the TAF
period with some mid-lvl ceilings (above 7k ft.) working their way
towards the terminal this evening. There is some uncertainty in this
afternoon`s wind forecast and there is a 40 percent chance shower
activity to our south will flip winds southerly in the 23-01Z time
frame. Otherwise westerly/northwesterly winds should shift to the
south around 03-04Z.





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