Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 231009
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
409 AM MDT Wed May 23 2018

.SYNOPSIS...High pressure will expand across the interior west
for the end of the week. A new low pressure system will move into
California Friday night. This low pressure will continue east
into the Great Basin where it will linger through the holiday
weekend.

&&

.SHORT TERM (Until 00Z Saturday)...The upper low that moved north
across Utah this evening currently sits over west-central Wyoming.
This feature will continue northeast away from the area this
morning with high pressure aloft replacing this exiting upper low
by late tonight or early Thursday.

Convection directly associated with the upper low has all but ended
across the far north at this time. A weak trailing vorticity lobe
rotating east into west-central Utah from Nevada will spawn light
showers early this morning. Convection will increase farther east
later this morning/this afternoon as solid daytime heating, weak
dynamic lift and abundant moisture combine to generate convection.
Dynamic subsidence will take hold by this evening as heights
begin to build ahead of the upper ridge settling over the area for
Thursday. Convective precip should decrease quickly during the
evening, with a few lingering showers over the far north and
northeast late tonight.

Looking at increasingly warm conditions across the forecast area
as the upper ridge moves over and then east of the area Thursday
through Friday. Can not rule out a terrain-based shower or storm
both afternoons, otherwise dry conditions will exist across the
forecast area through end the week.

.LONG TERM (After 00Z Saturday)...Mid level ridging will continue to
shift east heading into the early portion of the weekend allowing a
largely dry southerly flow to be in place Saturday in advance of a
closed low translating east across the Great Basin. A net increase
of diffluence aloft by late Saturday could spawn some isolated high
based convection across the far north during the peak heating hours
(primarily terrain based), but dry and unseasonably warm conditions
look to continue to dominate attm.

Global guidance continues to depict that the upper low will settle
overhead Sunday through Monday, prior to filling and lifting NE
Monday night through Tuesday. While overhead, steepening lapse rates
within the core of the low will drive modest instability, while weak
upglide within the northern/western periphery of the low should
provide additional accent to aid development of scattered
convection, greatest during the afternoon/evening hours (through
Monday). Confidence is highest regarding precip potential across
central/northern portions of the area, but this wanes across the
south due to subtle difference in details regarding track and
placement of the circulation center. Cooler conditions (near
seasonal norms) will spread across the area regardless of those
details however.

The upper low is expected to begin to fill heading into Tuesday,
prior to phasing with the northern branch flow allowing a NE
translation during the day. If this evolution holds precip potential
will focus over northern portions of the area thereafter into day 7
maintaining somewhat unsettled conditions into midweek, with temps
beginning to warm again within a modifying airmass. Continue to
trend forecast in that direction.

&&

.FIRE WEATHER...An upper low lifting across northern Utah will
maintain a scattering of showers and isolated storms across northern
portions of the district today, with elevated wetting potential
highest in the mountains and along the UT/ID border region. High
pressure will then build into the area through late week providing a
brief warming and drying trend across the area. The approach of the
next upper low will kick up breezy southerly winds Friday into
Saturday, with increasing potential of showers/storms developing
late Saturday as the low settles over the area. With this, Cooler
and more moist conditions will exist across much of Utah over the
weekend, prior to concentrating across the north early next week.

&&

.AVIATION...Southerly surface winds are expected to prevail at the
KSLC terminal through the day, but a 30 percent chance exists that
light northerly winds will develop within the 17z-21z window.
Isolated showers and storms are expected to be in the vicinity of
the terminal this afternoon, most likely in the 21z-02z window, and
will likely enhance southerly wind gusts during that timeframe.

&&

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

$$

CONGER/MERRILL

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


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