Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

626
FXUS65 KSLC 211117
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
517 AM MDT SAT MAY 21 2016

.SYNOPSIS...A low pressure system will slowly cross the region over
the weekend, with unsettled conditions lingering into next week.

&&

.SHORT TERM (Through 18z Tuesday)...An upper low with its center over
southeast Oregon this morning will continue to impact the Great
Basin today. Utah remains under a southwesterly flow aloft although
a fairly significant thermal gradient is in place across Utah and
eastern Nevada. The surface front, meanwhile, has already pushed
into northwest Utah and will slowly cross into central Utah this
afternoon. Expect much cooler temperatures today behind this front,
but a majority of the forecast area will see at least some cooling
as 700mb temperatures fall. Winds will remain strong across the
southeastern portions of the forecast area ahead of the cold front
and a wind advisory remains in place.

The core of the upper jet is currently rounding the base of the low
and punching into central Utah. This jet combined with upper
diffluence and a weak disturbance lifting into northwest Utah has
triggered some precipitation which extends from southwest into north-
central Utah. Since the upper dynamics will become more focused
across the north, expect the precipitation across southwest Utah to
wind down early this morning, and satellite trends support this as
cloud tops across southwest Utah are warming. The boundary layer has
taken awhile to moisten, so little of these showers have translated
to measurable rain overnight. With rising dewpoints, there will be a
better chance for measurable rain this morning and into the
afternoon hours. The dry boundary layer overnight combined with
downward momentum transfer of 40-50kt 700mb winds led to windy
conditions near showers. However, these winds will become more
isolated now with the moistening of the airmass so the wind advisory
issued for the western Utah valleys and Salt Lake and Tooele Valleys
last night has been cancelled.

The center of the closed low will migrate to southern Alberta by
tomorrow morning, leaving a mean longwave trough over the western
CONUS. Embedded shortwave disturbances will continue to rotate
through the area, keeping cool, moist, and unsettled weather in
place tomorrow. A weak shortwave ridge will develop into the area
tomorrow night bringing a break in precipitation, but this will be
short-lived as southwesterly flow is progged to return by Monday.
Another shortwave disturbance will then eject across the area late
Monday into Tuesday.

.LONG TERM (After 18z Tuesday)...The overall longwave trough will
persist over the western CONUS through this week with series of
disturbances rotating around this trough and across mainly northern
portions of the CWA. Have gone with at least climo or higher pops
across central and northern portions of the CWA while southern
portions the threat of precipitation is much less. Confidence is low
as to which day has a better threat of showers or thunderstorms as
the EC and GFS are at odds with each other on the timing of the
disturbances.

Temperatures are expected to run a few degrees below normal through
this period.

&&

.AVIATION...Winds at the SLC terminal are expected to remain
westerly or southwest through about 12Z then shift to the south
southeast as more high based showers develop and cause gusty outflow
winds. However, there is a 30 percent chance that west to northwest
winds will prevail. Cigs will likely to come down to BKN050-BKN060
in and around showers between 13 and 18Z.

&&

.SLC Watches/Warnings/Advisories...
UT...Wind Advisory from 9 AM this morning to 9 PM MDT this evening
     for UTZ013-020-021.

WY...None.
&&

$$

Cheng/Struthwolf

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.