Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 181544
Area Forecast Discussion
National Weather Service Salt Lake City UT
944 AM MDT MON JUL 18 2016
.SYNOPSIS...High pressure over the southern plains with an upper
level trough settling into the Pacific Northwest will leave the
Great Basin under a southwest flow through much of the week.
Moisture will spread across southern and eastern Utah today, and
remain in place through much of the week.
.DISCUSSION...The region is under southwest flow this morning in
between the ridge over the central United States and the large
trough just off the Pacific Northwest coast. This flow is drawing
deep moisture into southern and eastern portions of the forecast
area. Satellite derived PWs are already in excess of 1.0 inch over
far southeast Utah, with PWs up to 0.8 inch extending into central
Utah. Instability is not particularly impressive, but showers with
a few thunderstorms persist over southeast Utah, primarily along
the moisture axis. However, given the dry sub cloud layer little
if any precip is hitting the ground.
Moisture will continue to spread northward today, with PWs in
excess of 0.8 inch expected this afternoon across all but far
northwest Utah. Showers will continue to develop with the heating
of the day this afternoon through the early evening, but
instability is expected to remain limited, so convection will be
on the weak side with the best coverage over the higher terrain.
Given the very dry lower levels, however, microburst winds will be
a threat with any convection that develops. The potential for
thunderstorms developing after a long dry period will result in
areas of critical fire weather conditions. See the fire weather
section of the AFD for more details.
Little change in the overall pattern is expected through at least
midweek with the Pacific Northwest trough and the central US ridge
moving little. As a result, the forecast area will continue to see
good moisture, particularly over southeast Utah, with enough
instability to produce showers and thunderstorms, primarily over
the higher terrain. Temperatures are progged to remain on the warm
side over northern Utah, with maxes running 5-8F above seasonal
norms. Temperature should be closer to climo over southern Utah.
No updates expected to the forecast this morning.
.AVIATION...Gusty southerly winds will prevail at the SLC terminal
through the forecast period. Periodic gusts above 35 mph remain
possible through 02z this evening. Additionally, there is a 10
percent chance that convection will develop over the Oquirrh
Mountains to the southwest of SLC terminal and bring a threat of
gusty erratic outflow winds between 20z-02z.
.FIRE WEATHER...Southwesterly flow will prevail across the region
through much of the upcoming week. Moisture within this flow will
spread northward from Arizona today bringing an increased threat
for thunderstorms. Along the northern and western edge of this
moisture surge thunderstorms may initially be dry today with
lightning and gusty microburst winds possible, however as moisture
continues to increase storms should transition to wet across most
areas. Given the recent dry spell lightning associated with these
storms will pose a significant risk for new starts prompting a red
flag warning across much of central and eastern Utah. Meanwhile
dry and breezy conditions will continue across northwest and west
central Utah resulting in critical fire weather conditions.
Moisture will remain in place across the eastern half of the area
through much of the remainder of the week maintaining a threat for
showers and thunderstorms each day. These storms will be capable
of producing wetting rains given the moisture in place.
UT...Red Flag Warning until 9 PM MDT this evening for UTZ479-483-489-
Red Flag Warning until 9 PM MDT this evening for UTZ478-492.
Red Flag Warning until 9 PM MDT this evening for UTZ480-482-484.
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