Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 280952

Area Forecast Discussion
National Weather Service Salt Lake City UT
352 AM MDT Sun May 28 2023

.SYNOPSIS...Unsettled conditions will continue over northern Utah
today before drier air moves northward for Memorial Day, limiting
convection to far northern Utah. Southern Utah will stay dry
through midweek. A California low will bring an increase in
showers and thunderstorms for the middle to latter part of the


.SHORT TERM (Through 12Z Tuesday)...The weakening storm system
that has been slowly moving across the forecast area over the past
several days has moved east into Colorado this morning. Behind it,
a broad low is dropping south into California, currently putting
Utah and southwest Wyoming under shortwave ridging. As a result,
overnight coverage of showers and thunderstorms is limited to far
northwest Utah, where a boundary associated with the California
low is in place. This boundary is expected to pivot south and east
today as the low continues south across California, and will act
as a focus for convection this afternoon into the early evening.
However, overall coverage of showers and thunderstorms over
northern portions of the forecast area should be a bit less than
the last few days. With drier air in place, southern Utah will
stay dry. Due to the ridging, maxes will warm ever so slightly
today, running just above seasonal normals.

By Monday, the low will be over central California, shifting the
flow aloft to a more southerly direction and allowing a drier
airmass to advect northward for Memorial Day. The main impact of
this will be to allow coverage of convection to decrease further
and limiting the threat to far northern Utah and parts of
southwest Wyoming. In this drier airmass, maxes for northern Utah
will again warm slightly with temperatures remaining similar to
today over southern Utah.

.LONG TERM (After 12Z Tuesday)...Long term period begins with
shortwave ridging over the area. There will also be a closed low off
of the California coast. These features will limit the coverage of
afternoon showers and thunderstorms for Tuesday and into Wednesday
as the main stream of energy is in southern Idaho. The areas of the
CWA that will see the best chance at showers and thunderstorms would
be northern Utah and southwest Wyoming for both of these days. There
is some uncertainty in the speed and progression of the low as it
moves inland towards the Great Basin area. However, the low is most
likely going to weaken as it moves into the Great Basin area. This
will increase precipitation chances across the CWA on Thursday for
the remainder of the week.

Heading into Friday, another low moves into the Great Basin area and
merges with the weakening low. PWAT values will increase, 0.5" to
0.9", from Thursday through the rest of the period. This increase in
PWATs and the dynamics of the lows and daytime heating will increase
shower and thunderstorm activity across the CWA for Thursday and
Friday. The weekend appears to remain active as broad troughing
comes over the area. This would maintain the daily shower and
thunderstorm chance. Outside of the long term, deterministic models
show another closed low moving into the area early next week.

Temperatures for the period will stay pretty consistent. The main
difference is that prior to the lows impacting the area, highs will
be near normal to up to 7 degrees above normal with northern Utah
having the highest above normal temperatures. After the lows move in,
high temperatures will be near normal for the remainder of the week.


.AVIATION...KSLC...Light southeasterly drainage winds expected to
shift to northwest winds between 17Z and 19Z. There is a 30% chance
that scattered showers and thunderstorms could impact the terminal
between 10Z and 17Z. The better chance at seeing shower and
thunderstorm activity is when afternoon convection is expected to
begin, between 18Z and 20Z. Precipitation chances expected to
diminish by 05Z. These showers and thunderstorms could produce gusty
and erratic outflow winds, heavy rainfall, and frequent lightning.

.REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers with the
potential for some lightning will be possible across northern Utah
and southwest Wyoming through 17Z. Between 18Z and 20Z is when
afternoon convection is expected to begin. This coverage will be
more widespread than this morning`s coverage. Storms are expected to
diminish between 04Z and 06Z. These showers and thunderstorms could
produce gusty and erratic outflow winds, heavy rainfall, and
frequent lightning. Light and variable winds overnight will lead to
diurnal winds across northern Utah and southwesterly winds for
southern Utah.


.FIRE WEATHER...As one weather disturbance exits the area today a
second low will slide south along the California coast. The
resultant southerly flow will bring drier air over northern Utah
farther north. However, the threat of afternoon and evening
showers and thunderstorms will continue over northern Utah through
midweek. As the California low continues east, a more moist
airmass will push across the entire area for the middle to latter
park of the week, increasing coverage of showers and
thunderstorms. Temperatures will stay near seasonal normals over
the next several days.





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