Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 251602
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1002 AM MDT WED MAY 25 2016

.SYNOPSIS...The elongated upper level trough over the Great Basin
will shift slowly across the state through Thursday. Unsettled
conditions associated with this trough will persist through the end
of the week.

&&

.DISCUSSION...Two closed lows to note in morning water vapor and
H5 analysis. Both combine to maintain a broad long wave trough
across the western conus. The northern low continues to spin near
stationary along the Montana/Canada border, and the southern is
currently spinning over SoCal. Between these a weak short wave is
descending south across eastern Oregon. Interaction of all these
features has maintained a weak deformation zone across northern
Utah/southern Idaho. Scattered showers exist within this
deformation this morning as subtle forcing and convergent mid
level flow are both present.

Bufkit profiles and SPC SREF indicate a high probability of
realizing 500 J/KG MUCAPE this afternoon from roughly KSLC north.
12z KSLC RAOB supports this using a forecast parcel method. As
the aforementioned deformation slowly sags south coincident with
eastward translation of the SoCal low, forcing on the
destabilizing airmass will aid to spark numerous showers and
scattered storms this afternoon across the far north/northwest,
and scattered coverage as far south as Utah valley. The south is
expected to remain largely dry through much of the day beneath
subtle low amplitude ridging downstream of the SoCal low.

Updated earlier to increase PoPs across the north,
expanded/increased cloud cover across the north, and made minor
tweaks to winds.

The SoCal low will work into northern Arizona this
evening/overnight increasing convergent mid level flow along the
northeastern periphery from roughly I-70 south. Increasing clouds
and isolated showers (with snow over 9kft) are expected to
develop largely over the terrain as early as this evening,
continuing overnight. Additionally, the current deformation will
become more pronounced along the northwestern periphery of the low
tomorrow, with light northerly flow spreading into northern Utah
in wake (as the upper trough axis shifts east). Said forcing
along with diurnal destabilization will increase scattered
shower/storm coverage for most all areas tomorrow afternoon
(outside of far south/southeast low-lands). Current forecast
handles this well.

PREVIOUS DISCUSSION...A weak shortwave ridge is expected to develop
into the area tomorrow night into Friday morning while the next
storm system strengthens over the PacNW states. The northwesterly
flow will continue during this time and start to spread a drier
airmass into the area. However, this next storm system will
amplify and graze northern Utah late Friday into Saturday so a few
showers will continue to linger.

The bulk of the upper level trough will remain north of the
forecast area Saturday afternoon, but low level moisture and cold
advection should help increase shower and thunderstorm activity,
primarily across the northern 2/3 of the CWA. Somewhat increased
convection will likely continue into Sunday and Monday as well,
with weak forcing coming from both fringes of the northern trough,
as well as a secondary wave meandering across the Desert
Southwest. Have made relatively few forecast changes through this
time, though have increased temperatures a bit, as the northern
branch cold front isn`t quite as strong as previously indicated.

For those looking for warmer and drier weather, it currently looks
like you will get your wish starting Tuesday, and continuing through
much of the work week! Models are in good agreement about building a
ridge over the Great Basin starting Tuesday, with a significantly
warmer and drier airmass over Utah. Have indicated this warmer and
drier weather in the initial day 7 forecast for Wednesday, with
multiple days likely on tap of 80s along the Wasatch Front and 90s
in Dixie.

&&

.AVIATION...Winds at the SLC terminal will be light northerly or
light and variable through about 19z then prevail out of the
northwest. Scattered showers and thunderstorms will form across
northern Utah again today, and once again winds at the SLC terminal
could become erratic near these passing showers. VFR will prevail
but cigs could occasionally dip below 7000 ft in the passing
showers.

&&

.SLC Watches/Warnings/Advisories...
UT...None.
WY...None.
&&

$$

DISCUSSION...Merrill/Wilensky
PREVIOUS DISCUSSION...Cheng/Schoening

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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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