Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 161008

Area Forecast Discussion
National Weather Service Salt Lake City UT
408 AM MDT Sun Oct 16 2016

.SYNOPSIS...A series of fast-moving Pacific storm systems will
impact mainly northern Utah and southwest Wyoming through the
first half of the upcoming week. High pressure will return for the
latter half of the week.


Water vapor loop shows a broad cold closed low off the Pacific
Northwest coast, with a strong wave pivoting into the Northern
Rockies. MDCARS wind observations show a 125-165kt cyclonic jet
over northern California/Oregon into the northern Rockies.
GOES/HRRR/00Z KSLC RAOB indicate the precipitable water value
ranges from 0.25"-0.35" central and southern mountains to
0.50"-0.75" western valleys. Blended precipitable water product
shows an atmospheric river from the central Pacific into
central California.

Have issued a wind advisory for most areas south of Salt Lake
excluding Castle country, Dixie and Lake Powell areas. Have been
seeing areas of strong winds especially where favored by
channeling or downslope southerly flow. As the day progresses
these gusty winds should become more widespread but likely at a
lesser magnitude due to mixing. Same cycle repeats tonight ahead
of the cold front, where winds will mingle with warning criteria
in prone areas once again.

Its been gusty Salt Lake and northward as well overnight, but
thats about to end. RAP 850-700mb thickness/saturated equivalent
potential temperature/streamlines indicate the next cool front
currently across northwest Utah will sag south of Interstate 80
this morning before stalling. This will end the threat of
southerly gusts for the north.

A powerful Pacific jet will nose into the Eastern Great Basin from
the west this morning, supporting the continued development of
precipitation along the Idaho border as expected. Precipitation
will become widespread and heavy at times north of Ogden through
tonight. Snow levels along the Idaho border should dip to below
8kft today. From Salt Lake southward little to no precipitation is
expected until the next stronger cold front arrives from the west
late tonight.

A colder piece of the storm will send a cold front through from
the west on early tomorrow, crossing all except southern Utah by
tomorrow evening. Precipitation will turn from widespread and
heavy along the Idaho border before sunrise tomorrow to a fairly
extensive quick shot of precipitation across northern and portions
of central Utah in the morning before turning showery. Snow
levels will be lower with this piece of the system, closer to

Showers end tomorrow evening, with a quiet period expected
tomorrow night ahead of the last wave on Tuesday.

The final shortwave to move through the Great Basin looks on
track to move across mainly northern Utah Tuesday as the 500 and
700 mb cold advection develops. The operational EC and EC ensemble
mean are nearly identical in the 500 mb heights across the Great
Basin at 12Z Tuesday which is also close to the GFS so timing and
strength look reasonable between models. The EC is more generous
with the QPF from SLC northward and have leaned in this direction
as the dynamics of the jet and the 500 mb thermal cooling look
supportive of generating reasonable vertical lift. Have lowered
temperature across northern areas of the CWA on Tuesday as -5
degrees C at 700mb supports only a high of 54 at SLC. Undercut
this temperature by a degree but if precip occurs through the
afternoon then upper 40s is not out of the question for the
Wasatch Front from SLC northward. Snow levels will lower to near
6000 ft Tuesday afternoon and evening but any accumulations will
likely remain above 7000 ft.

In the wake of this system a strong surface high will build across
the region with gusty winds expected across southern portions of the
CWA developing Tuesday night through Wednesday. Temperatures will be
cooler across southern Utah as well on Wednesday.

The ridge will remain in place through the end of the week with
moderating temperatures and plenty of sunshine each day.
Temperatures are expected to be close to or above normal levels by
this weekend.


Strong southerly winds will prevail at the SLC terminal through
about 14Z this morning then shift to the west northwest and
decrease. Precip associated with this boundary should remain north
of the terminal but cigs could lower to below BKN070 briefly
between 15Z and 19Z. This boundary will remain south of the
terminal through this evening but then move back north with gusty
south winds developing again.


ERC values yesterday were below the 50th percentile across Utah,
with the exception of a few stations across west central Utah and
in the Uinta mountains.

The combination of strong transport winds and good mixing will
lead to excellent clearing through the early portion of the week.

The stronger piece of the broad Pacific storm moves into northern
Utah today lasting into tomorrow. This one looks much wetter for
the North, continued breezy, and also a bit colder with snow
levels falling below 8kft tomorrow. Excellent coverage of wetting
rain is expected from I-80 northward, and some locations as far
south as central Utah.

It will remain cool and unsettled during the middle of the week,
turning warmer and drier late week.


UT...Wind Advisory until 9 AM MDT Monday for UTZ004-008-010-013>016-




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