Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 231636
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1036 AM MDT Sat Jun 23 2018

.SYNOPSIS...An upper level low will graze extreme northern Utah
and southwest Wyoming late this afternoon through tonight. The
attendant cold front will bring somewhat cooler air to the
forecast area for Sunday. High pressure aloft will return to the
area to begin the work week.

&&

.DISCUSSION...Morning water vapor and H5 analysis place the core
of a mid level closed low over west central Montana with
translation trend SE towards Wyoming. H7 analysis trends indicate
tightening baroclinicity over eastern Idaho and extreme NW Wyoming
indicative a strengthening mid level front. Surface reflection
of this front attm remains negligible but is progged to become a
bit more organized over northern Utah through midday. Short term
guidance continues to depict an accelerating southerly surge of
the cold front this afternoon across northern portions of the area
as the core of the upper low shifts into western Wyoming, but
with this surge the boundary will become increasingly dissociated
from the upper dynamics allowing a largely dry passage into the
evening hours tonight. Will maintain slight chance PoPs across the
extreme NE portions of the forecast area this afternoon/evening
due to closer proximity to the mid level cold core, but vertical
profiles suggest limited instability will primarily drive mid
level CU formation and isolated at best convection (namely SW
Wyoming/Uintas).

Downstream translation of the upper low tonight will allow for a
rapid building of heights by Sunday as upper ridging begins to
translate overhead. Expecting the remnant front to pass much of
the area through that time, but it will be trending much more
diffuse again with time. Sensibly, the primary takeaway from all
this will be markedly cooler temps across the north Sunday, with
some cooling across the south as well.

No updates needed. Previous discussion below.

.PREVIOUS DISCUSSION...Flat ridging is taking place early
in the week and will remain through late week with very little day
to day changes in the forecast. Temperatures will remain near or
above seasonal normal through the week.

The next weather system and where models differ is late in the
week with the next trough (or not) to impact the forecast area.
While one model has this trough feature carving into the Great
Basin, another model keeps this feature up north and brushing by
on the northern fringe of the area. Temperatures will cool down by
late week into the weekend. Right now, little moisture is
associated with this weather system. However, given the time of
year and sufficient day time heating available, can not rule out
isolated thunderstorms as a possibility.


&&

.AVIATION...VFR conditions expected at the SLC terminal for today.
Surface winds are trending to the northwest currently and will
become increasingly gusty after 18/19z. There is a possibility of
the winds reaching AWW criteria between 20-03Z. Expect the winds
to become southeasterly overnight after 06Z.

&&

.FIRE WEATHER...A mostly dry cold front passing through will
strengthen the winds and maintain the low RH values especially
across the east and southern areas of Utah. Red Flag warnings will
continue until late tonight. Temperatures will cool before rapidly
warming to start the week under building high pressure. Isolated
showers and thunderstorms are possible late this evening across far
northern and northeast Utah.

Mostly dry conditions are expected to persist through the first half
of the week under building high pressure.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Red Flag Warning until 11 PM MDT this evening for UTZ493>498.

     Red Flag Warning until 11 PM MDT this evening for UTZ482-484-488-
     489.

WY...None.
&&

$$

DISCUSSION/AVIATION/FIRE WEATHER...Merrill/Bonnette/Conger
PREVIOUS DISCUSSION...Dewey

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


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