448
FXUS65 KSLC 201006
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
406 AM MDT Sat Jul 20 2024

.SYNOPSIS...High pressure will remain in place through much of the
upcoming week. Lingering moisture will allow for the development
of daily showers and thunderstorms over the higher terrain,
primarily focused over southern Utah. There are some indications
that convection could become more widespread by late in the
upcoming week.

&&

.SHORT TERM (Through 12Z Monday)...As it has been for the past
several days, high pressure remains in place over the region this
morning, with the axis currently near the Utah/Nevada border. This
position of the ridge axis is a bit different than the past few
days, and has put Utah and southwest Wyoming under a light north
to northwest flow aloft. The airmass over the area remains on the
warm side, with maxes expected to average around 5F above seasonal
normals. Moisture remains trapped under the ridge, with satellite
derived PWs in the 0.7 to 0.8 range over much of the area, with
values of up to 0.9 inch over southwest Utah, generally around the
75th percentile for this time of year.

In this pattern, anticipating another round of showers and
thunderstorms this afternoon, primarily focused over the higher
terrain, particularly over southern Utah. With the N/NW flow,
drift of showers and storms off the terrain will be to the south
and east. Thus, have kept southeast Utah in the probable range for
flash flooding, as storms will be slow moving and capable of
producing heavy rainfall.

For Sunday, a Pacific trough is expected to move northward over
the ridge into the Pacific Northwest. This is expected to adjust
the ridge so that the flow aloft over the area increases slightly
and becomes more straight northerly or a bit northeasterly. If
anything, this focuses the moisture a bit more over southern Utah,
decreasing the potential for convection over northern Utah Sunday
afternoon. Otherwise, the pattern will tend to remain as it has
been.

.LONG TERM (After 12Z Monday)...The extended forecast period
remains largely unchanged as compared to previous forecasts. The
pattern can be summarized as such; a ridge of high pressure will be
centered over the central Great Basin where anomalous atmospheric
moisture will be positioned. Utah and southwest Wyoming will sit on
the eastern periphery of this anomalous moisture, at least
initially, but will still see daily chances for showers and
thunderstorms through the week as broad mid-level moisture stays
trapped within the high. The area of high pressure shifts eastward
late in the week/ early in the weekend, bringing increasing areal
coverage of showers and thunderstorms and likely greater rain/ flood
potential as we tap into a deeper moisture profile.

Temperature-wise, day-to-day fluctuations in temperatures are
expected to be very minimal, but a slow warming trend is anticipated
through mid-week. By Wednesday, temperatures across the region will
be pushing about 5-7 degrees above average. Along the Wasatch Front
and lower Washington County, where significantly urbanized areas
exist, increased heat risk may exist as hot daytime temperatures are
followed by warm overnight lows, providing little relief from the
heat. That said, the anticipated duration of the heat is anticipated
to be fairly short-lived. Will need to pay closer attention to this
as we approach the beloved Utah holiday. After Wednesday, should
start to see a notable downward trend in temperatures as increasing
moisture will lead to greater afternoon cloud cover, and thus more
limited heating over the area.

As far as precipitation goes, being on the eastern periphery of the
high will allow at least some drier air to work into the northern
portions of the forecast area. As a result, areas north of roughly
Utah county and west of Uintah County will see little threat of
shower and thunderstorm activity. For areas south and east of these
generalized areas will continue to see diurnally driven showers and
thunderstorms. As has been the case with the past several days,
showers and thunderstorms are expected to form over the high terrain
features across the region, drifting off into adjacent valley areas
(mainly to the south and east of terrain). While deep atmospheric
moisture will not be fully realized until the latter half of the
week, slow moving storms will have the ability to produce brief
moderate to heavy rainfall, and could pose risk of flash flooding
over typical problem areas (slot canyons, burn scars, slickrock
areas, etc.). Anticipating this threat to begin increasing over a
greater areal extent as we move into Thursday through Saturday as
the deeper moisture arrives... providing opportunity for much more
efficient rain. It should be noted, however, that the moisture is
still not connected to monsoonal circulations... just run of the
mill anomalous moisture.

&&

.AVIATION...KSLC...VFR conditions are expected over the KSLC
terminal through the valid TAF period. Southerly drainage flow is
anticipated to remain in place through the late morning hours,
beginning a transition to a northerly flow around 17Z, with full
establishment of northerly winds anticipated by 18Z.

.REST OF UTAH AND SOUTHWEST WYOMING...Another day of showers and
thunderstorms is expected along the high terrain and adjacent valley
areas, mainly south of KPVU. Showers and thunderstorms will have
potential to produce gusty and erratic outflow winds in excess of
30kts, however, the predictability of these features is quite
difficult to time out and forecast. Outside of any outflow winds,
diurnally driven trends are expected in the wind fields today
alongside VFR conditions. Brief reduction in flight categories may
be possible in, and around, thunderstorms due to VIS restrictions
(BLDU, RA/+RA, etc.).

&&

.FIRE WEATHER...Little change in the weather pattern is anticipated
over the next several days, with high pressure remaining in place
over the region, keeping conditions on the hot side. Moisture
trapped under the ridge and instability from embedded shortwaves
will keep a threat of primarily afternoon and evening showers and
thunderstorms, with the greatest coverage anticipated over the
higher terrain of southern Utah. These storms will be
predominately wet in nature, with a decent chance of wetting
rains.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

SHORT TERM/FIRE WEATHER...Traphagan
LONG TERM/AVIATION...Webber

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity