290
FXUS65 KSLC 202149
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
349 PM MDT Thu Jun 20 2024

.SYNOPSIS...Deep moisture will spread into eastern Utah through
Friday, bringing the threat of showers and thunderstorms capable
of producing heavy rain. Drier conditions are expected over the
weekend and into early next week with increasingly hot
temperatures, though enough low level moisture is expected to
linger across southern Utah to support isolated showers and
thunderstorms through early next week.

&&

.SHORT TERM (Through 12Z/6AM Saturday)...Moisture is on the
increase this afternoon over eastern Utah with satellite derived
PWs predominately in the 0.7 to 0.8 inch range. Showers and
thunderstorms have sprouted over southeast Utah, but so far heave
primarily stayed east of the CWA. Any storms that develop through
the early evening will have the potential to produce gusty
microburst winds given the high based nature of the moisture.
Elsewhere across the area, seeing generally dry conditions with
maxes in excess of 5F warmer than values observed yesterday, about
5F above seasonal normals.

Moisture will continue to spread into eastern Utah through Friday
morning, with values topping out in the 1.0 to 1.2 inch range over
eastern Utah, in excess of the 90th percentile for moisture this
time of year. Convective development will be aided by shortwave
energy from a weakening trough moving across the area, also
providing good jet support and notable shear. Thus, a greater than
usual potential persists for storms that will produce heavy rain
capable of flash flooding, and a Flash Flood Watch remains in
effect tomorrow afternoon and into the early evening for much of
eastern Utah. Some concern of developing cloud cover limiting
convective development, as sometimes happens with an airmass this
moist. However, if such clouds fail to develop or erode, storms
will become fairly widespread and could result in dangerous
conditions for outdoor activities in eastern Utah.

.LONG TERM (After 12Z/6AM Saturday), Issued 416 AM MDT...Saturday
looks to have at least some potential to be another interesting
day across portions of the area. Similar to Friday`s setup,
forecast region will be positioned on the NW periphery of a strong
ridge extending throughout the southern Plains, though the
northern stream trough influence will be lessened as it exits.
Still, southern and eastern Utah in particular will see continued
favored moisture content with elevated PWAT values (around
125-200% of normal) in addition to enhanced upper level jet flow
overhead. While less than that of Friday, this jet flow should
still yield marginal deep layer shear around 20-30 kts or so.
Provided any lingering cloud debris from Friday has cleared,
modest destabilization (MUCAPE ~250-750 J/kg) should also occur.
Given the departure of the northern stream trough, a little less
trigger mechanism is noted, but combination of terrain and weak
PVA should yield some scattered convective development by the
afternoon, albeit likely with lesser of an areal extent. Given the
aforementioned ingredients, the ECMWF Extreme Forecast Index
(EFI) continues to also highlight southern to eastern Utah in
shading depicting anomalous CAPE-Shear values, further supporting
at least some potential for more mature and strong convection.
Additionally, given the moisture profile, any mature convection
should be able to efficiently produce rainfall, so those
recreating in rain sensitive areas (slickrock areas, slot canyons,
dry washes, etc.) should remain weather aware. Elsewhere, dry
conditions are expected, with increasingly hot weather as H7 temps
continue upwards.

Sunday onward into midweek, anomalous moisture lingers especially
across southern and eastern Utah leading to continued daily chances
of isolated to scattered convection, and the nearby strong ridge
continues to yield very warm temperatures. By Sunday, northern Utah
warms sufficiently that the urban corridor in particular will see
heat approaching potentially dangerous levels (upper 90s to low 100s
across much of Wasatch Front). Opting to hold off at least one more
set of guidance given it is still a few days out, but it appears
increasingly likely some sort of heat related headlines may be
needed for a portion of the region. The following several days show
similar levels of heat to maybe ever so slightly cooler, though
spread in guidance also increases a bit. For the southern half of
Utah, conditions will gradually warm day to day moving into the
middle of the week, with increasing potential for heat related risk
accordingly. By Wednesday, current suite of guidance shows
widespread upper 90s on into the 100s, with current NBM giving ~25%
chance to hit or exceed 110 at KSGU. Given the prior mentioned
lingering moisture and limited daily convective potential, these
high marks will have some potential to be modulated by whatever does
manage to develop. In any case, suffice to say the heat is very much
back as we move into astronomical summer.

Looking Thursday onward a little beyond the coverage of this
forecast package, guidance shows increasing consensus on a trough
deepening southward from the PacNW. Less consensus is noted on the
eventual evolution including how quickly it advances inland and how
deep it remains when it does. While some guidance shows any trough
influence could come as early as Thursday, ensemble membership
increases by Friday, with only a limited number of members showing
little to no influence. Still, this looks to be the next window to
see the heat abated a bit, at least across the northern half of the
forecast region or so.

&&

.AVIATION...KSLC...Northwest winds will transition to southeast
around 05Z. Mostly clear conditions or scattered clouds will prevail
overnight. South winds will increase around 15Z, with gusts around
20 knots through around 19Z. A transition to northwest winds is
likely around 20Z. Mostly cloudy conditions are likely, with around
a 20% chance for a shower or thunderstorm from 18-03Z.

.REST OF UTAH AND SOUTHWEST WYOMING...Mostly cloudy to overcast
conditions will build into eastern Utah, with isolated to scattered
showers capable of gusty, erratic outflow winds after 12Z. Showers
and thunderstorms capable of heavy rain are likely from around 18-
03Z. Almost all showers and thunderstorms will be in the eastern
half of Utah. Southwest winds will gust around 25 knots throughout
southwest Wyoming and southern Utah from around 15-03Z.

&&

.FIRE WEATHER...Moisture is starting to increase over southeastern
Utah this afternoon, resulting in some development of showers and
thunderstorms. The moisture will peak Friday, with values quite
unseasonably high. An approaching trough will provide additional
instability, so showers and storms will be fairly widespread over
eastern Utah by Friday afternoon. Any storms that develop will be
capable of producing heavy rainfall along with gusty and erratic
winds. The trough will move east of the area on Saturday, allowing
high pressure to rebuild. This will bring a drying trend, but a
few showers will remain possible over the weekend over the higher
terrain of southern Utah. With the ridge building over the
weekend, temperatures will steadily warm, particularly over
northern Utah.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch from Friday afternoon through Friday evening for
     UTZ113-120-121-128>131.

WY...None.
&&

$$

SHORT TERM/FIRE WEATHER...Traphagan
LONG TERM...Warthen
AVIATION...Wilson

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