500
FXUS65 KSLC 042148
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
348 PM MDT Tue Jun 4 2024

.SYNOPSIS...An early season heat event begins to spread over the
region starting tomorrow, with peak temperatures anticipated to
arrive by Thursday and Friday. On the hottest days, high
temperatures will challenge daily records in quite a few
locations. Heading into the weekend, there is potential for active
convective weather to return, alongside a curbed warming trend.

&&

.SHORT TERM (Through 12Z/6AM Thursday)...A ridge of high pressure
begins settling into the eastern Great Basin region this evening,
with rapidly warming temperatures anticipated from Wednesday
through Friday. Afternoon satellite analysis already indicates
this area of high pressure as mostly clear skies span from
California through western Colorado and from southern Idaho
through southern Arizona. Locally, have seen minimal increases in
temperatures as a cooler, post-frontal airmass has lingered over
the northern half of the forecast area. That said, we have already
begun to see the influence of broad scale subsidence as skies
started out mostly cloudy across the eastern half of the area and
have since cleared out.

Tomorrow will feature a stout increase in 700mb temperatures, increasing
from about +3C on Tuesday morning potentially up to +11C by
Wednesday afternoon. Rapidly increasing lower level temperatures
and afternoon mixing will help to increase surface temperatures by
around 5-10F as compared to Tuesday. The most significant
increases in afternoon temperatures will be noted across the
northern half of the forecast area where the cooler airmass has
lingered. Across the southern half of the area, still expecting
increases of about 5-7F, which should push areas in lower
Washington County into the low-to-mid 100 degree range. Along the
Wasatch Front, Cache Valley, and southwest Wyoming, temperatures
will rise into the upper-80s, mid-80s, and upper-70s
respectively. Further warming of daytime high temperatures is
expected as we head into Thursday as the parent ridge axis begins
translating overhead. Have expanded an Excessive Heat Warning into
Zion National Park this afternoon, as well as added Heat
Advisories for the Grand Staircase, Capitol Reef National Park,
and a couple of Utah`s eastern valleys in anticipation of this
high confidence early season heat wave.


.LONG TERM (After 12Z/6AM Thursday), Issued 329 AM MDT...
Unseasonably warm conditions are forecast throughout southwest
Wyoming and Utah later in the week, with Thursday and Friday
likely the warmest. A strong ridge will expand throughout the west
late in the week into the weekend, with high pressure positioned
near the Four Corners. The ridge axis will be over Utah Thursday
and extend into Canada. Valley high temperatures will be in the
upper 80s or low 90s near the Idaho border, mid 90s for the urban
corridor, and mid to upper 90s for central valleys. Temperatures
will get into 100s around Lake Powell. As usual, lower Washington
County will be the warmest, with highs around 110F. As the ridge
axis slides slightly downstream, that will allow for shortwave
energy within anticyclonic flow for some clouds Thursday into
Friday. The extremely warm, sunny day will be followed by a warm
night, with clouds keeping temperatures warmer than if it were
clear. Friday morning lows will be in the 60s for many valleys,
but could stay in the 70s for the Salt Lake Valley. Lows will only
drop to the mid 70s around Lake Powell and lower Washington
County. An Excessive Heat Warning is in effect Thursday around
Lake Powell and for lower Washington County.

Synoptic conditions will be largely similar Friday, with the biggest
difference of more clouds. Weak shortwave energy will push in from
the west to southwest. There will be isolated showers and
thunderstorms around terrain, but that will likely have minimal
effects on valley temperatures. Forecast highs are nearly identical
to Thursday, with some places likely to be slightly cooler and
others slightly warmer, largely depending on clouds. The Excessive
Heat Warning for portions of southern Utah lasts through the day.

There is good model agreement through the weekend and into the week
on much warmer than normal temperatures. The ridge will likely stay
in place, but not be as strong, as more shortwaves push in from the
west. Isolated to scattered showers and thunderstorms will primarily
be around terrain, as forcing will be limited with little moisture
and wind shear. Gusty, erratic outflow winds would be expected near
showers and thunderstorms.

&&

.AVIATION...KSLC...No significant weather with VFR conditions and
clear to mostly clear skies expected to persist. Wind directions
largely diurnally normal, with S winds developing ~02-04Z Wednesday,
and once again becoming NW ~16-18Z thereafter. While an occasional
gust or two is possible, wind magnitudes generally anticipated to
remain below 15 kts or so.

.REST OF UTAH AND SOUTHWEST WYOMING...Conditions to remain VFR with
no significant weather anticipated at area terminals through the TAF
period. Skies remain clear to mostly clear, with wind directions at
most terminals largely following a diurnally normal pattern.

&&

.FIRE WEATHER...A significant early season heat-wave will bring record challenging
temperatures for Utah, particularly across the southern half of
the state. High pressure will intensify over Utah on Wednesday,
bringing lower mixing heights and weak transport winds. Winds are
expected to be light and out of a northwesterly direction on
exposed ridges and slopes while drainage areas and protected
slopes will favor diurnally driven upslope/ downslope flows. The
area of high pressure expands farther into Utah on Thursday with
the peak subsidence moving eastward, allowing for better mixing
heights. Though mixing heights will increase, transport winds are
expected to remain light. High temperatures will reach their peak
across the western half of Utah on Thursday and the eastern half
of Utah on Friday.

The center of the high pressure moves eastward by Friday, which
will allow for increasing southwest winds across the southern half
of Utah during the afternoon hours. Areas of elevated fire
weather conditions are expected as these hot, dry, and
increasingly breezy conditions spread over southern Utah. Moisture
increases on the northern periphery of the high pressure system
by Saturday in the mid-to-upper levels while there is an inherent
lack of moisture in the lower levels. Increased moisture with
strong heating may allow for elevated convective showers to
develop across portions of northern Utah over the weekend,
bringing the threat for at least isolated strong winds and
thunderstorms producing little to no rainfall.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Heat Advisory from 11 AM Thursday to midnight MDT Friday night
     for UTZ121-128>130.

     Excessive Heat Warning from 11 AM Thursday to midnight MDT
     Friday night for UTZ123-124-131.

WY...None.
&&

$$

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

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