658
FXUS65 KGJT 072152
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
352 PM MDT Fri Jun 7 2024

.KEY MESSAGES...

- Warm summer-like conditions continue this weekend with
  temperatures trending 10 degrees above climatology.

- Afternoon showers and thunderstorms remain a threat on much of
  the terrain into next week. Gusty outflow winds will impact
  locales in the vicinity of shower activity.

- A generally warm and dry trend continues into next week under
  the influence of high pressure over the West.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 332 PM MDT Fri Jun 7 2024

While monsoon season has yet to begin, a look at the satellite and
lightning detection looks an awful lot like July/August today.
Temperatures are pretty close to the later summer values as well. A
slow drifting cutoff low over Baja is sending some weak moisture
across the Four Corners and the zonal pattern draped across the
Great Basin is providing additional moisture transport and some
dynamic forcing as well. This all adds up to scattered showers and
convection on much of the terrain across the CWA this afternoon. The
dry lower levels and high DCAPE values on this morning`s sounding
will ensure some strong outflow winds from many of these showers. A
well organized pocket of convection has been active on the Tavaputs
in eastern Utah today, as well as on the eastern shoulders of the
Uintas. These are forming along the weak shortwave rippling through
the northern half of the CWA, versus the wave lifting northward into
southeast Utah and southwest Colorado that is bringing much less
organized convection to the Four Corners and San Juans. Tonight the
shortwave energy pulls away to the east and showers and
thunderstorms will diminish in coverage after midnight. On Saturday
we remain in the lee of a ridge over the Great Basin sending another
pulse of shortwave energy through the northern CWA. Meanwhile, the
drifting low down to the south remains in the picture, sending some
weak moisture northward to southern Colorado Saturday. Another round
of afternoon convection will turn up Saturday across northwest
Colorado and along the western terrain of the Continental Divide.
Dry boundary layer conditions will continue Saturday leading to more
gusty winds under showers and storms, but little in terms of wetting
rain. Temperatures will remain well above climatology(10 degrees)
Saturday afternoon, with a few locales getting `some` relief from
clouds and showers. Showers will lose their steam late Saturday
evening and the influence of the broader high pressure over the
West will quiet things down into Sunday morning.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 332 PM MDT Fri Jun 7 2024

Low pressure lifting into the Desert Southwest, will start to
displace the ridge of high pressure away from the CWA on Sunday. In
addition, another wave rounding the apex of the ridge, will drive a
region of positive vorticity towards the northeast corner of the
CWA. Said upper level dynamics, in conjunction with precipitable
water (PWAT) values ranging from 150 to 200 percent of normal, will
support another round of afternoon showers and storms across the
Western Slope. The GB trough will support showers across northeast
Utah, while the southern low will favor measurable precipitation
over the San Juans.

As these two waves quickly loft northeast, another wave and lobe of
PVA are progged to dive across the northern sector of the CWA on
Monday. A cold front associated with this wave will have a stronger
temperature gradient to our north, though even areas across the Four
Corners will dip 3 to 5 degrees cooler than high readings on Sunday.
Despite this "cool air", high temperatures on Monday are still
running above climo norms for early June...and this is the coolest
day in our forecast...

As the wave departs to the east, so do our chance for PoPs. Yet,
another warming period returns for the remainder of the week with
mostly dry conditions in the forecast. Probabilistic guidance
reveals over an 80% chance for the next possible 100 degree day in
Moab returning Wednesday, with greater than a 50% chance for the
Grand Valley. The next chance for precipitation will have to wait
for the end of the long term. Cluster mean analyses are in fairly
good agreement lofting another trough inland, from the southwest, by
Day 7. This won`t be a cool system by any means, but at least has
potential to return precipitation to our high desert terrain.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1122 AM MDT Fri Jun 7 2024

Isolated thunderstorms blossomed early this morning. Confidence
on direct impacts to terminals due to isolated storm coverage
remains low, though gusty outflow winds are the more likely
threat. Storms will continue to roll across the CWA through this
afternoon with another wave skirting northwest Colorado counties
around midnight tonight. However, VFR conditions are expected to
prevail for the next 24 hours.

&&

.HYDROLOGY...
Issued at 332 PM MDT Fri Jun 7 2024

High elevation snow will continue to melt under these anomalously
warm spring conditions. Cloud cover from today`s showers and storms
could suppress the rate of snowmelt, however, additional precip
would have the opposite effect. Thus, some areas under today`s
passing clouds may see some temporary relief in runoff, while
localized basins will see a ramp up from measurable rain and/or rain
on snow. Due to these highly localized influences, confidence in how
major streams and rivers respond remains low.

Following current guidance and river trends, we`re expecting an
increase in flows along the Colorado Headwaters. More specifically,
Gore Creek, Eagle River and the Roaring Fork River Basin have all
shown an increasing trend over the last 24 hours. Current advisories
all remain in place through the weekend, and we`ll continue to
monitor for any expansions to highlights or for any chance these
could upgrade to a warning.

Flow/stage in the Elk River in Routt County have slowed down, coming
in just under Action Stage last night/this morning. Forecasts have
dropped below minor flood stage, however, I am hesitant to take down
the warning due to uncertainty in rain on snow potential and another
crest approach minor flood stage tonight/Saturday morning. Improving
conditions are anticipated following this weekend, as large diurnal
swings taper off next week.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...None.
UT...None.

&&

$$

SHORT TERM...LTB
LONG TERM...ERW
AVIATION...TGJT
HYDROLOGY...ERW