042
FXUS65 KGJT 052055
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
255 PM MDT Wed Jun 5 2024

.KEY MESSAGES...

- High pressure begins building in today bringing mostly clear
  skies and warm temperatures to the region.

- Some of the hottest temperatures are expected late week with
  highs running 10-15 degrees above normal and triple digits
  likely for the lower desert valleys.

- Chances of mountain showers and storms will return for the
  weekend into early next week.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 122 PM MDT Wed Jun 5 2024

Plenty of sunny skies out there this afternoon with a few clouds
noted over the northern valleys. This is in response to high
pressure building in. Plenty of subsidence across the area will
preclude any convection from firing this afternoon and evening. As
the high pressure builds in, a cutoff low will spin off the
Baja Peninsula and won`t get moving until Saturday. This will
also be the start of the warmup which will top out on Friday.
Until then, high temps will remain about 10 degrees above
seasonal values today and close to 15 degrees above on
Thursday. As far as tomorrow is concerned, similar conditions
expected though some Cu buildup is possible over the higher
terrain. Outside of that, not much else to report.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 122 PM MDT Wed Jun 5 2024

Hardly any change noted in models with regards to the expected heat
and convection from the end of the week onwards High pressure will
remain overhead while the closed, cutoff low continues to spin off
the Baja Peninsula. Southwest through westerly flow will keep
pumping in warmer air from the south which will cause near record,
if not record highs for portions of the CWA. As previously
mentioned, the record at the Grand Junction airport is 100F for
Friday which is what the current forecast is calling for. In fact,
the NBM has not deviated from this 100F for Friday over the past few
days so confidence is high we`ll reach this value. You folks in
central and southeastern Utah will likely see temps between 100 to
105F, slightly cooler in those higher elevations. Would expect some
records to be tied or broken there as well. As previously mentioned,
if you have to be outside for any great length of time, make sure to
drink lots of water and wear light colored and loose fitting
clothes. The shade is your friend.

Outside of the heat, the location of the high and low will allow
some moisture to get entrained in the mean flow and move into our
area. Moisture is progged to start increasing during the day Friday
with PWAT values reaching around 0.7 inches across the forecast
area. Weak perturbations will move around the high and will tap into
instability aloft allowing some convection to fire. Coverage has
increased from 24 hours ago but with PoPs in the 10 to 30% range,
the probabilities still remain low. That being said, any convection
that fires, whether it`s showers or storms, will produce some gusty
outflow winds. Some drier air looks to move in Saturday which will
limit convection for central and SE UT and SW CO with the northern
valleys and mountains along the Continental Divide being favored.

On Sunday, the previously closed low off the Baja Coast will have
become an open wave and get in phase with an approaching
trough/surface cold front from the west. Moisture also looks to
rebound with PWATs reaching near 0.8 inches by Sunday afternoon.
This increased moisture and the two features will allow another
round of convection to fire and on Sunday, the upper level trough
will move through and become the focus for the next round of
convection. The two most active days will be Sunday and Monday with
the NBM giving the nod to Monday as having the most coverage and
activity. Will be interesting to see what happens to Sunday and
Monday with this convection once the short-range models get
involved.

High temps will run hot Friday, drop a few degrees Saturday, and
then several degrees Sunday and Monday thanks to frontal passage,
increased cloud cover and precip. It`s not summer yet though it
kinda feels that way.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1121 AM MDT Wed Jun 5 2024

High pressure continues to build in and will keep VFR in place
for the next 24 hours. Occasional gusts around 20 mph are
possible this afternoon.

&&

.HYDROLOGY...
Issued at 229 PM MDT Tue Jun 4 2024

High pressure building overhead through the end of the week
will result in an unseasonably warm period across the Western
Slope. Simultaneously, as those temperatures rise, so will the
rate of snowmelt across our high terrain. Even though low to mid
elevations have already melted out, there`s still an abnormally
high amount of snow left over basins generally at and above
11,000 ft. As a result, we`ll see creeks, streams and major
tributaries along the Upper Colorado River Basin rise. Seasonal
peak flows are expected over the next 10 days, with the Upper
Gunnison, Upper Yampa and Colorado Headwaters basins potentially
peaking this weekend. Current guidance oscillates diurnal peaks
cresting the Action Stage for portions of Gore Creek and Eagle
River in Eagle County. No highlights needed, yet, for that area
after discussion with local officials but we will keep an eye on
things over the coming days.

The Elk River near Milner in Routt County, on the other hand,
is expected to exceed Action Stage each morning from Friday
through Sunday so did issue a Flood Advisory to account for
this possibility. Also, the East River near Almont is forecast
to reach Action Stage each morning from Friday through Sunday so
a Flood Advisory may also be required in that area as well.
Stay tuned.

As scorching temperatures lure folks to the water, please
remember the potential hazards associated with high flows during
the snowmelt season. Fast flows are not just dangerous for
those choosing to float the rivers. In addition, high diurnal
swings may drastically change the depth and flow for normally
small creeks and streams. Swift currents and cold water
temperatures can catch you off guard, so please be vigilant with
current conditions and look for forecast updates when
recreating or working near the water`s edge.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...TGR
LONG TERM...TGR
AVIATION...TGR
HYDROLOGY...TGJT