073
FXUS65 KGJT 061113
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
513 AM MDT Thu Jun 6 2024

.KEY MESSAGES...

- The hottest temperatures of the season so far are expected
  today and tomorrow, with highs running 10-15 degrees above
  normal.

- Increasing moisture will bring a return of mountain showers
  and thunderstorms starting Friday, with expanding coverage
  through the weekend.

- Temperatures gradually cool back to near normal values by
  early next week.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 323 AM MDT Thu Jun 6 2024

The dome of high pressure centered over the Southwestern US remains
firmly in control today, with clear skies and above normal
temperatures being the rule. Areas along the Divide will likely see
their warmest temperatures of the season this afternoon, as
increasing moisture and cloud cover over the terrain tomorrow
afternoon will keeps temperatures down. For the lower elevations,
tomorrow still looks to be the peak of this period of unusual heat,
with triple digits and near record highs expected for the desert
valleys. Look for highs to run around 10 degrees above normal, with
near 15 degrees above normal favored for lower elevations tomorrow.
Overnight lows continue mild, also running around 10 degrees above
normal.

In the meantime, moisture across the region will be on the increase
over the next several days as counterclockwise flow around a cutoff
low lurking off the southern Baja peninsula combines will clockwise
flow around the high pressure dome to pull some subtropical moisture
northward. This afternoon, at best this will result in an increase
in clouds over the higher terrain. By tomorrow afternoon, enough
moisture will have advected into the Southwest to fuel some showers
and storms over the terrain. Diurnal heating will be the main source
of lift, although a weak trough riding around the high will also
provide some broad, weak dynamic lift as a modest boost. All this to
say, look for increasing storm coverage over the higher terrain
Friday afternoon and evening, most favoring the Colorado Divide. Dry
surface air will limit how much precipitation makes it to the
ground, keeping main threats as gusty outflow winds and
lightning.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 323 AM MDT Thu Jun 6 2024

The relocation of the SubTrop High from the Desert SW to the
Southern Plains will be complete by early Saturday. Easterly flow
around the southern periphery of this High will begin to transport
Gulf of Mexico moisture back toward our southern CWA...which gets
enhanced later in the day as a cold front dives along the lee of the
Rockies into New Mexico and the upslope flow drives it through the
gaps. Finally...a low pressure system will be drawn northward out of
the Baja region on Sunday into Monday tapping into another moisture
source with a Pacific origin. The bigger picture of this is PWAT is
pushed up to near and above 3/4 of an inch for the weekend into
early next week...which for early June is in the region of the 90th
percentile. The moisture will help fire daily afternoon
thunderstorms while also easing the temperatures back a bit each day
back to just a single digits above normal instead of 10 to 15
degrees. With the higher then normal moisture in the profile there
will be a threat of some of the organized storms producing moderate
to maybe even heavy rainfall rates. However sounding profiles in the
lower to mid elevations suggest gusty outflow winds will likely be
more of a threat than wetting rainfall. Sunday afternoon looks to be
the peak of the convective activity as the Baja low rotates south of
the 4 Corners. As we get later into the week the SubTrop High looks
to try and re-establish itself over the Desert SW with greater
uncertainty on where the next cutoff low in the SoCal/Baja region
will reside. Moisture will begin to wane by Tuesday with afternoon
storms mainly becoming focused on the higher terrain. The decrease
in moisture and storms will allow the temperature trend to increase
with highs once again approaching the triple digits in the lower
desert valleys by midweek.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 512 AM MDT Thu Jun 6 2024

Clear skies and light, terrain driven winds will prevail today.
Afternoon clouds will develop over the higher terrain, but are
not expected to impact airport operations. Gusts up to 20 knots
will be possible during the afternoon. VFR conditions will
prevail for the next 24 hours.

&&

.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...and it`s melting...fast. As a result, creeks,
streams and major tributaries along the Upper Colorado River
Basin are on the rise. Seasonal peak flows are expected over
the next 10 days, with the Upper Gunnison, Upper Yampa and
Colorado Headwaters basins likely peaking for the season 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 Minor Flood Stage each morning through
Sunday. This increase in forecast stage/flow warranted an
upgrade from Flood Advisory to a Flood Warning. Also, the East
River near Almont is forecast to exceed Action Stage each
morning through Sunday, with the potential for exceeding Flood
Stage by Saturday. For now, a Flood Advisory is in effect for
this stretch of river. However, stay tuned for the potential
upgrade to a warning and/or extending the advisory downstream
into the Gunnison at Gunnison.

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...BGB
LONG TERM...15
AVIATION...TGJT
HYDROLOGY...ERW