249
FXUS65 KGJT 121128
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
528 AM MDT Wed Jun 12 2024

.KEY MESSAGES...

- Hot and dry conditions develop today and Thursday, with area
  temperatures 10-15 degrees above climatological averages.

- A few showers and thunderstorms will develop on terrain this
  afternoon, capable of producing gusty outflows of 40-50 mph.

- Another storm approaches the region Thursday night and will
  lead to widespread showers and a few thunderstorms.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 314 AM MDT Wed Jun 12 2024

Mid level water vapor satellite imagery, as well as the Grand
Junction evening sounding show a shot of moisture working across the
Great Basin and into the central portion of the CWA this morning. A
few raindrops were observed here at the office, but mostly just mid
clouds are popping on terrain features from Moab to Aspen. The low
spinning off the SOCAL coast will continue to drive height rises up
over the Four Corners, thus amplifying the ridge of high pressure
overhead this afternoon. This will turn up the heat across the CWA
with temperatures in the triple digits in our deserts and low
valleys both today and Thursday. Elsewhere, temperatures are
expected to remain 10-15 degrees above climatology today and
tomorrow. Any moisture left overhead this morning will get pushed
northward along the top of the ridge. There does appear to be enough
fuel for some terrain based showers, favoring locales northward of I-
70 this afternoon. Isolated showers can`t be ruled out farther south
along the Divide, but subsidence under the ridge and drier air will
prove challenging for convection. While a few of these storms will
take some of the edge off afternoon highs, the main concern will be
gusty outflows and lightning. Shower activity will taper this
evening and quiet conditions will return overnight under the ridge
with overnight lows in the 50`s and 60`s across the region. Thursday
will be a rinse and repeat of Wednesday. The ridge axis will shift
east slightly, and temperatures will respond to a few more clouds
and winds picking up ahead of the incoming low. Nonetheless, it will
still be hot and dry Thursday afternoon.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 314 AM MDT Wed Jun 12 2024

The closed low that has been spinning off the California coast
finally gets moving Thursday night and will weaken as it does so.
Said low will track across northern Arizona overnight into Friday
morning and will also bring an increase in moisture across our
region. Forecast PWATs will be around 0.4 inches Thursday morning
but reach near 0.8 inches for portions of the CWA by Friday morning.
For this reason, models are picking up on some light precip to
overspread eastern UT and extreme western CO for the early morning
hours on Friday. As the low continues to weaken and become more of
an open wave, precip is expected to expand across the area and by
noon reach the I-70 corridor and areas south with the San Juans
being favored for the most precip (about 0.25 inches). Might see
some thunderstorms along with the showery precip but plenty of cloud
cover and cooler temperatures will likely keep storms to a minimum.
The main push of precip will shift to the Front Range Friday
afternoon and evening but residual instability will be worked on by
a mid to upper level trough as it moves overhead. Some spotty
showers will continue as this occurs but QPF amounts are lackluster
with 0.1 inches or less with this second push of precip. More good
news along with the precip will be daytime highs dropping anywhere
from 10 to 15 degrees on Friday as opposed to what we saw on
Thursday. A welcome reprieve after the last few days.

Saturday onwards, flow becomes southwesterly thanks to a low
pressure system moving into the Pacific NW. Supporting this low will
be an upper level jet that will approach our area through the
weekend. The core of highest winds in the jet may just clip our CWA
Monday. The reason this is important is because with limited cloud
cover (over the higher terrain...par for the course), deeper mixing
will allow some of these winds to reach the surface. In fact, we`ll
start seeing some gusty winds Saturday for the northern valleys of
around 20 to 30 mph. By Sunday, these winds will increase to 25 to
35 for the entire CWA and again on Monday...maybe a bit higher.
Along with these winds, RH values will drop to single digits/low
teens and with some fuels deemed critical (for some fire weather
zones), Red Flag Warnings may be needed. Of course, we`re a ways out
so this may change. Outside of the winds, dry conditions remain in
place as highs start to warm up reaching about 10 degrees above more
seasonal values for mid-June by Tuesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 523 AM MDT Wed Jun 12 2024

VFR conditions will prevail at terminals today under a ridge of
high pressure. A few clouds will sneak under the ridge today and
lead to some scattered mid and upper clouds. A few showers are
expected to form on terrain, favoring areas north of I-70. Along
with showers will come the potential for a couple of 40-50 mph
outflow gusts. Winds will prevail from the west, with a few
gusts this afternoon, then settle at sunset back to terrain
driven nocturnal winds.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...LTB
LONG TERM...TGR
AVIATION...TGJT