670
FXUS65 KGJT 042355
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
555 PM MDT Fri Sep 4 2026

.KEY MESSAGES...

- Isolated afternoon showers and storms possible through
  Saturday.

- Precipitation chances increase throughout the holiday weekend,
  with peak coverage expected Sunday and Monday. Flash flooding
  will be the primary threat with periods of heavy rain
  possible.

&&

.DISCUSSION...
Issued at 1115 AM MDT Fri Sep 4 2026

ISOLATED SHOWERS AND STORMS FRIDAY AND SATURDAY:

A weak jet accompanied by some modest moisture will nose into
the Four Corners region tonight. Some of the hi-res models
support the development of showers along the moisture transport
gradient, especially in southern foothills of the San Juans.
This moisture remains in place for much of Friday and Saturday,
especially along the Divide. As a result, afternoon convection
favoring the higher terrain will return to the forecast, but
most locales will remain dry with seasonable temperatures and
breezy afternoon winds.

MONSOONAL MOISTURE SURGES SUNDAY AND MONDAY:

A strong low pressure over the Pacific Northwest will advect a
plume of anamolous moisture on Sunday and Monday. This could
result in scattered to widespread convection across the region.
PWATs upwards of 200% of normal will support the potential for
heavy rainfall and flash flooding, especially around recent burn
scars and areas with steep terrain. This threat is particularly
heightened where soils have reached peak saturation after
multiple rounds of storms this past week. Models are beginning
to show that the peak moisture might be overnight Sunday. Also,
attm on Sunday afternoon there is not much instability or it may
be limited to a certain area. This will play a role in the
coverage and intensity of showers and storms.

Beyond Monday the low pressure moves across the northern US
causing high pressure to build over the region. The uncertainty
is if we stay in the moist southwest flow. There is also signs
of an active Pacific Northwest, which may too play a role in
precipitation chances.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 544 PM MDT Fri Sep 4 2026

VFR conditions are forecast through the TAF period. A slight
chance (10-15%) for showers and storms exist for the higher
terrain areas for the next couple of hours. Wind speeds will
begin to subside this evening before strengthening again
tomorrow afternoon with periodic gusts up to 25 knots.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

DISCUSSION...TGJT
AVIATION...TGJT