107
FXUS65 KGJT 261132
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
532 AM MDT Thu Sep 26 2024

.KEY MESSAGES...

- Dry and unseasonably warm conditions are expected for the
  remainder of the week through next. Near-record highs are
  expected to continue today through the weekend.

- A weak disturbance brings potential for isolated afternoon
  storms over the eastern portions of the southern and central
  Divide mountains on Friday. Outside of Friday, dry conditions
  prevail.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 310 AM MDT Thu Sep 26 2024

High pressure will remain in control today with dry, southwest
flow as the ridge axis remains to our east. This will also lead
to another day of very warm, near record high temperatures,
which will be between 10 and 15 degrees above normal. Overnight
lows will continue to be cool with efficient radiational cooling
under clear skies, but for this time of year, lows will still be
around 5 to 10 degrees above normal. A shortwave trough will
move across the Intermountain West and Northern Rockies late
this afternoon and evening, resulting in occasionally breezy
winds across the north with some localized critical fire weather
conditions but overall, winds should remain light and terrain
driven for most areas. This disturbance disrupts the flow and
breaks down the ridge only temporarily, pushing the high back
westward as the shortwave pushes south down the Plains and Front
Range on Friday. We may see a little moisture sneak westward
over the Divide, allowing for isolated afternoon storms over the
far eastern Divide and eastern San Juans, but at the very least,
expect some cumulus buildups over the ridges during the
afternoons with mostly clear conditions in the lower valleys.
Given the hi-res CAMs are picking up on this activity with the
NBM still showing fairly dry conditions and minimal chances,
decided to blend in some of the HRRR and hi res WRF models to
better reflect these afternoon storm chances. The resilient
high pressure ridge builds back in over the area by Friday
evening, with a quick end to any convection by sunset.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 310 AM MDT Thu Sep 26 2024

Upper-level ridging remains the dominant synoptic forcing
through the weekend resulting in continued warm and dry
conditions. Predictability decreases heading into the new work
week with an upper-level trough tracking along the US/Canada
border, squishing the northern portion of the ridge. To the
southwest along the southern California coast there could also
be a low pressure disturbance, although the evolution of this
feature varies drastically between global models. We will have
to wait and see how these two storm systems evolve and
potentially interact with one another, but current trends
locally support additional warm, dry days through the first half
of the week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 532 AM MDT Thu Sep 26 2024

VFR conditions will prevail with mostly clear skies and dry
conditions over the next 24 hours. Some cumulus may develop over
the ridges during the afternoon. Winds will generally be
terrain driven with gusts to 20 kts at times.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...MDA
LONG TERM...KAA
AVIATION...TGJT