611
FXUS65 KGJT 141114
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
514 AM MDT Sat Sep 14 2024

.KEY MESSAGES...

- Expect dry and warm temperatures again today before unsettled
  conditions return Sunday.

- Above normal temperatures persist through Monday before a cold
  front moving through the region on Tuesday brings cooler than
  normal readings for the latter part of the week.

- Aside from Wednesday, off and on showers can be expected
  across eastern Utah and western Colorado next week.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 251 AM MDT Sat Sep 14 2024

Another sunny and hence dry day is in store with temperatures
warming back to a few degrees above normal in most areas today.
Things are happening already to change this pleasant weather and
bring back shower and thunderstorm chances by tomorrow. There is
a weakening tropical storm down in the southern Baja region this
morning. Isentropic surfaces suggest moisture from this system
will be pulled northward by digging trough over the Pacific
Coast...arriving to the 4 Corners region as early as sunrise
tomorrow. The question is will this mainly be in the form of
ACCAS with some virga or will there be a trigger strong enough
for this elevated moisture and instability get showers to the
ground or even pop an isolated thunderstorms during the morning
hours over our SW CWA. There is an ill defined wave moving
toward the Bay Area of California this morning which PVU fields
show arriving just about the time the moisture arrives tomorrow
morning over SE Utah. This wave will definitely help enhance
lift over the eastern CWA during the heating of the day along
with the usual ascent aided by the topography. Pulled some
small pcpn chances farther West early tomorrow with this
forecast with the best chances over the central and southern
Colorado mountains tomorrow afternoon. Moisture will be on the
increase but gusty outflow winds will still be more probable
than excess runoff from storms...this may change by Monday.
Temperatures Sunday may end up a degree or two cooler thanks to
the added cloud cover and precipitation.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 251 AM MDT Sat Sep 14 2024

By Sunday night, a deep low pressure trough will be diving southward
over the west coast, increasing the southerly flow across the area.
Some sub-tropical moisture will advect northward allowing for
increasing clouds and showers, although precipitation may initially
have a tough time reaching the ground with more virga and gusty
outflow winds initially before top down saturation occurs. The deep
western low will park itself over the heart of the Great Basin on
Monday before lifting northward across the Intermountain West
Tuesday, helping drive a cold front and the negatively trough axis
across the region Tuesday afternoon and evening. Monday and Tuesday
appear to be the more active days in terms of more widespread
showers and storms with plenty of diffluence as the region maintains
a southwest flow ahead of this trough. Temperatures will start off
near seasonal Monday before dropping to 5 to 10 degrees below normal
on Tuesday in the valleys and 10 to 15 degrees below normal in the
mountains following the trough and cold front passage. It looks to
be breezy to windy as well during this time with a 100 kt jet streak
rounding the base of this trough, H5 winds in the 50 to 60 kt range
and H7 winds around 30 kts. Some of the highest peaks could end up
with a dusting of snow by Tuesday.

Wednesday and Thursday will still maintain a southwest flow but a
much drier air mass looks to move in by then, affording us a break
in the unsettled showery weather for a couple days. Another trough
is projected to track through the Great Basin Thursday and move
through our area Friday as an open wave, but this one looks weaker
than the early week system and doesn`t appear to have as much
moisture. This is different from previous model solutions so the
jury is out beyond Wednesday. It does appear that the weather will
turn cooler for mid to late week though and feel more like autumn
which is right around the corner as the Autumnal Equinox occurs next
weekend. &&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1030 PM MDT Fri Sep 13 2024

Expect mostly clear skies over the next 24 hours with terrain
driven winds, becoming breezy at times during the afternoon.
VFR conditions will prevail.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 513 AM MDT Sat Sep 14 2024

Clear skies and light winds can be expected over the next 24
hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...MDA
AVIATION...TGJT