Area Forecast Discussion Issued by NWS Grand Junction, CO
000
FXUS65 KGJT 160515
AFDGJT
Area Forecast Discussion
National Weather Service Grand Junction CO
1115 PM MDT Fri Mar 15 2024
.KEY MESSAGES...
- A cutoff low in southwestern Arizona continues to push
moisture into the region tonight into Sunday, producing an
additional six inches to a foot of new snowfall for our
southern mountains and the high country above 7000 feet in
southeast Utah.
- Models continue to struggle with a solution in the evolution
and eventual departure of the cutoff low. Current expectations
are for light snowfall to continue into the work week over our
mountains down south and perhaps spread northward later in the
week.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 333 PM MDT Fri Mar 15 2024
The cutoff low centered over southwestern Arizona continues to pump
moisture north into eastern Utah and Western Colorado. The models
are in good agreement and seem to be tracking well with satellite
imagery. Satellite imagery does show a mid-level dry slot has moved
into southern Colorado that has brought a temporary break in the
heavier snowfall, but the abundance of low-level moistures is
keeping lighter orographic showers going along the southern faces of
the mountains. The snow has pretty much ended for now north of the
San Juans and on the Uncompahgre Plateau, and hence, canceled the
Winter Weather Advisory for these areas. The stronger gusty winds in
the Four Corners area from this morning have dropped below 40 mph
and will continue to decrease through the afternoon and evening,
thus canceled the Wind Advisory for these areas.
Behind this dry slot, another band of deep moisture is moving up
through Arizona and New Mexico with a shortwave rotating around the
low and upper-level jet support that will impact the region tonight.
This band is currently firing off a line of thunderstorms along the
Black Mesa down to the White mountains in Arizona. Look for this
band to move up over the San Juan Mountains bringing another round
of heavy snow overnight into Saturday morning. Extended the Winter
Storm Warning for the San Juans until noon tomorrow with this next
push of moisture and the dynamics associated with the shortwave. The
high mountain roads and passes will continue with winter driving
conditions, especially overnight into the early morning hours. The
flow aloft becomes more easterly north of the San Juan Mountains
tomorrow afternoon with the shortwave passage that will support
heavier snow along the northern side of the San Juans and on the
Uncompahgre Plateau above 8,000 feet lasting into the evening. Issued
a Winter Weather Advisory from late morning to midnight tomorrow for
four to eight inches new snow accumulation in these areas.
Another dry slot moves in behind this second band of moisture which
will bring an end to this winter storm, but isolated orographic
showers will linger in the region with the low-level moisture
trapped in the valleys. The temperatures around the region will
generally remain mild with the blanket of clouds to keep diurnal
heating radiative cooling to a minimum. Daytime temperatures will
run a few degrees below the seasonal normal for mid March and the
morning lows will be a few degrees above normal.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 333 PM MDT Fri Mar 15 2024
Even a fairly strong trough approaching the upstream coast near the
PacNW this weekend will not budge this persistent Rex Block over the
Intermountain West/Southwest. So we are stuck in a holding pattern
until the mid-week timeframe when yet another upstream wave arrives
to get the whole pattern moving again. By Sunday and especially on
Monday the Rex High will have a bit more influence as the low
becomes more barotropic and the energy more sheared out and
channelized. This will limit the northern extent of the
precipitation bands that have been rotating around the low with a
bit less available conditional instability. With warming mid and low
level temperatures the impact of snow will lessen in most areas
outside the highest elevations and we can move onto other systems
coming down the pipe later through the weekend. So daily shower
activity across the South expands a bit by Wednesday as the low
finally opens and lifts out but under much warmer conditions. Highs
on Sunday will continue to be below normal most area with a few
warmer spots up North away from the precipitation. Temperatures will
then gradually warm to around 5 to 8 degrees above normal as we move
through the week. Again the southern locations will lag a bit due to
the cloud cover and afternoon precipitation.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1112 PM MDT Fri Mar 15 2024
Another round of showers will bring deteriorating conditions
later today. They will result in prolonged periods of MVFR to
IFR conditions mainly to the southern sites. For the remaining
terminals across the north, conditions will remain VFR through
the period, although skies will remain SCT to OVC. Some gusty
afternoon winds are also possible for this northern group of
terminals.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory from 9 AM Saturday to midnight MDT
Saturday night for COZ017-018.
Winter Storm Warning until noon MDT Saturday for COZ019.
UT...Winter Storm Warning until 6 AM MDT Saturday for UTZ028.
&&
$$
SHORT TERM...DB
LONG TERM...15
AVIATION...TGJT