Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 161836
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1236 PM MDT Sat Mar 16 2024

.KEY MESSAGES...

- Scattered to widespread valley rain and mountain snow showers
  are expected today and tonight across southeast Utah and
  Southwest Colorado.

- Accumulating snow possible in the southern mountains today
  generally above 8 kft.

- The chances for showers will continue just about each day
  across the south until the system lifts out of the Desert
  Southwest.

- Impacts from any snow should stay confined to the overnight
  and early morning hours as well as the highest elevations.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 206 AM MDT Sat Mar 16 2024

Latest satellite shows the cut off low pressure currently centered
over Arizona. A piece of vorticity is rotating counter clockwise
around the low. This energy passes over our area today, bringing
some lift and another surge of moisture. Precipitation has already
developed in southeast Utah and southwest Colorado. Expect this band
of showers to gradually migrate northward through out the day, but
it hits the breaks when it gets to I-70. Therefore a majority of the
precip will fall over the southern mountains and surrounding
valleys. The cold core of this system brings slightly cooler temps
in from the southwest, which should help keep the midlevel lapse
rates steep. The surface temps are dealing with the higher sun angle
and lack of advection. Snow levels hover around 6-7 kft through
tomorrow. Snow ratios have been a struggle with this chaotic air
mass. When all said and done the southern mountains have the
potential to see periods of moderate to heavy snowfall over the next
24 hours. Total snow accumulations line up with advisory criteria
and impacts should be limited to the overnight and early morning
hours. During the day the highest passes may be able to accumulate
snow on the roads, so impacts are possible. Locations north of I-70
start out cool with partly cloudy skies and dry conditions through
out the day. Another midlevel dry slot sneaks into the Four Corners
later today causing the showers to thin out down there, but the band
will continue over the San Juans to the eastern Tavaputs.

Overnight this band of showers gradually diminishes. After midnight
the rates and coverage decreases with the exception of the San
Juans. This where the models show yet another wave and moisture
pushes in from the south. Tomorrow a trough digging over central US
causes the midlevel flow to become northerly. This causes overall
suppression of precip and keeps it confined to the southern third of
the forecast area. So expect another day of scattered showers in the
San Juans and Four Corners region. More isolated showers will be
possible in between those locations and I-70.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 206 AM MDT Sat Mar 16 2024

Deterministic models remain in lockstep with keeping the cutoff low
and rex block system in place into the early half of the work week.
Models place the roughly stationary low over the SOCAL/AZ border
through Tuesday. Late Sunday night QPF is expected to erode quickly
thanks to another round of dry air getting wrapped into the low.
Monday and Tuesday see a sort of rinse and repeat cycle of
moisture/dry air entrainment. This will be good enough to keep light
rain and snow chances for much of southeast Utah and southwest
Colorado and even up towards the Grand Mesa. Snow accumulation will
be pretty meager under these pulses circulating around the low.
Roughly 1 to 2 inches per day at the higher elevations on Monday and
Tuesday. Late Tuesday night, models hint at height falls breaking
down the rex block and shunting the low northeast and just south of
the Four Corners early Wednesday morning. Under this scenario,
precipitation will spread northward up the Continental Divide and
bring some light snow to the Central Mountains, Gore Range and Flat
Tops. Again, these will be meager accumulations, as we are working
with recycled moisture still. Models continue to flatten the ridge
Thursday and push some shortwave energy across the northern portion
of the CWA in the zonal, westerly flow. This will deliver some light
precipitation to the Central Mountains and northward. By Friday, a
wave coming ashore on the PACNW Coast is expected to deliver some
new moisture and beef up snowfall for the northern Mountains on
Friday and into Saturday morning. These are early, back of the
napkin proposals, but we`re trying to be optimistic with shaking
loose of this stubborn rex block and the soupy, cloudy regime it has
brought to the region. Speaking of clouds, expect more of the same
through this extended period for the southern half of the CWA, while
northward, moisture will thin enough to get some breaks
periodically. A general warming trend is expected to kick off
Tuesday with desert valleys getting into the 60`s and 70`s through
the week. The northern half of the CWA is expected to trend above
normal this week, while down south, temperatures will remain at or
below climatology thanks to the cloud cover and precipitation
activity. Overnight lows will be highly dependent on cloud cover,
but expected to trend warmer down south and cooler up north, where
drier air is expected to settle in.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1224 PM MDT Sat Mar 16 2024

Expect continued scattered to widespread showers generally south
of the line KGUC-KGJT-KCNY through 06Z, there after retreating
to the southern mountains. MVFR/IFR conditions are likely within
these showers. KGUC, KTEX and KDRO will see periods below ILS
breakpoints. Some TAF sites will see gusty east to southeast
winds later this afternoon through the evening hours. Otherwise
winds will generally be light and terrain driven.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory until midnight MDT tonight for COZ017.
     Winter Weather Advisory until 9 AM MDT Sunday for COZ018-019.
UT...Winter Weather Advisory until midnight MDT tonight for UTZ028.

&&

$$

SHORT TERM...KJS
LONG TERM...LTB
AVIATION...DB


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