162
FXUS65 KGJT 070535
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1135 PM MDT Mon May 6 2024

.KEY MESSAGES...

- Light mountain showers will linger through the night, with an
  expected upturn in activity around daybreak tomorrow morning
  with an approaching disturbance. Winter Weather Advisories
  have been extended through tomorrow afternoon.

- Windy conditions return tomorrow with gusts of 40-50 mph
  likely across the region. Numerous Wind Advisories have been
  issued.

- In the wake of tomorrow`s disturbance, clear skies and much
  colder air will lead to a threat of sub-freezing temperatures
  for the lower elevation valleys. Freeze Watches have been
  issued for susceptible areas.

- Cool and unsettled weather will linger through the remainder
  of the week, with a parade of disturbances keeping chances of
  light mountain showers in the forecast most afternoons.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 321 PM MDT Mon May 6 2024

Showers have lingered across northwest Colorado, and even into
portions of central Colorado, well into the afternoon hours
today, although we are starting to see a downturn in activity as
subsidence finally takes hold. Breezy conditions also continue
across the northern half of the CWA thanks to a modest 25-35
knot northwesterly 700mb jet still lingering over the north.
This jet combined with favorable downsloping conditions in the
Uinta Basin has led to the need for a Wind Advisory for the
Eastern Uinta Basin through 8PM this evening. Elsewhere, aside
from a stray strong gust here and there, winds have remained
sub-advisory. The same cannot be said for tomorrow. As today`s
low ejects into the Northern Plains, the jet will lift back
north overnight, with the core of a 90-100 knot northwesterly
200mb jet centered over eastern Utah and western Colorado by 6AM
tomorrow morning. Moving downward, at 700mb, two distinct jet
streaks will be in place over the region, one over Southeast
Utah and Southwest Colorado, and one over far Northeast Utah and
northwest Colorado. This event is not quite as anomalous as
yesterday`s event, but it`s still registering in the 90th
percentile of the 1991-2020 climatology. Under northwest flow
this time, and with that split 700mb jet, the areas looking at
high winds are a bit different. Wind Advisories go into effect
for the Eastern Uinta Basin and areas of the Gunnison River
Valley at 6AM, with more Advisories for the entire I-70 corridor
from Green River to Edwards and for the Southwest Colorado and
Southeast Utah valleys joining at 9AM. Widespread gusts of
50-60mph will be possible in these areas through the day.

In addition to all the wind, an approaching shortwave will
drive another strong cold front through the area during the day
tomorrow. This will bring another round of snow to the northern
and central Colorado Divide mountains, mainly during the morning
hours. Amounts have come up a bit for these areas, with 6-10
inches possible above 8000 feet. Combined with the expected
gusty winds and the timing being around the morning commute,
have elected to extend the current Winter Weather Advisories
through tomorrow afternoon. Rain showers will be possible along
the front at lower elevations. Behind this cold front, a
reinforcing shot of cold air and clearing skies under subsidence
will allow temperatures to fall into near-record low territory
by Wednesday morning, with many areas seeing sub-freezing
temperatures. And, unfortunately, much of the lower elevations
of eastern Utah and western Colorado are already well into the
growing season. As such, Freeze Watches have been issued for
Tuesday night into Wednesday morning. Now would be the time to
prepare susceptible vegetation for the coming cold snap. Daytime
highs won`t fair much better, with tomorrow`s forecast topping
out 10-15 degrees below normal for early May. Certainly, the
next few days will feel more like early spring than almost
summer.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 321 PM MDT Mon May 6 2024

The theme of the day is Rex block as this stubborn...blocky
pattern will persist through the end of forecast into early next
week. If you like cool and unsettle conditions then the news is
good...for the rest of us not so much. The Rex pattern starts
Wednesday with our current system rotating up into the Dakotas
where is stalls and takes on a more East-to-West orientation.
The blocking ridge is meanwhile is sitting over the Canadian
Prairies. The only good news on Wednesday will be the cold air
is so expansive that the lack of a thermal gradient across the
region will keep the winds in check. This will be at the expense
of high temperatures some 10 to 20 degrees below normal. Cold
air aloft and W/NW orographics are likely to keep some snow
showers going over our northern and central mountains...but with
minimal impacts expected. By Thursday the Plains system will be
splitting with one piece retrograding back into the
Intermountain West to form the next Rex pattern with high
pressure building into the Pacific Northwest. Grand Junction and
Seattle could end up with the same forecast high for Thursday
with the former cooler than normal and the latter warmer. Again
cooler temperatures aloft and lingering moisture will keep a
threat of afternoon showers in place across the higher terrain
and adjacent valleys. The lower elevations look to remain on the
dry but cool side. The forecast beyond this gets a bit fuzzy as
the models are not handling this blocky pattern very well. When
and where this Rex Low ejects will decide when and who gets the
better precipitation chances later into the weekend. Otherwise
the low spinning to the West of the 4 Corners into Friday the
Southern CWA will have the better chances of a passing shower.
The airmass will be moderating a bit by late week and this
should push snow levels above the 9500 foot mark with little
impact expected during the daylight hours. The forecast for now
has showers lingering into Sunday afternoon with some reflection
of the trough in the GFS or a more closed circulation in the
EURO. Either way the trend of warmer conditions will continue to
push snow levels higher and bring temperatures closer to normal
by late in the forecast.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1135 PM MDT Mon May 6 2024

Another round of gusty winds is on tap on Tuesday as a
disturbance swings down from the north and west. Gusts of 40 to
50 mph will be common at most terminals, especially during the
afternoon hours. The disturbance will also bring lowering clouds
and the threat of scattered snow showers, with KHDN and perhaps
KEGE and KASE the most likely TAF sites to be impacted.
Ceilings will approach and even drop below ILS breakpoints
during showers, with MVFR/IFR ceilings and visibility also
possible. Additionally, visibility and terrain obscuration will
likely be worsened when factoring in the wind. Showers and winds
gradually diminish late Tuesday night into Wednesday morning.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory until 6 PM MDT Tuesday for COZ004-010-
     013.
     Wind Advisory from 9 AM to 9 PM MDT Tuesday for COZ006>008-
     021>023.
     Freeze Watch from Tuesday evening through Wednesday morning
     for COZ006-007-011.
     Wind Advisory from 6 AM to 9 PM MDT Tuesday for COZ011-014.
UT...Wind Advisory from 9 AM to 9 PM MDT Tuesday for UTZ022-027.
     Freeze Watch from Tuesday evening through Wednesday morning
     for UTZ022-027-029.
     Wind Advisory from 6 AM to 9 PM MDT Tuesday for UTZ024.

&&

$$

SHORT TERM...BGB
LONG TERM...15
AVIATION...MDM