Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 072030

Area Forecast Discussion
National Weather Service Grand Junction CO
230 PM MDT Tue Apr 7 2020

.SHORT TERM...(Tonight through Wednesday night)
Issued at 230 PM MDT Tue Apr 7 2020

Quiet and benign afternoon across the Western Slope today with only
a few fair weather cumulus and passing high clouds to disturb the
sky. Current temperatures are sitting near or slightly above normal
in response to warm air advection aloft. This warming trend will
continue through the short term period as southwesterly flow
persists ahead of the next Pacifc low pressure system. Overnight
lows will remain mild both tonight and tomorrow night...especially
since mid and high level clouds will moderate temperatures late
Wednesday in advance of the slow-moving low. The Pacific low is
projected to move onshore and into the Great Basin late Wednesday
with isolated showers developing across southeast Utah and far
southwest Colorado around midnight Wednesday night. However, virga
will likely dominate with little to no precipitation expected as
Bufkit soundings across the southern tier of the forecast area
remain dry in the low levels. Midlevel moisture does not look to
saturate down until Thursday morning as this system sits to our
west...more on that in the long term discussion below.

.LONG TERM...(Thursday through Tuesday)
Issued at 230 PM MDT Tue Apr 7 2020

The aforementioned Pacific low will remain situated over the
Great Basin on Thursday with moisture wrapped around the cyclonic
circulation advecting into the region throughout the day
Thursday. As the previous forecaster mentioned, QPF projections
remain inconsistent between the models with shower coverage most
likely to be scattered and convective at this point. The low`s
circulation will retrograde south towards Baja Thursday night and
into Friday as it remains firmly planted between a ridge of high
pressure to the west and a broad trough extending along the
eastern CONUS. As a result of this transition precipitation
chances will taper off and potentially diminish over the Western
Slope through much of the day Friday. However, another midlevel
trough will elongate from Manitoba, Canada and push south through
the Northern Rockies late Friday and continuing through the
weekend. As this feature begins to clip our northern zones we will
see precipitation chances increase once again.

The base of the Canadian trough will extend through south-central
Colorado on Sunday, providing the greatest coverage of showers
across the forecast area as a result. While the finer details still
need to be worked out in regards to forecast QPF, the main headline
with this system will be the accompanying surface front and bitterly
cold temperatures. 700mb temperatures are expected to plummet to at
least -10 to -16 degrees C across the north and 5 to 10 degrees C
below zero further south. This will result in well below normal high
temperatures and widespread freezing temperatures at night. The
potential for Freeze Watches will need to be monitored in the
coming shifts as several valley areas have eclipsed their 30
growing degree days threshold. Lower heights continue to dominate
the western CONUS into early next week resulting in the continued
potential for unsettled conditions and below seasonal


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1058 AM MDT Tue Apr 7 2020

No big issues in the TAFs today as skies will remain mainly sunny
with just some passing high clouds or building cumulus on the
ridges. Winds could get breezy for a few hours this afternoon with
some sites gusting over 25 mph. Winds should die off quickly to
diurnal trends after sunset.




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