Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Grand Junction Colorado
326 PM MDT Tue Jun 27 2017
Short term...(tonight through Wednesday night)
issued at 314 PM MDT Tue Jun 27 2017
A shortwave trough drifting eastward along the northern Colorado
border was responsible for an area of thunderstorms which erupted
over the eastern Uinta Mountains and tracked along the Colorado-Wyoming
border this afternoon. This shower/thunderstorm activity is
expected to hold together and exit to the northeast by 5 PM MDT.
Additional activity is likely to occur this evening, but will be
isolated to scattered in coverage producing strong outflow winds
to 45 to 50 mph, but little measurable rainfall. Breezy winds will
decrease early this evening with normal drainage flows becoming
established later this evening and overnight. Meanwhile, clouds
will be clearing behind the disturbance bringing clear or mostly
clear skies to the area overnight.
A second shortwave trough will be making its way across the
northern Great Basin on Wednesday. An 80 knot jet streak moving
ahead of the trough axis will set up over Wyoming's southern
border. This feature, combined with the destabilizing effects of
diurnal warming will bring isolated showers and thunderstorms to
the eastern Uinta Mountains and the Elkhead and park mountains
during the afternoon and evening. Warmer than normal temperatures
Promise deep mixing which will Transfer momentum from higher
levels to the surface resulting in another hot and breezy day for
the area. Dry vegetation under these conditions is expected to
bring critical fire weather conditions. Details are in the fire
weather and watch/warning/advisory sections which follow.
Nocturnal showers are possible along the northern border region
Wednesday night as the shortwave discussed previously sweeps
across northern Colorado Wednesday night. Otherwise, look for
winds to diminish with decreasing clouds to the south and west.
Long term...(thursday through tuesday)
issued at 314 PM MDT Tue Jun 27 2017
The potential for critical fire weather conditions will lessen
Thursday after as cooler temperatures spread across the area. The
winds aloft will become more northwesterly with speeds
decreasing. Friday and Saturday will remain dry under weaker
northwest flow aloft. Sunday will see a slight chance of afternoon
showers as a weak trough will clip the northern half of the area.
There will only be a slight increase in moisture with this weak
system so in the mountains generally north of Interstate 70 and
east of Rifle there will be only a small chance of rain. On Monday
through Tuesday the ridge over the Great Basin will travel over
the area producing warmer conditions again and no let up in the
hot and dry weather.
Aviation...(for the 00z tafs through 00z Wednesday afternoon)
issued at 314 am MDT Tue Jun 27 2017
VFR conditions will prevail at all taf sites the next 24 hours.
Smoke from the Brian Head fire will decrease visibility but not
less than 10 miles at any sites.
issued at 241 PM MDT Tue Jun 27 2017
A red flag warning will remain in effect through 8 PM this evening,
after which gusty winds will decrease shifting to a light drainage
flow during the latter part of the evening. Diurnal cooling will
allow relative humidity to recover above 15 percent, though recovery will be
On Wednesday, another stronger jet streak will move overhead and
deep mixing is expected to recur. Little change is expected in
atmospheric moisture levels or fuels so critical fire weather
conditions appear probable. Therefore, will go ahead with a red
flag warning from noon to 8 PM MDT Wednesday evening for all fire
weather zones with the exception of utz485.
Colorado...red flag warning until 8 PM MDT this evening for coz200>203-205-
Red flag warning from noon to 8 PM MDT Wednesday for coz200>203-
Utah...red flag warning until 8 PM MDT this evening for utz486-487-490-
Red flag warning from noon to 8 PM MDT Wednesday for utz486-487-