FXUS65 KGJT 222353

Area Forecast Discussion
National Weather Service Grand Junction CO
553 PM MDT Sat Sep 22 2018

.SHORT TERM...(Tonight through Sunday night)
Issued at 144 PM MDT Sat Sep 22 2018

Sustained wind speeds and gusts have been slow to increase in
support of the Red Flag warning in effect for parts of northwest
CO this afternoon and evening. But, at 2 PM RHs lowered to
criteria and wind gusts were finally close to the 25 MPH gust
criteria at a handful of sites. Believe the wind gusts will
increase the rest of the afternoon and red flag conditions will be
widespread over fire zone 200, which in mainly in Moffat CO.

Southwest flow aloft will gradually increase due to a tightening
gradient ahead of a trough and weak cold front over the northwest
U.S. The model consensus shows a stronger gradient flow but
precipitable water and dew points are also rising. Surface and
boundary level moisture increase beginning late tonight and
throughout tomorrow. The increasing moisture appears to be enough
that the humidity will not be low enough to meet the red flag
warning criteria, except in isolated spots for very brief periods.
Thus, I cancelled the fire weather watch for Sunday.

The cold front should move through the part of area Sunday night
from late evening through sunrise, reaching as far south as about
Gunnison, Montrose and Moab. There is enough moisture and
instability accompanying the boundary for some nocturnal

.LONG TERM...(Monday through Saturday)
Issued at 144 PM MDT Sat Sep 22 2018

The front will continue moving through the southern half of the
area Monday and appears to get hung up over the San Juan mountains
in the afternoon. It then slowly drags through the four corners
and reaches the southern CO and UT borders by sunrise Tuesday.
Drier air and northwest flow follow the front. Wednesday and
Thursday a broad trough will cover most of the eastern U.S. with a
sharp ridge over the western U.S.

This pattern should continue through Friday and then a strong
trough is projected to develop of the northern CA coast which will
begin to shift the winds to the southwest.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 539 PM MDT Sat Sep 22 2018

Some gusty winds up to 20 kts will continue for the northern TAF
sites over the next few hours. Otherwise VFR conditions will
prevail across all TAF sites through the weekend. Gusty
southwesterly winds will make a return tomorrow ahead of an
approaching cold front. This front will bring increasing clouds
towards Sunday evening with the slight chance of showers or
thunderstorms developing over the higher terrain.


Issued at 144 PM MDT Sat Sep 22 2018

The red flag conditions will continue over northwest CO through
8 PM this evening due to moderate southwest winds at the surface
and aloft and low humidities. The fire weather watch for Sunday
afternoon was cancelled because moisture will increase over the
area from the south which will keep the RH wetter than criteria.


CO...Red Flag Warning until 8 PM MDT this evening for COZ200.



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