Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 181746

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1146 AM MDT Mon Sep 18 2017

.SHORT TERM...(Today through Tuesday)
Issued at 308 AM MDT Mon Sep 18 2017

Seasonable conditions expected today as drier air works in
on southwest flow aloft. Subsidence behind the exiting system
will also lead to a much drier and mainly sunny day across the
region. Southerly winds however will be on the increase over the
next 48 hours as cooler air passes to our north in a trough and
tightens the gradients. Soundings and moisture profiles do not
seem very favorable for precipitation except along the Wyoming
border starting tomorrow afternoon. A cold front slowly sinking
southward late in the day will be where the better focus for
precipitation will occur. However dry southerly flow will continue
to advect northward and confidence like pops will be low.

.LONG TERM...(Tuesday night through Sunday)
Issued at 308 AM MDT Mon Sep 18 2017

Dry and breezy conditions stay in place Wednesday into Thursday as
downstream blocking allows high latitude energy to begin to carve
out a strong trough over the West. Temperatures will again hover
near normal with a rather significant cold front knocking on our
door for the late week and weekend period. The strong southerly
flow ahead of this slow system would suggest the cooler air will
ooze in rather than hit us head on. However temperatures will be
some 10 to 15 degrees below normal by the weekend with showers and
high mountain snowfall becoming more of a threat Friday into
Saturday. The models are suggesting drier air mixing into the
storm by the time the colder air and wrap around moisture move
into the northern half of the CWA on Sunday. Thickness and thermal
profile suggest snow could be dropping to near mountain bases in
the north late Sunday into early Monday. Models are surprisingly
in fair agreement will into the weekend which suggests this change
is highly probable. Just need to iron out some of the details
which will come over the next few days. Overall cool and unsettled
looks likely to close out the forecast.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1146 AM MDT Mon Sep 18 2017

The upper level wind gradient will continue to tighten over the
next 24 hours as a strong and broad Pacific trough begins to dig
into the western CONUS. These winds will mix to the surface
resulting in widespread breezy conditions. Gusts today will be in
the range of 15-25 mph increasing to greater than 40 mph in some
areas Tuesday afternoon. Some ridge top turbulence will also be
experienced. Apart from the winds, no other impacts to aviation
are expected and VFR conditions will prevail at all TAF sites.


Issued at 308 AM MDT Mon Sep 18 2017

Nothing says a change of season like wind and this will become
apparent over the next few days. Warmer conditions expected today
and Tuesday ahead of the next passing system to the north. Minimal
precipitation is expected with this system but it will knock
temperatures back a bit. A stronger system arrives by late week
with a significant cool down along with better probability of
precipitation. Critical fire weather conditions are possible
Tuesday afternoon in the southern and western fire zones. Fuel
data is either not available or out of date in concerned zones so
opted not to make a decision about these potential critical
conditions at this time.




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