Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 222341

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
541 PM MDT Mon May 22 2017

.SHORT TERM...(Tonight through Tuesday night)
Issued at 325 PM MDT Mon May 22 2017

The probability for the next 6 to 14 days appears to favor cooler
and wetter than what is usually expected. With that said,
troughing will dominate the lower 2/3 of central NOAM with high
latitude storms dropping into the upper Great Lakes region. This
scenario is already apparent on this morning`s H500 U/A hand
analysis map. With the Rockies and the High Plains being on the
Western side of the trough cold air and Pacific mositure will
easily drop southward and help verify the cool forecast. The first
front dropping through the area extends from Northeast Colorado
back through S.Wyoming and will bring a shot of precipitation to
the eastern half of the CWA this evening into the early morning
hours. Do expect the snow level to drop down to near 7000 feet by
the mid evening hours and with instability on the moderate side,
some brief moderate to heavy snow showers could create driving
impacts over the area passes. Significant accumulations will be
at or above 9500 feet over the Flat Tops and Gore to Elk Ranges
where 3 to 5 inches over the peaks will be possible. No winter
highlights planned at this time as this system is very fast moving
and by midnight Think will be winding down with lingering showers
mainly over the central divide and eastern San Juan range. The
front should make it past the southern border by sunrise. NAM
guidance continues to trend upward behind this front which doesn`t
seem to make sense though upper heights will be increasing as
ridging temporarily replaces the trough over the central states.
Did go for the cooler side of guidance for Tuesday which will be
at or slightly below normal.

.LONG TERM...(Wednesday through Monday)
Issued at 325 PM MDT Mon May 22 2017

The transitory ridge will be passing overhead then east of us by
Wednesday afternoon. This will bring strengthening westerlies
ahead of the next system to dropping through the Canadian
prairies. Wednesday will be the warmest day of the forecast as a
result and the dry air in place should allow for warming into the
80s in the lower valleys and 60s in the mountain towns. For the
late week period, well into the weekend, cool and active northwest
flow will be dominating the weather pattern in our region.
Temperatures will cool from the Wednesday`s readings but look to
hold near normal during this time frame. However cooler
temperatures aloft will favor PM showers and storms and this cloud
cover may lead to a downward trend in the current forecast high
temperatures. The western ridge will try and build eastward early
next week.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 528 PM MDT Mon May 22 2017

Aviation conditions will vary this evening as a weak front passes
to the east of the Continental Divide. A few showers with an
isolated rumble of thunder have developed in northern Colorado and
will drift southward across the I-70 corridor this evening. Some
of these storms may briefly drop CIG heights and VSBY at ASE and
EGE, with a few other higher elevation terminals seeing some
showers as well. Overnight theses showers will diminish in
intensity after 9pm or so with clearing skies and dry weather
moving in for Tuesday. Winds will be generally northerly through
the period.




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