Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 120545

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1145 PM MDT Wed Oct 11 2017

Updated aviation section

.SHORT TERM...(Today through Thursday night)
Issued at 355 PM MDT Wed Oct 11 2017

Quiet today across the CWA with only some high level clouds to
contend with. These formed in response to a weak 60kt jet streak
moving overhead. Temperatures are already 9 degrees warmer than
they were yesterday at this time due, in large part, to
southwesterly flow advecting in warmer air from the south. Skies
will become mostly clear tonight as temperatures drop to more
normal values.

Tomorrow, more of the same though an upper level trough will move
from west to east from Oregon to Montana. While the trough won`t
bring us any precipitation, it will tighten the surface pressure
gradient. The jet stream will also be moving overhead which will
allow some stronger winds to mix to the surface. For now, most
locations will see gusts between 20 to 30 mph in the afternoon
though higher elevations will see higher gusts than that.

.LONG TERM...(Friday through Wednesday)
Issued at 355 PM MDT Wed Oct 11 2017

The general troughiness that has plagued the Pacific northwest for
the last several days will finally get moving during the long term
period. A strong portion of the jet stream will dig down from the
Gulf of Alaska and force the trough eastward. At the surface,
this will be reflected by a cold front that will be quite dry when
it reaches our area.

Friday will be a repeat of Thursday as southwesterly flow keeps
the warm air in place and a tight gradient keeps some gusty winds
going. By daybreak Saturday, the cold front will be just entering
far northeastern Utah where some light rain/snow is possible. By
noon Saturday, winds will become more west to northwesterly
ushering in cooler air with the strongest effects being felt over
the northern valleys. Both GFS and Euro do show some precip for
those areas but amounts are very light so expect some showers and
that should be about it. Temperatures will drop to a few degrees
below normal once the front passes. After that, a return to
southwesterly flow, dry conditions, and warming temperatures is
anticipated. All in all, not too shabby for mid-October.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1145 PM MDT Wed Oct 11 2017

VFR conditions will prevail over the next 24 hours...but winds
will be greatly increasing after 12z Thursday morning. An upper
level jet moving overhead will increase downslope/downvalley and
upslope/upvalley flow during the early and late parts of the day
with southwesterly winds mixing down by 17 or 18z Thursday and
lasting through approximately 00z. LLWS may be an issue during
the entire TAF period.




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