Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 220440

Area Forecast Discussion
National Weather Service Grand Junction CO
1040 PM MDT SUN AUG 21 2016

.SHORT TERM...(This evening through Monday night)
Issued at 350 PM MDT Sun Aug 21 2016

Moisture has begun to move northward into southwest Colorado and
southeast Utah today. As a result an area of thunderstorms
developed over the southern slopes of the San Juan mountains early
this afternoon, with isolated activity over southeast UT. An
increasing trend for these showers and thunderstorms is expected
into the early evening, with convection possibly spreading into
the central portion of the forecast area. By late evening activity
will become less convective, however the moisture will continue
spread into the area. This will keep the chance of showers ongoing
into Mon morning with isolated thunder possible as well. Models
indicate an embedded disturbance will move into the 4-corners late
tonight which will help enhance the nocturnal showers. The
increased clouds and chance of showers will keep overnight
temperatures on the mild side, with lows a few degrees warmer than
last nights most locations. Due to the convective element, small
hail, ice pellets or even snow may be possible over the highest
peaks of the San Juan Mountians, where a layer of white may be
visible by daybreak above 12K FT or higher.

The north will remain drier for less clouds and cooler nighttime

The disturbance that moved into the 4-corners overnight will
remain somewhat stalled over southwest CO through the Tuesday.
This, along with the continued surge of moisture will result in an
uptick in showers and thunderstorms area-wide by the afternoon. A
Pacific low pressure center will gradually shift onshore over
southern CA by the afternoon. This feature will be partially
responsible at least some of for the better moisture moving into
the area, and some channelized energy that will stream into the
4-corners through Mon night and Tue. Therefore activity is
expected to persist Mon night, albeit not as intense once daytime
heating fades. Look for cooler temperatures for both highs and
lows. However minimum temps will generally not drop as low as some
of the readings we have seen during the past couple of nights.

.LONG TERM...(Tuesday through Sunday)
Issued at 350 PM MDT Sun Aug 21 2016

Models indicate that the moisture surge will peak on Tue. Also
the above mentioned Pacific low will reach the forecast area
during the afternoon. This combination should result in another
increase in late day showers and thunderstorms, both in areal
coverage and possibly in intensity. Heavy rain and small hail
will be possible, with precipitable water values near an inch.
Also, storms may be slow moving as steering will will stay on the
light side. The extra clouds and precipitation will keep
temperatures quite cool and well below normal through the day.

A modest drying trend will take place on Wednesday, only to
reverse again on Thursday. Therefore after a downturn in
convective activity Wed, showers and thunderstorms will again
increase on Thu and through the remainder of the forecast period.
As usual, the southern portion and the late day hours will be
favored. High temperatures will remain below normal, with lows
near normal.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1040 PM MDT Sun Aug 21 2016

VFR conditions will prevail at all TAF sites through Monday
morning. Isolated showers and thunderstorms will prevail across southern
sections and along the Continental Divide south of Interstate 70
overnight with activity diminishing after 10z. Outflow erratic
wind gusts are possible through 10z at all TAF sites along and
Showers and thunderstorms will spread north and strengthen Monday
afternoon. ILS breakpoints may be met, and brief MVFR conditions
will be possible in the heavier showers, mainly at KTEX and KDRO.
Shower activity will slowly diminish Monday evening.


.GJT Watches/Warnings/Advisories...


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