Area Forecast Discussion
Issued by NWS Grand Junction, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS65 KGJT 251052

Area Forecast Discussion
National Weather Service Grand Junction CO
352 AM MST Sat Feb 25 2017

.SHORT TERM...(Today through Sunday)
Issued at 349 AM MST Sat Feb 25 2017

Another splitting shortwave trough was positioned along the coast
of CA and OR. this feature will move into the Great Basin this
morning. The northern portion of the split will extend from off
the CA coast ENE to central Montana, with the southern portion and
the main energy weakening as it moves onshore over northern CA and
travels east into Nevada this evening. The weak lower and mid
level front connecting both parts of the split trough will plunge
from N to S across the area tonight bringing cold enough air and
enough lift for snowfall in the mountains. The remnants of the
southern portion of the split should travel across southern CA
tonight the travel through AZ Sunday morning, then lift across SW
Colorado Sunday afternoon. So, the northern half of UT and CO will
see the stronger focus for precip today and tonight, while SW CO
and SE UT will see more precip through Sunday afternoon.

.LONG TERM...(Sunday night through Friday)
Issued at 349 AM MST Sat Feb 25 2017

The last in this recent series of upper level troughs will move
through early in the week. A long wave trough moves over the Pac
NW Sunday night...then additional energy farther west dives
south...elongating the trough a bit Monday before phasing and the
whole trough moves east across our region Monday night. Precip
will likely break out in the increasingly moist southwesterly flow
and isentropic lift ahead of the trough Monday. 700 mb
temperatures do not warm that much in the warm sector...only to
about -5C south and - 9C north. This will keep temperatures on the
cool side of the guidance and keep snow the main precip type at
all but the lower valleys. Strong winds in the mid to upper levels
will have a chance to mix down Monday and this potential will
have to be watched for wind highlights.

Best dynamics with jet aloft and frontogenetical forcing move west
to east across the region Monday night coincident with surface front
moving southeast. Enough instability to warrant threat of thunder as
well late Monday for central mountain region. Flow turns to the
northwest later Monday night...with a return to a cold unstable
airmass leading to numerous snow showers Tuesday...especially for
favored northwest facing slopes. While still room for adjustments,
early snowfall estimates Monday through Tuesday range generally from
6-12 inches in the mountains to 0.5-3 inches for central and
northern valleys, to 2-6 inches for foothills/valleys south of San
Juan Mtns. The Four Corners region over toward Pagosa Springs look
to have best chance of snow late Monday night and Tuesday after
colder air moves back into the region.

Northwest flow dries out by Thursday but temperatures will remain
below normal through the end of the week, though showing some subtle
warming each day. Went on the cooler end of guidance through the
period. Next chance of snow showers comes into the picture next
Saturday across the north as an upper level trough rides southeast
in the northwest flow and a front moves south over High Plains.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 349 AM MST Sat Feb 25 2017

Only isolated mountaintop snow showers are expected this morning
with VFR conditions prevailing at all the TAF sites. Another
trough will move in from the northwest this afternoon and tonight.
This will bring a redevelopment of scattered showers over the
valleys and numerous snow showers over the mountains. cigs below
ILS breakpoints are expected at all TAF sites beginning about 00z
and continuing overnight. MVFR conditions and occasion IFR
conditions are possible at KEGE, KASE and KTEX after 06z.
Mountains and higher passes will become obscured by 06z as well.




AVIATION...CC is the U.S. government's official web portal to all federal, state and local government web resources and services.