Weather Service Report


591 
FXUS65 KGJT 232105
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
205 PM MST Sun Feb 23 2020

.UPDATE...
Issued at 203 PM MST Sun Feb 23 2020

Current webcams showing some snow at the higher elevations but the
majority of accumulating snowfall looks about over. Visible
satellite imagery showing plenty of holes through the cloud cover
and disorganization associated with the low. With that, went ahead
and cancelled the rest of the advisories across the area.

UPDATE Issued at 1057 AM MST Sun Feb 23 2020

The low continues to move across Colorado at this hour and has
almost made it over to the Front Range. Snow continues under the
banding that has set up over the northern valleys and northern
facing side of the Book Cliffs. As the low continues to drift
eastward, precip will end from west to east though some snow
showers are possible through this afternoon. Even so, significant
accumulations have ended for the San Juans, La Sals, and Grand 
Mesa so went ahead and cancelled those advisories. 

&&

.SHORT TERM...(Today through Monday)
Issued at 453 AM MST Sun Feb 23 2020

A well defined clear slot has wiped out quite a bit of the
precipitation in our southern CWA. Two main areas of precipitation
remain...one focused in the deformation zone arcing from northwest
Colorado back toward the parent low in central Utah. The other 
area of heavier precip is in the unstable air the nose of the dry
slot which is lifting across the central mountains early this 
morning. This low will be getting a nudge eastward by the arrival
of the next upstream system digging into the PacNW. The ascent
from the low overhead and conditional instability will keep a
threat of moderate to heavy snow showers at times today with the
best focus over the central mountains. The northern San Juans will
also be favored at times this afternoon and early evening as the 
flow turns northerly on the back side of the low. In the end there
could be some higher amounts thanks to the convective banding but
overall the warm nature of the storm and dry slot put some
limitations on this system. Much of the snow will taper of this
evening as the storm progresses into the Plains. The upstream
kicker system will be arriving during the pre dawn hours bringing
much colder air into the mix. Snow-2-Liquid ratios 12:1 or less
will be closer to 20:1 up north snow begin to spread across the
northern and central mountains through Monday morning. Moisture is
very underwhelming in this cold storm but snow amounts should be
inflated and on the fence on whether winter headlines needed attm.
This snow will be easily blown around and this will come into 
play but mainly near to above timberline. Impacts to travel will
also be a concern from Rabbit Ears down to Vail with much colder
air also playing a role at elevation. The Park and Flat Tops look
to benefit the most from this storm.

.LONG TERM...(Monday night through Saturday)
Issued at 453 AM MST Sun Feb 23 2020

Cold northerly flow on the backside of the trough will bring an 
anomalously cold air mass to the area. 700 mb temperatures drop 
to 10-20 C below zero on Tuesday with goose feather snow still
falling over the higher terrain of the central and northern
mountains through the day. Models suggest some clearing in the
evening with thin overcast moving in early Wednesday morning. 
This will be a difficult forecast but much like last week the 
Yampa valley could end up well below normal and current guidance. 
We stay in the northwest flow with a week wave moving through 
Wednesday night into Thursday and bringing a small chance of snow 
to the high Park range. Beyond this an expansive ridge builds over
the western CONUS allowing for temperatures to moderate and 
conditions to dry out.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1031 AM MST Sun Feb 23 2020

The closed low responsible for the clouds and rain/snow is moving
across western Colorado and continues to bring precip to the
region. However, conditions will be improving through the
afternoon and evening hours. Until then, expect MVFR to IFR
ceilings and vis from time to time for KHDN, KASE, and KEGE. These
TAF sites will be moving from category to category as a heavier
shower moves through...drops cig/vis...then jumps back up as the
shower leaves. Expect this to continue through 00 to 02Z before
clouds start to lift and precip stops. Remaining TAF sites will
likely stay VFR though a quick drop under a stronger showers is
not out of the question.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

UPDATE...TGR
SHORT TERM...15
LONG TERM...15/TGR
AVIATION...TGR

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Western Regional Climate Center, wrcc@dri.edu