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000
FXUS65 KGJT 212117
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
317 PM MDT Thu Mar 21 2019

.SHORT TERM...(Tonight through Friday night)
Issued at 300 PM MDT Thu Mar 21 2019

Only slight changes in the short term forecast this afternoon as
the previous package remains on track. Snow levels have continued
to remain relatively high today in regions of light to moderate
precipitation, and with 700mb temperatures still progged to remain
AOA -2 or so, this trend will continue throughout the evening. The
lone exception will be in the far southern San Juan Mountains,
where convective elements and intense precipitation rates have
resulted in a few reports of soft hail/graupel as low as 5500
feet. While a few more instances of hail may be possible this
evening...especially in Archuleta County...the general trend will
be for convection to decrease in intensity as daytime heating is
lost.

Temperatures aloft do not decrease notably until the late morning
hours on Friday. By this time, precipitation coverage will thin,
but light to moderate snow will continue in the higher elevations
as favorably light flow persists in the base of the trough. It
will not be until Friday evening until winds finally turn
northerly, carrying slightly drier air in from this direction. For
these reasons, we have opted to extend the winter weather
headlines slightly. Headlines for the southeast Utah high country
now go until 6pm Friday, and headlines for the San Juan Mountains
now extend until midnight Saturday morning. Storm total snowfall
forecasts remain on track. Borderline advisory amounts exist in
the higher terrain of the Grand Mesa and Elk Mountains, but
limited impacts and borderline confidence preclude any areal
extensions of current products.


.LONG TERM...(Friday night through Wednesday)
Issued at 403 AM MDT Thu Mar 21 2019

Trough axis will be pushing east of us Friday evening with lee-
side cyclogenesis closing off a low across eastern Colorado.
Cool and unstable conditions will remain in place through Saturday
with showers persisting, although they will become more scattered
in nature and will tend to hug the higher terrain. Moisture
infested shortwave ridge fills in behind the exiting trough/upper
low Saturday night with light orographic showers hanging around
through the night. Then one last piece of energy works through on
Sunday to bring another uptick in the rain/snow through Sunday
evening. Showers come to an end by early Monday morning with
building heights as another warming ridge works in from the west.
Expect breezy conditions by Tuesday as the ridge slides east and
gradients tighten back up as we start to see the battle with these
late winter/early spring storms. Next round of rain snow will
arrives Wednesday night/Thursday with unsettled conditions again
in place as we close out the week.

After a cooler than normal weekend in the temperature department,
expected pretty aggressive warming by midweek with lower valleys
temps climbing into the 60s and lower 70s if this ridge comes
true. Should signal an increase in mid-slope melting, especially
on south facing slopes and possible bring another increase in
water flows on smaller creeks and streams. The good news is we
should cool back down by the end of the week to slow the melting
again.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1212 PM MDT Thu Mar 21 2019

A strong, moist Pacific storm system has begun to impact the area
this morning and will remain over the area through the next 24
hours. KCNY, KDRO and KTEX have already begun to receive
precipitation this morning. The snow level was around 8000 feet
MSL at sunrise, but will rise to near 8500 feet with warming
temperatures during the afternoon. In addition to showers,
thunderstorms will begin to rumble across southwest Colorado with
a band moving over extreme southwest Colorado as of this writing.
Expect strong outflow winds of 45 to 50 MPH from stronger cells.
Impacts from this storm will be periods of MVFR visibility and
ceilings for all TAF sites with IFR, and even LIFR, conditions
possible at KDRO and KTEX. Though showers along the I-70 Corridor
from KRIL eastward will be less frequent, there will be prolonged
periods where CIGS fall below ILS breakpoints.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until midnight MDT Friday night for
     COZ018.

     Winter Storm Warning until midnight MDT Friday night for COZ019.

UT...Winter Storm Warning until 6 PM MDT Friday for UTZ028.

&&

$$

SHORT TERM...MAC
LONG TERM...JDC
AVIATION...NL