Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 202159
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
359 PM MDT Wed Mar 20 2019

.SHORT TERM...(Tonight through Thursday night)
Issued at 359 PM MDT Wed Mar 20 2019

The break was nice while it lasted but the pattern will again be
transitioning to a more active one through the weekend. Strong
Omega block has been in place and this continue to slow the next
system down just a bit and have backed off pops a bit through the
evening. We did get a balloon in the air this morning which
showed a very dry atmosphere in place and this verified with the
very low dewpoints sitting at elevation and even mixing down in
spots this afternoon. This dry air is a bit concerning as we will
be using some of the lift from the approaching storm to start the
the top down saturation process. QG ascent will be increasing this
evening but especially after midnight across the 4 Corners region.
This is when the trough will be undercutting the ridge and
negatively tilting as the trailing jet max begins to move through
the base of the trough. All models show an elongated north to
south precipitation max over SE Utah. The 300K surface shows this
area as a strong area of moisture convergence between Gulf and
Pacific moisture sources. Also there will be low to mid level warm
front structure that will help with upglide into this
region...with a favorable jet location aloft to help with deep
lifting. So pops and qpf are high in our SW CWA to start the day
though can`t help but to think some of the heavy precip output is
feedback in the model as instability will be quite strong in this
region. Strong southerly flow into the San Juans almost guarantees
another round of heavy snow at elevation. Time of year and warm
temperatures however makes a low confidence forecast for snow
sticking on roadways and mid to lower mountain elevations. The
current headlines look on track and no plans to adjust. Again QPF
amounts came in a bit higher and can not totally rule out, but
feel these higher amounts will be more isolated due to the
convective nature of the precipitation in the afternoon. In fact
this instability will be strong enough to that storms in the SW
CWA could be organized enough to be hail and wind producers. A
pseudo dry slot will be working through the region tomorrow
afternoon as well and breaking up the precipitation a bit. However
the moist southerly flow continue into the San Juans through the
overnight hours.

.LONG TERM...(Friday through Wednesday)
Issued at 359 PM MDT Wed Mar 20 2019

This negatively tilted trough will be slow to move through the
Rockies Friday through Saturday with temperatures aloft cooling as
well. This will keep instability on the moderate side and could
add to precipitation totals into Saturday afternoon before a
transitory ridge moves through. The flow becomes more westerly and
this should spread some better snow rates into the central and
northern mountains. Confidence...again time of year...is low but
could see some low end advisories across the high country. Another
system drops in behind the weak ridge by early Sunday and will
spread precipitation over the area through early Monday. Beyond
this a stronger ridge will build in and return dry and warmer
weather.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1129 AM MDT Wed Mar 20 2019

VFR conditions will persist through the day at all terminal
locations. Expect thickening clouds overnight as a system moves in
from the southwest. A few isolated snow showers will break out at
TEX after 12z.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory from 6 AM Thursday to 6 AM MDT Friday
     for COZ018.

     Winter Storm Warning from 6 AM Thursday to 6 AM MDT Friday for
     COZ019.

UT...Winter Storm Warning from midnight tonight to 6 AM MDT Friday
     for UTZ028.

&&

$$

SHORT TERM...15
LONG TERM...15
AVIATION...MAC


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