Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 152250

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
450 PM MDT Thu Mar 15 2018

Issued at 444 PM MDT Thu Mar 15 2018

Updated to increase showers and thunderstorms this evening over
western CO. The best uplift moved into western CO and helped spawn
numerous showers and isolated thunderstorms.


.SHORT TERM...(Tonight through Friday night)
Issued at 211 PM MDT Thu Mar 15 2018

Regional satellite imagery showed quite a bit of low topped
convection developing in response to a large upper level trough
across western Colorado and eastern Utah. As the main brunt of
the forcing moved overhead, RADAR and lightning data showed this
activity was increasing in strength. Temperatures have held steady
in the upper 40s to low 50s across the area. Increasing showers
and thunderstorms should hold temperatures near this point the
rest of the afternoon.

Higher up in the mountains, most of the precipitation is expected
to fall as snow. Winter Weather Advisories went into effect at
noon today and will continue until 9 am Friday. 4 to 8 inches of
storm total accumulation is expected across much of the area.
Locally higher amounts near 10 inches are possible under any
convective structures that setup later this evening. While
instability is not particularly high, cold 500 mb temps near -25C
and strong vertical wind shear will continue to keep low topped
convective activity going into this evening. The NAM Nest in
particular showed a large SW to NE oriented swath of higher QPF
possibly associated with a banded convective structure developing
on RADAR this afternoon. Models want to push this band slightly
further east near the Grand Mesa northeast toward the Flat Tops
later this evening. Will have to watch this for higher storm
totals through this afternoon and evening. Things will die down
quickly Friday afternoon and evening as the first wave exists to
the east. This quick break wont bring much change in airmass
compared to Thursday, with temperatures in the low 50s to upper
40s for the valleys and the 30s for the mountains.

.LONG TERM...(Saturday through Thursday)
Issued at 211 PM MDT Thu Mar 15 2018

A second upper level trough will begin to swing through Saturday
afternoon, bringing the area another round of rain and snow. The
winds on Saturday across northern Colorado and Utah look to be
quite strong. A developing surface low and strong jet overhead
seem likely to produce a few 40kt gusts in Colorado Zones 01/02
and Utah Zone 23. In addition, sustained southwesterly at
23-27kts look to fall within Wind Advisory criteria Saturday
afternoon. This system also looks a touch colder than the last,
with the cold front pushing through on Sunday. High temperatures
will fall off, lowering snow levels Sunday morning and afternoon.
As such, another decent round of widespread mountain snowfall
appears possible through the weekend.

Precip should end overnight Monday with temperatures on a slight
warming trend through the first part of next week. The upper level
trough hangs out to the west and will eventually send another
storm through late next week and weekend. Details are pretty hazy,
but another round of winter-like precip could be possible through
next weekend as an active storm track continues.


.AVIATION...(For the 00Z TAFS through 00Z Friday afternoon)
Issued at 444 PM MDT Thu Mar 15 2018

Scattered to numerous showers with isolated thunderstorms will
continue through about 04Z this evening, then taper off. Expect
lowered CIGS/VSBY in showers with periods of heavy valley rain or
mountain snow. Brief MVFR and IFR CIGS and VSBYs are expected at
KEGE, KRIL, KASE and KTEX with ILS breakpoints will be reached at
times where heavier showers occur. Mountains will be obscured
through the period. Showers will linger over the mountains
through Friday morning before conditions improve after 12Z Friday.


CO...Winter Weather Advisory until 9 AM MDT Friday for COZ004-009-010-



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