Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 191022

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
422 AM MDT Mon Mar 19 2018

.SHORT TERM...(Today through Tuesday)
Issued at 422 AM MDT Mon Mar 19 2018

The storm system which brought snow to the area over the past
twenty-four hours continued to shift eastward across the southern
Plains early this morning. Meanwhile, snow persisted over the
northern, and portions of the central Colorado mountains early
this morning despite the absence of large scale dynamic forcing.
Regardless, the combination of steep lapse rates and orographic
lift provided by moderate northwest flow were sufficient to
sustain snowfall over the northern and central Colorado mountains.
Though snowfall rates will decrease this morning, models
indicated moisture and orographic forcing will continue to
generate snowfall well into the morning before snowfall becomes
more scattered this afternoon. Therefore, will keep the Winter
Weather Advisories going over the Elkhead, Park, Gore, and Elk
Mountains through midday. However, will drop advisories a couple
of hours early for the Grand Mesa, West Elk and Sawatch Mountains
with this package as snowfall had become light and scattered over
those ranges. Except for the lower elevations east of a KCAG to
KRIL to KASE line this morning, expect dry conditions today with
partly cloudy to mostly sunny skies.

Instability showers were indicated to linger over the northern
Colorado mountains tonight, though coverage and intensity will
continue to decrease. GFS maintains this activity through Tuesday
afternoon while the NAM and ECMWF finally bring an end to
convective showers Tuesday morning. Given model differences, held
onto slight chances of snow for the higher terrain of northeast
Utah and northwest Colorado through Tuesday afternoon. Elsewhere,
dry weather will continue.

Expect temperatures to remain cool today and tonight, running
from 5 to 10 degrees below seasonal norms. Temperatures trend
upward Tuesday with highs approaching normal for most locations
during the afternoon.

.LONG TERM...(Tuesday night through Sunday)
Issued at 422 AM MDT Mon Mar 19 2018

A weak ridge will allow for steady warming through the middle
portion of the week over the western slope. As the ridge axis
passes on Wednesday afternoon, guidance suggests enough
saturation in the mid and upper levels to possibly squeeze out a
few orographic showers in the highest terrain of the central and
northern mountains. Flow turns southwesterly on Thursday as a
notable atmospheric river event comes ashore along the California
Coast. Moisture from this event spills into the Four Corners
region by late in the day on Thursday. Temperatures will be quite
warm ahead of this system, as is typical for these kind of
events, with highs in the mid-60s in the lower elevations and
700mb temperatures in the +2 to +5C range throughout most of the
mountains as precipitation begins. Precipitable Water normalized
anomalies climb to 4 to 5 Sigma by Thursday evening, and remain
in this general range through Friday afternoon. The 0z GFS has
come in a bit wetter as far as surface QPF is concerned, in
comparison to the past several deterministic runs. This appears to
be due to a slight southward shift to the overall AR plume. These
kinds of swings will likely continue over the next few days of
model cycles and will ultimately determine what ranges see the
most liquid out of this event. Guidance suggests this system will
exit by Friday evening with ridging moving in for Saturday and a
dry start to this coming weekend, before another storm of Pacific
origins skirts the central and northern mountains on Sunday.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 422 AM MDT Mon Mar 19 2018

Light snow remains possible over KHDN, KEGE and KASE through 15Z
resulting in MVFR CIGS and VSBY with brief IFR VSBY. In the
absence of snow this morning, CIGS are likely to linger below ILS
breakpoints at these sites as late as 18Z. After 18Z, these TAF
sites will have VFR conditions through the next 18 hours.
Elsewhere, expect VFR conditions throughout the next 24 hours.



CO...Winter Weather Advisory until noon MDT today for COZ004-010-013.




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