textproduct: NWS Flagstaff

SYNOPSIS

One last winter storm system will impact the area overnight/early this morning. Periods of heavy snow and strong southwest winds expected, but look for improving conditions west to east by this afternoon/evening. Cold temperatures will quickly follow the exit of this shortwave, but warmer/drier conditions will return Sunday onward.

DISCUSSION

Pre-frontal showers are on-going mostly along I-40 and southward, but activity will continue through the overnight hours and should still ramp up in intensity once the front moves through early this morning. AZ511.com is already indicating slowed traffic along I-40 between Seligman and Winona and similarly along I-17 between Flagstaff and Camp Verde. Travel conditions will remain hazardous through the early morning hours today, so either give yourself plenty of extra time or consider adjusting your plans if possible. Hi-res guidance has been consistent with forecasting the bulk of our snow accumulation from this last system between now and 5 AM MST. Afterwards, most of the activity will be focused along the eastern Rim, White Mountains, and Chuska Mountains, with improving conditions elsewhere. As a result of these winter weather conditions, a Winter Storm Warning is in effect for the Kaibab Plateau and Western Mogollon Rim until 5 AM MST today, and a Winter Weather Advisory is in place for the Coconino Plateau, Yavapai County Mountains, Grand Canyon Country through 5 AM MST today as well. Areas falling in the Warning could see new snow accumulation between 2-6", with locally higher amounts up to 8". And locations under the Advisories may see new snow totals of 1-4". These totals will once again be difficult to accurately measure due to the blowing snow concern where southwest winds gusting 35-45 mph will be present. Just another reason why travel conditions will be rough overnight/this morning, due to poor visibilities from blowing snow. And speaking of wind, a Wind Advisory is in effect for the Little Colorado River Valley in Apache County and White Mountains until 5 PM MST this evening, where gusts up to 55 mph will be possible.

Once this system pushes eastward out of the state later this evening, cold temperatures will quickly settle in. Widespread below freezing morning lows anticipated for Friday night/Saturday morning with many locations dipping into the single digits. Afternoon temperatures look to remain chilly for much of the High County where daytime highs may not surpass the 30s. On the bright side, an area of high pressure should quickly build across much of the West Coast Sunday onward, allowing above normal temperature and dry conditions to return.

AVIATION...Friday 20/12Z through Saturday 21/12Z

A cold front stretches from KPRC - KFLG - K0V7 around 12Z and will continue to move east this morning. Expect areas of IFR/LIFR in SHSN along and ahead of the front, as well as SW winds 20-30 kts gusting 30-40 kts. Snow levels around 3,000 to 4,000 ft MSL along the cold front passage this morning. Behind the front, expect improving conditions with gradually clearing CIGS and winds shifting to the W. VFR returns area-wide after 18Z. Winds largely decrease this afternoon, but will continue to gust near 35-40 kts across far eastern AZ through 00Z.

OUTLOOK...Saturday 21/12Z through Monday 23/12Z...VFR conditions are anticipated as high pressure builds. Plan on light easterly winds, 5-15 kts, on Saturday followed by light east-northeast winds on Sunday.

FIRE WEATHER...Friday and Saturday

A winter storm system and cold front will bring rain and snow across the area early this morning, with clearing by late morning. Expect accumulating mountain snow with light snow possible down to around 4000 feet. Strong southwest winds 20-30 mph gusting 40 to 50 mph will continue this morning. Winds decrease and shift to the west behind the cold front passage, but will remain gusty across eastern Arizona through the day. Dry weather returns Saturday with light east to northeast winds 5-15 mph.

Sunday through Tuesday...Expect dry weather and a significant warming trend for this period. Light easterly winds Sunday and Monday turn west-southwest around 10-20 mph Tuesday.

FGZ WATCHES/WARNINGS/ADVISORIES

Winter Storm Warning until 5 AM MST early this morning for AZZ004-015.

Winter Weather Advisory until 5 AM MST early this morning for AZZ006>008.

Wind Advisory until 5 PM MST this afternoon for AZZ014-017.

Winter Weather Advisory until 8 AM MST this morning for AZZ016.