textproduct: NWS Flagstaff

SYNOPSIS

Expect additional rain and snow showers moving from west to east from this evening into early Friday morning. Snow will be heavy at times. Strong south through southwest winds will once again be present, creating blowing and drifting snow concerns. A variety of Winter Weather Advisories and Winter Storm Warnings are in effect tonight through early Friday. Milder and dry weather then returns over the weekend and into next week.

DISCUSSION

Shower activity is on pause across northern AZ for now, as our third and final round of winter weather looms. Activity will resume in the form of upslope showers along the Mogollon Rim and Kaibab plateau in the mid to late afternoon, then continue to ramp up as moisture advection increases ahead of an approaching cold front. The most intense and widespread period of showers is expected as the frontal band moves west to east. Current timing has the heaviest reaching western Coconino county and the Kaibab around 7-9 PM, the Flagstaff area around 10 PM-12 AM, then White Mountains and Chuskas around 3-5 AM MST. The heaviest activity will continue for a few hours at any one location. Showers look to move past the I-40 I-17 interchange by 5 AM, and fully clear out of far eastern AZ by the late morning. It's important to note that there is potential for this timing to be a few hours earlier or later depending on how progressive the front is. Strong winds will once again accompany this system, though not quite as strong as yesterday. Gusts 45-55 mph are possible especially along the front, so blowing snow is once again a concern.

This system will be the coldest yet, and snowfall will reach into lower elevations. The highest snow accumulations are expected in the Flagstaff Area with 3-6'' locally up to 8'', as well as the Kaibab Plateau with 4-8'' locally up to 12''. A Winter Storm Warning will be in effect tonight for these areas, especially with the added hazard from strong winds. We still anticipate impactful winter weather outside of these zones, and Winter Weather Advisories are in effect for the Eastern Mogollon Rim, Grand Canyon Country, Coconino Plateau, and Yavapai County Mountains with accumulations generally 1-4'' and strong winds. Trace accumulations are possible as low as 4000'. Expect travel delays on Friday morning due to slick/snow covered roads.

There isn't much to talk about after this system moves through. Showers fully end by the late morning and winds diminish through the evening. Very cold temperatures are expected on Saturday morning, down to the low teens or single digits across the high country. Ridging begins to build this weekend through early next week, dry conditions with warming temperatures are forecast. Daytime highs are expected are to return above normal by Monday.

AVIATION...Thursday 19/18Z through Friday 20/18Z

Expect VFR through 01Z-04Z Friday, then areas MVFR/IFR/LIFR spreading from west to east overnight through early Friday. Flight restrictions caused by SHSN/SHRA/CIGS/BR/FZFG. Expect rapid improvement from west to east after daybreak Friday morning. Sfc winds S-SW15-25g30-40kts from early Thursday afternoon through the night Thursday night. Winds decrease rapidly Friday morning.

OUTLOOK...Friday 20/18Z through Sunday 22/18Z...Lingering MVFR/IFR/LIFR over Apache County through early Friday afternoon. Otherwise, expect VFR conditions through the weekend. Expect sfc winds SW-W15-25kts through Friday afternoon, primarily east of a KPAN-KFLG-KPGA line. Winds generally not impactful AFT 19Z-23Z Friday.

FIRE WEATHER...Friday and Saturday

Areas of rain and snow will move west to east across the district tonight, through late Friday morning. Strong and gusty southwest winds from 20 to 30 mph, with gusts over 50 mph, will also develop overnight. Most winds decrease and turn westerly later on Friday. Rain and snow showers will also end Friday afternoon, with clearing skies into the evening.

Saturday through Monday...Expect fair skies and a warming trend for this period, especially Sunday and Monday.

FGZ WATCHES/WARNINGS/ADVISORIES

Winter Storm Warning until 5 AM MST Friday for AZZ004.

Winter Weather Advisory until 5 AM MST Friday for AZZ006>008.

Wind Advisory from midnight tonight to 5 PM MST Friday for AZZ014-017.

Winter Storm Warning from 8 PM this evening to 5 AM MST Friday for AZZ015.

Winter Weather Advisory from 8 PM this evening to 8 AM MST Friday for AZZ016.