textproduct: NWS Flagstaff

SYNOPSIS

A couple of disturbances are expected to bring winter weather conditions to much of northern Arizona through the end of the week. Gusty winds also likely, especially today. Mild weather looks to return for the weekend and into next week.

DISCUSSION

Today will hold the second shortwave of the series we've been mentioning the last several days. This disturbance is anticipated to be more impactful than the first we experienced yesterday. This system will come in colder than the last, gradually dropping snow levels west to east throughout the day. These lower slow levels will allow for areas down to 5000' to receive accumulating snowfall later this afternoon during the heaviest of the precipitation. Accumulation amounts down to this level will be minimal, but a dusting to an inch or so is not out of the question. Locations generally above 6000-6500' will be the areas with more impactful snow amounts. Our forecast remains consistent with snow totals between 4-10" for the Kaibab Plateau and Mogollon Rim, which aligns with our Winter Storm Warning that goes into effect at 5 AM MST. We also have a Winter Weather Advisory for the Coconino Plateau, Grand Canyon Country, Yavapai County Mountains, Black Mesa, Chuska Mountains, and Defiance Plateau where new snow accumulation looks to be 1-5". Slick roads will likely be present this morning, but with the bulk of the precipitation falling this afternoon/evening, travel later in the day will be more hazardous. Not only will roads become quickly snow covered, but visibilities will greatly reduce with gusty winds causing blowing snow concerns. Southwest winds are already elevated currently with gusts between 25-35 mph across many areas of the High Country. These winds will only strengthen throughout the day, where gusts could reach 50-60 mph. Not only will these winds create poor visibilities with falling snow, but localized power outages could also be a concern.

A brief break in precipitation is expected between shortwave number 2 and shortwave number 3. The timing of this final shortwave has slightly trended later, but we are still expecting impacts Thursday evening into Friday afternoon. With snow total amounts remaining fairly consistent over the last few model runs, a Winter Storm Watch was issued for Thursday evening through Friday afternoon for the Mogollon Rim and Kaibab Plateau. This last disturbance will be the coldest of the series, so additional lower elevation snow accumulation is likely, but the Watch was focused over areas of greatest concern for impactful snowfall. Over the next day or so, this product will likely be upgraded and/or expanded. Or if model guidance decided to do a complete 180, it could also be cancelled. Elevated winds also look to be present with this last wave where gusts could reach 35-45 mph. Definitely check back for additional details on this last system, but might be wise to start thinking about adjusting any potential travel plans Thursday evening/Friday afternoon.

Once this last shortwave exits the region, cold and dry conditions will return. Widespread single digit to low teens low temperatures expected for Saturday morning, with daytime highs landing 5-10 degrees below normal to kick off the weekend. High pressure looks to build by Sunday and into the beginning of next week, so afternoon temperatures will gradually recover to a few degrees above normal by Monday.

AVIATION...Wednesday 18/18Z through Thursday 19/18Z

Look for widespread SHSN/SHRA spreading eastward through the afternoon, with areas of IFR/LIFR conditions and blowing snow. General clearing expected after 00Z from west to east but with isolated MVFR/IFR conditions continuing over mountain areas. Areas of BLDU with visibility down to 1-2SM near KINW through early afternoon. South to southwest winds generally 25-35 kts with gusts 35-45 kts. Locally higher gusts 50-60 kts along and north of a KIGM-KPRC- KSOW line through 00Z. Winds weaken after 00Z, becoming south to southwest at 10-20 kts with gusts 20-30 kts into the evening and then light overnight. Areas of MVFR ceilings redeveloping after 12Z over higher terrain from KFLG north and west.

OUTLOOK...Thursday 19/18Z through Saturday 21/18Z...Mainly VFR conditions through 21Z Thursday with patchy MVFR ceilings KFLG northwest. After 21Z Thursday, worst impacts expected, especially between 00Z-18Z Friday with areas of IFR/LIFR conditions in +SN/+RA and blowing snow. Southwest to west winds 10-20 kts with gusts to 30 kts on Thursday, increasing to 15-25 kts with gusts 30-40 kts on Friday. Diminishing winds Friday night.

FIRE WEATHER...Today through Thursday

Expect widespread rain/snow to develop form west to east through the day. A wintry mix down to 4500 feet is possible with higher elevations seeing snow. Accumulations of 4-8 inches will be possible along the Mogollon Rim and over the Kaibab Plateau above 6000 feet with lesser amounts elsewhere. Scattered showers will linger thereafter, with another round of widespread showers returning Thursday evening. Winds southwest through west 20-35 mph gusting 40-55 mph locally to 60 mph today, then 10-20 mph gusting to 30 mph Thursday.

Friday through Sunday...Chances for rain and snow showers continue through Friday afternoon, with snow levels dropping as low as 3500- 4000 feet. Fair weather looks to return for Saturday and Sunday. Southwest to west winds at 15-25 mph gusting to 35 mph are forecast on Friday, then variable at 5-15 mph for Saturday and Sunday.

FGZ WATCHES/WARNINGS/ADVISORIES

Winter Storm Warning until 8 PM MST this evening for AZZ004-015- 016.

Winter Storm Watch from Thursday afternoon through Friday morning for AZZ004-015-016.

Winter Weather Advisory until 7 PM MST this evening for AZZ006>008-011-039.

Wind Advisory until 7 PM MST this evening for AZZ009-010.

High Wind Warning until 7 PM MST this evening for AZZ012>014-017- 040.