textproduct: NWS Flagstaff

SYNOPSIS

Cold and unsettled weather will develop for the rest of the week, with widespread rain and snow into this evening and additional shower chances each day through Saturday. Brief periods of moderate to heavy snow will be possible this afternoon and evening in the higher elevations. High pressure begins to build back into Arizona early next week, with dry and warmer weather expected.

UPDATE

Rain and snow showers were gradually decreasing in coverage during the evening hours, much as forecast. The remainder of the night most locations will see a continued decreasing trend in showers. The exception will be the Black Mesa, Four Corners and Utah border area where the passing low center will keep a more active snow shower regime through the night. The current forecast package appears on top of these trends and we will let it stand for now.

PREV DISCUSSION /457 PM MST/

A cold longwave trough covers the western US this afternoon, with an embedded shortwave rotating through western Arizona headed eastward. Widespread showers have developed over much of northern Arizona, with the highest coverage so far from Yavapai County up to the Mogollon Rim into western Coconino County. There is enough instability for isolated thunderstorms as this activity spreads northward through this evening. These vigorous snow showers will cause sudden drops in visibility as well as snow covered roads at times, especially as we get later into the afternoon. Road surface temperatures have kept the snow from accumulating on the roadways so far, but this may change as showers get heavier and the late afternoon sun angles get lower. By late evening and overnight, the focus will shift to the northern 1/3 of the state as the initial shortwave moves to near four corners by sunrise Thursday. There will still be some scattered upslope snow showers at times along the Mogollon Rim. A general 2-5" snowfall is forecast through Thursday morning along the Mogollon Rim to the Kaibab Plateau and the northeast AZ high terrain. Thursday - another shortwave rotates into northern Arizona from the northwest, bringing additional showers especially during the afternoon. A few thunderstorms will be possible once again. Temperatures will be slightly warmer with this one, so additional snow amounts will be a trace to 2" above 6000 feet and may melt off between showers. The low remains over our region Friday with another round of rain and snow showers and light accumulation above 6500 feet. Finally by Saturday the low moves east of the state, with some lingering showers mainly along the AZ/NM state line. Starting Sunday and continuing into at least the middle of next week, high pressure will lead to dry and much warmer weather.

AVIATION...Thursday 03/06Z through Friday 04/06Z

Widespread SHRA/SHSN are gradually tapering off. Lingering MVFR-IFR VIS and CIGS expected overnight. Ceilings could even drop to LIFR over higher terrain. Shower activity picks up again after 18Z, bringing further periods of MVFR-IFR through Thursday evening. Winds are VRB less than 10 kts tonight then W-SW 5-15 kts tomorrow. Gusty/erratic winds could occur near showers.

OUTLOOK...Friday 04/06Z through Sunday 06/06Z...Chances for spotty SHRA/SHSN bringing MVFR-IFR conditions continues Friday. Showers also possible Saturday with the best chances along higher terrain in far eastern AZ. Winds are N-NW 5-15 kts on Friday, then N 10-20 kts on Saturday. Winds are light and VRB or terrain driven during the overnight periods.

FIRE WEATHER...Thursday through Friday

Scattered rain and snow showers remain in the area both days. Best chance for wetting rain or snow water equivalent amounts on Thursday is the Western Mogollon Rim and Kaibab Plateaus, with the White Mountains seeing a better chance for wetting rain or snow water equivalent on Friday. Winds will be W-SW 5-15 mph on Thursday, switching to N-NW 5-15 mph on Friday. Some brief gusty and erratic winds are possible near showers. Minimum RH values 35-60% each afternoon.

Saturday through Monday...A chance of rain and snow showers hangs around on Saturday with the eastern mountains of the state seeing the best chances. Things begin to dry out Sunday, with temperatures warming back to seasonal averages Sunday onward and above average towards midweek. Winds N 10-20 mph Saturday, NW 5-15 mph Sunday, then W-SW 5-15 mph Monday.

FGZ WATCHES/WARNINGS/ADVISORIES

None.