textproduct: NWS Flagstaff

SYNOPSIS

Strong gusty winds are expected into this evening ahead of a cold front, along with areas of critical fire weather conditions. Chances for rain and high elevation snow showers increase later tonight and into Monday morning, mainly across far northern Arizona. Cooler and breezy conditions remain on Monday, before gradually warmer and less windy conditions return for the remainder of the week.

DISCUSSION

A vigorous shortwave trough and associated cold front was centered over Nevada midday Sunday, rapidly approaching Arizona. For the remainder of today through Monday afternoon strong winds and near-critical to critical fire weather conditions will be the main concern. For this afternoon into the early evening, look for sustained winds of 15-25 mph across all of northern Arizona, with late afternoon/early evening gusts to 45-55 mph over the higher terrain of Yavapai County and from the Mogollon Rim northward. Lower elevations to the south will see gusts in the 30-40 mph range. As a result, much of northern Arizona is under a Wind Advisory into the evening hours. Gusty winds will then linger through the night at 10-20 mph but with gusts of 30-40 mph along and downwind of terrain features. Monday will see the strongest winds shifting eastward with gusts of 35-45 mph likely along and east of a Winslow to Four Corners line. Along with the wind, afternoon and early evening relative humidity values ranging from 10-15% across the northeast corner of Arizona will result in dangerous fire weather conditions with a Red Flag Warning in effect.

In addition, the fast moving shortwave will come with moderately strong upward motion. Moisture will be drawn northward today into this evening as the trough approaches but generally will not be enough to produce any showers. The exceptions, the strongest lift and coldest air mass aloft will be along the Arizona/Utah border and this combined with orographic lift over the Kaibab Plateau and Black Mesa could produce a few showers, generally less than 0.10 inches of liquid equivalent. There might even be a brief period of snow showers above 7000 feet toward the Utah border with only minor/brief accumulations. Also, there may be just enough moisture for a few light showers over the western Mogollon Rim where orographic lift will be quite strong with a few brief snow showers possible over the San Francisco Peaks.

From Tuesday onward...Weak trough will remain over Arizona. With each passing day look for warming daytime temperatures as the air mass slowly moderates, climbing to slight above seasonal average by Thursday or Friday. Nothing special about the winds just the fairly typical west to southwest winds at 10-20 mph each afternoon.

AVIATION...Sunday 17/18Z through Monday 18/18Z

Mainly VFR conditions, although brief MVFR is possible along the Arizona/Utah border region where light rain showers are possible between 00Z and 18Z. Winds S-SW 20-30kts, gusts 40-50kts and will stay elevated throughout the night before calming down to SW-NW 10-20kts after 12-15Z.

OUTLOOK...Monday 18/18Z through Wednesday 20/18Z...VFR conditions, no precipitation expected. Daytime winds SW-NW 10-20kts, gusts 25 to 30kts Monday, variable 5-15kts Tuesday. Light and variable or terrain driven overnights.

FIRE WEATHER...Monday and Tuesday

Slight chance for light rain/snow showers early Monday morning across far northern Arizona, otherwise dry and cooler with temperatures 5 to 10 degrees below mid May averages. Wetting precipitation from these showers is not expected. Winds W-NW 10-20 mph with gusts 25-35 mph on Monday, variable winds 5-15 mph on Tuesday. Minimum afternoon RH 10-30% Monday, dropping to 8-20% on Tuesday.

Wednesday through Friday....Dry conditions with temperatures gradually warming to seasonal averages. Winds SW-NW 5-15 mph Wednesday and Thursday, SW-W 10-20 mph on Friday. Minimum afternoon RH 5-15% each afternoon.

FGZ WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 8 PM MST /9 PM MDT/ this evening for AZZ104>106-109>114-116-117-139-140.

Wind Advisory until 8 PM MST /9 PM MDT/ this evening for AZZ004- 006>009-011>017-038>040.