textproduct: NWS Flagstaff

SYNOPSIS

Windy weather continues today. The next round of showers is expected this afternoon into Tuesday, with the highest chances tonight. Accumulating snow is possible above 6000 feet tonight into Tuesday morning which could lead to slick travel conditions. Another round of windy weather is expected Thursday, followed by cooler temperatures Friday as a weather system passes to our north.

DISCUSSION

A closed low is dropping into southern California this afternoon, and will move northeastward across our region this evening into early Tuesday morning. Ahead of this low, southwest winds have increased to 15-25 mph with some gusts 30-45 mph. A Wind Advisory continues until 8 PM MST from the Mogollon Rim/White Mtns northeastward. As the low moves closer this afternoon, isolated rain showers are expected to develop. Instability is limited, so only isolated thunderstorms are possible. By later this evening and overnight, the closed low moves across our region, bringing an increase in shower activity from west to east. Colder air with the system will drop snow levels as low as 6000-6500 feet by mid to late evening, including portions of I-40/I-17 and Hwy 180/64 up to the Grand Canyon. Precipitation rates may be briefly heavy, with general snowfall accumulation of 1-3" forecast along the western parts of the Mogollon Rim (Flagstaff region), Kaibab Plateau, and higher parts of the Black Mesa/Chuska Mtns. Forecast amounts farther east along the Mogollon Rim into the White Mtns have trended down, with under an inch in our latest package. By sunrise Tuesday, the low will be in southeast Utah and moving out of our area. Some lingering rain and snow showers are expected mainly along the AZ/UT state line, with isolated showers later in the afternoon down to the Mogollon Rim but impacts will be minimal by that time. Daytime highs Tuesday will be around 10 degrees below normal for mid April.

Wednesday - a shortwave ridge moves in, bringing temperatures back near normal and lighter winds. Thursday and Friday - another trough is forecast to pass by to our north, bringing windy (gusts 35-45 mph) but continued mild weather Thursday followed by cooler temperatures Friday. It still looks like the trough passes too far north for precipitation in Arizona, with PoP values less than 10% along the northern border Friday. Very dry air behind this shortwave and decreasing winds could lead to some of the coldest temperatures we've seen in well over a month on Saturday morning at high country locations. For example, our current forecast low Sat AM is 20F at Flagstaff and the last time it was that cold was March 8th. If you live above 6000 feet you may want to think about protecting any outside plants and/or disconnecting hoses. The rest of the weekend looks dry with a warming trend.

AVIATION...Tuesday 14/00Z through Wednesday 15/00Z

Mainly VFR conditions with MVFR conditions in scattered -SHRA/-SHSN moving from west to east through 12Z. Periods of IFR are possible in SHSN over the higher terrain. ISO showers possible through 00Z/Wed. Lingering MVFR CIGs through 15Z, then mainly VFR expected. S-SW winds 15-25 kts with gusts 30-40 kts through 03Z, becoming SW 10-20 kts. Locally higher gusts of 30+ kts possible along a KSOW- KSJN line overnight. Winds become W 5-15 kts gusting to 25 kts after 16Z.

OUTLOOK...Wednesday 15/00Z through Friday 17/00Z...VFR conditions. SW winds 5-15 kts on Wednesday, increasing to 10-20 kts with gusts to 30 kts on Thursday.

FIRE WEATHER...Tonight through Wednesday

Showers will spread across northern Arizona this afternoon through the evening, with snow levels dropping to 6000-6500 ft overnight. General snow accumulations of a trace amounts to 3 inches are anticipated. Isolated showers linger through Tuesday afternoon, then dry conditions return on Wednesday. Winds are west at 10-20 mph gusting to 30 mph on Tuesday, then southwest through west 5-15 mph on Wednesday.

Thursday through Saturday...Dry through the period. Winds are southwest at 10-20 mph gusting 25-35 mph on Thursday, shifting northwest on Friday, then variable 5-15 mph on Saturday. Minimum RH is 10-20% on Thursday and Friday, then 10-15% on Saturday.

FGZ WATCHES/WARNINGS/ADVISORIES

Wind Advisory until 8 PM MST /9 PM MDT/ this evening for AZZ009- 012>017-039-040.