637 FXUS65 KFGZ 212202 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 302 PM MST Wed Oct 21 2020 .SYNOPSIS...Dry weather to persist through Saturday, and high temperatures to continue the cooling trend. For the weekend, a potent cold front will bring gusty winds both days. The front to move across northern Arizona Sunday night and Monday, bringing very much colder temperatures. Slight chances for showers start Sunday afternoon and increase through the day Monday. Accumulating snow is probable across the high country. && .DISCUSSION... Satellite imagery this afternoon shows broken cirrus across the northeast quarter of the state. These clouds are due to an upper level shortwave (above 400 mb), that will track eastward through this evening. Aside from the decreasing cloud cover, another fair weather night is forecast. Thursday and Friday - On Thursday, a few hours of elevated fire weather conditions are possible Thursday afternoon near the Utah border due to low relative humidity and breezy westerly to southwesterly winds. The winds are due to a cold front that should stall across south central Utah Thursday afternoon. Friday looks like another fair weather day, with cooler high temperatures. Saturday through Wednesday - Progs continue to show gusty southwest-west from Saturday afternoon through Sunday afternoon ahead of a strong cold front. The forecast has gusts to 30 mph Saturday and to 35 mph Sunday. Fortunately we should see a further increase of low level humidities this weekend. We do expect a sharp change to colder and unsettled weather from Sunday through Wednesday. Forecast differences in the upper air pattern from the various models continue, and we are more confident in the ECMWF family and GFS ensemble mean forecasts. These show a cold frontal passage from north to south across Arizona in the Sunday night / Monday time frame. On Monday, a closed low pressure system is shown to set up over western Arizona, where it then lingers through Tuesday night. The operational GFS is much faster with the trough passage out of Arizona on Tuesday, and discounted at this time. We are confident that gusty winds this weekend that could affect any new wildfire starts. Afternoon max temperatures to be near normal for the date Saturday and then dropping around 10 degrees each day Sunday and Monday. Precipitation chances start Sunday afternoon, with the highest chances for precip Monday and Monday night. Shower chances continue Tuesday and are highest east of a Jacob Lake to Prescott line. There is less confidence in storm total liquid and snow accumulation's as well as snow levels. This afternoons forecast has a rain and snow shower mix, or all snow showers, north of line from Flagstaff to Window Rock by sunrise Monday. All are encouraged to monitor our forthcoming forecasts as new data comes in and tweaks are made. && .AVIATION...For the 00Z package...VFR conditions will continue over the next 24 hours. Light winds overnight will become southwest at 10-15 kt gusts 20-25 kt Thursday afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect dry weather through Friday. For Thursday, expect slightly cooler temperatures and higher humidity, with values remaining above 15% along and south of the Mogollon Rim area. A few hours of elevated fire weather conditions are possible Thursday afternoon near the Utah border. Saturday through Monday...The cooling trend continues. On Saturday and Sunday, gusty southwest winds are expected as a cold is forecast to move across the area Sunday night and Monday. Shower chances start Sunday afternoon and increase through Monday. Wetting precip amounts are possible on Monday, with snow at the higher elevations. WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...DL AVIATION...DL FIRE WEATHER...DL For Northern Arizona weather information visit weather.gov/flagstaff