textproduct: NWS Flagstaff

SYNOPSIS

Seasonable temperatures will persist through the end of the week, before slightly cooler conditions return this weekend/next week. Isolated to scattered showers/storms forecast for today and Thursday, with much drier conditions returning Friday onward. Critical fire weather conditions expected this weekend.

DISCUSSION

Light showers overnight brought increased cloud cover this morning/early afternoon, keeping our convective activity at bay for the time being. The 15Z HRRR run of the U of A WRF model suggests thunderstorms picking up later this afternoon into the evening hours, but this will likely depend on how much clearing we start to see here. Not to mention a band of light to moderate showers is currently extending from New River up to Tuba City and migrating eastward, so a large portion of our CWA may be too worked over for any major build up later this afternoon. Additional showers/storms are still in the forecast for tomorrow afternoon, but recent model guidance suggests majority of activity being focused along and north of the Mogollon Rim. This increase in moisture is thanks to an area of high pressure centered over southern New Mexico.

Friday through Sunday...Strong winds and dry conditions will be the main topic over the weekend due to a large area of low pressure moving in from the Pacific Northwest. This disturbance will bring elevated southwest winds and low relative humidities. As a result, a Fire Weather Watch is still in place for Friday morning through Sunday evening for the entirety of our CWA. The latest NBM suggests widespread wind gusts generally between 30-40 mph Friday and Sunday, with the strongest winds Saturday afternoon mostly between 35-45 mph. Localized areas downwind of higher terrain could see gusts closer to the 50-55 mph range too. So between the potential for new fire starts with any lightning activity today and/or tomorrow, and the low RH values and gusty winds this weekend, critical fire weather conditions will be the main story this weekend. Do your part and obey all fire restrictions!

Into next week a broad trough will still remain over much of the West Coast, but pressure gradients appear to loosen up allowing winds to return to more typical breezy southwest winds. Daytime highs will also gradually climb back up, but still remain below normal for this time of year.

AVIATION...Wednesday 24/18Z through Thursday 25/18Z

Mainly VFR, brief MVFR possible near heavier showers/storms. Scattered showers and storms possible areawide today, with the main focus becoming north of the Mogollon Rim after 21-23Z. Most of the state dries out overnight, but isolated showers and thunderstorms remain possible along the Arizona Utah border. Areas of haze or smoke are possible along the Arizona Utah border overnight into tomorrow morning from local fires. Winds SW-W 10-20kts, gusts 25-30kts daytime, light and variable or terrain driven overnight.

OUTLOOK...Thursday 25/18Z through Saturday 27/18Z...Mainly VFR conditions, brief MVFR possible Thursday from showers/storms. Expect scattered showers/storms midday Thursday to Friday evening. Drying out across most of the state Friday but an isolated shower/storm is possible along the Arizona/New Mexico border. Areas of haze/smoke may be possible from local wildfires along the Arizona/Utah border. Winds SW 10-20kts, gusts 25-30kts Thursday, SW 15-25kts, gust 30-40kts Friday.

FIRE WEATHER...Thursday and Friday

Chance for showers and thunderstorms Thursday, mainly from the Mogollon Rim northward. Isolated showers or thunderstorms possible along the Arizona/New Mexico border Friday, drying out elsewhere. Fire Weather Watch is in effect for all of northern Arizona Friday due to increasing winds and decreasing humidity. Winds SW 10-20 mph, gusting 25-30 mph Thursday, SW 15-25 mph, gusts 30-40 mph Friday. Minimum afternoon RH 15-30% Thursday, 10-20% Friday.

Saturday through Monday...Fire Weather Watch continues Saturday and Sunday for higher winds and low humidity. Dry weather with no precipitation expected. Winds SW 20-30 mph with gusts 40-50 mph on Saturday, subsiding slightly on Sunday to SW 15-25 mph with gusts 35- 45 mph, dropping to SW 10-20 mph, gusts to 30 mph on Monday. Minimum afternoon RH values each day as low as 7-10% northeastern desert regions to 15-20% Rim and White Mountains .

FGZ WATCHES/WARNINGS/ADVISORIES

Fire Weather Watch from Friday morning through Sunday evening for AZZ104>118-137>140.