textproduct: NWS Flagstaff

SYNOPSIS

Showers and thunderstorms will continue through Tuesday night into Wednesday morning as an upper level low moves through the region. Expect dry but cool weather Wednesday and Thursday, but a chance of showers may return to the region Friday as another upper level Low moves by the area.

DISCUSSION

Slow moving trough continues to impact the region today with more showers and occasional thunderstorms moving across the state. By Tuesday a cold core upper level system drops into the state bringing colder but a bit drier air than we've seen the last few days. Many normally dry washes are running at this time and some local creeks and rivers are showing some elevated flow, but the greatest heavy rain threat is likely behind us with that drier air moving in. Will go ahead and let the Flood Watch expire at 5pm tonight.

Shower and thunderstorm chances continue Tuesday but will begin to end from west to east Tuesday night into Wednesday morning as the Low moves off to the northeast. Expect breezy conditions to continue as the polar jet wraps around the base of this trough. With the aforementioned cold air being brought with this Low, elevations above 6500-7500ft along the Rim, Kaibab Plateau and White Mountains could see some snow mix in Tuesday night/Wednesday morning. No accumulations are expected except maybe the tip top of the San Francisco Peaks. The coldest low temperatures so far this Fall are expected early Wednesday morning which will give higher elevations their first hard freeze and mid elevations their first significant frost.

After Wednesday afternoon when the last shower chances leave the state along the Arizona/Utah border expect the first real break we've seen in a few days. Things dry out but the colder air remains in the area so temperatures will be about 10 degrees below mid October averages.

Things become a bit uncertain for Friday and Saturday as models diverge on what's coming up. The trough moving away from our area takes a positive tilt and pinches off an upper level Low to our southwest located under an incoming West Coast ridge giving us a Rex Block pattern. Some models show this upper level Low bringing up some moisture from the south to give a chance for some showers and storms along the higher elevation, some models don't. For right now low grade POPs have been introduced for both those days, but this could change with newer model runs.

AVIATION...Monday 12/18Z through Tuesday 13/18Z

MVFR/VFR conditions expected for much of the period, with SCT-NUMRS -SHRA across much of the area. Periods of IFR possible in +RA and BR/low CIGS, especially over the higher terrain. Occasional TS mainly near KPRC-KPAN. Winds S 15-25 kts with gusts 30-45 kts through 02Z, subsiding to 10-20 kts overnight.

OUTLOOK...Tuesday 13/18Z through Thursday 15/18Z...-SHRA continue through 03Z Wednesday, with periods of MVFR possible. Occasional TS possible Tuesday afternoon. Periods of IFR possible in +RA and BR/low CIGS, especially over the higher terrain. Winds W/SW 10-20 kts on Tuesday, becoming N/NW 5-10 kts on Wednesday.

FIRE WEATHER...Tuesday and Wednesday

Scattered showers and occasional thunderstorms are expected on Tuesday, mainly over the higher terrain. Drier conditions are expected by Wednesday. Winds west/southwest 15-25 mph with gusts 30-40 mph on Tuesday, becoming north/northwest 5-15 mph on Wednesday.

Thursday through Saturday...Turning warmer. Mainly dry conditions, outside of a slight chance for showers and thunderstorms over the higher terrain Friday and Saturday. Winds north/northeast 15-25 mph on Thursday, becoming east on Friday. Winds subsiding to 5-15 mph on Saturday from the east/southeast.

FGZ WATCHES/WARNINGS/ADVISORIES

Flood Watch until 5 PM MST /6 PM MDT/ this afternoon for AZZ004>008-015-016-018-037-038.