textproduct: NWS Flagstaff

SYNOPSIS

Scattered showers will continue in northeast Arizona, mainly this morning, with dry conditions elsewhere. Expect dry, cool, and breezy weather Thursday and Friday. A chance of showers may return to the region Friday night through the weekend.

DISCUSSION

An upper low is centered over northwest Arizona early this morning, and is forecast to move to near 4 corners by mid day and off into Colorado by afternoon. Instability and lift with the low will produce scattered showers and a few thunderstorms, mainly this morning, primarily north of I-40 but focused in northeast Arizona. With colder air moving in, snow levels will be around 7000 feet, with some light accumulation above 7500-8000 feet from the Kaibab Plateau to the Chuska Mountains. The ADOT cam at Jacob Lake (7900 ft) shows a dusting of snow as of 130 AM. By this afternoon, showers and isolated thunderstorms will be focused in far northeast Arizona, ending by sunset. Elsewhere around the region, look for gradually clearing skies today with northwest breezes 10-15 mph and highs 10-15 degrees below normal. The early mornings will also be chilly across the region the next couple days, and a Freeze Warning continues through 8 AM this morning for the western half of Coconino County including Flagstaff, Williams, and Grand Canyon North and South Rims.

Thursday through Friday - a weak upper low is forecast to cut off from SW Arizona to northern Baja, with strong surface high pressure diving southward to our east through the Rockies and plains states. This will produce tight east/northeast pressure gradients in our region, leading to gusty winds. Sustained speeds of 20-30 mph with gusts 35-45 mph are currently forecast for much of the region, peaking Thursday evening into Friday. The strongest winds in this pattern are typically along and just south of the Mogollon Rim and Yavapai County mountains. Some moisture could also move back into the region from the southeast by Friday night into the weekend, and a low (10-20%) chance of showers and thunderstorms is included in our latest forecasts. Rain chances may increase as we get closer, depending on the track of the weak upper low as it ejects northeastward over the weekend and possible interaction with deeper moisture associated with Tropical Cyclone Simon. The official NHC forecast for Simon weakens it to a depression in the central Gulf of California by Sunday. While most of the ensemble guidance keeps the deeper moisture to our east, a small percentage bring it farther west, so this will be something to monitor. Daytime highs look to stay below normal into the weekend. Next week is looking unsettled as another low pressure system is forecast to set up off the California coast and eventually move into our area with additional rain chances.

AVIATION...Wednesday 14/12Z through Thursday 15/12Z

Isolated to scattered -SHRA/-TSRA north of a KPGA-KRQE line through 22Z, with otherwise dry conditions. Localized MVFR ceilings some higher terrain areas through around 16Z, including near KGCN. West- northwest winds 5-15 kts, becoming northeasterly after 02Z.

OUTLOOK...Thursday 15/12Z through Saturday 17/12Z...VFR conditions expected. Look for NE to E winds 15-25 kts, gusting 30-40 kts, from Thursday afternoon through Friday evening. Winds will gradually decrease by 12Z Saturday.

FIRE WEATHER...Today through Thursday

Scattered showers will continue in north central and northeast Arizona today, with dry conditions elsewhere through Thursday. Winds becoming north/northwest 5-15 mph today, then northeast 15-25 mph with gusts 30-40 mph on Thursday and continuing overnight. Daytime temperatures 10-15 degrees cooler than normal.

Friday through Sunday...Slight chance for showers and thunderstorms over the higher terrain Saturday and Sunday. Winds are east 15-25 mph with gusts 30-45 mph on Friday, subsiding to 10-20 mph from the east/southeast on Saturday, then light and variable by Sunday. Daytime temperatures 5-10 degrees cooler than normal.

FGZ WATCHES/WARNINGS/ADVISORIES

Freeze Warning until 8 AM MST /9 AM MDT/ this morning for AZZ004- 006-007-015.