textproduct: NWS Flagstaff

SYNOPSIS

Mild and dry weather is forecast through Thursday. Cooler, more unsettled weather looks to return for Friday and the weekend.

DISCUSSION

A dry westerly zonal flow will remain over Arizona through Thursday before a Pacific trough delivers unsettle weather over the weekend.

For today through Thursday...With zonal flow aloft fair weather is forecast, with mild temperatures and dry conditions. As the end of the week trough approaches Arizona, look for increasing mid- to high-level clouds from Wednesday into Thursday. As far as the winds, a very weak shortwave trough brushing Arizona on Tuesday will deliver southwest winds a 10-20 mph during the day. Lighter winds on Wednesday behind the weak shortwave will be followed by stronger southwest winds on Thursday as the more substantial weekend trough approaches.

From Friday into early Monday...A strong Pacific trough will move across the western states tapping into subtropical moisture. Friday will see the first chance for precipitation as a shortwave trough interacts with increasing moisture to produce scattered showers and isolated thunderstorms. We are expecting the Friday rain event to remain on the light side with liquid equivalent amounts ranging from 0.05 to 0.40 inches. Severe thunderstorms are no expected. Moisture will continue to increase on Saturday but with no large-scale upward forcing the main source of lift will be in the form orographic assent where .05 to 0.15 inches of precipitation are expected over the mountain areas of northern Arizona. There could be a few drips Halloween night so plan accordingly. The Friday/Saturday system will be relatively warm with any accumulating snow likely confined to above 9000 feet. The main body of the Pacific trough will move through from Sunday into Monday. Strong large scale lift, moderate upslope flow and subtropical moisture will combine for widespread showers and isolated thunderstorms. At the current time we are looking at rainfall totals ranging from 0.50-1.50 inches with the second, stronger trough, but this is apt to change as forecast amounts could go higher with subtropical moisture in play. The air mass will remain mild with accumulating snow levels remaining largely above 9000 feet.

Later next Monday and for most of next week...Fair and dry weather returns under high pressure.

AVIATION...Tuesday 27/00Z through Wednesday 28/00Z

VFR conditions. Localized MVFR due to HZ/FU possible for sites near prescribed burns. Light and variable or terrain driven winds overnight, then becoming S-SW 5-15 kts after 18Z.

OUTLOOK...Wednesday 28/00Z through Friday 30/00Z...VFR conditions. Daytime winds S-SW 5-15 kts, becoming light and variable or terrain driven overnight.

FIRE WEATHER...This afternoon through Wednesday

Dry conditions and gradual warming through Wednesday. Light and variable winds this afternoon, becoming south/southwest 5-15 mph during the daytime Tuesday and Wednesday.

Thursday through Saturday...Max daytime temperatures will hold steady Thursday and then decreasing slightly Friday and Saturday. The chances for showers and thunderstorms start to increase late Thursday and continue to increase Friday and Saturday. South/southwest 10-20 mph on Thursday through Saturday.

FGZ WATCHES/WARNINGS/ADVISORIES

None.