textproduct: NWS Flagstaff

SYNOPSIS

Breezy winds and chances for high-based showers arrive today with cooler and unsettled weather returning through the middle of the week.

DISCUSSION

A low pressure system centered off the California coast early Sunday morning is expected to gradually make its way across the southwest United State over the coming days.

For today...A weak shortwave trough will spin off the California low and move across Arizona. In response, the flow across Arizona will turn more southerly with an associated increase in moisture. In addition, the shortwave trough will have some weak upward motion and cooler mid-level air associated with it. The result will be the development of a slightly unstable atmosphere as daytime heating progresses. Look for a 20-30% chance of showers and thunderstorms mainly focused from the Interstate-40 corridor northward this afternoon into the evening. Showers will be fairly high based with this activity today with only a few hundredths of measurable precipitation anticipated. Along with the trough will be strengthened pressure gradients for south to southwest winds at 10-2o mph locally gusting to 30 mph. Mild daytime highs will continue.

On Monday...The weak trough heads eastward to be replace by a shortwave ridge. The California low will draw closer ushering in a cooler air mass along with strengthening pressure gradients. Consequently, Monday is expected to see dry, windy and cooler weather. Winds will be stronger on Monday generally south to southwest at 15-25 mph with gusts of 30-40 mph. Also mid- to high- level clouds spinning off the low will deliver partly to mostly cloudy skies. Daytime temperatures are expected drop by 5-10 degrees compared to Sunday.

From Tuesday into Wednesday...The center of the California low will move across Arizona from west to east. The low will bring with it even cooler air aloft along with another round of upward dynamics which will interact with lingering moisture. As a result, we're looking at a good chance of showers on Tuesday focused from the Mogollon Rim northward. The threat of thunderstorms will arrive in the afternoon as daytime heating helps create additional instability. The low weakens and moves to the southeast on Wednesday with only a lingering slight chance of showers and thunderstorms. Showers will amount to a bit more than on Sunday with storm total precipitation in the 0.10-0.20 inch range forecast. Daytime temperatures will drop another 5-10 degrees with the passing low. Winds will remain breezy from the southwest on Tuesday but as the low weakens and moves to the southeast lighter northwest winds will develop on Wednesday.

From Thursday onward...Generally dry and warmer as a shortwave ridge moves across our area from Thursday into Saturday.

AVIATION...Sunday 03/12Z through Monday 04/12Z

Expect VFR conditions. Isolated to scattered -SHRA from 19Z-02Z, mainly to the north of I-40. A stray thunderstorm possible from KGCN northward. Winds becoming S to SW at 10-20 gusting to 30 kts after 18Z. Winds diminishing after sunset.

OUTLOOK...Monday 04/12Z through Wednesday 06/12Z...Expect mainly VFR conditions. Dry conditions on Monday will be followed by scattered -SHRA and isolated -TSRA on Tuesday. Brief and heavier showers may produce local MVFR conditions over higher terrain. Daytime winds SW at 15-25 kts gusting to 30-35 kts Monday and Tuesday, the slightly higher speeds favoring Monday afternoon.

FIRE WEATHER...Today and Monday

A slight chance of showers is forecast today from the Mogollon Rim northward with dry conditions arriving on Monday. Winds south/southwest at 10-20 mph gusting to 30 mph today, increasing to 15-25 mph with gusts 30-40 mph on Monday. Minimum RH in the 15-30% range each afternoon.

Tuesday through Thursday...Scattered showers are forecast across much of northern Arizona on Tuesday, with activity lingering into Wednesday. Look for dry weather to return on Thursday. Winds south/southwest at 10-20 mph on Tuesday, becoming west/northwest at 5-15 mph on Wednesday, then variable on Thursday.

FGZ WATCHES/WARNINGS/ADVISORIES

None.