textproduct: NWS Flagstaff

SYNOPSIS

Moisture begins to return to the region by this evening, with a chance of showers and thunderstorms especially in northwest Arizona. More widespread precipitation is expected Tuesday, along with breezy southerly winds. Uncertainty increases Wednesday onward, but daily shower and thunderstorm chances remain in the forecast through the work week, highest in eastern Arizona.

DISCUSSION

After a dry weekend, we will start to see some changes in the pattern beginning today. An upper low just offshore the California coast will move just north of Las Vegas by this afternoon and then northeast through Utah on Tuesday. By late this afternoon through the overnight hours, an increase in instability primarily northwest of Flagstaff will result in a 30-50% chance of showers and thunderstorms. Moisture levels are not impressive with this initial round of showers, so generally light rainfall amounts are expected. By Tuesday, precipitable water values increase significantly across eastern Arizona bringing a 40-60% chance of showers/thunderstorms. Isolated storms will be possible farther west. By Tuesday night through Wednesday - a plume of deep moisture is forecast to move northward into New Mexico, with eastern Arizona on the fringes of the plume. A disturbance moving northward out of Mexico should enhance precipitation chances especially in eastern Arizona - with a marginal risk of flash flooding included in the latest WPC outlooks now including areas as far west as Prescott/Flagstaff, though the heaviest rainfall is expected to be east of the AZ/NM state line. Thursday - weak troughing off the southern CA and Baja coasts is forecast to shift northeastward, pulling some deeper moisture farther west to include most of northern AZ. There is still uncertainty in this scenario, but Thursday currently looks like the highest rain chances (30-60%) for areas farther west including Coconino/Yavapai counties. The overall heavy rain/flood threat is low, with only isolated areas of heavy rain. Friday through the weekend - isolated to scattered showers and thunderstorms remain in the forecast, though the details remain uncertain.

AVIATION...Monday 21/12Z through Tuesday 22/12Z

Primarily VFR conditions. ISO-SCT -SHRA/-TSRA returns late this afternoon and evening, with the best coverage across northern Coconino county. Winds are SW-W 5-15 kts from 17Z-02Z, light and VRB or terrain driven overnight.

OUTLOOK...Tuesday 22/12Z through Thursday 24/12Z...Primarily VFR conditions. SCT-NMRS SHRA/TSRA across Navajo and Apache counties, ISO-SCT elsewhere. Localized MVFR in heavier precipitation. Daytime winds are S-SW at 10-20 kts gusting to 25 kts Tuesday, then light/variable mainly 10 kts or less Wednesday.

FIRE WEATHER...Today and Tuesday

Shower and thunderstorm chances return starting this evening. Best chances are across northwest AZ this evening and overnight, then across eastern AZ on Tuesday. Winds are south through southwest 10-15 mph on Monday, increasing to 10-20 mph gusting to 25 mph on Tuesday.

Wednesday through Friday...Chances for showers and thunderstorms continue each day, declining slightly on Friday. The best chances will be seen across eastern Arizona each day. Winds outside of thunderstorm activity are forecast to be generally light, 10 mph or less.

FGZ WATCHES/WARNINGS/ADVISORIES

None.