textproduct: NWS Flagstaff

SYNOPSIS

Isolated showers and thunderstorms continue through Friday, with higher coverage across eastern AZ. An increase in storm coverage is expected into the holiday weekend. Expect breezy southwest winds through the end of the week, along with slightly below normal temperatures.

DISCUSSION

A large and persistent trough is still present, currently centered over the Pacific Northwest with a trough axis extending along the west coast. This has generally brought a drier southwest flow that has limited storm activity over the past few days, and will continue to be an influence today. However, moisture does begin to creep up from the south in far eastern AZ. The result will be scattered showers and thunderstorms mainly across the White Mountains and Eastern Mogollon Rim this afternoon/evening, with very isolated activity elsewhere. The west coast trough will also keep us under a tight pressure gradient aloft, and continued breezy southwest winds with gusts up to 35 mph are expected (especially towards western AZ). On Thursday evening/Friday morning, there is potential for storm activity to continue overnight across eastern AZ. This is a very uncertain setup, and will be highly dependent on how convection evolves during the day in southeastern AZ. Agreement remains low among CAMs, but the overall forecast calls for a 30-50% chance of showers and thunderstorms during this period. Moisture continues to trend upwards on Friday, with similar placement and slightly higher chances of storms. On Saturday and Sunday, the forecast remains in flux as the details of Hurricane Marie evolve. The west coast trough will remain strong through this period, but moisture from Marie begins to get wrapped into the southwest flow. Many ensemble members bring an enhanced surge of PW across western AZ, while eastern AZ continues to experience a moist southerly flow. The details still vary on the exact placement and timing of the deepest moisture. Overall, the forecast calls for storm chances gradually increasing on Saturday then peaking on Sunday/Monday. As we move into next week, thunderstorm chances continue each day.

AVIATION...Thursday 03/18Z through Friday 04/18Z

Mainly VFR conditions. Scattered SHRA/TSRA east of a KPAN-KRQE line, isolated elsewhere. Nocturnal activity may continue tonight into Friday morning east of a KPAN-KRQE line, but confidence remains low. Between 10Z-15Z local MVFR ceilings possible along a KFLG-KSOW line. Otherwise, afternoon winds southwest 10-20 kts gusting to 30 kts. Overnight winds remaining locally gusty 20-25 kts west of a KPAN-Four Corners line.

OUTLOOK...Friday 04/18Z through Sunday 06/18Z...Mainly VFR conditions. Scattered SHRA/TSRA activity continues mainly for the eastern portions Friday afternoon, possibly becoming more widespread heading into Saturday. Winds daytime Friday southwest 10-20 kts gusting to 30 kts, then overnight Friday local gusts to 20 kts continuing. Saturday will see lighter winds at 5-15 kts gusting to 20 kts.

FIRE WEATHER...Thursday and Friday

Drier and breezy across western AZ, increasing moisture across eastern AZ. Scattered thunderstorms are expected each day across the White Mountains and Eastern Mogollon Rim, which chances for activity to continue overnight. Isolated storms elsewhere. Winds are southwest 10-20 mph with gusts up to 35 mph, strongest in northwest AZ. Daytime highs slightly below normal.

Saturday through Monday...Increasing moisture will cause shower and thunderstorm coverage to expand across most of northern AZ. Highest chances for rainfall will be seen on Sunday and Monday. Winds are expected to decrease, becoming south through southwest 5-15 mph each day. Max daytime temps are expected to remain near or just below normal, but will depend on storm and cloud coverage during the day.

FGZ WATCHES/WARNINGS/ADVISORIES

None.