textproduct: NWS Flagstaff

SYNOPSIS

Increasing moisture will bring scattered showers and thunderstorms today with more isolated coverage on Friday. Dry weather is expected Saturday and much of Sunday before rain chances may increase again early next week.

DISCUSSION

At 230 PM, there are scattered thunderstorms mostly over Yavapai County. An area of low pressure over northern Mexico is drifting northward into southern Arizona. With well above average moisture remaining over our area, we expect another round of scattered showers and thunderstorms tonight, with the highest coverage (40-60%) along and south of the Mogollon Rim/White Mtns and 10-30% to the north. This is generally east of the I-17/US89 corridor. With slow storm motion and plenty of available moisture, the main threat with today's activity will be locally heavy rainfall and flash flooding. By Friday, the upper low moves northeast of our area with a drier westerly flow behind it. This will bring a decrease in storm activity, with isolated to scattered showers/storms over the eastern half of the state. Saturday is looking storm free at this time as even drier air moves in from the west.

Sunday through Monday - a trough developing along the west coast is forecast to move eastward across our region. Moisture associated with two tropical cyclones (Hurricane Polo forecast to be off the southern Baja at this time and TS Odalys much farther west) will be pulled northeastward into the southwest United States in advance of this trough. There is still plenty of model spread regarding the depth/speed of the developing trough as well as the location of the deepest moisture plume from the south. Although shower and thunderstorm chances will increase quickly by late Sunday through Monday, it's still too early to tell how heavy the rainfall might be and where the heaviest rain will be placed. Confidence has edged enough higher to place a Slight Excessive Rainfall Outlook for Monday/Monday night. The timing of the trough combining with the moisture would need to line up just right for this to happen, but it's not out of the question. Around 20-30% of the ensembles from the latest 00Z runs show a heavy rain signal (1-2"+) for our area, though almost all show at least some rainfall. Rain chances linger into Tuesday and will depend on the timing of the trough, then dry weather looks to return by mid week.

AVIATION...Friday 25/06Z through Saturday 26/06Z

Mainly VFR. ISOLD-SCT SHRA/TSRA through 03Z, mainly near and east of a KPAN-KINW line. ISOLD activity over the higher terrain possible again after 19Z. Brief MVFR conditions and gusty winds possible in and around TS. Winds VRB 5-10 kts, becoming W-S after 18Z.

OUTLOOK...Saturday 26/06Z through Monday 28/06Z...VFR conditions through 18Z Sunday, with MVFR possible in SCT-NMRS SHRA/TSRA thereafter. Daytime winds S 5-10 kts each day, becoming VRB overnight.

FIRE WEATHER...Friday through Saturday

Isolated to scattered showers and thunderstorms are expected along the Rim and mountains of eastern Arizona. Things will dry out for Saturday with no precipitation expected. Outside of storms, winds will be SW 5-10 mph on Friday, S-SW 5-10 mph on Saturday.

Sunday through Tuesday...Shower and thunderstorm chances increase on Sunday with widespread showers and thunderstorms possible on Monday. Some uncertainty remains in this portion of the forecast but the area could see some potentially heavy rain and flash flooding on Monday. Morning showers and thunderstorms remain possible Tuesday morning with some drying Tuesday afternoon. Winds SW 10-20 mph on Sunday and Monday, shifting NW-N 10-20 mph on Tuesday.

FGZ WATCHES/WARNINGS/ADVISORIES

None.