textproduct: NWS Flagstaff

SYNOPSIS

Isolated showers and thunderstorms are expected today across the area, with scattered activity in northwest Arizona and the White Mountains. Storm activity will be confined to far eastern Arizona Monday before spreading back westward through next week. Temperatures will be close to normal through Labor Day, warming above normal by mid week.

DISCUSSION

Moisture has increased from south to north over our region over the past 24 hours, as deeper moisture arrives from distant Hurricane Marie (well offshore the southern tip of Baja). Precipitable water values rose from 0.73" Friday afternoon to 0.93" Saturday afternoon on the sounding here at Bellemont. This will continue today as additional moisture gets pulled northward toward a shortwave approaching the southern California coast through the afternoon. Although isolated light showers have developed early this morning from Flagstaff northwestward, model guidance still indicates the more steady band of rain later this afternoon will set up west of our forecast area, from southern California through the Las Vegas area and into far NW Arizona/SW Utah. This area coincides with the better forcing from the shortwave and higher values of low level moisture. For our forecast area, the best chance for rain today will be over northwest Coconino County, closest to the main band, with some upslope showers also possible due to moderate southwest flow over higher terrain of the Kaibab Plateau. Most other areas will see plenty of clouds limiting instability, so only isolated showers or thunderstorms are forecast today. By later tonight through Labor Day, the northwest US low pressure system will shift eastward and introduce a drier southwest flow to most of our area with rain chances less than 10%. The exception will be southern Apache County around the White Mountains where deeper moisture lingers and a 30-60% chance of showers/t-storms continues.

Tuesday through Saturday - a large ridge is forecast to stretch from Arizona to the east coast Tue/Wed but then gradually become centered over the southwest US Thursday onward. This will be favorable for a return of monsoon moisture from the east starting Tuesday and continuing through Wednesday, with 20-50% chances for storms along the higher terrain. The forecast trend of building the high right over our area Thursday and possibly even west of us by Friday continues, which could result in a downturn in storm chances along with hotter temperatures - this scenario is still uncertain so watch for updates for later next week.

AVIATION...Sunday 06/12Z through Monday 07/12Z

Expect mainly VFR conditions. Mainly BKN-OVC CIGS 09-13 kft AGL through the period. Scattered -SHRA/-TSRA through around 02Z, mainly west of a KCMR- KPGA line, with isolated activity elsewhere 18Z-02Z. Daytime winds SW-W 10-20 kts.

OUTLOOK...Monday 07/12Z through Wednesday 09/12Z...Expect mainly VFR conditions. SCT -SHRA/-TSRA Monday in southern Navajo and Apache counties, spreading NW to near KFLG by Tuesday. Daytime winds mainly SW-W 5-15 kts.

FIRE WEATHER...Today and Monday

A band of moisture from distant Hurricane Marie will bring some showers and thunderstorms in northwestern Arizona including the Grand Canyon region, with only isolated activity elsewhere. On Monday, isolated to scattered afternoon showers and thunderstorms will be confined to the eastern third of Arizona. High temperatures near normal. Winds SW-W 5-15 mph with gusts to 25 mph each afternoon.

Tuesday through Thursday...High pressure builds in from the east with increasing moisture and monsoon activity across northern Arizona. Temperatures warming to 5-10 degrees above normal. Winds S- SW 5-15 mph each day, light and variable overnight.

FGZ WATCHES/WARNINGS/ADVISORIES

None.