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Area Forecast Discussion
Issued by NWS Flagstaff, AZ
Issued by NWS Flagstaff, AZ
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984 FXUS65 KFGZ 162014 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 114 PM MST Fri Aug 16 2024 .SYNOPSIS...Warm and mostly dry conditions continue this afternoon, before chances for showers and thunderstorms return to northern Arizona over the weekend and into next week. && .DISCUSSION...So far today, quiet weather has been observed across northern Arizona. Satellite imagery shows some cumulus development over the White Mountains and eastern Mogollon Rim. Hi-Resolution model guidance continues to predict the development of some isolated showers and thunderstorms within the cumulus field this afternoon, with dry weather elsewhere. Surface observations in far southwest Arizona indicate that a moist southerly flow has developed there. This minor surge of Gulf of California moisture will continue to spread northward into the lower deserts and up the Colorado River basin through the evening and overnight hours. As monsoon moisture moves into northern Arizona, a corresponding increase in shower and thunderstorm activity is expected on Saturday. The greatest storm coverage is forecast to be west of a line from Prescott to Flagstaff to Page. Tomorrow`s storms will be fast moving, with storm motions to the north between 20-30 mph. However, due to the potential for training storms and the existence of several flash-flood-prone areas, a Flash Flood Watch has been issued from Saturday morning through Saturday evening for western Coconino County. We are particularly concerned about flash flooding in and around Havasupai Creek, the side canyons of the Grand Canyon, the Mangum Fire near Jacob Lake, and the various slot canyons of northwest Arizona including Water Holes and Antelope Canyon. In addition to the threat for flash flooding, strong storms capable of producing large hail and damaging winds due to the presence of moderate CAPE and deep-layer wind shear cannot be ruled out. Model guidance is generally in agreement that the subtropical high responsible for transporting moisture into northern Arizona will remain in a favorable location to keep daily chances for showers and thunderstorms going through at least the end of next week. However, spread regarding the exact location of the ridge axis grows as the week progresses. Little to no model guidance predicts a complete shutdown in storm activity, but the overall coverage and intensity of the convective activity are uncertain at this point. && .AVIATION...Friday 16/18Z through Saturday 17/18Z...Primarily VFR conditions will prevail today. Scattered TSRA possible from KSOW southeast, with dry conditions elsewhere. Winds outside of any storms, SW at 10-20 kts, becoming light after 02Z. There`s a 20-50% chance of morning showers west of KFLG after 12Z Sat. OUTLOOK...Saturday 17/18Z through Monday 19/18Z...Scattered SHRA/TSRA each afternoon/evening with coverage favoring areas from KFLG westward. Brief MVFR to IFR conditions in stronger storm cells. Away from storms, expect southerly winds 10-20 kts during the daytime. && .FIRE WEATHER...Tonight through Sunday...Scattered thunderstorms will be confined to the White Mountains today with dry conditions continuing elsewhere. Moisture and thunderstorm chances increase Saturday through the weekend. Storm coverage and the best chances for wetting rain will favor northwestern Arizona. Outside of thunderstorm outflow winds, expect southerly winds 10 to 20 mph. Monday through Wednesday...Expect daily chances for showers and thunderstorms to continue. Winds will be southwest around 10 mph or less away from any thunderstorms and/or outflows. && .FGZ WATCHES/WARNINGS/ADVISORIES... Flood Watch from late tonight through Saturday evening for AZZ004>007. && $$ PUBLIC...RR AVIATION...MCT FIRE WEATHER...MCT For Northern Arizona weather information visit weather.gov/flagstaff