textproduct: NWS Flagstaff

SYNOPSIS

A few showers and thunderstorms will continue near the New Mexico border and far northern Arizona through this evening, with much drier air moving in from west to east for the weekend. Expect warm high temperatures and cold overnight low temperatures over the weekend, as shower chances disappear. This may last through Monday, before unsettled weather returns for the rest of next week.

DISCUSSION

Low pressure moving through the northern Rockies today will continue to push a drier air mass eastward into our region. This is reflected in the satellite precipitable water estimates showing PW values falling to <0.50" over the high country compared to 0.80"+ yesterday at this time. Enough moisture lingers over the far eastern portions of the forecast area (Apache County) for some isolated to scattered thunderstorm activity later this afternoon, and some of this could produce additional localized heavy rain. Also, as the trough axis swings by to our north later this evening, a few showers or storms could develop north of I-40 to the AZ/UT line, and a 10-30% PoP is in the forecast in that area. By Saturday and Sunday, models show continued drying as westerly flow persists. Precipitable water values fall even more, to under 0.30" for most locations with dewpoints in the 20s and 30s. Pleasant daytime temperatures close to normal will be followed by some cool nights. With these lower dewpoints, expect some high elevation locations to fall into the 30s overnight, with near-freezing temperatures Sat-Mon mornings at the typical cold spots (Bellemont, Tusayan, Ft. Valley).

Monday through Tuesday - a low pressure system is forecast to cross west to east across the region. Much of the guidance has it tracking through southern NV into UT Monday night into Tuesday. Most of Monday is looking dry at this time, with rain chances entering the forecast Monday evening in NW Arizona, spreading eastward through the night and into Tuesday. Moisture return ahead of the trough looks sufficient for some showers and thunderstorms to develop, but forecast PW values are nothing like we saw earlier this week so the threat of heavy rainfall/flooding is fairly low. The exception may be right along the AZ/NM state line as deeper moisture in New Mexico could be drawn in to that area so that is something to watch. Wednesday through Friday - majority of ensemble members indicate high pressure strengthening over the south central United States, with south-southwest flow aloft over our area. Moisture values are forecast to remain sufficient for daily thunderstorm chances, currently in the 20-50% range each day. Daytime temperatures forecast to be within a few degrees of normal.

AVIATION...Friday 18/18Z through Saturday 19/18Z

Expect VFR conditions. SCT -SHRA/-TSRA near the NM border this afternoon, then ISOLD near the UT border this evening. Winds are SW 10-15 kts gusting near 20 kts through 03Z, then light and VRB overnight.

OUTLOOK...Saturday 19/18Z through Monday 21/18Z...Expect VFR conditions. ISOLD -SHRA/-TSRA near the NM border on Saturday, then fully dry on Sunday. Winds are SW 10-15 kts gusting near 20 kts each day, light and VRB during the overnight periods.

FIRE WEATHER...Saturday and Sunday

Turning much drier this weekend. Very isolated showers possible along the AZ-NM border on Saturday, then fully dry on Sunday. Expect much colder overnight lows, especially Saturday night. Winds are southwest 10-20 mph each day.

Monday through Wednesday...Chances for showers and thunderstorms return by Monday evening and continue through Tuesday and Wednesday. Best chances each day will be across far eastern AZ. Winds are south through southwest 5-15 mph on Monday and Tuesday, then light and variable on Wednesday.

FGZ WATCHES/WARNINGS/ADVISORIES

None.