582
FXUS65 KFGZ 200248
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
748 PM MST Thu Sep 19 2024

.SYNOPSIS...Seasonably cool temperatures remain through Saturday,
before warmer temperatures return next week. A cold front will
bring a chance for showers and possibly thunderstorms to the area
late Friday into Saturday, with otherwise dry conditions expected.

&&

.UPDATE...A few high clouds are drifting into the region ahead of
our next low pressure system, currently centered over southern
California. Seasonable temperatures and dry weather will continue
overnight with no forecast updates needed. See the discussion
below for more on the expected impacts of this approaching low.

&&

.PREV DISCUSSION /431 PM MST/...Arizona remains under a mild
southerly flow ahead of a Pacific low pressure system moving
southward along the California coast. A mild and breezy day is
underway with wind gusts peaking around 25-30 mph this afternoon.
A band of upper level clouds is migrating northwest across the
state. Similar conditions can be expected through the early part
of Friday, but as the closed upper low begins to move eastward
toward Arizona, we`ll see the chance for showers/thunderstorms to
develop across western Arizona Friday afternoon.

The low is forecast to gradually move northeastward across the
state Friday night through Saturday. The main changes today are a
slightly slower movement of the low, which prolongs precipitation
chances through Saturday afternoon, and a continued upward trend
in precipitation chances. Ensemble membership today is even more
supportive of precipitation with fewer members showing zero
precipitation. The best rain chances and accumulation potential
remain generally along and north of a Prescott to Window Rock
line. Precipitation amounts will most likely remain less than 0.25
inches. Given the strength of the low, we can`t rule out an
isolated strong or severe storm, but the precipitation looks to
mostly lag behind the better shear profiles. Some very light snow
is possible over the highest mountain peaks above 10,000-11,000
ft. Saturday will be the coolest day yet this season in response
to the trough passage and shower activity. Daytime temperatures
will be about 7-10 degrees below normal.

Sunday begins a warming trend that will last through next week as
the dominant weather feature becomes a strong ridge building over
the west. The one exception is a shortwave trough passage near
the four corners that could bring some additional wind and
chances for showers on Tuesday. Some model guidance this morning
indicates a stronger trough passage with additional precipitation
potential, so we`ll have to keep an eye on this trend.

&&

.AVIATION...Friday 20/00Z through Saturday 21/00Z...VFR conditions
persist. Expect south-southwest winds 10-20 kts through 02Z,
becoming variable under 10 kts overnight. South-southwest winds
increase again after 18Z Friday with speeds 10-20 kts and gusts
20-30 kts. There is a slight chance of a light shower west of a
KPRC-KPGA line after 22Z.

OUTLOOK...Saturday 21/00Z through Monday 23/00Z...Cloud cover
increases from west to east on Friday night through mid day
Saturday, with chances for -SHRA and an isolated -TSRA. Greatest
chances will be along and west of a KPRC-KFLG-KPGA line. Showers
could linger throughout Saturday near the AZ/UT border before
ending by sunset. VFR conditions with SKC return on Sunday.
West-northwest winds 10-20 kts on Saturday, then variable winds
mostly 10 kts or less for Sunday.

&&

.FIRE WEATHER...Friday and Saturday...Clouds increase throughout the
day on Friday as a low pressure system begins to move through from
west to east. Seasonal temperatures will remain on Friday with
scattered showers and isolated thunderstorms developing later in the
day. Precipitation chances persist overnight and into Saturday as
temperatures cool. Anticipate southerly winds, 15 to 30 mph, for
Friday afternoon, followed by west-northwest winds, 10 to 25 mph, on
Saturday.

Sunday through Tuesday...A warming and drying trend develops on
Sunday and continues on Monday. Afternoon humidity is forecast in
the 10 to 20% range on Monday. Humidity increases on Tuesday with a
10 to 15% chance of precipitation. Light west to north winds, under
15 mph, are likely on Sunday and Monday, followed by northerly
winds, 10 to 20 mph, on Tuesday.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

PUBLIC...JJ/MCT
AVIATION...JJ
FIRE WEATHER...LaGuardia

For Northern Arizona weather information visit
weather.gov/flagstaff