390
FXUS65 KFGZ 192023
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
123 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.

&&

.DISCUSSION...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...Thursday 19/18Z through Friday 20/18Z...VFR conditions
persist through the period with variable cloud cover. Expect
south-southwest winds 15-25 kts through 01Z, becoming variable
under 10 kts thereafter.

OUTLOOK...Friday 20/18Z through Sunday 22/18Z...Cloud cover
increases from west to east on Friday with chances for -SHRA and
an isolated -TSRA late Friday through Saturday morning. Greatest
chances will be along and west of a KPRC-KFLG-KPGA line. Showers
could linger throughout the day on Saturday near the AZ/UT
border. Widespread VFR conditions with SKC returns on Sunday.
Anticipate south-southwest winds 15-30 kts on Friday, followed by
west-northwest winds 15-25 kts on Saturday.

&&

.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...MCT
AVIATION...LaGuardia
FIRE WEATHER...LaGuardia

For Northern Arizona weather information visit
weather.gov/flagstaff