604
FXUS65 KFGZ 162253
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
353 PM MST Mon Sep 16 2024

.SYNOPSIS...Gusty winds area wide, and chances for showers and
thunderstorms across the eastern half of the state will continue
through tonight. Mostly dry, cool, and breezy weather then returns
on Tuesday through much of the week.

&&

.DISCUSSION...A sharp dividing line between a very dry air mass and
deeper moisture lies near the I-17/US89 corridor this afternoon.
Surface dewpoints to the east of this line are in the 50s while
west of the line readings in the 20s and 30s are common. Showers
and a few thunderstorms continued overnight southeast of a Payson
to Window Rock line, with some moderate rainfall amounts measured
in the White Mtns region (just over 0.50" in Pinetop-Lakeside to
nearly an inch on the southern slopes of the White Mountains).
With the approach of the upper low and some meager daytime heating
we are seeing additional shower and thunderstorm development east
of the I-17/US89 corridor and this is expected to continue
through early evening before being confined mainly east of Payson-
Window Rock line overnight through around sunrise Tuesday. With
the combination of increased deep-layer wind shear due to the
approaching trough and higher instability in northeast Arizona,
there is a chance for some isolated strong/severe thunderstorms
this afternoon and early evening north of I-40 and east of a
Winslow-Kayenta line. The main threats would be strong wind gusts
and hail up to 1" diameter. The other story today in the gusty
southwest winds due to the low to the west, gusting 40-50 mph for
much of northern Arizona. A Wind Advisory remains in effect
through 7 PM.

Tuesday afternoon through Friday - as the first low departs to the
northeast, another one dives down the west coast to central
California by Wednesday, then across Utah and northern AZ by
Friday. This timing is a bit slower than earlier forecasts
indicated, so the low chance of light showers north of I-40 has
been pushed back to Friday. Otherwise, temperatures (both highs
and lows) will be 5-10 degrees below seasonal averages through
this period, with some near to slightly below freezing morning
temperatures for the favored high country locations (Bellemont,
Tusayan, Ft Valley).

Saturday and Sunday - there`s a low chance that some light showers
could linger in northeast AZ early Saturday depending on how fast
the low departs, but otherwise high pressure is forecast to build
in from the west for the weekend. As a result, warmer and less
breezy weather is expected.

&&

.AVIATION...Tuesday 17/00Z through Wednesday 18/00Z...Isolated to
scattered SHRA/TSRA are forecast to persist east of a KPAN-KFLG-
KOV7 line through around 02Z, then confined east of a KPAN-KRQE
line through around 15Z Tuesday morning. MVFR conditions and hail
are possible with any stronger storms that develop. Outside of
storms, expect southwest winds 15-25 kts with gusts 30-40 kts.
Wind speeds decreasing after 02Z but remaining elevated at 10-20
kts overnight. Winds increase again after 16Z, becoming southwest
15-25 kts gusting 25-35 kts. There is a 30% chance that some
localized MVFR cigs will develop over high terrain areas including
KGCN/KFLG between 06Z and 15Z Tuesday.

OUTLOOK...Wednesday 18/00Z through Friday 20/00Z...VFR conditions
expected. On Wednesday and thursday, south-southwest winds at
10-20 kts gusting 20-30 kts.

&&

.FIRE WEATHER...This evening through Wednesday...Scattered showers
and thunderstorms are expected through Tuesday morning, mainly
east of a Payson to Page line. Drier weather will arrive by Tuesday
afternoon. South to southwest winds at 10-20 mph will persist
tonight through Tuesday, with gusts of 25-35 mph during the
afternoon. Southwesterly gusts 20-30 mph Wednesday afternoon.

Thursday through Saturday...Remaining cool, breezy and mostly dry.
Another low pressure system could bring a few showers to northwest
Arizona late Thursday or Friday. Look for southwest winds at 10-20
mph gusting to 30 mph Thursday and Friday, becoming light northerly
by Saturday for most areas.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM MST /8 PM MDT/ this evening for
AZZ004>009-012-013-015-016-038>040.

&&

$$

PUBLIC...JJ
AVIATION...JJ
FIRE WEATHER...JJ

For Northern Arizona weather information visit
weather.gov/flagstaff