682
FXUS65 KFGZ 151611
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
911 AM MST Sun Sep 15 2024

.SYNOPSIS...A few showers will be possible in eastern Arizona
this morning with mainly dry weather elsewhere. Cooler weather
with chances for showers and thunderstorms will move in later
today and continue through Monday, with the best chance of rain
over the eastern half of the state. Look for breezy weather today
with windy conditions on Monday. Dry but cool and breezy weather
then returns on Tuesday and for much of next week.

&&

.UPDATE...Scattered showers and thunderstorms developed early this
morning between 400 and 730 AM over portions of Apache County,
including Eagar-Springerville, St Johns, and Window Rock as
increased moisture interacted with a passing shortwave. This
activity has moved into New Mexico, with dry weather as of 9 AM
area wide. For the rest of today, isolated to scattered showers
and thunderstorms are expected to redevelop mainly east of a
Payson-Kayenta line with daytime heating. Later tonight, as the
main low pressure system approaches, low level winds are forecast
to back and pull some additional moisture north and west.
Instability should increase, and scattered showers and
thunderstorms are forecast by most CAMs to develop and move up
into Gila, southeast Coconino, and Navajo/Apache counties through
the overnight hours. With 0-6km wind shear in the 35-40 kt range,
a few strong to possibly severe storms could develop, along with
some training cells producing localized heavy rainfall. PoPs were
increased in these areas for the overnight hours in an update
this morning. The other thing we are watching for Monday as the
low approaches is strong gusty southwest winds (unrelated to
storms). With gusts in the 35-45 mph range forecast by the latest
guidance, we may be issuing a Wind Advisory from around
Winslow/Flagstaff northwestward for Monday afternoon.

&&

.PREV DISCUSSION /623 AM MST/...A trough continues to approach Arizona
from over the Pacific Ocean with some moisture streaming northward
in advance of the trough. The moisture from the south is still
coming but not quite as much as we were previously forecasting.
We`ll need to dial back our expectations with most decent rainfall
amounts confined to the area along and south of a line extending
from Payson to Window Rock. The highest precipitation amounts of
0.50 to 1.00 inches look to be located along the eastern Mogollon
Rim and White Mountains region southward.

Today...Mainly isolated and brief showers across most of northern
Arizona. The highest moisture values and best chances for showers
will be from Payson to Window Rock southward, especially with
daytime heating. But even then only a 30 to 40 percent chance of
showers and thunderstorms for a given location. Otherwise, look
for cooler temperatures under the influence of the approaching
trough. In addition, pressure gradients will be strengthening with
afternoon southwest winds at 10 to 20 mph gusting to 30 mph
across much of the area.

Tonight and Monday...Increasing moisture from the south and
residual boundary layer instability from the previous days heating
will interact with passing large-scale upward motion associated
with the approaching trough. As a result, we will see the best
chance for showers and thunderstorms later tonight into Monday,
especially over eastern portions of Arizona. There will remain the
limited threat of a stray severe thunderstorm and localized
flooding. As the trough axis draws nearer anticipate additional
cooling. Pressure gradients strengthen further on Monday with
southwest winds at 15 to 25 mph gusting to 30 to 40 mph
developing, with the stronger gusts located from the Mogollon Rim
northward.

For Tuesday and much of next week...Some moisture will linger
over the White Mountains region for a slight chance of showers and
thunderstorms on Tuesday. Otherwise, mainly dry and seasonably
cool temperatures are forecast. The potential for below freezing
temperatures at elevations above 6500 feet will enter the picture
starting Wednesday with the drier air mass. It will remain breezy
to windy as an additional mainly dry trough heads our way toward
the end of next week. There could be a few showers across
northwest Arizona and along the Utah border later next week but at
this time don`t appear to amount to more than a few hundredths of
an inch.

&&

.AVIATION...Sunday 15/12Z through Monday 16/12Z...Mainly VFR
conditions persist through the period with FEW-SCT cloud cover
near 11,000 feet MSL. Cloud cover increases east of a KPAN-KOV7
with isolated to scattered -SHRA/-TSRA. Variable winds of 5 kts
will become southwest winds, 15-25 kts, from 17Z-02Z.

OUTLOOK...Monday 16/12Z through Wednesday 18/12Z...ISLD-SCT
-SHRA/TSRA through Monday with greatest chances across eastern
 Arizona. Winds increase again Monday with gusts 25-35tks.
 Widespread VFR conditions are expected Monday night and Tuesday
 with mostly clear skies. Southwest winds will remain elevated on
 Tuesday, 20-30kts.

&&

.FIRE WEATHER...Today through Monday...Moisture increases from the
south resulting in isolated to scattered showers and thunderstorms
into Monday. Greatest coverage will be across east-central
Arizona. Cooler temperatures are expected, becoming 5 to 10 degrees
below average on Monday. Breezy southwest winds, 15 to 25 mph,
today will increase to 30 to 40 mph on Monday.

Tuesday through Thursday...Cooler, breezy, and mainly dry. Another
low pressure system could bring a few showers to northwest Arizona
Thursday. Southwest winds 15 to 25 mph each day.

&&

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

&&

$$

PUBLIC...JJ/McCollum
AVIATION...MAS
FIRE WEATHER...JJ

For Northern Arizona weather information visit
weather.gov/flagstaff