096
FXUS65 KFGZ 160545
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1045 PM MST Wed May 15 2024

.SYNOPSIS...Scattered showers and isolated thunderstorms this
evening will diminish and shift eastward overnight. Rain and
thunderstorm chances remain Thursday for portions of northern and
northeast Arizona. High pressure returns Friday through the
weekend, resulting in breezy, warm, and drier conditions.
Unsettled weather returns next week.

&&

.UPDATE...Scattered showers persist across northern Arizona this
evening. Despite extensive cloud cover to end the day and the
loss of daytime heating, instability remains due to cooler air
aloft. CAPE values from the afternoon upper-air sounding (launched
at 4:30 PM MST) show around 300-400 J/kg with RAP presenting
200-500 J/kg across much of the area (at 8:30 PM MST), allowing
for ongoing thunderstorm activity. A few updates were made to the
forecast PoPs to track current observations and the latest CAMs.
Rain chances this evening will decrease overnight into the early
morning both with regards to coverage and probability. The low`s
center has progressed and now resides along the southern border of
Arizona. Water vapor satellite imagery shows drier air beginning
to enter the northwestern portion of the state as the trough and
low continue their trek eastward. These are early signs of
decreasing chances for showers and storms tomorrow. Don`t expect
as active of a day on Thursday with most of the rainfall and
convection occurring east of Flagstaff.

&&

.PREV DISCUSSION /433 PM MST/...The closed low along with a
longwave trough to the northeast are working in conjunction to
bring showers and thunderstorms to a good portion of northern
Arizona. Mostly light westerly winds are being impacted
significantly by the erratic gusts from the scattered storms. A
few of the stronger storms have produced wind gusts of 40 to 50
mph as outflow boundaries propagate in various directions. Be
aware, thunderstorms do not have to be directly overhead to bring
hazardous winds and/or lightning. These gust fronts continue to
trigger additional activity, tapping into the 250-500 J/kg of CAPE
across the area. Most of the gauges where precipitation has
fallen thus far have recorded only a few hundredths of an inch.
However, heavier showers are impacting localized areas along the
Mogollon Rim, Coconino Plateau, and Black Mesa with radar
indicated QPE of 0.5" to 1.25". Additional isolated strong storms
and rainfall will continue to be possible, especially over high
terrain.

Tonight through Thursday...The scattered showers and storms will
continue through the afternoon and evening hours before shifting
eastward as the low to our south tracks eastward. More isolated to
widely scattered showers and convection will linger overnight,
primarily relegated to Navajo County and Apache County. While the
dynamics will not be nearly as conducive for precipitation
Thursday, the ECMWF and GFS show a small shortwave ripple through
eastern Arizona. This wrinkle in the atmosphere along with left
over moisture will allow for a slight chance of rain. The best
chances will be along the Arizona/New Mexico border and White
Mountains (20-35%) that will extend along the Mogollon Rim as far
west as the Flagstaff area (10-15%). Much of western Arizona is
expected to remain dry tomorrow with diminishing cloud cover. Once
again, widespread heavy rainfall is not forecast with
precipitation amounts of less than 0.1" likely.

Friday through Sunday...By Friday, an upper-level ridge will begin
to form across the Southwest U.S., leading to a warming and drying
trend that will extend through the weekend. Afternoon highs will
be roughly 5 degrees above average each day. Winds do strengthen
out of the southwest, becoming breezy each afternoon as a longwave
trough to our north pushes against the ridge, tightening pressure
gradients. Overall, winds are forecast to remain below advisory
levels with gusts of 25 to 35 mph expected.

Monday through Wednesday...More unsettled conditions are expected
as models show a trough pushing into the region to start next
week. There is low confidence that this system will have the
moisture required to bring precipitation to Arizona. Anticipate
another increase in the already breezy west-southwest winds along
with temperatures cooling to near to just below seasonal norms.
These winds along with drier conditions will push us towards near
critical fire weather conditions once again. However, the rainfall
we are currently experiencing should help somewhat in this regard.
More updates to follow.

&&

.AVIATION...Thursday 16/06Z through Friday 17/06Z...Isolated SHRA with
brief MVFR remain possible across northern AZ overnight. Light
winds overnight become W to NW at 10-20 kts on Thursday. Scattered
SHRA/TSRA east of a KSOW - KRQE line Thursday afternoon with
isolated SHRA/TSRA as far west as KFLG. Very brief MVFR
conditions and wind gusts up to 40 kts possible in/near shower
activity.

OUTLOOK...Friday 17/06Z through Sunday 19/06Z...Mainly VFR
conditions expected with W to SW winds 10-20 kts each afternoon.

&&

.FIRE WEATHER...Tonight through Friday...Scattered showers and
thunderstorms will continue through tonight, becoming more isolated
on Thursday. Variable winds overnight, becoming west to northwest on
Thursday. Erratic outflow winds up to 40 mph possible in or near
showers and storms. Dry conditions return on Friday. South to west
winds 10-20 mph with afternoon RH values between 10-20%.

Saturday through Monday...Warmer and drier weather conditions are
expected through the weekend. Southwest to west winds 15-25 mph
gusting 30-35 mph, increasing to 35-40 mph on Monday. Afternoon
RH values will range between 5-15%, increasing to 10-20% on Monday.

&&

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

&&

$$

PUBLIC...Mazon
AVIATION...MCT
FIRE WEATHER...MCT

For Northern Arizona weather information visit
weather.gov/flagstaff