Flash Flood Warning 82, NWS Flagstaff, AZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
946 AM MST Wed Jul 27 2022

.SYNOPSIS...An active monsoon pattern will continue this week
with widespread showers and thunderstorms expected. This will
result in the flash flood threat persisting through at least
Friday.

&&

.UPDATE...Multiple mesoscale convective vortices (MCVs) can be
seen on current visible satellite imagery this morning across
Arizona. These features have contributed to the ongoing isolated
to scattered shower activity with the best coverage taking place
across Yavapai and western Coconino counties. Cloud cover has
cleared towards the east along the New Mexico border with some
erosion taking place westward. This will allow for some daytime
heating to take place as the sun peaks through the scattered to
broken cloud cover.

Expect another busy convective day across northern Arizona with
widespread shower and thunderstorm activity forecast by the early
afternoon hours. Flash flooding remains the main concern during
this time with forecast rainfall rates of 1 to 2 inches per hour
likely in any storms. Based on this morning's soundings from
Flagstaff and Phoenix, sampled PWATs came in around the 1 to 2
inch range with a "skinny" CAPE profile. Sufficient saturation
also was detected in both soundings up to around 300 mb,
signaling this "soupy" airmass remaining in place over Arizona.
The Flash Flood Watch for the region remains in effect through
Friday morning with WPC's Excessive Rainfall Outlook leaving us in
a Marginal to Slight flash flood risk through Friday.

&&

.PREV DISCUSSION /335 AM MST/...This monsoon is not slowing down
with another night of convection lighting up radar. Currently,
storms are moving across Coconino and Yavapai Counties. Most of
them have rain rates between 1-2"/hr., however, there are some
small areas receiving rain rates upwards of 4"/hr. This pattern
will continue for the foreseeable future. Of major concern is the
saturated soils out there and the flash flooding/urban flooding
we have already seen so many times in the last few days. Due to
this, and the signal that much more rain is on the way, we have
extended the Flash Flood Watch through Friday morning at 5 AM MST
for all of northern Arizona. Slot canyons, swimming holes, burn
scars, normally dry washes, creeks and areas downstream from
these places will be particularly vulnerable- which could result
in a tragic end to otherwise enjoyable recreation. Have more than
one way to receive warnings especially in areas with limited cell
service. Keep in mind that just because it isn't raining on you,
it doesn't mean that you're not in the path of a deadly flow of
water! Low water crossings will also be a hazard which could
create deadly travel conditions with nighttime flooding even more
of a threat. Turn around, don't drown! It's impossible to know
how deep that water is if the road beneath that water has been
washed away.

&&

AVIATION...For the 18Z TAF package...Widespread showers and
thunderstorms are expected throughout the day and evening. Storms
will produce MVFR/IFR VIS & CIGS at times with VFR conditions
outside of storms. Scattered activity is likely to remain overnight
with extensive low to mid cloud cover. Overall light winds
anticipated during this time, except near any strong storms with
gusty and erratic outflows likely. Aviation discussion not updated
for TAF amendments.

&&

FIRE WEATHER...Widespread showers and thunderstorms are expected
through Thursday with moderate to heavy rainfall as the main threat.
Rain rates of 1 to 2 inches per hour are anticipated, increasing the
flash flood potential. Storm coverage decreases overnight, however,
isolated to scattered storms will remain. Light winds away from
storms with cool conditions overall.

Friday through Sunday...Anticipate widespread storm coverage to
continue through the weekend with the main threat of flash flooding.
Temperatures begin a slight warming trend with light winds forecast.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Flood Watch through late Thursday night for AZZ004>018-037>040-
104>118-137>140.

&&

PUBLIC...LaGuardia/Kobold
AVIATION...LaGuardia
FIRE WEATHER...LaGuardia

For Northern Arizona weather information visit
weather.gov/flagstaff