523
FXUS65 KFGZ 190858
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
158 AM MST Sun Jul 19 2026

.SYNOPSIS...Deep monsoonal moisture will remain over the area
through this weekend and well into next week. With this moisture
comes the daily threat of thunderstorms, along with the risk for
locally heavy rainfall and flooding. With the added moisture and
cloud cover, daytime temperatures will remain below normal.

&&

.DISCUSSION...Another night of widespread nocturnal activity is
slowly tapering off this morning, but not before large areas of
moderate to heavy rain were recorded. The pattern of rain-cooled
air, rain-cooled ground and extensive debris cloud cover will be an
issue again today, with many areas staying suppressed into the
afternoon.

Aside from that, we expect yet another day that features PW values
and dew points about as high as the Monsoon Season can furnish. It
will rain, just a question of when and where. Our current steering
flow (this governs where storms go after they form) remains easterly
or northeasterly for the next several days. This steering flow may
transition to more of a southeasterly direction later next week, but
that remains to be seen.

The current steering flow heavily favors locations just to the
southwest, south and west of the central Mogollon Rim. A secondary
area usually forms later each day across Apache and Navajo counties
or over western New Mexico. These secondary areas are what supports
nocturnal convection, which is expected at least for the next few
nights. The nocturnal signal is fairly strong, largely due to the
delayed convective development each day.

Compounding the issue is the arrival of an easterly wave, likely
arriving Monday and Tuesday, possibly residing over central Arizona
even into Wednesday. This easterly wave will increase storm motion
and shear, which could strengthen storms and lead to a hail threat.
While increased storm motion may lessen the flooding threat, it also
leads to the possibility of training storms (additional thunderstorms
forming over the same location). The bottom line, a very active and
possibly historically wet period will continue until further notice.

Pertaining to the daily possibility of a Flash Flood Watch, we will
again hold off, due the the complications of convective development
that were outlined above.

&&

.AVIATION...Sunday 19/00Z through Monday 20/00Z...Rounds of
SHRA/TSRA will continue through the evening hours becoming
isolated after 06Z. Stronger storm cells will produce brief MVFR
and IFR conditions.  Outside of thunderstorms, expect light winds
5-10 kts. Another active day of monsoon storms is in store on
Sunday. Expect scattered to numerous SHRA/TSRA with isolated +TSRA
from late Sunday morning through the afternoon. The primary
threat will be MVFR to IFR conditions in heavy rain. Gusty outflow
winds up to 40 kts and hail are also possibilities.

OUTLOOK...Monday 20/00Z through Wednesday 22/00Z...Expect
scattered to numerous SHRA/TSRA and isolated +TSRA each day,
storms most numerous in the afternoon hours. Any stronger storms
will produce brief MVFR to IFR conditions. Some IFR low clouds
and fog possible, mainly for overnight hours. Outside of storms,
expect light winds around 5-10 kts.

&&

.FIRE WEATHER...Sunday and Monday...Expect a medium to high grade
monsoon environment, with generally light winds outside of outflow
and thunderstorm activity. Most storms will produce wetting rain and
any stronger storms may produce Flash Flooding. The presence of a
weak low pressure system, moving from east to west, may introduce
an enhanced hail threat for Monday.

Tuesday through Thursday...Chances for showers and thunderstorms
continue, generally light winds outside of outflow and thunderstorm
activity. Most storms will produce wetting rain and any stronger
storms may produce localized Flash Flooding. The continued presence
of a weak low pressure system will prolong the potential for an
enhanced hail threat through Wednesday.

&&

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

&&

$$

PUBLIC...Peterson
AVIATION...McCollum
FIRE WEATHER...Peterson

For Northern Arizona weather information visit
weather.gov/flagstaff