438
FXUS65 KFGZ 192306
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
406 PM 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, most daytime temperatures will remain below normal.

&&

.DISCUSSION...Despite a night of widespread nocturnal thunderstorm
activity, skies are the overall the clearest they have been in
several days this morning. The increased heating and delay in
convective initiation until the afternoon does increase the
chance for some stronger wind gusts, especially just north of the
rim. However, the main focus remains isolated flash flood
potential with 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...Monday 20/00Z through Tuesday 21/00Z...Isolated to
scattered SHRA/TSRA will continue through 06Z. Stronger storms
this evening will be capable of producing wind gusts to 40 mph
and brief MVFR and IFR conditions. After 06Z, activity becoming
extremely isolated. Localized IFR conditions due to low clouds and
fog are possible during the overnight hours. Outside of storms,
winds light and variable.

OUTLOOK...Tuesday 21/00Z through Thursday 23/00Z...Look for
SHRA/TSRA activity through the period, most numerous during the
afternoon/evening hours. Stronger storms will produce brief MVFR
and IFR conditions. localized IFR conditions due to low clouds and
fog possible during the overnight hours. Outside of storms,
surface winds light and variable.

&&

.FIRE WEATHER...Monday and Tuesday...A medium to high grade monsoon
environment continues, 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 and Tuesday.

Wednesday through Friday...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...Zanker
AVIATION...McCollum
FIRE WEATHER...RR

For Northern Arizona weather information visit
weather.gov/flagstaff