049
FXUS65 KFGZ 190742
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1242 AM MST Tue Aug 19 2025

.SYNOPSIS...Isolated showers and thunderstorms will be possible
this afternoon over eastern Arizona, with hot and dry conditions
expected elsewhere. Monsoonal moisture looks to increase over the
coming days, with scattered to widespread storms developing by
weeks end. Otherwise, hot temperatures and light winds look to
prevail.

&&

.DISCUSSION...Today...Hot and mainly dry conditions and expected
today across northern Arizona as a strong area of high pressure
begins to build into the Four Corners region. Given the more
favorable position of the high, moisture does look to gradually
increase starting today. However, much of the activity will looks
to be limited to the eastern portions of Arizona and potentially
extended up the Mogollon Rim. Even so, given the 596-598 dam
ridge, strong subsidence aloft will act to suppress any storms
that do develop, thus mainly isolated activity is expected at
best.

Wednesday and Thursday...Heights continue to rise as the ridge
continues to strengthen over Four Corners. As a result, high
temperatures look to remain hot for most of the area, with highs
around 5-10F above normal for this time of year. An Extreme Heat
Warning remain through Wednesday for the lower elevations of the
Grand Canyon, with a watch then following. Additional headlines may
be need for some of the lower elevations of Yavapai for Thursday,
but to what extent increased moisture (and thus increased cloud
cover) may affect the temperatures is still not certain.

While monsoonal moisture does look to continue to increase, the
strength of the high looks to continue to be the limiting factor.
Model soundings do some to indicate a slightly weaker cap by
Thursday as the ridge starts to weaken and begin to retrograde.
However, some uncertainty still remains here. Additionally, decaying
storms over northern Mexico may become a favor in leading to
increased storm chances. As of now, coverage looks to be mainly
focused over the higher terrain with some isolated storms
potentially moving into the lower elevations in the late afternoon
and evening hours.

Friday through Monday...As heights begin to fall with the weakening
ridge, the odds for showers and thunderstorms look to increase by
the end of the week and into next week. Ensemble guidance from the
EPS, GEFS, and CMCE all continue to signal a notable increase in
PWATs through the weekend. Thus, a period of active monsoonal
activity, with a threat for flash flooding, looks probable.

&&

.AVIATION...Tuesday 19/06Z through Wednesday 20/06Z...VFR
conditions expected to persist through the TAF period. Isolated
-SHRA possible through 06Z primarily across Apache County. Light
 and variable winds expected through 18Z, before winds increase to
 ~ 10kts but remain variable in direction. Additional
 -SHRA/TSRA possible after 18Z along and south of a KPAN-KRQE

OUTLOOK...Wednesday 20/06Z through Friday 22/06Z...VFR conditions
will persist outside brief MVFR conditions in heavier SHRA/TSRA.
Daily chances for showers/storms possible between 18Z-03Z, with
greatest activity likely across the higher terrain. Outside of
storm driven gusty winds, look for variable winds 5-10 kts.

&&

.FIRE WEATHER...Today and Wednesday...Hot and mainly dry conditions
continue. Isolated showers and thunderstorms today, mainly across
eastern Arizona then spreading further westward on Wednesday. Winds
generally variable 5-10 mph. Gusty and erratic winds possible in and
around thunderstorms. Minimum afternoon RH values 10-30%, highest
across the White Mountains.

Thursday through Saturday...Chances for showers and thunderstorms
increase each day, with wetting rain possible by the weekend. Winds
will primarily be variable 5-10 mph. Gusty and erratic winds
possible in and around thunderstorms. Minimum afternoon RH values 10-
30%, highest values across the White Mountains and Mogollon Rim.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning from 10 AM this morning to 8 PM MST
Wednesday for AZZ006.

Extreme Heat Watch from Wednesday evening through Friday evening
for AZZ006.

&&

$$

PUBLIC...Humphreys
AVIATION...Konieczny
FIRE WEATHER...Humphreys

For Northern Arizona weather information visit
weather.gov/flagstaff