Area Forecast Discussion
Issued by NWS Flagstaff, AZ
FXUS65 KFGZ 211042
Area Forecast Discussion
National Weather Service Flagstaff AZ
342 AM MST THU JUL 21 2016
.SYNOPSIS...Another round of showers and thunderstorms is expected
from late this morning through early evening. Drier westerly flow
will decrease shower and thunderstorm coverage across western
Arizona Friday into the weekend, though decent chances for
thunderstorms will remain across southern Navajo and Apache
counties. Moisture and storm chances could increase again next
week, especially along and south of the Mogollon Rim.
.DISCUSSION...Another round of showers and thunderstorms is
expected across all of northern Arizona today, beginning after
10 AM MST. Storms will initially develop in the higher terrain
and slowly work their way to the lower elevations. The main threat
with storms will once again be localized very heavy rain due to
the slow storm movement, which could lead to localized flash
flooding. The stronger storms will also be capable of producing
small hail and gusty winds.
Beginning Friday, the axis of strong high pressure will shift over
or just south of the forecast area and drier air will start to
move in from the west. This will reduce storm chances across
Coconino and Yavapai Counties into the weekend. The greatest
storm chances will remain over southern Navajo and Apache Counties
where the highest moisture will linger. Most model guidance shows
the ridge shifting back northward possibly as early as Sunday but
more likely Monday into midweek. This would allow for some
better moisture and storm chances to return, especially for areas
along and south of the Mogollon Rim and White Mountains. Depending
on where the high eventually sets up, we could see some east or
northeast steering flow off the higher terrain which is favorable
for some stronger storms in the late afternoon and evening in Gila
County and the lower elevations of Yavapai County. Far northern
Arizona (along/north of Grand Canyon to Window Rock) often remains
drier in this pattern. With high pressure in place, expect hot
temperatures in this area, 110+ at Phantom Ranch, 102-104 at Page
and near 90 at Grand Canyon south rim.
.AVIATION...For the 12Z package...Expect scattered to numerous
SHRA/TSRA to develop aft 17Z. Conditions will remain primarily VFR
but local MVFR with +RA and gusty winds possible in stronger storms.
Activity should decrease after sunset. Aviation discussion not
updated for TAF amendments.
.FIRE WEATHER...A wet monsoon pattern will remain in place today
resulting in scattered thunderstorms with locally heavy rain
possible. By Friday, a drier westerly flow will begin a downward
trend in thunderstorm activity.
Saturday through Monday...Expect lower thunderstorm chances and
decreased afternoon humidity over the weekend. Moisture may increase
on Monday from the Mogollon Rim south.
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