Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 210436

Area Forecast Discussion
National Weather Service Flagstaff AZ
936 PM MST SAT AUG 20 2016

.SYNOPSIS...Monsoon moisture will remain in place with the
potential for shower and thunderstorm activity continuing into the
middle of next week.


.DISCUSSION...It was an active day across portions of northern
Arizona, especially along and south of the Mogollon Rim. Hail was
observed at many locations, with the largest hail stone being 1.25
inches in diameter near Prescott. In addition, a few storms
produced heavy rainfall causing large increases in runoff through
washes in the vicinity of Gisela and north of Wickenburg in
Yavapai County. At the moment, shower activity is rapidly
decreasing as storms have largely moved into southern portions of
the state. The current forecast calls for a quiet night across
northern Arizona.

In terms of updates, only minor adjustments were made to the
forecast to broadly reduce the chances for precipitation to
match current trends.


.PREV DISCUSSION /310 PM MST/...Very weak flow and relatively
cool temperatures aloft continue across the area...with AZ between
high pressure over N. CA/NV and the pinched remnants of elongated
low pressure to the south. This pattern remains in place for
Sunday, with similar convective activity expected. Slow storm
motion to the northeast may promote more storm development north
of the Rim on Sunday afternoon. The primary threats again will be
heavy rain with the slowly moving storms.

The models continue to show a slight strengthening of the westerly
flow late on Monday...transitioning to a drier W to NW flow regime
by Wednesday as a broad, weak trough develops over the Western US.
The result will be some warming aloft (1.5-2.0C at 500mb) by late
Monday...and some drying of the atmosphere...persisting through
next week. With the lingering moisture we expect to maintain at
least low- grade monsoon conditions through the week with the
greatest storm coverage over the eastern portions of the forecast


.AVIATION...For the 06z package...Expect VFR conditions overnight.
After 17z Sunday, another round of showers and thunderstorms is
forecast. MVFR conditions in heavy rainfall and erratic, gusty
winds are possible in the vicinity of stronger storms. Aviation
discussion not updated for TAF amendments.






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