Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 280408

Area Forecast Discussion
National Weather Service Flagstaff AZ
910 PM MST Thu Jul 27 2017

.SYNOPSIS...Expect daily chance for showers and thunderstorms as
an active monsoon pattern remains in place across northern Arizona
into next week.

.DISCUSSION...Storms have generally decreased in coverage this
evening. However, a few areas north and northwest of Flagstaff have
flaired up again. Have made adjustments to the grids this evening to
account for this activity.

. PREV DISCUSSION /321 PM MST/...On Friday, most model guidance
suggests slightly higher boundary layer moisture. In addition, an
inverted trough is forecast to move into southern Navajo and Apache
Counties. Forcing from this feature is expected to make eastern
portions of the area the most active, and a favorable location for
MCS development. Elsewhere, another round of scattered storms are
expected, but an extensive mid and upper level cloud deck may limit
instability. Flow around the inverted trough will cause storm
mostion to switch to a more northerly direction, but will remain
quite light - generally 10 knots or less. Given deep layer shear
values of 20 knots or less and slow storm movement, flash flooding
remains the primary hazard from Friday`s storms.

Over the weekend, The inverted trough to the south will turn the
flow aloft to the southeast over the weekend. This will advect in
more moisture over the region keeping good chances for storms in
the forecast. Latest model guidance suggest this pattern may
persist into early next week.


.AVIATION...For the 06Z package...ISOLD -SHRA/-TSRA will
continue overnight tonight. MVFR/IFR conditions possible in the
stronger storms.  SCT SHRA/TSRA expected again from around 18Z to
02Z with MVFR to IFR conditions in the heavier storms. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER...Slow moving thunderstorms will continue to develop
and move across the area today, Friday afternoon and evening. Some
flash flood potential exists due to the high rainfall rates and slow
movement of the storms.

Saturday through Monday...Moisture is forecast to increase across
Arizona with a greater chance for showers and storms expected across
the fire district.






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