Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 212155

Area Forecast Discussion
National Weather Service Flagstaff AZ
255 PM MST Sat Jul 21 2018

.SYNOPSIS...Expect scattered showers and thunderstorms to develop
today. Storms may produce heavy rain that could lead to flooding.
A Flash Flood Watch remains in effect for parts of northwestern
Arizona until this evening. Warmer afternoon temperatures and
decreasing storm coverage should start Sunday and persist through
much of next week.


.DISCUSSION...A remnant mesoscale circulation from last night`s
convective system can be seen on satellite this afternoon moving
northward along the Colorado River near Bullhead City. Northern
Arizona remains on the eastern periphery of this feature and has
seen scattered thunderstorm activity develop this afternoon.
Storms have mostly been producing a lot of cloud to ground
lightning and locally heavy rainfall. Storms are moving to the
north or northwest at about 10-20 mph. A Flash Flood Watch
continues for a portion of northwestern Arizona where training
storms could lead to areas of heavy rain and flash flooding. A few
stronger cells could also produce hail. Storms should begin to
decrease after sunset this evening as the circulation moves north.

Sunday will begin to see decreasing moisture levels leading to a
downward trend in thunderstorm activity lasting into the coming
week. Isolated to scattered thunderstorms can be expected,
favoring the higher terrain areas of northern Arizona.
Thunderstorm threats will transition to lightning and gusty
outflow winds. Temperatures will also begin to increase Sunday
through the upcoming week reaching at least 5 to 8 degrees above
late July averages. Heat advisory/warning products may be needed
by the middle of the week for some of the lowest elevations.


.AVIATION...For the 00Z package...Scattered thunderstorms with
heavy rain and hail will affect central and northwestern Arizona
through this evening affecting KFLG, KGCN and KPGA terminals.
Isolated to scattered storms elsewhere in northern Arizona. MVFR
and IFR conditions expected in the strongest storms. Storm
coverage and intensity will gradually diminish after 02z Sun. VFR
conditions outside of storm activity. Aviation discussion not
updated for amendments.


.FIRE WEATHER...Scattered to numerous showers and thunderstorms will
affect Coconino County through the afternoon. Isolated to
scattered storms can be expected elsewhere. Sunday will begin to
see a gradual decrease in thunderstorm activity lasting into next
week. Temperatures will also begin to warm above average Sunday
into next week.

Tuesday through Thursday...Expect warming temperatures as a
strong high builds over the southwest US. Isolated to scattered afternoon
showers/storms are expected to continue, but with less coverage
and intensity than observed last week.


this evening FOR AZZ004>007-015.




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