Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 250448

Area Forecast Discussion
National Weather Service Flagstaff AZ
948 PM MST Mon Jul 24 2017

.SYNOPSIS...Scattered showers and thunderstorms are expected
across northern Arizona tonight. Some of the storms could produce
heavy rainfall. Another round of scattered thunderstorms will
develop Tuesday. A decrease in storm coverage is anticipated
starting Wednesday, especially across western and central Arizona.


.UPDATE...We have seen an increase in shallow convection across
northern Arizona over the past few hours in response to ample
moisture in place and a mid-level circulation rotating through
western Arizona. The evening FGZ sounding showed just over 1 inch
of precipitable water with plenty of instability available. Have
updated the forecast to keep a good chance of showers/storms
across north-central and northwestern Arizona this evening and
overnight. Storms will be moving to the north. Heavy rain is the
primary threat and a Flash Flood Watch continues this evening
generally from I-40 north.


.PREV DISCUSSION /327 PM MST/... Todays flash flood watch for
areas generally north of I-40 will continue through midnight. Area
radars show widespread showers and thunderstorms across Navajo
and Apache counties this afternoon. The inverted trough is seen
in H5 streamlines and satellite loops, and now located over
Yavapai county. It is headed northward into Utah by early Tuesday
morning. While we have been overcast for much of the day, we are
seeing better convective development here at the office, and the
threat of heavy rain is still out there.

On Tuesday, very high amounts of moisture will remain for much of
the day, with greater instability for most of the area vs today.
While another round of scattered afternoon/evening thunderstorms
is likely for most, southern portions of Yavapai county should
start to stabilize and less storm coverage is expected there.

Wednesday through Thursday - Progs continue to show drier and
stable air moving over central and western Arizona, leading to
decrease in storm coverage. Moisture lingers along the AZ/NM
border with scattered storms.

Friday into the weekend - high pressure centered near the four
corners will result in a moistening east to southeast flow for
northern Arizona. A return to more typical monsoon storm coverage
is forecast.


.AVIATION...For the 06Z package...Scattered showers across Yavapai
and Coconino counties this evening will diminish in the early
morning hours as they move north into Utah. Periods of low
ceilings and/or fog around the area are possible tonight with all
the moisture in the area. Rain showers and thunderstorms will
re-develop after 18Z Tuesday.These will be numerous over the
white mountains and northwestern coconino county, and isolated to
scattered over the rest of northern Arizona. MVFR/IFR conditions
are likely in the stronger storms. Aviation discussion not updated
for TAF amendments.


.FIRE WEATHER...Slightly drier and more stable conditions
will arrive on Tuesday with more typical late morning to early
evening thunderstorms. On Wednesday, the chances for showers and
thunderstorms will continue, but coverage and frequency should
further decrease.

Thursday through Saturday...For Thursday and Friday the coverage and
frequency of showers and storms are expected to remain on the low
side. Slightly drier and warmer conditions near the surface will
enhance the threat for gusty outflow winds. On Saturday, a renewed
push of moisture should spell the return of active monsoon


.FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch until midnight MST
tonight FOR AZZ004>007-009>012-039-040.




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