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369
FXUS65 KFGZ 181004
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
304 AM MST Sun Jun 18 2017

.SYNOPSIS...An Excessive Heat Warning is in effect for the lower
elevations of Yavapai, Coconino and northern Gila counties through
Thursday, with a Heat Advisory for the remainder of Coconino,
Yavapai, Navajo, and Apache counties. Isolated showers or
thunderstorms with gusty winds could develop over the higher
terrain from Flagstaff eastward each afternoon through Tuesday.

&&

.DISCUSSION...Forecasts for record or near record high
temperatures remain on track with Excessive Heat Warnings at
lower elevations and Heat Advisories at higher elevations through
Thursday. Only minor changes have been made to the forecast with
this morning`s package. Limited moisture filtering in from the
north combined with very strong surface heating will lead to some
cloud buildups later this afternoon over the higher terrain. A
slight chance of some dry thunderstorms was added to the forecast
for this afternoon for the Mogollon Rim and White Mountains
including the Flagstaff area. Any storms that develop will be
capable of gusty winds but little if any rain. By Monday and
Tuesday, this moisture becomes a bit more pronounced over the
higher terrain from Flagstaff eastward, and the chance of showers
& thunderstorms was increased into the 20-30 percent range. Gusty
winds and the threat of new fire starts with lightning will be the
main concerns with this activity. Still thinking our forecast
high temperatures are on track even with the increased cloud cover
at higher elevations, since these highs are likely to be reached
just before clouds/storms begin to form. Toward the end of the
week and the weekend, most model guidance indicates the strong
ridge shifting southward into northern Mexico, with temperatures a
few degrees lower for northern Arizona, though still above
normal.

&&

.AVIATION...For the 12Z package...Smoke from area fires may create
localized MVFR visibility near the ground, especially overnight.
Smoke could also affect flight paths. ISOLD thunderstorms are
possible over high terrain areas this afternoon, which would be
capable of producing very strong wind gusts. Otherwise, VFR
conditions are expected to persist for the next twenty-four hours.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Hot temperatures with afternoon RH in the single
digits and teens are expected today and Monday. High Haines indices
will promote rapid fire growth. There is a slight chance of
thunderstorms over the higher terrain this afternoon and Monday
afternoon. Any storms that do develop would produce minimal rainfall
with strong gusty winds.

Tuesday through Thursday...Thunderstorms producing gusty winds will
once again be possible on Tuesday. A few storms may occur on
Wednesday and Thursday. Hot temperatures, high Haines indices, and
low RH values will persist. Breezy southwest to west winds are
expected Wednesday and Thursday afternoons.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Heat Advisory from 10 AM
this morning to 8 PM MST Thursday for AZZ004-007>017-039-040.

Excessive Heat Warning until 8 PM MST Thursday for AZZ005-006-
018-037-038.

&&

$$

PUBLIC...JJ
AVIATION...MAS
FIRE WEATHER...MAS

For Northern Arizona weather information visit
weather.gov/flagstaff