Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 171700

Area Forecast Discussion
National Weather Service Flagstaff AZ
1000 AM MST Sat Jun 17 2017

.SYNOPSIS...A strong warming trend will continue into next week
with record high temperatures likely during this period. An
Excessive Heat Warning is in effect for the lower elevations of
Yavapai, Coconino and northern Gila counties through Thursday. A
Heat Advisory is in effect for the mountains of Yavapai County
from Sunday through Thursday.


Short-term forecast looks in good shape with no significant
updates anticipated this morning.


.PREV DISCUSSION /243 AM MST/...Very little change in the forecast
thinking this morning. Model guidance remains in good agreement
over the next several days with very strong high pressure becoming
centered over Arizona through at least the middle of next week,
if not longer. Temperatures will be a degree or two warmer today,
then the hottest temperatures of the year are forecast Sunday
through at least Thursday. An Excessive Heat Warning will be in
effect today through Thursday for the lower elevations of
Coconino, Yavapai and northern Gila Counties, with a Heat Advisory
for the Yavapai County mountains including Prescott for Sunday
through Thursday. The hottest days are currently expected on
Tuesday and Wednesday, when temperatures in many areas are likely
to reach within 2-4 degrees of all-time records. Daytime humidity
will be extremely low today (4-7 percent) before some slightly
higher dewpoints move into the region from the northeast early
next week. These higher dewpoints will lead to some afternoon
cumulus development over the mountains and a slight chance of a
few high- based thunderstorms from around Flagstaff eastward
Mon/Tue, lingering near the White Mtns Wed/Thu. Any shower or
thunderstorm activity will produce gusty winds but is unlikely to
produce much in the way of rainfall due to the dry sub-cloud
layer. Most model guidance indicates only slight decreases in the
strength of the high pressure ridge by the end of next week, with
above normal temperatures persisting. There is a chance that we
will have to extend the heat warning/advisory products beyond


.AVIATION...For the 18Z package...Smoke from area fires may create
localized MVFR visibility near the ground, especially overnight.
Smoke could also affect flight paths. Otherwise, VFR conditions are
expected to persist for the next twenty-four hours. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER....Expect hot temperatures and high Haines indices
this weekend. Single digit RH values are expected during the
afternoons, with poor overnight recovery to only the 15-25 percent
range in the lower elevations. Winds will be largely terrain-driven.

Monday through Wednesday...Expect the hottest temperatures of the
year so far with Haines indices of 5 or 6. Some high-based
thunderstorms are possible over the higher terrain of central and
eastern Arizona Monday and Tuesday and could may produce gusty and
erratic winds. Wetting rains are unlikely.


.FGZ WATCHES/WARNINGS/ADVISORIES...Excessive Heat Warning until 8
PM MST Thursday FOR AZZ005-006-018-037-038.

Heat Advisory from 10 AM Sunday to 8 PM MST Thursday FOR AZZ008.




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