Wildfire in Arizona, May 1 to 8, 2018

Area Forecast Discussion
National Weather Service Flagstaff AZ
844 PM MST Mon Apr 30 2018

.SYNOPSIS...Gusty southwest winds will continue Tuesday with the
strongest winds again expected in eastern Arizona. A strong low
pressure system will bring rain and snow showers to the region
from Tuesday afternoon through Thursday. Much warmer and drier
conditions develop later this week and into next weekend.

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.DISCUSSION...Winds have decreased across northern Arizona this
evening, with gusts at or below 20 mph at most place. Wind speeds
will continue to decline overnight. Low temperatures are forecast
to range from the low 30s to mid 40s across most of Arizona's High
Country. The current forecast captures these trends well, and no
forecast updates are anticipated at this time.

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.PREV DISCUSSION /259 PM MST/...A drastic change in the weather is
upcoming over the next 36-48 hours for northern Arizona as a slow
moving storm system crosses the region.

The gusty southwest wind regime will persist into Tuesday with
near advisory level gusts of 35-40 mph for much of the region.
However, enough moisture will creep in ahead of our approaching
storm system that relative humidity values will be higher than we
have seen over the past several days. This will avoid any further
critical fire weather conditions over the region.

The upper level low will slowly cross the state Tuesday night
into Wednesday. The cold pool aloft associated with this system
will help to generate scattered to numerous convective shower
activity beginning Tuesday afternoon and persisting through
Wednesday. 700 mb temperatures of -4 to -6 C indicate snow levels
will fall to around 6500 feet after the cold front passes Tuesday
night. Some light snow accumulation is anticipated across the
higher terrain. The colder air aloft will also promote the
potential for embedded thunderstorms within the showers. Wednesday
high temperatures will range from 10-20 degrees below normal for
early May. Showers will remain possible into Thursday especially
across the higher terrain before the system completely departs the
region.

High pressure will build in quickly behind this system with warm
and dry conditions returning to northern Arizona Friday into the
weekend. A much lighter wind regime is anticipated for this time
frame as the pressure gradient relaxes across the region.

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.AVIATION...For the 06Z package...VFR conditions will prevail over
the next 24 hours, though clouds will increase with bases 040-060
during the afternoon along Mogollon Rim and higher terrain. A slight
chance of -SHRA 18Z-01Z, then increasing chances of -SHRA/-SHSN
after 01Z producing MVFR conditions. Snow level falling to 6500-7500
ft by 06Z/Wed. Smoke from the Tinder Fire may produce smoke layers
aloft and limit visibilities extending to the Four Corners/New
Mexico. Locally gusty southwest winds will persist overnight,
increasing again to 15-20kt gusting 25-35kt 18Z to 02Z. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Breezy southwest winds will persist Tuesday with
increased moisture. The approaching storm system will bring much
cooler temperatures, 10-20 degrees below normal with rain showers
and high elevation snow showers developing by Tuesday night, lasting
into Wednesday evening.

Thursday through Saturday...Shower activity ending Thursday. Expect
a return to warm, dry conditions Thursday through Saturday. Winds
will be generally light northerly Thursday, light easterly Friday
and light south to southwesterly Saturday.

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.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

PUBLIC...RR/TPS
AVIATION...JJ
FIRE WEATHER...DB

For Northern Arizona weather information visit
weather.gov/flagstaff