Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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146
FXUS65 KFGZ 181733
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1033 AM MST Sat Feb 18 2017

.SYNOPSIS...A Pacific storm system will bring periods of rain and
high elevation snow along with colder temperatures to northern
Arizona this weekend. Dry weather and warming temperatures are
forecast for Monday and Tuesday. Another round of showers is
possible Wednesday and Thursday.

&&

.UPDATE...
Updated probability of precipitation along with precipitation
amounts and weather groups of the forecast this morning to better
match satellite and radar trends. Have divided the forecast grids
into 3 hour segments to hopefully increase resolution of the
precipitation amounts types and probabilities. Otherwise forecast
looks on track as southerly flow ahead of the cold front continues
to push moisture up the rim and across Northern Arizona.


&&

.PREV DISCUSSION /534 AM MST/... SHORT TERM (Today through
Monday)...The strong Pacific storm system continues to move
toward Arizona this morning, spreading gusty winds and
precipitation into the area. Most precipitation has been
along/south of the Mogollon Rim, and that trend is expected to
continue through most of the day as moisture and upslope flow
increase out ahead of the deep moisture plume and cold front.
Snow levels through mid evening will range from around 7000 up to
8000 feet, with little in the way of accumulation below 7500
feet. From mid to late evening, colder air is forecast to move
into the region from west to east, dropping snow levels down
close to 6000 feet. A Winter Weather Advisory for snow remains in
effect from 5 PM today through 5 PM Sunday for the Mogollon Rim
and White Mountains above 6000 feet, check weather.gov/Flagstaff
for point snowfall forecasts. Models continue to develop a
circulation center within the broad trough as it moves across the
state late tonight and early Sunday, but there are some
differences between models as to exactly where it develops (Euro
model farther north, GFS/NAM farther south). This could have an
impact on placement of the heavier precipitation. The farther
north solution would bring increased amounts to the Flagstaff and
Prescott areas with the southern solutions favoring southern
Yavapai and Gila counties. Our forecast went with a blend of these
scenarios, close to the WPC forecasts for QPF amounts. Through
Sunday afternoon, a general 1-2 inch rainfall is forecast for
Yavapai and northern Gila, with localized higher amounts over
south facing slopes. A Flash Flood Watch continues for these areas
as streams are likely to rise, possibly making low-water
crossings impassable. Precipitation will start to decrease by
Sunday afternoon, then gradually end Sunday evening. Fair weather
returns Monday with warming temperatures. Tuesday looks mainly
fair, though a system passing north of the state could bring some
increased clouds and a slight chance of showers to northwest
Arizona.

LONG TERM (Tuesday through Friday) Few changes were made to the
overall extended forecast period. Southwesterly flow begins to
increase Tuesday after the ridge axis heads east. A weak passing
disturbance could bring some showers to northern Arizona as early
as Tuesday afternoon/evening. The passage of a quick moving
trough and cold front are still on track for Wednesday evening
into Thursday bringing the chance for rain and snow across the
area. At this time precipitation amounts look light and to favor
areas generally north of I-40. Cool conditions look to continue
through Friday.

&&

**** CAN NOT DECODE AVIATION DISCUSSION ****

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Sunday FOR AZZ015>017.

Flash Flood Watch through Sunday afternoon FOR AZZ008-018-037-
038.

Wind Advisory until 5 PM MST this afternoon FOR AZZ007.


&&

$$

PUBLIC...Suk/JJ
AVIATION...Suk


For Northern Arizona weather information visit
weather.gov/flagstaff



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