Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Flagstaff Arizona
806 PM MST Wednesday Apr 23 2014

Synopsis...
expect fair weather through Thursday night. On Friday...windy
conditions return as a strong late season storm system
approaches the state. The bulk of the storm will move through
northern Arizona on Saturday with strong winds and rain and snow
likely. Expect clearing from west to east on Sunday with fair
weather through at least next Tuesday.

&&

Discussion...
forecast appears to be in good shape this evening...with no
significant short-term updates anticipated.

&&

Previous discussion /300 PM MST/...
expect fair weather from tonight through Thursday night as a
shortwave ridge crosses the Desert Southwest.

On Friday...winds will increase across the Northland as a very
cold late season storm moves into central California. The current
forecasts are for S-SW winds 20-30 miles per hour west/ gusts to 45 miles per hour and the
fastest speeds occurring along and north of the Mogollon Rim.

Friday night through Saturday night...forecasts are in very good
agreement bringing the strong late season cold front and upper
low through Arizona during this period. We are expecting a comma
shaped cloud feature to move from west to east during this period.
A north to south aligned warm conveyor/cold front (containing most
of the precipitation accumulations) to be moving into western Arizona around
midnight Saturday morning...along a line from Page to Payson
around noon Saturday...and reaching the New Mexico line by 6 PM
Sat. Snow levels are expected to fall to 6000 feet behind the
front. While model quantitative precipitation forecast supports several inches of snow above 7000
feet...the warm ground should reduce accumulations as will cloud
cover breaks behind the front. Falling snow will affect Highway
travel Saturday above 6000-6500 feet due to low visibilities for
sure and possible accumulations on the Road. Check future
forecasts for snow accumulations...at this time we expect 3-6
inches above 8000 feet. Not sure yet about accumulations between
6000-8000 feet.

Areas south of the Mogollon Rim should see rain accumulations of
40-.75 of an inch. Wind shear and cold temperatures (-27c at h5)
with this storm will also support at least scattered
thunderstorms...with a low probability of severe storms. These
are timed with the frontal passage.

Wrap around moisture and instability continue Saturday night and
scattered to numerous rain and snow showers are forecast across
the Northland.

On Sunday....look for clearing from west to east. Fast north
northwest flow aloft is expected to bring gusty north northwest
afternoon winds to all.

Monday through Wednesday...expect mostly clear skies and a warming
trend.

&&

Aviation...
for the 06z package...VFR conditions under occasional upper-level
cloudiness are expected for the 24 hour taf period. Winds will be
generally light overnight...becoming sw10-15g20-25kt after 18z
Thursday. Aviation discussion not updated for amendments.

&&

Fire weather...
Thursday...a warm and dry westerly flow aloft will bring light
winds in the morning becoming breezy in the afternoon.

Friday...an approaching Pacific low pressure system will result in
strong winds and low relative humidity with portions of
northeast Arizona reaching critical fire weather thresholds. A
Fire Weather Watch has been issued for Friday.

Saturday...a low pressure system and cold front will move across
Arizona on Saturday bringing widespread Rain...Mountain
snow...and isolated thunderstorms.

Sunday and Monday....breezy northerly winds and cooler
temperatures can be expected on Sunday...with much warmer
temperatures on Monday.

&&

Fgz watches/warnings/advisories...
Fire Weather Watch from Friday afternoon through Friday
evening for azz105-109-110-112>114-140.

&&

$$

Public.........Kd/dl
aviation.......kd
fire weather...db

For northern Arizona weather information visit
weather.Gov/Flagstaff