Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Flagstaff Arizona
1000 am MST sun Dec 28 2014
Synopsis...cold and dry weather will continue through at least
Monday and into Tuesday for northeastern Arizona. A potentially
significant storm is brewing up winter weather for Wednesday through
Friday. The peak snowfall will likely occur on Wednesday and
Thursday. Plan for significant snow accumulations for your new years
travel plans. Drier weather returns just in time for next weekend.
Keep updated on our weather forecast for this event as impacts may
evolve over time.
Discussion...northwesterly flow aloft will keep northern Arizona in
a cold an dry weather pattern through at least Monday and into
Tuesday for northeastern areas. Breezy winds will also develop ahead
of an approaching winter storm system.
A potentially significant storm is brewing up winter weather for
Arizona from Wednesday through Friday. Over the next several days
this storm system will move slowly southwest through Nevada and
California. This southerly track will cut off the low from the main
steering flow (polar jet stream). Forecast models continue to show
the storm drifting slowly eastward across Arizona and New Mexico
from the middle to end of next week. Winter travel conditions are
Cut off lows such as this are notoriously difficult to pin down on
both impacts and timing. For now...plan for significant snow
accumulations for your new years travel plans. Keep updated on the
latest forecast as winter impacts to your location may change over
Previous discussion...a strong trough will move through the
northern rockies today and into the Great Basin on Monday. This
trough will eventually cut off over central California late Tuesday
and will drift southeastward into Arizona by Wednesday and Thursday.
Models have been all over the place over recent days...concerning
placement and timing of this low...specifically differing on the
amount of retrograding before the low ejects. 00z runs have come in
much closer agreement and even the ensembles are clustering toward
operational solutions. Blending everything together yields slightly
slower timing from what we have been advertising...but also yields a
fairly healthy and cold system. We think it is safe to say at this
point that this will be a significant storm and will easily produce
the most snowfall so far this winter.
Amounts and timing still need some time to be sorted out...but the
feeling is that this will be at least an advisory type storm...if
not a Winter Storm Warning. Grids still do not go out far enough to
encompass all the snowfall...but early time periods through late
Wednesday already have several inches of snow in the forecast.
These types of storms are notoriously difficult to time and the
ejection will likely be slower than what is now in the model runs.
Grids have precipitation ending by Friday or early Saturday for
now...with a ridge building back over the western United States
by next weekend. Stay tuned as this situation evolves.
Aviation...for the 18z package...expect VFR conditions and light
winds under variable high clouds over the next 24 hours. Aviation
discussion not updated for taf amendments.
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