Scientific Forecaster Discussion
fxus65 kfgz 131607
Area forecast discussion
National Weather Service Flagstaff Arizona
907 am MST Fri Dec 13 2019
Synopsis...dry and mild conditions will continue through Friday.
A cold front will cross the region this weekend bring gusty
southwest winds and a chance of snow and rain showers. Expect much
colder daytime temperatures Sunday through Tuesday.
Discussion...mid and high level clouds are seen on visible
satellite this morning streaming across northeast Arizona. Periods
of cloud cover will continue throughout the day. Otherwise, dry
and mild conditions will continue. Daytime temperatures will
range from 5 to 15 degrees above normal.
The weekend forecast remains on track with a cold front set to
bring gusty southwest winds and increasing chances for rain and
snow showers. Significant precipitation still looks to be confined
to near the Utah border, with lesser amounts to the south. Behind
the front, a much colder airmass will move into the region Sunday
into early next week.
A minor update was made to the sky cover this morning to account
for the mid and high level cloud cover. Otherwise, the forecast
remains on track.
Previous discussion /410 am MST/...one more day of quiet weather is
in store for US on Friday as zonal flow continues. The approaching
trough will tighten the pressure gradient aloft, allowing for
increasing winds to mix down to the surface beginning this
afternoon. Wind speeds will not be high, but will be slightly
stronger than yesterday.
Wind speeds will continue to increase through the day Saturday, as
the trough and associated cold front approaches.
The cold front will begin to move across the area on Sunday,
bringing some precipitation, especially across the the higher
terrain near the Arizona Utah border. Precipitation will be rather
limited further south approaching the Mogollon Rim, where a lack
of moisture and instability will limit amounts to generally less
than one inch.
Behind the front cold temperatures will dominate on Monday and
Tuesday morning, with temperatures warming across the area Tuesday
afternoon as quick moving ridge traverses the area. Warming will
continue into the middle of the next week.
Models begin to diverge on how long the ridge remains over the
area, as a closed low pressure system moves in off the California
coast by the middle of next week. Different solutions have ridge
making room for the low at different speeds, causing quite
dramatic differences in the second half of next weeks forecast.
Have gone with a middle of the Road solution for the time being.
Confidence remains low in an particular solution at this point
including this one.
Aviation...for the 18z package...light winds and VFR conditions
will prevail through this evening. Clouds will lower and thicken
tonight into Saturday morning, with some MVFR conditions possible
late in the taf period over the higher terrain. Aviation
discussion not updated for taf amendments.
Fire weather...dry and mild weather will continue today. An
approaching cold front will bring gusty southwest winds and
increasing chances for rain and snow showers on Saturday.
Sunday through Tuesday...the cold front will cross the region on
Sunday, with continued chances for rain and snow showers mainly
north of I-40. Behind the front, expect much colder temperatures and
breezy northerly winds into early next week.