Area Forecast Discussion
Issued by NWS Flagstaff, AZ
FXUS65 KFGZ 210348
Area Forecast Discussion
National Weather Service Flagstaff AZ
848 PM MST Mon Feb 20 2017
.SYNOPSIS...Dry weather and above average temperatures are
forecast through Wednesday. Expect breezy winds Wednesday
afternoon followed by much colder temperatures Thursday as a
passing cold front moves through the area. There will be a chance
of showers from Wednesday into Thursday, while additional chances
for precipitation return over the weekend.
Have updated tonights sky as todays stratus deck has shrunk and
is now north of a line from Kingman-Tusayan-Four Corners.
Otherwise the forecast is in good shape.
.PREV DISCUSSION /327 PM MST/...Low clouds have been holding on
over much of northern Arizona this afternoon. The clouds over the
Chinle Valley and the eastern Coconino Plateau have thinned or
dissipated, but they persist over many other areas. Forecast
soundings and short- term hi-res models indicate that low clouds
will continue to thin or dissipate through this evening. As they
do so, a few patches of fog could briefly form while dew points
remain elevated. Fog is not expected to be extensive.
Tuesday is forecast to be the warmest day of the week as northern
Arizona is influenced by southwest flow atop a shortwave ridge
with heights peaking at the 99th climatological percentile over
southern AZ/northern Sonora. Wind speeds will increase to the
northeast of high terrain features early on Wednesday morning,
and area-wide by Wednesday afternoon as southwest flow increases
between the weakening ridge over TX and a trough over the Pacific
Northwest/northern CA. The aforementioned trough is forecast to
bring a strong cold front through northern Arizona from Wednesday
night into Thursday morning. Some light precipitation will be
possible in association with the frontal passage, with snow levels
lowering to 4500-5500 feet behind the front.
High temperatures will be around 15-20 degrees colder on Thursday
compared to Wednesday`s values, with breezy west winds. A
relatively zonal flow pattern is forecast to continue through the
early part of the weekend. Low temperatures on Friday and Saturday
morning will be near to a few degrees below average, with high
temperatures around seasonal averages.
Substantial model spread continues for the Sunday 26 Feb - Tuesday
28 Feb period. The NAEFS mean shows a weak disturbance for Sunday
with some precipitation in the ensemble average for northern
Arizona, followed by a deeper trough a couple of days later.
Confidence is fairly low for the Sunday disturbance, and somewhat
higher regarding the second feature. We will stick with a chance
of rain/snow for now.
.AVIATION...For the 06Z package... Cloud cover is retreating to
the north with most locations experiencing vfr conditions. Some
cloud cover could impact KGCN with lower flight categories over
the next few hours. There is a low chance of some areas of lower
CIGS or patchy fog with IFR/LIFR redeveloping 05Z-15Z for
elevations above 6500 feet MSL. VFR conditions will prevail
Tuesday, with a slight chance of -SHRA from KGCN northwest after
20Z. Probability of occurrence too low to include in KGCN TAF.
Aviation discussion not updated for TAF amendments.
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