Area Forecast Discussion
Issued by NWS Phoenix, AZ
FXUS65 KPSR 080248
Area Forecast Discussion
National Weather Service Phoenix AZ
745 PM MST Wed Dec 7 2016
Dry weather with seasonably comfortable temperatures will persist
over the region through the weekend. Only periods of passing high
clouds will interrupt an otherwise beautiful stretch of early winter
Broad cyclonic flow continues to dominate the vast majority of the
Conus with several low amplitude shortwaves embedded within the
overall flow pattern. One such wave was propagating through southern
AZ this evening and primarily responsible for the thicker high cloud
cover throughout the region. Satellite imagery indicates subsidence
and clearing incoming behind this wave and this should promote
better nocturnal cooling than last night. Correspondingly, low
temperatures look to fall a couple degrees cooler than this morning
(which has already been captured in the previous forecast). Given
the stagnant pattern and high confidence forecast, very little
changes were made in the evening update tonight.
/154 PM MST Wed Dec 7 2016/
After today`s shortwave passage and jet streak exit from the region,
flow aloft remains persistently low amplitude across the CONUS
heading into the weekend. Boundary layer humidities will dry and ML
height fields remain rather steady state in the 570dams to low
580dams through early next week. Low amplitude pattern yields high
confidence and predictability through the extended forecast period
with daytime temperatures at or slightly above seasonal normals and
periods of passing high level clouds. Confidence is very good that
H5 heights will oscillate in a 576-582dm range with the primary jet
core displaced through the northern tier of states.
South-Central Arizona including KPHX, KIWA, and KSDL:
Very little aviation impacts through Thursday afternoon as high
clouds generally thin overnight. Winds will remain light which will
allow pollution build up trapped under the inversion layer Thursday
morning. Thus, slantwise visibilities may be compromised for much of
the morning Thursday.
Southeast California/Southwest Arizona including KIPL and KBLH:
Minimal aviation concerns through Thursday afternoon under thinning
cirrus clouds. Sfc winds will generally favor a NW/N component,
however a very weak pressure gradient will allow light and variable
winds for extended periods as well.
Aviation discussion not updated for amended TAFs.
Friday through Tuesday:
Slightly above normal temperatures and mostly dry conditions are
likely through the period with high clouds moving across the area at
times. Overall, the weather patterns shows little day to day change
with a zonal westerly flow aloft over the area. Winds each day will
mostly stay on the light side with typical afternoon breeziness
favoring the southwest or west. Humidities will be elevated through
the five day period with minimum RH values mostly between 20 and 30
percent each day. There are no significant fire weather concerns for
the next five days.
.SPOTTER INFORMATION STATEMENT...
Spotters activation will not be needed this week.
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