Scientific Forecaster Discussion
fxus65 kpsr 162055
Area forecast discussion
National Weather Service Phoenix Arizona
155 PM MST Fri Nov 16 2018
high pressure will remain stationed over the area through early next
week resulting in temperatures near or just below the seasonal
average. Dry conditions and light winds will also prevail through
Monday, before a mostly dry storm system moves through the region
during the middle part of next week.
a quasi-zonal, weak southern stream jet will persist across the SW
conus through the weekend. Embedded within this jet core are several
low amplitude shortwaves which will bring periodic thicker high
clouds into the forecast area. Given the relatively non-descript
nature to these waves and predominant westerly flow, no appreciable
low level moisture will be available towards precipitation
processes. Cloud cover will likely be somewhat thinner Saturday
versus Sunday when forecast soundings suggest a least a period of
Temperatures through early next week will remain near or just shy of
seasonal normals with 500 mb heights hovering right around a typical
late fall 573dm. Day to day temperature fluctuations will be
primarily driven by variations in cloud cover versus any synoptic
change. Models are still showing a more defined, amplified shortwave
propagating through the region Tuesday, but it still looks moisture
starved with no realistic chances of rain. This system will at least
increase moisture levels modestly, displacing the abnormally dry
airmass which has been locked in place for the past week. A follow-
up trough late next week may have a shot at bringing minimal rain
chances, but models continue to maintain lower latitude ridging
and deflecting the system mostly north of Arizona.
south-central Arizona including kphx, kiwa, and ksdl...
southeast California/southwest Arizona including kipl and kblh:
Very weak weather disturbances embedded in light westerly to
northwesterly flow aloft to continue to push scattered-broken high cirrus
cloud decks over the entire region through the taf period. Strong
high pressure at the sfc to keep winds quite light through the taf
period, with directions mainly following typical diurnal trends.
Extended periods of light/variable winds are likely to occur at all
of the taf sites as well.
Aviation discussion not updated for amended tafs.
Sunday through thursday: for the most part, dry westerly flow aloft
will dominate the Desert Southwest over the next 5 days keeping
conditions dry. There will be a couple of fast moving weather
systems pass through the districts but they will bring little if any
chance for precipitation; the system on Thursday may be a bit wetter
and could result in a few showers over the higher terrain east of
Phoenix but little else. High temperatures will fluctuate slightly
day to day but generally remain near seasonal normals with desert
highs staying in the low to mid 70s for the most part. Look for
minimum relative humidity values in the deserts mostly 15 to 25 percent through
Tuesday, then climbing into the 20 to 35 percent ballpark later in
the period, as the stronger weather system moves through the area.
Winds will be on the light side each day only weakly following
typical diurnal tendencies.
Spotter information statement...
spotters should follow Standard reporting procedures.