Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Phoenix Arizona
250 PM MST Thursday Aug 28 2014
dry and stable air will keep storm chances out of the forecast
through at least early next week. Anticipate a bit more warming
Friday and Saturday reaching at least a few degrees above
normal...around 110 degrees at most locations in southwest Arizona
and southeast California. High pressure will weaken some early next
week for modest cooling...to near normal. There is a slight chance
of storms returning to the higher terrain of south-central Arizona
by the middle of next week.
rest of today through Sunday...
only cumulus clouds today as the high pressure ridge centered near
the California and Baja California Mexico coast makes its presence known.
Expect even less cloudiness tomorrow with even drier and more stable
air. In the mean time...models advertise a trailing short wave to
break off over Sonora and settle between two anticyclonic centers.
Latest NAM indicates some cape trying to creep back into far
southern and far eastern Arizona Saturday. The sref GOES so far as
to depict modest quantitative precipitation forecast over the southeast third of Arizona. This looks
to be an outlier and the forecast remains dry. Temperatures increase
a little bit more...getting at least a few degrees above normal.
This will mean highs around 110 for the lower deserts of southwest
Arizona and southeast California...a bit less for the south-central
Arizona deserts. Models are in better agreement on lower level
moisture seeping into the area Sunday. Cape will be spotty but it
will be moot getting nullified by the cin. High temperatures nudge down a
bit as well.
Monday through Thursday...
some additional moistening is advertised for Monday by GFS and
European model (ecmwf)...mainly over Southeast Arizona. With westerly flow aloft...it
will be difficult to advect storms into our forecast area. May be a
bit better opportunity Tuesday with more of a southerly component to
the steering flow...according to European model (ecmwf) but less so GFS as they
differ a bit on how far north the main anticyclone center resides.
Held on to low end slight chances for easternmost portions of our
forecast area. Similar pattern in place for Wednesday though there
could be some temporary decline in the moisture. As troughing to the
north retrogrades...GFS and European model (ecmwf) depict a somewhat more favorable
flow pattern for Thursday though they definitely disagree on
moisture availability...European model (ecmwf) quite a bit more generous. Held on to
the flatline trend in probability of precipitation and temperatures given lack of clear cut
agreement and inherent uncertainty that comes with forecasts further
out in time.
south-central Arizona including kphx...kiwa...and ksdl...and
southwest Arizona and southeast California including kipl and kblh...
Cumulus developing over higher terrain of central and Southeast
Arizona will continue to drift southward. Clouds will dissipate
quickly after sunset. Light winds will favor north and northwest
directions with stronger north and northwest winds aloft. Surface
winds will become light and variable tonight favoring drainage
Aviation discussion not updated for amended tafs.
Sunday through Thursday...
humidities increase early next week as moisture from Mexico seeps
northward. A slight chance of thunderstorms returns to the higher
terrain of south-central Arizona by the middle of next week. Winds
will follow typical patterns with locally breezy conditions Sunday
over the lower Colorado River valley and adjacent portions of
southwest Arizona and southeast California. Anticipate temperatures
being close to normal.
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