Scientific Forecaster Discussion
fxus65 kpsr 130507
Area forecast discussion
National Weather Service Phoenix Arizona
1007 PM MST Tue Nov 12 2019
Update...updated aviation discussion.
a quiet weather pattern will continue to bring dry weather with
above normal temperatures and periods of high clouds this week.
Winds will generally be light except today when gusty easterly
winds will occur behind a weak back door cold front. Lower Desert
high temperatures be in the lower to mid 80s, with lows in the
50s. Cooler temperatures and increased shower chances are
expected by the middle of next week as an upper level disturbance
approaches the region.
temperatures today are about 5-7 degrees cooler than they were
yesterday behind a weak back door cold front that is in the
process of dissipating as it moves into southwest Arizona.
Easterly winds are persisting across the Phoenix Metro behind this
front, with high temperatures climbing into the upper 70s and
lower 80s a few degrees above normal. Temperatures are a bit
warmer ahead of the weak front in southeast California and
southwest Arizona where highs in the mid 80s under light and
variable winds are expected. Clear skies with relatively calm
winds tonight will allow for efficient radiational cooling, with
lows decreasing into the lower to mid 50s near seasonal normals
for the first time in over a week. Temperatures tomorrow will be
very similar to today under mostly clear skies and north-northwest
flow aloft as a ridge builds into the Desert Southwest behind a
slow-moving cutoff low that will finally eject eastward across
Mexico towards south Texas tomorrow.
For the remainder of the forecast period, generally all signs
continue to point to a dry forecast period with little or no weather
impacts. Temperatures will increase a few degrees for Thursday to
Saturday as the region remains under the influence of a mid-to-
upper level ridge of high pressure, though periods of high clouds
should keep high temperatures from climbing above the mid 80s. A
shortwave digging into The Rockies and Southern Plains on Sunday
will cause a slight decrease in high temperatures into the lower
80s for Sunday into the first half of next week as upper level
ridging briefly reasserts itself over the region. However, cooler
and wetter conditions are expected late Tuesday into Wednesday
just beyond our forecast period as a relatively deep trough and
significant increase in moisture is forecast by over 75 percent of
the GFS and ecm ensemble members. In agreement with this signal,
CPC is forecasting odds tilted towards above normal precipitation
for the week 2 period with the potential for another shortwave to
continue precipitation chances through the end of next week.
Aviation...updated at 0508z.
South-central Arizona including kphx, kiwa, ksdl, and kdvt:
Light easterly winds will prevail during the overnight hours with
clear skies. Late morning expect a period of light and variable
winds followed by a shift to west-southwest winds mid afternoon. Typical
night time easterly flow resumes mid evening Wednesday. Skies will
generally be clear with just a few cirrus clouds developing by
Southeast California/southwest Arizona including kipl and kblh:
No aviation concerns with clear skies and light winds through
Wednesday morning. Kblh will favor light southerly winds on
Wednesday afternoon with kipl shifting from light southerly to
westerly. Few to scattered upper level clouds will move into the area
from the west on Wednesday afternoon.
Thursday through monday:
relatively dry conditions will persist through the period with
increasing high pressure aloft through the work week. Above normal
high temperatures will persist across the lower deserts each day
with warmer deserts mostly in the low to mid 80s. Look for light
winds following diurnal trends expected for the rest of the week.
Minimum relative humidity values will fall into the mid to upper
teens each day through Saturday with lower values in the lower
teens for Sunday and Monday.
Spotter information statement...
spotters should follow Standard reporting procedures.