Scientific Forecaster Discussion
fxus65 kpsr 102126
Area forecast discussion
National Weather Service Phoenix Arizona
226 PM MST Tue Dec 10 2019
drying conditions under weak high pressure will bring mostly
sunny skies today with highs in the mid to upper 60s. A weak
weather system mostly skirting by to the north of Arizona will
then bring mostly cloudy skies tonight into early Wednesday.
Increasing high pressure and warming conditions are then seen for
late week with high temperatures likely topping 70 degrees over
the lower deserts for Friday and Saturday. Another weak but dry
weather system should bring cooler temperatures into early next
high pressure will dominate the weather pattern through next
week, with a couple of weak disturbances moving across the region.
The first wave will move through late tonight through tomorrow
and result in an increase in high clouds. Current, satellite
imagery already shows thicker high clouds moving into southeast
California, with these clouds expected to spread eastward into
southwest and south-central Arizona by later this afternoon. Due
to increased cloud cover overnight, we nudged overnight lows a
couple of degrees warmer. In addition, the enhanced cloud cover
and warmer temperatures will bring down the threat for dense fog
re-development tomorrow morning, but latest hrrr guidance
continues to indicate patchy fog developing, especially in
northwest Pinal County and around the San Carlos area in southern
Gila County. It looks like the best window for fog will be from
around 4 am to 10 am MST Wednesday morning.
High clouds will clear from west to east tomorrow, with mostly
clear skies expected in southeast California by mid-morning and
in southwest and south-central Arizona by early-afternoon. Strong
high pressure will then begin to build into the region in the
wake of the aforementioned wave and remain situated over US
through the early part of the weekend. This will lead to a warming
trend with highs in the upper 60s/low 70s by Friday and Saturday.
It still looks like another weak weather system will move across
the region on Sunday and bring rain to the far eastern portions
of southern Gila County. Most of our forecast area will likely not
see any rain from this system, however, what we will see is
another cool down with high temperatures across the lower deserts
dropping back into the low 60s by next Monday.
Aviation...updated at 1755z.
South-central Arizona including kphx, kiwa, ksdl, and kdvt:
Very light, less than 6 kts, and diurnal winds will persist
through the next 24 hours with periods of variability. Mid and
high clouds will pass west to east over the area beginning this
evening through early Wednesday afternoon with a weak disturbance.
No other impacts expected from this disturbance.
Southeast California/southwest Arizona including kipl and kblh:
Winds will remain light and variable through the taf period,
favoring typical diurnal tendencies. A quick-moving disturbance
will bring a period of scattered-broken mid and high clouds this afternoon
through early Wednesday morning, but VFR conditions will persist.
No other impacts expected with this disturbance.
Thursday through monday:
dry conditions under increasing high pressure aloft will prevail
through Saturday before a weak low pressure system affects the
region Sunday into Monday. Moisture levels with the late weekend
system should be too dry, hindering precipitation chances. Minimum
humidity levels initially should stick around 25-30% much of the
period, potentially lowering slightly into early next week. Winds
will stay light through Saturday before some breezy conditions
move in for Sunday and Monday.
Spotter information statement...
spotters should follow Standard reporting procedures.