Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 090221
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
720 PM MST Thu Dec 8 2016

.SYNOPSIS...
Dry weather with seasonably comfortable temperatures will persist
through the weekend and into at least the middle of next week. Only
periods of passing high clouds will interrupt an otherwise beautiful
stretch of early winter weather while no precipitation will affect
communities into next week.

&&

.DISCUSSION...
Although the overall flow pattern appears nearly identical this
evening from the past couple days, 00Z sounding data sampled H5
heights 4-5dm higher than this morning (576-580dm range locally)
with H8 temperatures around 2C warmer than yesterday afternoon.
Consequently, ambient air temperatures were somewhat warmer than 24
hours ago, and this subtle warming trend will continue the next few
days. Skies should remain mostly clear tonight allowing good
nocturnal cooling, though there is a small slug of upper level
moisture streaming east from the Pacific basin that could interrupt
the cloudless skies overnight. Regardless, only minimal changes to
account for short term hourly trends were necessary in the evening
update.

&&

.PREVIOUS DISCUSSION...
/119 PM MST Thu Dec 8 2016/
Tonight through next Thursday...
A very tranquil period is expected through at least the middle of
next week. All global model guidance and their respective ensemble
members continue to be in outstanding agreement for the entire
period. They all keep the Desert Southwest under flat ridging/dry
northwesterly flow aloft as the main longwave trough remains
positioned well off to our north over central Canada and the central
US, with very strong ridging building northward across the eastern
Pacific into Alaska as time goes on. So while an extended period of
below/well below normal temperatures is expected across the northern
tier of the CONUS, our CWA will be seeing dry conditions and a slow
warming trend from Friday into the early part of next week. Warmer
air in the mid-levels of the atmosphere will gradually imported into
the region from the west with lower desert highs rising into the low-
mid 70s by Sunday and Monday. Some slight cooling is possible on
Tuesday as a stronger shortwave passes well to our north across the
Great Basin before temperatures once again warm up a bit next
Wednesday and Thursday. Skies will remain mainly clear through the
entire period with just some high cloudiness passing overhead from
time to time as shortwaves pass off to our north.

&&

.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL and Southeast
California/Southwest Arizona including KIPL and KBLH:

No aviation concerns through Friday afternoon under mostly clear
skies. Winds will follow normal diurnal headings and remain light
aob 5 kts. However due to very light wind speeds, directions will be
variable at times.

Aviation discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Saturday through Wednesday:
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.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.

&&

$$

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DISCUSSION...MO/Percha
AVIATION...MO/Hernandez
FIRE WEATHER...CB/Deemer



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