Area Forecast Discussion
Issued by NWS Phoenix, AZ
FXUS65 KPSR 282103
Area Forecast Discussion
National Weather Service Phoenix AZ
203 PM MST FRI OCT 28 2016
.UPDATE...Aviation and Fire Weather Discussions...
A large and wet Pacific weather system is forecast to move into
northern Nevada today, and this system will spread considerable
clouds over the region with a slight chance of showers over the
southeast California deserts and a somewhat better chance over the
mountains. Dry weather with mostly clear skies will return this
weekend, with desert temperatures continuing in the lower 90 degree
range. Another massive Pacific weather system will approach the
central California coast by Tuesday, then move into the western
states Wednesday providing mostly cloudy skies and cooler afternoon
temperatures to southeast California and southern Arizona.
Very amplified pattern across the western states today with a
deepening closed low west of Washington/Oregon and a strong anti-
cyclone over the Rio Grande Valley. Inbetween, plenty of upper level
moisture in the southwest flow was throwing lots of high clouds
across our area. There was a short wave embedded in the flow, though
it was moving through central California and into Nevada. The clouds
helped keep temperatures very warm this morning, with KPHX notching a
low of 76; if that holds, it`ll easily break the record high low of
70 for this date and will establish a new latest occurrence of a 75+
low (previous was Oct 15).
The 28.12Z KTUS sounding exhibited near-record level warmth for this
time of year based on 850/700 T/GH variables. This is translating
once again to a very warm, some may say hot, afternoon. The thicker
cloud cover does seem to be tempering temperatures a bit more than
yesterday. We`re also seeing a few light showers across SoCal and
northern Arizona weak PVA traverses the region, a trend that will
wane this evening.
Saturday through Tuesday will see a continuation of the strong
southwest flow across our region as the larger scale pattern remains
fairly locked and stable. A few shortwaves will pass by in this flow,
to our north, that will very slightly push temperatures down and
enhance winds a bit but overall a warm, tranquil weekend.
Toward the middle of next week, a surprisingly good amount of
consistency among the GFS/EC ensemble members. A very strong jet will
extend across the north Pacific, culminating in a somewhat persistent
negatively titled trough impinging on the PacNW. In turn, this will
promote a very broad downstream ridge across much of the remaining
west and central states. NAEFS H5 mean heights will be above the 90th
percentile. The fly in the ointment, which is also well supported by
the ensembles, is a closed low that is currently forecast to develop
and meander across the Southwest Wed-Fri. Based on this scenario,
lowered temperatures a bit more for that time frame and included
low-end, broad-brushed PoPs for our eastern CWA. If the closed low
does not come to fruition, temperatures will remain quite warm.
South-Central Arizona including KPHX, KIWA, and KSDL:
Light diurnal winds will continue with some mostly broken mid to hi
cloud decks. Cigs should remain above 12kft.
Southeast California/Southwest Arizona including KIPL and KBLH:
Southerly flow 10 to 15 kts will remain for both sites through 03Z.
Skies have mostly scattered out but good chance remains to pick up
broken ceilings again this evening but cigs should remain above
Aviation discussion not updated for amended TAFs.
Sunday through Thursday...
More noticeable cooling trend will begin after the weekend as a storm
system moves into the region from off the Pacific. Temperatures will
still be above seasonal averages, but not near the record-breaking
levels observed over the end of previous week. Moisture continue
remains on the low side with this storm system, so precip chances are
next to none and the most noticeable impact will be the slight
temperature cool down and some elevated breeziness Sunday afternoon.
Winds will be at their strongest across southeast California, where
from daytime gustiness will be possible up to 25 mph. Daytime
humidities will range 20 to 30 percent and make good overnight
.SPOTTER INFORMATION STATEMENT...
Spotter activation will not be needed this week.
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