Area Forecast Discussion
Issued by NWS Reno, NV
FXUS65 KREV 270916
Area Forecast Discussion
National Weather Service Reno NV
216 AM PDT TUE SEP 27 2016
High pressure will persist through Wednesday morning with above
normal temperatures and light winds. The high begins to weaken on
Wednesday with a few showers possible over southern Mono County.
The ridge weakens further late week as a trough of low pressure
moves into the West Coast. This will bring breezy and cooler
conditions to northeast California and western Nevada.
High pressure will keep temperatures well above normal through
Wednesday with light winds. The upper low currently over the
northern Gulf of California will move north ahead of incoming
northeast Pacific trough and shear apart as it tracks across the
Desert Southwest and into the eastern Great Basin Wed-Thu. Much of
the moisture will stay south and east of Mono County and the Basin
and Range, although some increase in clouds can be expected in
these areas Wed-Wed night. A slight chance of showers continues
for the Mammoth Lakes area and the White Mountains. Instability is
almost non-existent so the risk for thunder with the showers is
very low (less than 10%).
For Thursday, gradients will increase as the airmass begins to
cool in the Sierra and northeast CA ahead of incoming trough.
Meanwhile, southwest flow aloft will increase to 15-25 kts around
10,000 feet MSL (700 mb). Breezy conditions (gusts 20-30 mph) will
develop along the ridges as well as lower elevations from the
Sierra Front/areas north of I-80 as the winds aloft mix down
Thursday afternoon and evening.
There could be a few leftover cumulus in the afternoon over Mono
and Mineral Counties Thursday. However, the flow aloft should
begin to kick out moisture so no precipitation is expected at this
.LONG TERM...Friday through Monday...
The long wave trough that has been advertised the past few days is
still on track to affect the region through the weekend. Again,
there are some differences with the depth and timing, but this is
more towards Sunday and Monday. For Friday, winds do look set to
increase with 700 mb winds of 25-35 kts and windy conditions most
areas. This will be a fire weather concern as RH will be down near
15-20% for much of the day.
The initial cold front passes through overnight Friday night with
cooler temperatures, but it is a dry front with no precip expected.
Saturday will be noticeably cooler as highs will be 5-10 degrees
below average with some locally breezy west winds behind the front.
For Sunday and Monday, the GFS and EC are showing a couple secondary
waves coming down the backside of the trough and reinforcing it.
Both models are showing more moisture with these systems and also
some cooler temperatures. This is quite a change from 24 hours ago
as the models were much more progressive with no reinforcing shots.
However, there is some support from the ensembles this morning. The
EC is deeper, wetter and cooler with the systems, especially for
Monday afternoon and evening while the GFS keeps it further north.
The GEFS is between the two runs and went more along its lines and
the GFS to keep more of a continuity with the previous forecast. It
is still 6-7 days out so we have time to make adjustments to the
wetter solution if needed. I did increase the pops to chance near
the Oregon border and added a slight chance in the Sierra as far
south as Alpine County for Monday into Monday night. No matter the
solution, a continuation of the below average temps is expected
early next week. Wallmann
VFR conditions through Thursday. Light east winds to continue into
Wednesday. Winds will increase some Thursday with the strongest
winds likely Friday ahead of a cold front. Wallmann
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