Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Reno Nevada
152 PM PDT Sat Mar 15 2014
strong high pressure building over the region this weekend will
bring well above average temperatures. A backdoor cold front will
provide some cooling Monday and Tuesday with temperatures closer to
average. With weak west flow later in the week, expect near
average temperatures but little if any precipitation.
models in better agreement with the front for Sunday night/Monday
and are more of an average solution from this time yesterday. Have
made few changes except to increase the winds a bit more Monday
Warm temperatures will continue into Sunday under the ridge overhead with
another cool night tonight with good radiational cooling. Temperatures
could exceed records in the Sierra. As the front approaches
Sunday night, expect winds to increase. NAM/GFS/ec in good
agreement now with 700 mb winds peaking at 60 kts around 12z
Monday just ahead of frontal passage. Model cross sections on NAM
do not show much downslope signature with more trapped Lee waves.
Given the fast movement of the system and the brief period of
strongest winds, this makes sense. Have increased the winds along
the 395 Corridor North of Walker though with gusts to 40-45 miles per hour
With the stronger winds we will likely need a lake Wind Advisory
tomorrow night into Monday for Tahoe and for Monday as well for
Pyramid Lake. Only location that looks susceptible to a Wind
Advisory at this time is the Surprise Valley. Stronger winds aloft
last longer there so there could be enough time for a weak
breaking wave. Will not issue now and let future shifts investigate.
Behind the front Monday, cool northwest flow will keep it breezy.
Temperatures will cool closer to average with highs around 60 in western Nevada
and low 50s in the Sierra valleys. With another weak, dry short
wave expected to pass through Tuesday morning, a reinforcing shot
of cooler air arrives. With cool northeast flow at the surface and
700 mb temperatures -5 c or below, temperatures likely to be below average for
daytime highs in western Nevada but closer to average in the Sierra.
Long term (wednesday-saturday)...
no significant changes made to this period of the forecast. West/northwest
flow aloft will bring a fast moving storm across the Pacific northwest
Wednesday into Thursday. Main impact this would have for US is to
increase the winds as a cold front moves across northern Nevada.
Gusts on the order of 30-40 miles per hour are likely given current model
guidance. Precipitation chances are meager but will continue ongoing
slight chances north of Susanville-Gerlach in case storm moves
further south than currently forecast. Did remove slight chance
probability of precipitation for Thursday night into Friday based on recent guidance.
Looking further out - there is some (slim) hope of turning back to a
wetter pattern the week after next. Analogs suggest increased
chances of seeing 1" or more along the Sierra crest in the d8-14
period. Latest GFS/ec ensemble guidance suggests ridging maintaining
influence over the region through Mar 24 though they both show a
large upper trough developing off the West Coast. In any event, low
high pressure overhead will lead to light winds and clear skies
through Sunday morning with no aviation weather concerns. High
confidence in latest taf issuance.
Ridge moves off to the east Sunday afternoon with cold front
approaching from the northwest. This will increase winds aloft to 20-30 kts
at Ridgetop levels by Sundown Sunday and SW winds 7-12 kts with
gusts to 20 kts at rno and nearby taf sites. A period of stronger
winds with mountain wave activity is likely between 6z-18z/Monday
with SW surface winds gusting to 30-35 kts at rno/cxp/tvl/trk.
Forecast confidence in the winds is medium and increasing. Cs
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