Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 302152

Area Forecast Discussion
National Weather Service Reno NV
252 PM PDT Thu Mar 30 2017


A strong cold front brought snow showers and high winds to the
region Thursday. Weather should quiet down with warming temperatures
through the weekend. Gusty winds and light rain are possible Sunday
night with a passing storm. Potential exists for a stronger Pacific
storm late next week, but impacts and flood potential remain low
confidence this far out.


.SHORT TERM (through Sunday night)...

Spring in the Great Basin can be quite variable and we definitely
saw a remnant of winter today. Strong cold front brought a classic
snow squall scenario around the morning commute but fortunately road
temperatures were warm enough to melt much of it, outside of the
mountains where more of an impact was seen. Winds gusted above 50
mph and temperatures dropped 10-15 degrees in less than 20 minutes.
Here are the key points for the coming days...

* Winds Today - Very impressive pressure gradient over Nevada.
  HRRR showing pressure drops with low near Las Vegas over 1- 2
  MB/hour! This will prompt a resurgence of strong sustained winds
  across our region through early evening, with highest risk of
  damaging winds in areas south of Hwy 50 including Hawthorne,
  Mammoth, Owens Valley.

* Ridge/Lake Winds Friday - Winds should diminish later this
  evening as the low moves eastward but remain somewhat gusty into
  Friday. On the Sierra ridges, NE winds will remain stronger
  Friday with 700mb flow 40-50kts. Rough waters possible on Lake
  Tahoe especially west shore with mixed layer up to about 700mb
  by afternoon.

* Snow Showers This Evening - Airmass behind the cold front is
  moderately unstable resulting in continued snow showers.
  Accumulations until sundown will be sporadic and limited to
  areas above 6000` due to late March solar energy. Latest HRRR
  shows showers persisting over Mono-Mineral Counties this evening
  with weak instability aloft, so will note that in forecast.
  Could be some localized and quick snow accumulations.

* Weekend - Should be a pleasant spring weekend for the most part
  with gradually warming temperatures each day Fri-Sun. Sunday has
  potential to get warm as low level flow switches from cool NE on
  Sat to a warmer SW flow Sun. Increased lower elevation snowmelt
  will result which may yield slight increases in stream, river

* Sunday Night "Wanna Be Slider" - Simulations have been consistent
  showing another front dropping in from the NW Sun night. Has the
  look of a slider but the wave isn`t as sharp as today`s and scoots
  off to the east. Main results for our region are typical gusty SW
  winds starting late Sun afternoon, and a band of rain or snow
  showers near the front Sun night. Right now, system looks warmer
  than today`s with precip type mainly rain except in mountains, so
  travel impacts appear low.


.LONG TERM...Monday into next weekend...

The system exits quickly on Monday, with a ridge building over
northeast California and western Nevada for Monday night into
Wednesday. Afternoon temperatures near average Monday will rise to
well above average by mid-week as the ridge axis moves overhead.

Thursday, the ridge slides east and allows a lead wave with a
large-scale North Pacific trough to move into the West. The most
recent ECMWF simulation and last two runs of the GFS indicate a
weak lead wave with only minor precipitation amounts, while
yesterday`s ECMWF shows a stronger wave and more direct hit from
an atmospheric river (AR) by Thursday night. Moisture transport
simulations from the GFS ensemble only indicate a moderate
probability of AR conditions near the northern CA coast Thursday
night. With this in mind and the fact that recent AR probabilities
have backed off on probabilities through Thursday, confidence is
wavering for substantial precipitation through Thursday night.

For next Friday and into the following weekend, it is likely that
the AR will finally move into the West Coast. Current forecasts
favor the Pacific Northwest; however, intensity and especially
latitude are still in the realm of lower predictability with the
main question revolving around how far south the moisture and jet
stream drop. Increased chances are not a guarantee, but definitely
worth keeping an eye on as a direct hit from another AR would
again increase flooding concerns in the region. Snyder/Tolby



Scattered snow showers will dissipate this evening with the loss
of daytime heating and the exit of the upper low (into southern
NV). Lower clouds and widespread higher terrain obscuration should
begin to break up this evening for most of northeast CA and
western NV, although lower clouds (generally 095-120 MSL) along
with occasional light snow showers could remain banked up against
the Mono County Sierra through most of the night.

Ridging builds in Friday and persists through Saturday for VFR
conditions with light-moderate northerly flow. The flow could
bring turbulence along and west of the Sierra crest. Snyder


.REV Watches/Warnings/Advisories...
NV...Wind Advisory until 11 PM PDT this evening NVZ004-005.

     High Wind Warning until 8 PM PDT this evening NVZ001.

     Lake Wind Advisory from 10 AM to 6 PM PDT Friday for Lake Tahoe
     in NVZ002.

     Wind Advisory until 8 PM PDT this evening NVZ002.

     Wind Advisory until 8 PM PDT this evening NVZ003.

CA...Wind Advisory until 11 PM PDT this evening CAZ070.

     High Wind Warning until 8 PM PDT this evening CAZ073.

     Lake Wind Advisory from 10 AM to 6 PM PDT Friday for Lake Tahoe
     in CAZ072.

     Wind Advisory until 8 PM PDT this evening CAZ072.



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