Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 222006

Area Forecast Discussion
National Weather Service Reno NV
106 PM PDT Tue Aug 22 2017

Scattered to numerous thunderstorms are expected through this
evening. Flash flooding is the main hazard. Storms will return
Wednesday but coverage is not expected to be as much as today. Drier
and hotter weather will return starting Thursday into this weekend and
potentially much of next week. Record highs are possible.



So if you were thinking that summer is largely over, think again...

* With precipitable waters in the "sweet spot" of 0.6 to 0.8" and weak
  upper low nearby, afternoon and evening thunderstorms will remain an
  issue through tomorrow. Short range guidance indicates today should
  have the most coverage compared to Wednesday. Storm motions today
  are not overly slow but 18z sounding, radar trends, and high-res
  guidance all suggest training is a good possibility. So flash
  flooding remains our primary hazard today. A few strong/severe
  storms possible today with hail and strong winds, but tomorrow could
  have a greater risk of severe with stronger flow aloft and
  increased low level westerly convergence zones.

* Ridge builds in starting Thursday and based on ECMWF, GEFS guidance
  it has the potential to be unusually strong and long lasting, into
  next week. This will yield hot temperatures compared to late-August
  norms, even close to some record highs this weekend. Hitting 100 at
  RNO not out of the question at some point Sunday-Tuesday. This is
  abnormal since our frequency of 100+ usually drops off a cliff after
  mid-August. Since 1893 Reno has only hit 100+ 7 times after August
  22nd. Zephyr type westerly winds and mountain buildups likely as
  well each day starting Thursday.



* Thunderstorms will be the main issue for flying today and Wednesday.
  Coverage could become numerous in some areas today impacting enroute
  and approach/departure routes in the region including at RNO.
  Roughly about a 40-60% chance of thunderstorms directly impacting
  terminals today between 20z-03z. Storm motions to the NW 10-15 kts.
  Wednesday storm coverage looks to be less than today in high-res
  guidance and with more of a westerly flow aloft storms will kick off
  the Sierra quicker. So about a 10-20% chance of storms for
  TVL,TRK,MMH and 30% for RNO,CXP in the afternoon and early evening.

* Outside of storms, just a few issues to note. If the TRK area
  receives heavy rainfall today then fog or stratus would likely be an
  issue Wednesday morning if skies clear enough. For Friday into early
  next week, unusually warm temperatures will drive up density
  altitudes that may impact some aircraft during peak heating times of
  day. Weak to moderate westerly zephyr winds each afternoon from
  Thursday into the weekend.



.REV Watches/Warnings/Advisories...


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