National Weather Service (2025)

Area Forecast Discussion
Issued by NWS Reno, NV

994FXUS65 KREV 100901AFDREVArea Forecast DiscussionNational Weather Service Reno NV201 AM PDT Tue Sep 10 2024.SYNOPSIS...* Breezy winds and dry conditions keep elevated to critical fire weather conditions through Wednesday.* A cold front brings stronger winds and chances for showers and a few thunderstorms Wednesday, especially in areas north of I-80.* Beyond Wednesday, lighter winds and cooler temperatures are expected with another system bringing winds and rain chances by late weekend.&&.DISCUSSION...An upper level trough will reach the west coast today, bringingsome increase in winds this afternoon, with peak gusts 30-35 mphespecially for far western NV. Otherwise, dry conditions andtemperatures similar to Monday will prevail today.The more significant winds will arrive Wednesday as this troughmoves inland across the northwest US/northern Great Basin accompaniedby a decent cold front dropping into western NV. West winds with a30-40 kt 700 mb flow will increase in higher elevations early inthe day with peak ridge level gusts of 50-60 mph, then mix downto lower elevations during the morning and continue through earlyevening, with peak gusts mainly 30-40 mph and possibly near 50 mphin wind prone areas. This will produce impacts for recreation (aLake Wind Advisory will be issued for Wednesday for both Tahoe andPyramid), air/road travel, and fire weather concerns. See theFire Weather section below for more details on fire-relatedweather impacts through Wednesday.Along with the winds, temperatures will begin to trend lower withhighs about 10-15 degrees colder compared to today in areas northof I-80, and around Tahoe, with a smaller temperature drop farthersouth. The front brings some moisture too, with the best chancesfor measurable light rainfall (up to 0.10") remaining north of aSusanville-Lovelock line Wednesday afternoon-evening, and wettingrainfall (0.10-0.20") farther north near the OR border whereisolated thunder is also in the mix. The shower chances drop offto less than 15% southward to the Tahoe basin and far western NVwith the ensemble guidance in relatively good agreement for thestorm track/timing, as these shower chances kick out quickly tothe east by late Wednesday night. As cloud cover and windsdecrease, temperatures cool off to the 40s in most lowerelevations, and 30s for typically cooler western NV valleys and20s for Sierra valley communities.The coolest day of the week will be Thursday with lighter northbreezes lingering in the post-frontal air mass, while highs dropto the upper 60s-mid 70s across most areas--about 6-12 degreesbelow seasonal average. Another cool fall-like night will thenfollow with lows similar to Wednesday night.Beyond Thursday with a flat ridge of high pressure overhead,we`ll see temperatures warm up gradually and return to near mid-September averages (highs in mid-80s for lower elevations andmid-70s for Sierra communities) for this weekend. The next weathersystem is projected to arrive by late Sunday with some increasein afternoon breezes. Another cooldown is then in store for earlynext week with chances for light rain showers. MJD&&.AVIATION...Mostly VFR conditions are expected at the main terminals for thenext few days. SW winds will increase this afternoon with gustsnear 25 kt at most main terminals. By Wednesday, the winds shiftmainly to the west with more widespread gusts of 30-35 kt throughmuch of the day.Visibility concerns continue south of KRNO due to the Davis Fireagain today, especially between 20-04Z when increased fireactivity brings heavier smoke. On Wednesday, the smoke plume islikely to set up in a narrower area between KRNO and KCXP due tothe increased west winds. Also, some slantwise visibilityreductions due to smoke aloft from fires in Oregon could reachfar northeast CA-northwest NV late tonight into Wednesday morning.MJD&&.FIRE WEATHER...The theme for the next two days is gusty winds resulting inelevated to critical fire weather conditions. For today, the mainarea of concern is centered over the western NV Sierra Front,where the Davis Fire is burning. The combination of low relativehumidity ranging from 12-16% with limited recoveries, and gustywinds of 30-35 mph will bring periods of critical conditions.Farther north into eastern Lassen and northern Washoe counties,short 1-3 hour periods of similar wind/RH conditions are alsolikely, although the impacts are fewer compared to the conditionsaround the Davis Fire.For Wednesday, winds will be stronger with the passage of a coldfront resulting in speeds of 15-30 mph and gusts to 40 mph acrossmuch of western NV. The main concern is in the proximity of theDavis Fire (where wind prone/higher elevation areas could seegusts exceeding 40 mph), with a shift to a more westerlydirection also impacting the fire`s spread and smoke transport.Even though RH values won`t be as low compared to today, thestronger winds will override this change in humidity. Inaddition, much of the west central NV Basin and Range and possiblysoutheast Mono County look to have at least 3 hours of criticalconditions Wednesday afternoon where lower RH (7-14%) will stickaround longer.By Thursday, conditions will improve with lighter winds, highermin RH and good overnight recoveries. A slow warming and dryingtrend then resumes into the weekend. The next period of increasedwinds isn`t expected until late this weekend, which includes anincreased chance for showers with possible wetting rains earlynext week. MJD&&.REV Watches/Warnings/Advisories...NV...Red Flag Warning from 11 AM this morning to 8 PM PDT Wednesday NVZ420. Lake Wind Advisory from 8 AM to 8 PM PDT Wednesday NVZ002. Lake Wind Advisory from 11 AM to 8 PM PDT Wednesday NVZ004.CA...Lake Wind Advisory from 8 AM to 8 PM PDT Wednesday CAZ072.&&$$