Area Forecast Discussion
Issued by NWS Reno, NV
Issued by NWS Reno, NV
645 FXUS65 KREV 132108 AFDREV Area Forecast Discussion National Weather Service Reno NV 208 PM PDT Thu Jun 13 2024 .SYNOPSIS... One more hot day today, then our attention turns to a dramatic pattern shift this weekend into early next week. A couple dry cold frontal passages bring a significant cooling trend through early next week, with temperatures bottoming out well below average on Monday. These systems will also bring increased afternoon winds, with periods of elevated fire concerns Friday through Monday. && .DISCUSSION... The closed low off the coast of southern California tracks inland today, introducing diffluent flow aloft over the region which will support increased instability this afternoon. Model soundings indicate greatest CAPE values (300-500 J/kg) for areas south of US- 50, generally between the Eastern Sierra and the US-95 corridor. As such, today`s convective activity will favor these areas, mainly during the 2 PM-8 PM timeframe. Forecast DCAPE values in these areas are between 1400-1600 J/kg, indicative of the chance for some isolated storms to produce strong to severe wind gusts. Other threats include small hail, localized heavy rainfall, and new fire starts from lightning strikes. Otherwise, after another record-setting day for temperatures, we have one more hot day in store today. High temperatures approach the 100 degree mark again across lower western Nevada valleys and top out in the low-mid 80s for Sierra communities. A major pattern shift looks increasingly likely this weekend into early next week, with a couple upper-level shortwave troughs digging into the western US. The first in the series drops into the Pacific Northwest Friday into Saturday, introducing increased west- southwesterly winds on Friday afternoon and evening. Widespread gusts 25-35 mph are likely, with localized areas 40+ mph possible. Winds stay elevated into the weekend as a general troughy pattern remains over the western US. A secondary shortwave drops farther south into northern California and Nevada on Monday. The trajectory of this system promotes the potential for even stronger winds than those observed on Friday. These strong winds, in conjunction with widespread low daytime relative humidity, will support several hours of critical fire weather conditions where fuels are cured. Please refer to the Fire Weather section below for more details. Ensemble cluster analysis supports a general weak troughing pattern persisting through the remainder of next week, supportive of seasonably warm temperatures and low shower and thunderstorm chances. Whitlam && .AVIATION... VFR conditions with typical afternoon westerly breezes expected for all regional terminals today. Showers and thunderstorms are expected to develop over the Eastern Sierra this afternoon with coverage expanding eastward into southern Lyon/Mineral counties this evening. There is a 15-25% for thunderstorms to impact KCXP, KMEV, and KMMH between 22-03z. Otherwise, expect mostly dry conditions to prevail with some cumulus buildups through this evening. Whitlam && .FIRE WEATHER... A multi-hour period of critical fire weather conditions is likely for the Sierra Front and Basin & Range on Friday afternoon. Sustained west-southwest winds 15-20 mph with gusts to 25-35 mph, coupled with daytime relative humidities of 10-15% will create a 3-6 hour window of Red Flag conditions across the aforementioned areas. Due to increasing confidence, Fire Weather Watches have been replaced with Red Flag Warnings, in effect 2-10 PM on Friday. Note that the Churchill/northern Lyon county areas have been added to this product -- recent fuels intel from cooperators in the northern Lahontan Basin indicate fuels have reached critical levels in this area. Winds remain elevated into the weekend, yielding elevated to locally critical fire weather conditions on Saturday and Sunday. Confidence is increasing in another dry cold frontal passage on Monday, with widespread critical conditions possible once again. Avoid activities that could cause a spark! We`ve had multiple 100+ acre fires in the Truckee Meadows over the past few days, even with sub-critical fire weather conditions. Whitlam && .REV Watches/Warnings/Advisories... NV...Red Flag Warning from 2 PM to 10 PM PDT Friday NVZ420. Lake Wind Advisory from 2 PM to 10 PM PDT Friday NVZ001>004. Red Flag Warning from 2 PM to 10 PM PDT Friday NVZ423-429. CA... Lake Wind Advisory from 2 PM to 10 PM PDT Friday CAZ071-072. && $$