textproduct: Reno

KEY MESSAGES

* Rain showers with embedded thunderstorms expected through tonight and into early Friday morning. Snowfall likely in mountain areas, mainly above 8000 feet.

* Isolated showers Friday and Saturday with gradual warming.

* More appreciable warming starts Sunday lasting all of next week with temperature rising to above normal mid to late week.

DISCUSSION

* Cold upper low overhead (500mb temperatures of -22C on the 12z sounding) is promoting widespread showers with embedded t-storms today. Based on latest HREF and NBM guidance those showers will persist through the evening hours. Highest probabilities for wetting rains this evening are from roughly Hwy 395 west into the Sierra and NE California. With cold temps, lightning and small hail are the main hazards along with rainfall rates ~0.5" per hour, though this pattern in spring can yield a funnel cloud aloft out of the strongest cells. More significant severe weather risk is to our north up into Oregon and Idaho where instability and shear are more pronounced.

* High res guidance is showing an area of rain and embedded t-storms dropping south from Oregon into NE California overnight into Friday morning. Chances for 0.25" of rainfall between Midnight and 9 AM Friday range from 30% near Susanville to 90% up in Modoc County. Friday morning showers likely to extend southward into the Reno/Tahoe area, with 40-60% chances for measurable precip (0.01") during the same timeframe. A few showers remain possible into Friday afternoon, though instability and forcing for ascent isn't as pronounced as today, so odds are 10-30%.

* Rain-snow lines are a little higher than yesterday but still down to 7500-8000' through tonight, perhaps lower in heavier precip cells. So we're expecting snowfall in the Sierra and even some of the higher peaks in far W Nevada (e.g. Peavine). 60%+ odds of 1-2" snowfall above 8000', with 20-40% chance of 6" in the highest peaks around Mt Rose, Freel, Tioga Pass, Mammoth, and the White Mountains. Speaking of cold, while temperatures are well below normal, clouds and breezes will keep Friday morning readings from dipping into hard freeze territory. NBM showing only a 10% chance of sub-32 temps at typical cold spots like Minden and Reno-Stead.

* Saturday we see hints of ridging starting to build but it'll have to wait until Sunday-Monday to start for real. Quick moving shortwave looks to scoot across the area Saturday keeping a small chance (10-20%) for showers in the forecast along with a 5-10 degree warmup vs Friday. Sunday onward has a higher confidence in ridging and more appreciably warming temperatures, lasting through next week. Starting Wednesday we see areas of moderate Heat Risk develop in the W Nevada valleys, likely expanding Thursday-Friday to include urban areas.

-Chris

AVIATION

* Numerous showers and embedded t-storms expected through tonight and early Friday morning. Probabilities for MVFR/IFR conditions in rain showers range from 40-50% along Hwy 95 to 80%+ along and west of Hwy 395 into the Sierra, including RNO. Mountain obscuration is certain.

* Thunderstorms will produce lightning, erratic winds to 30 knots, and small hail. A 20-40% chance at any one point through this evening. * Snowfall is likely in the Sierra though rain-snow lines are higher versus yesterday, mostly at or above 7500-8000'. Latest HREF guidance showing only 10-20% chance of measurable snow (0.1") at TRK/TVL through this evening but higher odds for MMH, 40-70%. Raising the threshold to 1" snowfall drops the odds to 20% at MMH.

* Showers becoming more isolated (10-30% chances) Friday afternoon and again Saturday as main upper low moves out. Typical early- summer zephyr westerly wind pattern with warmer temperatures starting Sunday.

-Chris

REV Watches/Warnings/Advisories

NV...None. CA...None.