Marine Weather and Tide Forecast for Floriston, CA

DISCUSSION

Last night's snow was limited to central-southern Mono County where about 6 inches fell at Mammoth Mountain, while a deep layer of dry air below the cloud layer to the surface kept the remainder of the region dry.

The closed low off the central CA coast will continue to drift slowly toward the SF bay area through Wednesday. The main activity will come in the form of afternoon instability producing showers and isolated thunderstorms across central and eastern CA, transitioning to heavier snow shower bands across the Sierra and northeast CA through tonight. Some of the higher resolution guidance extends the lightning risk into far western NV this evening. While the prevailing snow levels range from 6500-7500 feet this afternoon before dropping to 5500-6000 feet overnight, these levels could dip by 500-1000 feet within the heavier convective bands, and lower elevations could see brief pellets/graupel if a stronger shower/t-storm passes overhead. The overall snowfall amounts remain similar for the Sierra and northeast CA within the Winter Weather Advisory, although parts of Mono County and western Lassen/central Plumas counties could receive a few extra inches within more persistent snow shower bands. In western NV, higher foothills such as Virginia City could see a dusting up to about 1/2 inch of snowfall tonight, but elsewhere the risk of snow accumulations on roads through the Wednesday AM commute is low (less than 10%).

For Wednesday, additional showers continue to move across eastern CA and western NV although coverage is looking more spotty compared to tonight, as the main low is now projected to stall near the SF Bay rather than push inland. The increased instability and risk for afternoon thunder (near 15% chance) shifts to west central NV, although a 5-10% chance extends into far western NV/northern Washoe County. Shower activity then winds down Wednesday night as the low then drifts southward off the CA coast and weakens.

For the remainder of this week and now a larger portion of this weekend, drier conditions are expected with temperatures warming up to the mid-upper 50s for western NV valleys by Saturday. The overall trend in the latest guidance is delaying the onset of the colder stormy pattern to either Sunday night or even Monday. We could still see a few snow showers near the Sierra/northeast CA during the day Sunday, but widespread travel impacts are less likely. Additional storms are still on track to follow through at least the middle of next week, which would bring widespread heavy snow and travel impacts for the Sierra, and increased risk of snow accumulations and slick travel for western NV valleys. The amount of cold air eventually spreading into lower elevations continues to be the most challenging factor for the Monday-Wednesday time frame. MJD

AVIATION

* Periods of valley rain and mountain snow increase through this evening and continue overnight thru Wed AM, with conditions degrading to IFR/LIFR for the Sierra terminals mainly between 03-18Z and MVFR at times with terrain obscuration for the western NV terminals.

* All main terminals also have up to a 15% chance of lightning through 06Z this evening, producing enhanced snow intensity for the Sierra terminals or brief graupel for western NV sites.

* FL100 wind gusts of 45-55 kt through early Wed AM will keep the risk of turbulence with periods of LLWS at the main terminals.

* The coverage of rain/snow shower bands lingers through early Wednesday evening mainly for the Sierra terminals, with renewed shower development and isolated lightning chances into western NV (5-10% for KRNO-KCXP-KMEV and up to 15% in west central NV).

* All shower activity winds down Wednesday night with mainly VFR conditions and light winds to follow through the start of this weekend, except for patchy FZFG each morning around KTRK.

MJD

AVALANCHE

Impacts from heavy snow and gusty ridge winds expected across all avalanche center terrain through Wednesday.

* Snow totals, levels, and rates: Up to 1 foot of snow across the highest terrain for all avalanche centers, with locally up to 20" or higher for isolated parts of BAC and ESAC terrain (south of Sonora Pass and around June Lake, respectively). Snowfall rates up to 1"/hr, with the most intense period around midnight (rates up to 2"/hr in southern Mono county). Snow levels start above 7 kft this afternoon, before steadily dropping below 6 kft just after midnight.

* SLRs and SWE: 10-12:1 SLRs expected through the majority of this system, locally lower for the Tahoe Basin. SWE mainly around 1", with localized areas up to 1.5" in the aforementioned areas of BAC and ESAC terrain. SWE near June Lake may reach upwards of 1.75".

* Ridgetop gusts: SSW gusts up to 70 mph.

-Giralte

REV Watches/Warnings/Advisories
NV...Winter Weather Advisory until 4 PM PST Wednesday NVZ002.

CA...Winter Weather Advisory until 4 PM PST Wednesday CAZ071>073.