Marine Weather and Tide Forecast for Truckee, CA

DISCUSSION

* Spring storm will bring rain, mountain snow, and widespread breezy to strong winds through early Wednesday morning. Even just 1-2 days out, confidence is medium at best due to high- res models showing potential for more shadowing east of the Sierra crest versus what the NBM guidance depicts.

* Tightening gradient will yield south/southwesterly winds today and tonight with gusts on the order of 25-35 MPH. Potential for stronger winds shifts eastward Tuesday more into Central NV where highest ECMWF EFI values are, but with potential for shadowing, wind prone parts of Mono Co, the Eastern Sierra, and into the Hwy 95 corridor could see gusts 50-70 MPH Tuesday.

* Southerly IVT component of this storm will heavily favor west slopes for precip versus the east side. That being said, NBM and global models show showers spilling over after 9-12z/Tuesday and lingering on/off much of the day. Snow levels start off high, above 7000', but drop as the day goes on to 5500-6000' Tuesday evening. So the combination of showers and low-enough snow lines will increase winter weather travel impacts across the Sierra tomorrow.

* Projected snowfall amounts are not large by any means. 25th-75th percentiles from NBM show 2-4" at South Lake Tahoe and 4-9" at Mammoth Lakes, with 9-14" for Donner Pass. Again some of the more recent high-res guidance would indicate a big dropoff in snowfall to the east of these points.

* Some of the guidance like the HRRR shows a secondary wave of precip coming in early Wednesday morning. If that pans out, it would have lower snow levels to work with which could extend impacts into the Wed AM commute and into W Nevada foothill areas.
But confidence in this particular scenario is low.

* Cold temperatures are expected post-storm with renewed freezes for W Nevada Wednesday and Thursday mornings, but not as cold as what we saw last week. Gradual warming trend forecast as we head toward the weekend with mostly dry conditions. We're starting to see some signs of afternoon buildups or even showers over the high terrain this weekend. Even a 10-20% chance of t-storms based on the NBM.
Something to watch, it's getting to be that time of year.

-Chris



AVIATION

* Pacific storm will bring increased winds along with rain/snow showers through early Wednesday morning.

* Pressure gradient yields widespread southerly winds through his evening, gusts 25-30 knots for the most part. Winds aloft strengthen overnight with low level wind shear and mountain wave turbulence through early Tuesday morning.

* Winds remain gusty Tuesday and switch to more of a W/NW direction.
Strongest winds, 60%+ odds of gusts above 40 knots, shift eastward from MMH over toward HTH/NFL and into Central NV.

* Showers will overspread the region Tuesday, starting as early as 12z/Tues, though some high resolution models like RRFS are showing more shadowing than others like the HRRR and ICON. TAFs will show MVFR to occasional IFR conditions in rain showers.

* Changeover to snow is expected at TRK/TVL/MMH between 21z/Tues- 03z/Wed with a 20-40% chance of at least 3" runway accumulation Tuesday night. Lower elevation sites like RNO should remain all- rain through Tuesday night but may see some light snow showers early Wed morning (20% chance).

-Chris

REV Watches/Warnings/Advisories
NV...Lake Wind Advisory until 10 PM PDT this evening NVZ002.

Winter Weather Advisory from 5 AM Tuesday to 5 PM PDT Wednesday NVZ002.

Lake Wind Advisory until 10 PM PDT this evening NVZ001-003-004.

Wind Advisory from 11 AM to 11 PM PDT Tuesday NVZ001-004.

CA...Lake Wind Advisory until 10 PM PDT this evening CAZ071>073.

Winter Weather Advisory from 5 AM Tuesday to 5 PM PDT Wednesday CAZ072-073.