The Morning Intel | Tahoe Sector Watch

Location: #HippieHaus | South Lake Tahoe, CA

Date: Saturday, December 20, 2025 | Time: 0438

¡Buenos días my friends,

Cup'O'Joe in hand, #StokeLevelRising, on a #StormySaturday. Looks like a break in the pattern (with the exception of winds) mid-morning, with the precip-tap opening back up around 3/4p (or earlier). This is a wet ride; snow levels late yesterday and overnight hovered in the 8k and above range. Snow was falling at KirkwoodMtn, Palisades, and up at Sugar Bowl, to name just a few zones.

Chain Controls were up regionally this morning; roads are open and free of controls as of 0448. I will update the page later in the morning, after I drop in and pinch-hit for Radar live on 101.5 Truckee Tahoe Radio for the morning Ski California Winter weekend show from 7a-10a today and tomorrow.

Here's the bottom line: weather, rain, snow in the form of #BaseBuilding #GorillaSnot above 8k- on and off through the weekend and into next week. Stay kind, mindful, and thirsty, my friends. Tune in at 7a for more details :)

Current Sector Data

Regional Temperatures:

• South Lake Tahoe (KTLV) at 6,308': 45ºF (Warm sector holding)

• Truckee (KTRK) at 5,899': 45ºF

• Mammoth Mtn Race (MTH03) at 11,034': 28ºF

• Chair 6 Ridge (9,100'): 32ºF (Freezing line hovering near 9k)

Regional Winds:

• HippieHaus: 225º (SW) 16mph

• Truckee: 232º (SW) 12mph

• Donner Pass: 184º (WSW) 21mph

• Carson Pass: 237º (WSW) 24/32mph

• Mammoth Race (MTH03): 217º (SSE) 35mph

Roads (CalTrans @ 0432):

• Sierra Sector: ALL CLEAR (SR88, Hwy 50, I-80).

• I-80 Alert: All westbound trucks must stop at the Nyack brake check.

Forecast Update: The Atmospheric River Intensifies

Comparing the data from yesterday to this morning, the "Freak Flag" has officially been raised. The models have shifted from "moderate confidence" to a high-confidence heavy rain event for Sunday.

1. The Change: Intensity Ramp-Up

• Yesterday: We were tracking a "moderate" pulse.

• Today: NWS Reno and Sacramento are now flagging a high-confidence, heavy rain event. 48-hour rainfall totals (QPF) have trended UP, with 4.5" to 5.5" of liquid possible from Tahoe northward through Monday afternoon.

• Flood Watch: A Flood Watch has been issued for the entire Tahoe Basin and Lassen areas from tonight through Monday afternoon.

2. The Wind: No Let-Up

• Update: If you thought yesterday was breezy, Sunday looks to be the main event. RRFS models are showing 700mb (ridge level) winds hitting 70 knots. That translates to ridge gusts exceeding 100+ mph again tomorrow.

• Impact: Expect significant lift holds to continue. The Bullwheels will likely be on pause at the peaks.

3. Snow Levels: The "Base Builder"

• Status: Snow levels remain stubbornly high (8,000' - 9,500') through Sunday.

• The Silver Lining: This is #GorillaSnot and #BaseBuilding cement for the upper elevations. It’s not the #ColdSmoke yet, but it’s the layer that sticks to the rocks and covers the sharks.

• The Pivot: Snow levels finally drop to 7,500' Monday, with a stronger signal for lower snow levels (5,500') by Tuesday/Wednesday (Christmas Eve).

AFD Comparative Summary: Reno vs. Sacramento

• NWS Reno (Tahoe/Eastern Sierra): They are hammering the Hydrology concern today. The key takeaway is the "Shadowing vs. Spillover" nuance. If the wind shadowing relaxes, Western Nevada could see significant spillover rain. They also highlight that while snow levels are high (9-10k ft tonight), roads could still be slick due to rainfall intensity (>0.1" per hour).

• NWS Sacramento (West Slope/Kirkwood): They are calling this a "Moderately Strong Atmospheric River" with high confidence. Their focus is on the sheer volume of water—probabilities of 10 inches of rain in Butte County are around 90%. For our sector, they warn of holiday traffic impacts starting Tuesday as the cold air finally arrives.

• Key Difference: Reno is focused on the immediate wind/flood risk in the Basin; Sacramento is looking at the broader Northern California soak and the mid-week travel nightmare.

✈️ Aviation Section

Current Status & Hazards:

• Turbulence: It is a "Buckle Up" kind of weekend. Low-Level Wind Shear (LLWS) is forecasted at ALL area TAF sites (RNO, TRK, TVL, MMH) today through tomorrow.

• Ceilings:

  • Reno/Carson (RNO/CXP): VFR mostly, but rain chances increase late afternoon.

  • Truckee/Tahoe (TRK/TVL): MVFR ceilings this morning, dropping to sub-VFR (IFR) visibilities tonight as heavier rain moves in.

• Winds: 700mb flow is strong (50+ kts), creating mountain waves and rotors.

⚓ Tahoe Mariners Forecast

Lake Tahoe:

• ⚠️ LAKE WIND ADVISORY: In effect from 10 PM Tonight to 4 AM Monday.

• Today: Mostly cloudy, chance of rain. Winds SW 10-20 mph, gusts to 40 mph.

• Tonight: Rain likely. Gusts increasing to 40 mph after midnight.

• Sunday: The main event. Rain. Winds SW 15-25 mph, gusts to 40 mph.

• Wave Heights: 1 to 4 feet.

• Coop's Note: The lake is active. With 4-foot rollers and 40mph gusts, this is not the weekend for a casual cruise. Check your moorings.

Sierra Avalanche Centers

Central Sierra (Tahoe/Carson Pass):

• Status: Pre-Season / Early Season.

• Hazard: Wet Loose & Glide Cracks.

• Update: "New snow above 8,000' to 9,000' will create the potential for some slab avalanches." Below the rain line, watch for wet loose slides. Daily forecasts expected to start Dec 21/22.

Eastside Region (Mammoth):

• Status: Rising Hazard.

• Hazard: "Avalanche hazard is expected to rise as a powerful storm impacts our region."

• Warning: Avoid steep terrain during and immediately after the stormy period.

The Bottom Line: We are in the thick of the "Pineapple" wash cycle. Today offers a brief window mid-morning, but the tap opens wide tonight. Be patient with the Mtn Ops crews—they are battling the elements to keep the mountain safe. The change to snow is coming mid-week. Until then, stay dry, drive slow, and tune in to 101.5 this morning!

Stay'nThirsty for POW,

Coop | RS#69