The Morning Intel | Tahoe Sector Watch

Location: #HippieHaus | South Lake Tahoe, CA

Date: Friday, December 19, 2025

Time: 0454 PST

¡Buenos días my friends,

Cup'O'Joe in hand, #StokeLevelRising, on a #FreakFlagFly'nFriday.

We are standing on the doorstep of a multi-day atmospheric marathon. If yesterday was the "Theologian's" pause, today is the "Freak Flag" flying high as the wind starts to scream and the Pacific moisture tap begins to drip. We've got a complex, multi-layered pattern in motion that is going to test every bit of gear we own. From ridgetop hurricane-force gusts to the "Pineapple" rain-soaking, and eventually—fingers crossed—the Christmas conversion, a slow-roll from rain/snain to base building #GorillaSnot to a #FreshCoat of Sierra-kindness.

The models are messy, the snow levels are stubborn, but the engine is running. Let's dig into the numbers and see where we stand. Catch my update today live on KTVU FOX 2's morning news with Pam Cook from the #HippieHaus at 0645.

Current Tahoe Sector Data

Regional Temperatures:

  • South Lake Tahoe (KTLV) at 6,308': 50ºF (Warm sector firmly in place)

  • Truckee (KTRK) at 5,899': 41ºF

  • Mammoth Mtn Race (MTH03) at 11,034': 23ºF

  • Chair 6 Ridge (9,100'): 41ºF (Freezing line is still way up the column)

Regional Winds:

  • HippieHaus: 226º (SW) 23/43mph

  • Truckee: 210º (SW) 13/26mph

  • Donner Pass: 204º (W) 25/39mph

  • Carson Pass: 231º (SW) 47/56mph

  • Mammoth Race (MTH03): 217º (SSW) 47/56mph

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.

  • Travel Note: With wind advisories active, high-profile vehicles need to watch the crosswinds on US-395 and I-580 today.

Forecast Update: The AR Pulse & The Wind Event

The big update today is the Wind Advisory and the Atmospheric River (AR) intensity.

1. Wind: Today & Sunday

  • Change: Wind potential has intensified. The RRFS models now show 700mb (ridge level) winds peaking at 60-70 knots on Sunday.

  • Today's Reality: Strong W/SW flow. 100+ MPH gusts are confirmed for higher Sierra terrain today.

  • Impact: Expect significant lift holds. If the Bullwheels aren't turning, it’s for your safety—these gusts are no joke.

2. Rain & Snow Levels:

  • Today: Mostly rain showers this afternoon/evening. Snow levels remain high (9,000'+).

  • The "Main Event" (Sat Night - Sunday): A moderate AR plume arrives. QPF (Precip Totals) are trending up. We could see 2-4 inches of rain in the Tahoe Basin through Monday.

  • Elevation Check: Snow lines stay above 8,000' through Sunday. This is the "Warm Sponge" scrubbing the base.

3. The Christmas Conversion (The Light at the Tunnel):

  • The Pivot: Snow lines finally drop Monday night into Tuesday morning.

  • The Signal: NWS Reno notes the 90th percentile for snow mid-week has increased significantly vs 24 hours ago. We are looking at a potential 7-15" per day mid-week.

AFD Comparative Summary: Reno vs. Sacramento

  • NWS Reno (Tahoe/Mammoth): They are hyper-focused on the Wind Hazards for today and Sunday. Unique highlight: localized fire weather concerns in Mono County today due to low humidity (teens) and high winds—a total December anomaly.

  • NWS Sacramento (Kirkwood/West Slope): They are leaning into the Hydrology and beneficial rain. They note a possible "Shasta County convergence zone" Sunday evening, which could amplify totals just north of our sector.

  • Nuance: Reno is flagging "rapid p-type changes" at the passes today if precip rates spike—stay sharp.

✈️ Aviation Section

Current Status & Hazards:

  • Buckle up: It is a rough day for flying. Strong W/SW flow at 700mb (60 knots) is triggering mountain waves, rotors, and Low-Level Wind Shear (LLWS) at all Sierra airfields (KTRK, KTVL, KRNO, KMMH).

  • Visibility: Showers developing this afternoon will periodically lower ceilings/visibility to MVFR-IFR conditions.

  • Surface Winds: 80% chance of peak gusts >35 knots at most airfields.

⚓ Tahoe Mariners Forecast

Lake Tahoe:

  • ⚠️ WIND ADVISORY: In effect until 4 AM Saturday.

  • Today: Southwest winds 20 to 30 mph, gusts to 50 mph.

  • Wave Heights: 2 to 4 feet.

  • Tonight: Still cranking. Gusts to 50 mph. Wave heights 2-4 feet.

  • Saturday: A slight lull. Gusts to 35 mph. Waves 1-3 feet.

  • Mariner Note: This is "Ocean-style" water on the Lake. If you aren't secured on a pin or a heavy-duty mooring, get it done before the afternoon gusts peak.

Sierra Avalanche Centers

Central Sierra (Tahoe/Carson Pass):

  • Status: Watch Mode.

  • Hazard: Rain on Snow. Very high-elevation rain on snow could create wet-snow avalanches.

  • Obstacles: The shallow snowpack means rocks and stumps are the primary "trauma" hazards.

Eastside Region (Mammoth):

  • Status: Low Tide.

  • Hazard: Variable surfaces. Watch for wind-drifted slabs above weak sugary snow in isolated high-elevation pockets.

The Bottom Line: It’s a "Pineapple" Friday. Respect the wind, support your Mtn Ops Teams as they battle the rain/snain to keep the runs open, and #KeepTheFaith for the Christmas cooling trend.

Stay'nThirsty for POW,

Coop | RS#69

A weather map showing North America with various weather patterns. There are high and low-pressure systems marked with 'H' and 'L'. Green, blue, and gray shading indicate precipitation areas, with a significant storm system in the northeastern US and Canada. Isobars, colored lines, and pressure readings detailed across the continent.
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GEFS AIFS AI [M] 0.25º 6-hr Precip (in.), MSLP (hPa), 850mb Temp.(ºC)

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Chair Six(6) Ridge 12/17 - KirkwoodMtn - 9,100’

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NAM 3km | 24hr Snow (10:1 Ratio) Idaho

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