How to Read the Climate Prediction Center’s Heavy Snow Map: November 7, 2026

Verified November 7, 2026, at 5:03 a.m. UTC (12:03 a.m. Eastern Standard Time, UTC−05:00).

The Climate Prediction Center’s heavy snow map shows where hazardous snow is possible eight to 14 days ahead—not how many inches will fall in a particular town. In its November 6 outlook, the center identified a moderate risk of heavy snow at higher elevations of the Klamath and Sierra Nevada mountains for November 14–15, 2026.

The same outlook also identified a broader slight risk across several western mountain areas through November 17. These are early indications, so travelers and residents should watch for changes and consult local forecasts as the dates approach. The CPC’s current Week-2 Hazards Outlook provides the latest map and accompanying discussion.

Destaques

• The heavy snow map identifies the chance of a hazardous event during a specified part of the eight- to 14-day outlook period.
• Slight, moderate, and high risk correspond to probability thresholds of more than 20%, 40%, and 60%, respectively.
• A risk area is not a forecast snowfall total, and its boundary is not an exact line between snow and no snow.
• Check the dates printed beside each risk area, then use local National Weather Service forecasts for location-specific details.

Where do you find the CPC heavy snow map?

Open the Week-2 Hazards Outlook and look for the Snow option in the probabilistic Days 8–14 row. If the page says “No Hazards” for that selection, the center has not identified a qualifying snow hazard on that map for the current outlook. That does not mean snow is impossible.

Start with the map title and its overall valid period. Then find the outlined risk area that includes, or is near, the place you care about. Read its label and dates: an individual snow risk may apply to only a few days within the broader seven-day window. Finally, check when the outlook was made. An older map may describe a different forecast period or show risk areas that have since changed.

What do slight, moderate, and high snow risks mean?

The legend describes the estimated likelihood that a heavy snow hazard threshold will be exceeded. According to the CPC’s product description, the experimental probability categories are:

• Slight: greater than a 20% chance.
• Moderate: greater than a 40% chance.
• High: greater than a 60% chance.

Read those numbers as likelihoods of the specified hazard, not as the percentage of the area that will receive snow or the proportion of days on which it will snow. A moderate risk is more concerning than a slight risk, but it is still a forecast with uncertainty. Consult the map’s own legend and the discussion for the risk and period being shown.

For example, the November 6 outlook placed a moderate risk at high elevations of the Klamath and Sierra Nevada for November 14–15. It also listed a slight risk for high elevations in the Cascades, Klamath, and Sierra Nevada through November 17, along with other interior western mountain regions. Those labels do not promise snow at every elevation or on every day in the stated windows.

How does the CPC decide what counts as heavy snow?

The CPC uses ensemble forecasts—sets of model projections that help represent different possible outcomes—alongside forecaster judgment. Its published guidance describes a typical heavy snow signal using three-day precipitation above the local 85th climatological percentile, snowfall exceeding half an inch in liquid equivalent, and temperatures favorable for snow. Forecasters also use an experimental snow water equivalent tool. The center says its hazard definitions are guidelines, because conditions and potential impacts vary by place and situation.

Liquid equivalent is the amount of water in melted snow, not the depth of snow on the ground. Half an inch of liquid equivalent therefore cannot be converted into one dependable snowfall depth: the relationship changes with snow characteristics and weather conditions. The map itself is not a city-by-city accumulation forecast.

The 85th percentile adds local context: it compares the forecast precipitation with the historical distribution for that location and period. It should not be read as an 85% chance of snow. The risk percentage in the map legend answers a different question: how likely the specified hazard is considered to be.

What do the map boundaries and dates tell you?

The outlines are drawn by forecasters to communicate broad areas of possible hazard at a long lead time. Conditions can differ sharply within an outlined area, especially between valleys, mountain passes, and higher peaks. A community just outside a line should not treat the boundary as a guarantee of safe conditions, and a community inside it should not assume every neighborhood will experience the same impacts.

The overall valid dates describe the Week-2 window; the dates attached to a particular area narrow down when that hazard is favored. They do not identify an exact start or end hour. In the November 6 discussion, CPC forecasters pointed to a West Coast weather pattern and a potential influx of moisture as reasons for the snow risks, while noting that the signal was expected to weaken as the pattern shifted inland. The actual timing, snow levels, and impacts can change as forecasts develop.

How should you use the outlook as a storm gets closer?

Use the map as an early prompt to check whether a trip, mountain route, outdoor work, or other plans could be affected. Revisit the CPC outlook for changes in the risk area and dates, and read its written discussion for the reasoning and uncertainty behind the map.

For nearer-term hazards, the CPC page links to the Weather Prediction Center’s days 3–7 outlook. For a specific address or route, consult the National Weather Service local forecast and any active winter weather watches, warnings, or advisories. Those products can provide more useful detail about expected snow amounts, timing, elevation, and travel impacts as the event approaches.

Frequently asked questions

Is the CPC heavy snow map a snowfall accumulation map?

No. It shows the risk of a qualifying heavy snow hazard over a broad area and period, rather than predicted inches at a specific location.

Does a slight risk mean there will be little snow?

No. “Slight” describes the probability category for the hazard, not how small the snowfall or its impacts would be if it occurs.

Does a blank area mean no snow is expected?

No. It means the map does not show a qualifying heavy snow risk there for that outlook. Snow or other winter hazards may still occur.