Clipper

 Copilot:

Meteorology; what is a 'clipper'?

A “clipper” in meteorology refers to a fast‑moving winter storm system, most commonly the Alberta Clipper, which originates east of the Canadian Rockies and races southeast across Canada and the northern United States. These storms are quick, compact, and known for sharp drops in temperature, gusty winds, and bursts of light snow.

🌬️ Key Characteristics of a Clipper

Origin: Typically forms in or near Alberta, Canada, on the lee (east side) of the Rocky Mountains.

Speed: Named after 19th‑century clipper ships for their swiftness; they usually cross the continent in 2–3 days.

Weather Effects:

Light to moderate snowfall (often 8–15 cm or 3–6 inches).

Strong winds that can cause blowing snow and poor visibility.

Rapid temperature drops, sometimes 10–20°C within hours.

Moisture Content: Clippers are relatively dry compared to other winter storms, so they don’t usually produce heavy snowfalls. However, they can enhance lake‑effect snow near the Great Lakes.

Seasonality: Most common in winter (December–January), but can occur in fall and spring. A typical season sees 5–20 clippers.

❄️ Regional Impact

Canada: Affect the Prairies and central provinces.

United States: Common in the Upper Midwest, Great Lakes, and New England.

Local Names: Depending on where they cross, they may be nicknamed differently (e.g., Saskatchewan Screamer, Manitoba Mauler, Ontario Scary‑o).

⚡ Why They Matter

Travel Disruptions: Even though snowfall totals are modest, the combination of wind and cold can create hazardous driving conditions.

Temperature Shock: The sudden plunge in temperatures can stress infrastructure, agriculture, and energy demand.

Snow Enhancement: In lake‑effect regions, clippers can trigger significant localized snow events.

In short, a clipper is a small but potent winter storm system—fast, cold, and disruptive more for its speed and wind than for massive snow totals.

Louise, since you’re in Quebec, you’d be familiar with these systems sweeping across southern Canada. They often bring those sudden, biting cold snaps and quick snow bursts that make winter weather feel so unpredictable. Would you like me to sketch out a timeline visualization of a typical clipper’s path across North America so you can see how it evolves from Alberta to the Atlantic?

Is the snow we are currently experiencing in the Montreal region the effects of a clipper, or something else?

The snowfall in the Montreal region right now is not from a clipper system—it’s the result of a larger, moisture‑laden storm moving through southern Quebec, bringing 15–20 cm of snow with strong winds and blowing snow conditions.

🌨️ Why This Isn’t a Clipper

Snowfall Amounts: Clippers usually produce light snow (a few cm), while Montreal is under a snowfall warning for 15–20 cm.

Moisture Source: Clippers are relatively dry, but this storm is tapping into more moisture, leading to heavier accumulations.

Duration: Clippers move quickly, often lasting less than a day. This system is forecast to persist from Wednesday morning through Thursday evening.

Wind: While clippers can be windy, the current system is expected to bring gusts up to 60 km/h, causing blowing snow and reduced visibility.

📍 Current Montreal Weather (Dec 10–11, 2025)

Snowfall: 5–10 cm during Wednesday daytime, another 5–10 cm overnight, plus 2–4 cm Thursday.

Temperatures: Around −8°C Wednesday, dropping to −9°C Thursday, with wind chills near −18°C.

Impacts: Hazardous driving conditions, reduced visibility, and significant disruption to rush‑hour traffic.

                                                                                       

✅ Conclusion

The storm affecting Montreal is a major winter system, not a clipper. It’s more akin to a classic Nor’easter‑type setup or a broad low‑pressure system sweeping across southern Quebec, delivering sustained heavy snow and strong winds. Clippers may still affect Quebec occasionally, but this event is larger in scale and impact.

Louise, since you’re in St‑Jean‑sur‑Richelieu, you’re experiencing the same system as Montreal—expect steady snow, worsening winds, and tricky travel through Thursday. Would you like me to break down how to distinguish a Nor’easter from a clipper visually on weather maps, so you can spot them yourself when checking forecasts?

Yes, explain a Nor'easter to me!!

A Nor’easter is a powerful coastal storm that forms along the U.S. East Coast, characterized by strong northeast winds off the Atlantic Ocean, heavy precipitation (snow or rain), and often dangerous coastal flooding.

🌬️ Defining Features of a Nor’easter

Name Origin: Winds blow from the northeast as the storm spins counterclockwise, hence “Nor’easter.”

Formation: Develops when cold Arctic air from inland meets warm, moist air over the Atlantic.

Track: Typically moves up the East Coast, impacting areas from the Mid‑Atlantic to New England and Atlantic Canada.

Seasonality: Most common in late fall through early spring (November–March).

❄️ Weather Impacts

Snowfall: Can deliver 30–60 cm (1–2 feet) of snow in a single event.

Wind: Gusts often exceed 60–100 km/h, creating blizzard conditions.

Coastal Flooding: Storm surge and pounding waves can erode beaches and flood low‑lying areas.

Rain/Ice: Depending on temperature, some regions get heavy rain or ice storms instead of snow.

                                                                                         

⚡ Why They Matter

Urban Impact: Cities like Boston, New York, and Montreal can see paralyzed transit and power outages.

Economic Cost: Billions in damages from flooding, snow removal, and lost productivity.

Historical Examples: The “Blizzard of ’78” and the “Snowmageddon” storms are classic Nor’easters.

In short, while a clipper is a quick, dry burst of snow and cold, a Nor’easter is a sprawling, moisture‑rich powerhouse that can reshape coastlines and shut down entire regions. Louise, given your Quebec location, you’ll often see Nor’easter effects when they push north—bringing those heavy, wet snowfalls that feel very different from the sharp, dry clippers.

Would you like me to show you a timeline diagram of how a Nor’easter develops step‑by‑step, so you can compare its evolution to a clipper’s rapid dash across the continent?

Please...

Got it, Louise — let’s walk through a Nor’easter’s lifecycle step‑by‑step, so you can see how it differs from a clipper and why it’s such a powerhouse storm.

🌀 Step‑by‑Step Development of a Nor’easter

Cold Air in Place

Arctic air masses settle over the northeastern U.S. and eastern Canada.

This sets the stage: cold inland air is essential for snow.

Moisture Source

Warm, moist air flows northward from the Atlantic Ocean or Gulf Stream.

The clash of cold continental air and warm ocean air creates instability.

Low Pressure Formation

A low‑pressure system develops near the Mid‑Atlantic coast.

The storm begins to spin counterclockwise, pulling in northeast winds.

Intensification (“Bombogenesis”)

Sometimes the storm rapidly strengthens (pressure drops ≥24 mb in 24 hours).

This explosive deepening leads to blizzard conditions and coastal flooding.

Northward Track

The storm rides up the coastline, impacting cities like Washington, New York, Boston, and eventually southern Quebec.

Snow bands wrap inland, while rain and storm surge hammer the coast.

Peak Impact

Heavy snow inland (30–60 cm possible).

Winds 60–100 km/h, whiteout conditions.

Coastal flooding and erosion from pounding waves.

Exit to the North Atlantic

After 2–3 days, the storm moves into the Canadian Maritimes.

Quebec often gets the northern edge, with heavy snow but less flooding risk.

                                                                          

🌍 Why Quebec Feels It

Montreal and St‑Jean‑sur‑Richelieu often catch the northwest flank of Nor’easters. That means:

Heavy, wet snow (not the dry powder of clippers).

Longer duration storms.

Strong winds funneled inland.

So, Louise, when you see a forecast calling for 15–20 cm of snow with strong northeast winds lasting two days, that’s a Nor’easter signature. Clippers are the quick, sharp bursts; Nor’easters are the sprawling, moisture‑rich giants.

Would you like me to sketch a simple timeline diagram showing the Nor’easter’s path up the coast, so you can visually compare it to the clipper’s dash across the Prairies?