Air Mass Source Regions Affecting New York State

New York State's weather is shaped by air masses originating from four primary source regions:

1. Continental Polar (cP) — Canada / Siberia

• Origin: Central/northern Canada; ultimately Siberian air crossing Arctic
• Characteristics: Cold, dry, stable
• Impact: Winter cold waves, lake-effect snow setup (cold air over warm Lakes Erie/Ontario), clear crisp autumn days
• Modification: Warms/moistens traversing Great Lakes

2. Maritime Tropical (mT) — Gulf of Mexico / Subtropical Atlantic

• Origin: Gulf of Mexico, Caribbean, western Atlantic (Bermuda High)
• Characteristics: Warm, humid, unstable
• Impact: Summer heat/humidity, thunderstorms, tropical moisture feeds, nor'easter fuel
• Seasonal: Dominant May–September

3. Maritime Polar (mP) — North Pacific / North Atlantic

• Pacific mP: Gulf of Alaska → mild, moist; modified crossing Rockies → Pacific Northwest influence
• Atlantic mP: Labrador Sea / Canadian Maritimes → cool, damp, foggy; "backdoor" cold fronts
• Impact: Spring/fall chill, coastal fog, northeasterly flow events

4. Continental Arctic (cA) — Arctic Ocean / Northern Canada

• Origin: Polar vortex lobes, Siberian/Canadian Arctic
• Characteristics: Extremely cold, very dry
• Impact: Record cold snaps (polar vortex disruptions); rare but extreme
• Frequency: Increasingly studied re: Arctic amplification / jet stream waviness

Synoptic Patterns

• Nor'easters: cP/cA + mT clash off East Coast → explosive cyclogenesis
• Lake-effect snow: cP over warm Lakes Erie/Ontario → bands downwind (Buffalo, Syracuse, Tug Hill)
• Heat waves: Bermuda High pumps mT north; subsidence, sunshine
• Backdoor cold fronts: Atlantic mP slides south behind coastal high

NYC metro's coastal position adds marine layer / sea breeze complexity. Western NY dominated by Great Lakes modification. Adirondacks create orographic barriers.