METEOROLOGIST JEFF HABY
The source region for mP air is over cold ocean currents or high latitude ocean waters. This air does not have
moisture content as mT air. Since mP air is always near saturation,
orographic lifting of the air mass can
widespread rain or snow. This air mass is notorious for producing
fog, drizzle, cloudy weather and long
lasting light to moderate rain. The temperature of mP air ranges from just above freezing to below 70 degrees F.
mP air is modified as it moves over elevated terrain. On the windward side of mountain ranges, mP air can produce
an abundance of rain and snow. Once on the lee side of mountains, the mP airmass modifies into a continental
airmass. These air masses produce cold fronts but the air is not as cold as polar or arctic fronts. They are often
termed "Pacific fronts" or "back-door cold fronts". Maritime Polar air occurs frequently in the Pacific Northwest
and to a lesser degree in New England.