Waking up on Saturday morning we already have a sense of the cold air. Temperatures this morning dropped into the mid 40s, with some 30s well west and north of the bay. I must confess, I am running the streets with a few thousand friends in the Baltimore Running Festival and this is the one time I don’t welcome these temps. But if the wind can stay calm most runnings warm up within a mile or two. Then again, the same winds will bring the first Lake Effect Snow of the season well to our northwest. That said, after a windy afternoon with some clouds for good measure, the wind will calm and the sky will clear overnight. Prime conditions to reach freezing. The map below shows the Freeze Warning for areas in Maryland, Pennsylvania, and Virginia likely to drop close to 30F Sunday morning. It might be colder Monday morning, but only a ‘Watch’ issued for now. Also, Frost Advisories are likely fill in many areas not shown at this time.
- Unhook garden hoses
- Tender plants- Cover or bring in your home
One parameter we use to measure temperatures in winter events is the thickness of the layer of air between 1000 and 500 mb. The classic ‘540’ line is 5400 meters, which correlates to support for snow in storms and freezing air at the ground. Considering this is going to be a clear sky and calm wind event, temperatures are likely to drop quite a bit, especially in inland valley locations. Near the Bay and urban areas, the surroundings act as enough heat to delay the coldest of air.
- Average First Frost in Maryland-Map and charts
- Lake Effect Snow Showers and Waterspouts
- NOAA’s Winter 2016 Outlook
- New NWS Forecast Zones Split Counties (2014)
Freeze Warning: Notes below
This ‘Warning’ issued includes much of southern and central Pennsylvania, as well as the Maryland suburbs north of Baltimore and western mountains. This is a typical colder region that often gets more snow in the winter because it is more rural, elevated, and away from the bay. I expect at least frosty conditions and advisories will be included for the rest of the counties west of the Bay, perhaps even into southern Maryland. Stay tuned…
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