Monday, December 1, 2014

"Surely, you can't be serious?
Yes, I'm serious, and don't call me Shirley." 
-Leslie Neilsen, in a famous line from a 1980s comedy (Youtube clip)

Screen capture of Frederick MD NWS forecast as of 3:30 AM 12/1

9:00 AM 12/1 - Another Fall tease, followed by another wintry surprise. Then again, it is December now, so time to get our game face on. Even though long range temperatures are set to go above normal in the 6-10 day period ahead, surprises lurk in the short range:

  • If you haven't checked your National Weather Service point-and-click local forecast, better do that soon. By this evening, following passage of a cold front, resurgent High pressure system nudges in dry, much cooler air tonight from the north. 
  • As the flow switches to north overnight, temperatures across the region drop to near 30 as shown on our snippet from the Frederick, MD forecast graphic

It's a classic "Cold Air Damming" setup, as alluded to on the NOAA surface map. It is a process where surface cold air wedges down the east side of the Appalachians, evidenced by the "bowed" isobar lines you see over the Mid-Atlantic states. Running over  the top of the denser air below will be moisture and southerly winds aloft streaming in from the Gulf of Mexico. The result at surface is temperatures hold right around 32 F as the moisture works itself out as either sleet or freezing rain. 

Regardless of the meteorological technicalities, Tuesday looks to be a challenging day for schools and travelers in the Blue Ridge region and along the PA/MD line.

Or as they said in the Airplane movie, "Yes I'm serious, and don't call me Shirley."

Forecaster Foot and the Maryland Team

2 comments:

Amy said...

Is it too early to hope for a 2 hour delay for Hoco? I'm hoping western howard county come through with bad roads.

Anonymous said...

Am I the only teacher alive who doesn't wish for delays and cancelled school? We already cram enough content into only 180 days as it is. Not to mention the fact that we just had half a week off.

And hoping for bad roads? C'mon now...