The Storm’s Footprint

The National Weather Service Office in Sterling, VA has released the color coded  map below showing snowfall accumulations west of the Chesapeake Bay from yesterday’s nor’easter.

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This morning’s visible satellite picture tells the story.

First a color enhanced wide view.

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A closer-in view in black and white.

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The gray areas seen in this image east of the mountains from North Carolina northeastward into New York and Southern New England is snow on the ground. The Susquehanna River valley is clearly seen cutting through the snowpack in Pennsylvania, ending at the northern tip of the Chesapeake Bay. Some very cold air is pouring into the region. Morning lows dropped into the single digits in many cases. That cold air moving across the open waters of the Chesapeake and Delaware Bays is producing “bay effect” cloud streamers that are carried out over the Atlantic Ocean. The National Weather Service Doppler Radar at Dover AFB in Delaware is picking up some snow flurry/shower activity from those clouds off Delaware Bay. It is likely in the form of “virga” and not reaching the ocean surface.

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Tom’s post below shows some of the snow totals across the region. The heaviest snow fell in a northeast-southwest band from the DELMARVA Peninsula into southern Maryland, just to the east and south of the Baltimore/Washington metro areas. If you compare these numbers to earlier posts which showed the computer model forecasts for snow for this storm you can see that the models came pretty close to pinpointing the areas where the heaviest snow was expected to fall and what the amounts were likely to be. 

The snowfall at BWI-Marshall established a new record for the date with 4.7 inches of snow falling from midnight to midnight on March 2.  An additional .9 inches fell on the evening of March 1, bringing the storm total to 5.6 inches. The old record for March 2 was 3.7 inches in 1969. Statistics for the first two days of March show 5.8 inches of snowfall in Baltimore, 5.6 inches above the seasonal average. It is a different story for the entire winter season though. Only 9.1 inches of snow has fallen, leaving the area 6.8 inches below the seasonal average. This speaks to the larger issue of dry conditions since July of 2008 (addressed in an earlier post). 

Speaking of records, the observed temperature at BWI-Marshall at 5:00, 6:00 and 7:00 this morning was 10.9 degrees Fahrenheit. This breaks the record low for the date of 12 degrees set in 1925. The 10.9 degree readings represent one observation in each of the three hours and the temperature may have dipped a bit lower at some point over that three hour period. The National Weather Service will issue the final word on the ultimate low for the day later this afternoon. 

Finally, a big THANK YOU goes out to all the folks who emailed snow reports to us yesterday. It is a big help to us in determining how a storm is behaving and fills in a lot of information blanks. Keep up the good work.

John Collins

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