Foot's Forecast | Weather Intelligence

WHAT WENT WRONG (OR RIGHT)

AND WHAT'S COMING NEXT

Before every big storm is even over, there is always speculation about another one lurking out there, just waiting to pounce before your back has had a chance to recover. This time, the crystal ball is more murky and there are big changes going on in the atmosphere, it will take some time to get the pattern aligned again to produce something on the magnitude of what we just had, if at all. A quick glimpse at the computer models shows two events following February Kahuna # 1. Storm # 2 seems likely to cut up west of mountains, which means rain for the East coast and possible flooding due to snow clogging storm drains. On the heels of this storm will be brutally cold Arctic air, the coldest of the season, arriving Sunday and dragging into the week after. With an active Subtropical Jet turning up in the face of a large Arctic high parking over the eastern 2/3rd of the country, one would surmise that this setup has potential to deliver another snow event for the Northeast sometime NEXT Tue or Wed. The other interesting factor is our old standy, the North Atlantic Oscillation, is scheduled to stay flat the next 7-10 days. This bodes well for storm development because a stable NAO in the neutral position would allow a big system to move gradually across the country from the SW to the Gulf to the Northeast while gathering lots of moisture on it's way. A strong negative NAO might overwhelm the pattern and push the storm out to sea along the Carolinas. A strong positive NAO would cause the storm to drift too far north as it comes up from the south, and you'd see snow change to rain. This much is certain:

1. There will be plenty of cold air in Canada that has to make it south sometime soon.

2. Each day we approach Spring the SubTropical Jet gets climatologically more active.

3. If the snowpack over the Northeast survives this week, that will only enhance your chance for another big storm in the February 18-22 time frame.

SO WHAT WRONG WITH BIG KAHUNA # 1 ? WHY DID IT TURN INTO SUCH A MONSTER ?

I am working on my storm grade numbers among other tasks around the house. But here is a synposis of what happened (and is still happening in this storm). I will add to this with a few links and some graphics later.

1. Conventional wisdom about storm dynamics did not work well. The waters off New Jersey and Southern New England are below normal. This should not have enabled the storm to explode the way it did. It is possible the above normal waters near NC provided more rapid evaporation and the transfer of moisture from the ocean to the storm to the land was faster than expected. Thus you read amazing reports of 11" in 3 hours at New York City.

2. The lack of "cold air damming" at the onset of this storm obviously did not impede it's ability to hammer us. There was enough thermodynamic energy in the right places (in the ocean) to allow the storm to quickly tap the reservoir of cold air in eastern Ontario. This cold air was drawn into the storm a lot quicker than I expected, resulting in a rapid conversion of moisture to snow and the strong upward motion which resulted from this produced the thunderstorm like effects of thundersnow and lighting. It was a classic clash of cold and warm in a dramatic way. I was real skeptical Saturday afternoon when the temps in Dundalk were 42 F and the sun was shining. Yet 5 hours later the snow was falling heavily and sticking to roadways. There was enough cold air drawn into to overcome the brief warmth.

3. The wide disparity in accumulations (8 - 21 inches in Baltimore Metro region, for example) was simply a wintertime example of what summertime thunderstorms do. In summer, one part of town can be drenched with a huge downpour while the other side of town is basking in the sun. Same thing with this storm, except that the thunderstorms developed inside a raging snowstorm, and when they popped, up went your snowfall rates almost instantly. Areas that did not see the crazy amounts of snow were simply missed by the little mini-thunderstorm cells that briefly materialized inside the snow bands, dropped their extra 3-4 inches and then fizzled. Had I thought ahead that the upward motion effect would produce thundersnow, I would have upped my totals. However, predicting where and when a random thunderstorm is going to strike, especially when the storm itself is buried inside a blizzard no less, it just about impossible. There were only a few rumbles of thunder in Dundalk, and we were on the low end of snowfall.. 11-12 inches. Other areas like Timonium have 18" and there were many reports of thundersnow for at least an hour last night. So there's the connection.

DON'T I HAVE TO WEAR THE BAG NOW THAT THE STORM IS OVER ?

Yes, friends I will be wearing the bag, and having Mommy take a picture for all of you to see. I challenge my news media counterparts to do the same when their forecasts bust, up or down. The pic will be posted here shortly, along with a pic from our local bus lot to show you how much work they have up there. See you later tonight.

"HOUSTON, I HAVE A PROBLEM..."

Take a look at this satellite loop if you don't believe me.

As of 7:45 AM...at least 11 inches in Dundalk, MD at Foot's Forecast HQ

Okay, I admit it, there is a teensy bit more than 4" out there at the present time.

Hey, quit complaining my forecast was off the mark, because the next statement

will make it all worth the hassle. My new name is Captain Obvious, and I want to say:

NO SCHOOL MONDAY FOR THE ENTIRE BALTIMORE AND DC METRO REGIONS,

AS WELL AS SUBURBAN PHILADELPHIA AND WESTCHESTER COUNTY, NEW YORK

We have crossed the 8" barrier necessary to make it impossible for school bus parking lots to be cleared in time for regular opening time on Monday. I will march myself the grueling 1/3 of a mile up the road later today and take a photo of our local bus parking lot to demonstrate proof of my theory.

Am working on an analysis of my snowfall amounts for the first 2 period of the storm (12 noon Sat - 12 midnight Sat, and 12AM Sun to 6AM Sun) now I have a third period to assess for how much more and when it will stop.

A reminder to anyone who has joined us since midnight today, if you wish to be added to the email distribution list, please send me a message at rfoot@bcps.org Note that I will not reply to your message, just be assured your address will be added to the list. This feature will be used when there is a developing situation and I cannot post to the site during school because our filtering system blocks most blogs from being viewed by school computers. If you already sent a message in the past 24 hours, you are already on the list.

WHERE DO WE GO FROM HERE...WHEN WILL IT BE OVER AND HOW MUCH BY THEN?

Let me use Dundalk as my guide for what is left of the storm. I estimated 4 inches would fall by midnight Saturday, and we had about 4. Then I said another 4 inches by 6:00 AM, and we have about 5.5 for a total of probably 10 at the moment. For Dundalk, MD I estimate another 2 inches will fall between 7 AM and Noon before the storm finally winds down to flurries. Looking at the Northeast radar, you can see the back edge is starting to approach, but as Andy from southern York County has pointed out before, that back edge sometimes keeps redeveloping further west as the storm rotates through. Appears to be about a 5 degree backing tilt every 15 minutes, and each tilt is shifting the axis of heavy snow from a SW-NE orientation to a more S to N orientation. Though the dark blues are heading south and east, the rotation may bring some of what is north of you on this map (wherever north of your location is) back down on top of you. Hence the reason Philly extended the Heavy Snow Warning to 1PM.

I am going to apply that rule to everyone from Central and Eastern PA south to DC, Virginia and NC who is under the blue region of the radar. I believe you'll see 2-4 more inches between now and Noon, less towards the west, more toward the East.

1. From DC to Balto to Frederick MD west to Harper's Ferry, WV... 1 more inch.

2. Along a line from DC to Balto to Philly and east to Del-Mar-Va, another 2-3 inches by noon

3. Along the extreme Eastern shores of Del-Mar-Va and New Jersey, believe it or not another 3-4 inches due to an ocean enhancing effect as the snow shield rotates with the departing Low.

SO WHY DID THIS STORM END UP BEING SO MUCH BIGGER THAN I THOUGHT?

Oh so you want the part about me wearing the bad, do you? Well as soon as Mommy wakes up, I'll get her to take a picture and then I'll the tail-between-the-legs commentary on what went wrong.