Foot's Forecast | Weather Intelligence

A KA'NO'NA FOR THE 95 CORRIDOR

It is very unlikely this system will trend far enough south to become a major coastal Kahuna/snowstorm. The surface Low will remain over land and not transfer energy or redevelop off the Carolinas. Regardless of that, this system will have tremendous energy and impact the northern half the country from California to the Northern Plains, Great Lakes and into New England...bringing heavy snow and significant icing across many states. This Accuweather graphic breaks down the storm evolution well. A current satellite image from the west coast shows quite a bundle of energy now moving through the Rockies.

SAT 2-23 7:00 PM. FEBRUARY FINALE IDEAS: The newest Euro and GFS (not shown here) is keeping the primary surface Low near West Virginia/PA Tuesday night. This is being closely followed by HPC as you would expect. You can follow the model animation here. Note that I don't hug just one exact model, I'm providing this as representative of the trend that's developed with our next storm between the GFS and Euro. Also of note are the trends with the NAO (risen to strongly positive) and PNA (still strongly positive but dropping sharply). Those indicate a more zonal or east west flow across the country, further limiting any chances for a big coastal storm. However, you will feel a SuperKahuna blast of cold air, and may set the stage for a Winter Finale as we head into the first week of March. For the sake of ravenous powderhounds, good ole' Mr. Margusity of Accuweather is keeping a distant eye on upcoming storms. You can also peruse the Eastern US Weather Forums on what others are saying about indicators of these storms or lack thereof. If you really want to take a trip down Weather Fantasyland lane, another blogger like me has..believe it or not..created an entire site just for the purpose of tracking ONE storm. Hey now, don't knock it, because regardless of the outcome, it's fun for us crazy powderhounds simply to have a potential storm to track over a 10 day period. The site title is "Storm of the Century" and the link is: http://youhavebeenwarnedmarch5th.blogspot.com/ (note: do not click on link if you're from BCPS, it will be blocked due to the domain name.) Laugh now, while you still can.

SAT 2-23 8:00 AM. POST-STORM SYNOPSIS: The Mid-Atlantic and Northeast did experience a prolonged period of wintry/frozen precipitation as originally anticipated, but it ended up being much more intermittent than forecast, which reduced storm totals. Despite lower accumulations, what did fall was more than enough to make travel extremely hazardous for many areas during a majority of the storm period, so this time it seems the region-wide closings were better aligned toward safety than over-reaction.

Before we launch into another 5 day period of storm analysis, there needs to be a debriefing on what was originally said about the current event compared to what happened. Some of the ideas I've thought of initially are this: I believe the storm's underperformance was due in part to temperatures Thursday night 2/21 not decreasing as much as originally anticipated. Had it been 26 in Baltimore as forecasted for example instead of 29-30, I ascertain the changeover from light snow to sleet/freezing would not have occured as quickly from the city south and east, robbing snow potential. Instead, evaporative cooling from snow falling through those lower temperatures might have kept the temp down in the 20's all day, enhancing the freezing rain potential once it did arrive. Granted there are lots of other factors, but one cannot ignore the effect a 3-4 degree difference in temp would do at the onset of a storm.

The GFS and NAM computer models overall handled the precip onset well, and 48 hours out had finally settled on a reasonable solution, but appeared to have overdone the amount of liquid available. In addition, it was clear to all of us watching the radar that the two systems were not going to phase together. Knowing this, we should have better anticipated the dry slot was going to monkey wrench the forecast...as in robbing some areas of precip (say from Anne Arundel-Howard Counties west to Frederick County). The NWS did actually factor this into their forecasting, but the results made it appear the whole situation caught them by surprise, which in fact they knew and saw it with their own eyes. The Sterling VA NWS office only recorded a trace of snow, when the expectation was for 1-2 inches overnight. The same story was repeated in many of your backyards, and it appears no one in the "comments community" observed an accumulation greater than 1.5" right?

I welcome any of your post-storm analyses, (the what happened and why) and will be glad to post them here in the main site with you as the author. Our first responder is Kyle from Howard County, and his writeup appears below the storm grading section.

POST-STORM ACCURACY CHECK: A general lookback at (1) The original forecast (first issued publicly Sat 2/16) and; (2) The final call (posted below). Where was the call right on, where did it bust, and why?

FINAL ACCUMULATION SUMMARY: Time frame for these total storm projections is the originally forecasted period of Wednesday 12PM 2/20 to Friday 12 AM 2/22.

MAXIMUM PRECIP AMOUNTS: FORECAST 3" along the I-95 corridor from Washington to Philadelphia. 4" in central and southern Maryland, 5" in northern Virginia, western Maryland, the WV panhandle and southeastern PA. My location of Dundalk and the nearest official reporting station, BWI, will be used to grade the prediction. I project BWI will have a total of 3" of snow/frozen precip, and Dundalk, MD will max at 4". These numbers included ice. ACTUAL: Because the original call was for totals to include Wed PM to Fri PM, that includes the clipper snow Wed afternoon. Results are listed as: -Location: Forecast / Clipper amount + 2/22 amount = total / forecast = Departure in % and Final Grade. Source was NWS Public Information Statements from my link pages.

THE "BUST-APOLIS" INCLUDED:

-Dundalk (Central MD): 4 / 1.80 + .30 = 2.1 / 4 = 50 % E
-BWI Airport: 3 / 1.0 + .20 = 1.2 / 3 = 40% E
-DCA Reagan National Airport: 3 / Incomplete no data, assuming it was E

-Fairfax, Northern Virginia: 5 / 1.25 + .1 = 1.35 / 5 = 27% E
-Martinsburg, WV (Panhandle): 5 / 1.5 + .20 = 1.70 / 5 = 34% E

THE "BLUE-RIBBONS" WERE:

-Garrett County (Western MD): 5 / 3 + 2.5 = 5.5 / 5 = 90% A
-PHL Philadelphia Airport: 3 / .2 + 3.2 = 3.5 / 3 = 86 % B (over by 14%)
-Paoli (Southeastern PA): 5 / .5 + 3.5 = 4 / 5 = 80% B

POST-STORM SUMMARIES SUBMITTED BY READERS: First up. Kyle from Howard County, MD. You are welcome to submit yours via the comments and I can post them here.

1)The NAO did not trend negative, rather trended positive while the PNA Index also stayed on the positive side. We wanted a negative/positive setup.

2) A strong La Nina hasn't helped us this whole winter, however I was thinking that it actually would on this storm because of the warmer than normal gulf, but alas it didn't.

3) The jet stream seemed to be too fast and too strong, thus carrying the storm quicker than predicted, perhaps robbing some moisture gathering time.

4) Longer than desired southerly winds eating at that cold air dome.

5) Those darn mountains and mean bay: Seems like storm after storm looks good on the radar over Ohio/Tennessee until they reach the Appalachian Mts. where any storm seems to come out deformed and weaker. The bay, as Mr. Foot has mentioned, keeps on radiating heat throughout the winter, which surely didn't help our pre-storm temps.