Tuesday, February 26, 2008


(No, not that one. I'm talking about the GFS Fantasyland...this one:

GFS FantasyLand

TUE 2-26 10:30 PM. I know it's hard for you ravenous powderhounds not to get excited when you see maps like this. It's similar to how the administration gets teachers to attend faculty meetings on time, they just announce that chocolate is being served to the first 25 people who show up. You've never seen teachers move so fast after a long school day. If they consider chocolate a food group, then people like you reading this site probably consider impossibly fun computer model scenarios sweeter than pure sugar itself. Just a minute, I need to grab my evening dose.

Ok, back now. ::head twitching:: I call this the GFS FantasyLand, because it is just one model run of the US based Global Forecast System from Monday 2/25 showing some crazy scenarios for next week's storms. One idea going forward from here is that it appears increasingly likely something very significant will pound the East Coast the middle of next week. While climate indicators don't seem that promising: The NAO is strongly positive, the PNA fading to near-neutral. This is opposite of the setup we prefer: a negative NAO (trough in the East), a positive PNA (ridge in the West). Regardless, the GFS, European, Canadian, et all are all showing a major major event swinging east by next Tuesday morning that is going to be hard to avoid. Although a lot can and will change over the next 7 days leading up to arrival of this event, it is interesting to note a number of models have continued to show something brewing for the 3/4-5 period now for several days in a row, so we will keep watching.

Yes, I know, the same thing happened in March 2001... for days before, the models projected a massive Day After Tomorrow type blizzard which was going to bury the 95 corridor under 2-3 feet of snow. The hype was galactic in nature, and schools were closed all the way to the Moon. Everything was shut down from Boston to DC, even BEFORE the storm struck. It was my first year of live classroom teaching in science, and I was in Lancaster County, PA at the time. I remember just before going to bed that night, a TV forecaster from Philadelphia showed the entire viewing area under a deep blue shading with 24" - 36" plastered over it. The next morning, I awoke to 2 inches. The storm had shifted east overnight, blasting northern and central New Jersey as well as parts of New England with just some of the crippling snow that had been expected in the cities. It was and still is in the minds of many weatherfolk, the biggest bust in the history of Mid-Atlantic weather forecasting.

Monday, February 25, 2008


TUE 2-26 10:00 PM. At least your week in the Mid-Atlantic started tranquil, with sunshine and seasonable temperatures on Monday. From here it gets interesting, and much colder. On Tuesday, the vigorous cross-country system that impacted western states Sunday arrives on the East Coast with force. By afternoon, heavy windswept rain overspreads the region, with temperatures rising into the 50's on southeast winds. Overnight into Wednesday, a powerful cold front sweeps to the coast and leftover moisture may briefly change to snow before ending. Noticeable sub-freezing temperatures will arrive behind the front, creating pockets of black ice that could cause some school delays Wednesday morning in Baltimore County's Hereford Zone along with some parts of Frederick, Carroll and Harford Counties. Starting Wednesday, the region spends remainder of the week in January-like conditions, with highs in the mid 30's to near 40. The next chance for precipitation looks to be a clipper on Saturday bringing flurries or light snow.

Later this evening, I will post some basic ideas about next week, as it appears there's one or two more chances for snow during the upcoming 10 day period. I did leave some snippets about it in the previous post if you want to go look for them!

Sunday, February 24, 2008


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.

February Finale 1

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.

February Finale 2

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.

-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

-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.