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verification

Snowfall Verification for Jan 21

This was an interesting one to watch unfold…

 
Cold air damming allowed for more snow at the onset of the storm than what I was expecting, which resulted in broader 1-2 inch coverage east of the mountains in central VA, MD, DC and southern NJ. This also allowed the freezing rain and sleet to work a bit further south. The back end of the system also had a surprise up its sleeve, bringing up to seven inches of snow to the Pittsburgh area. The snow underperformed a bit along the southern edge in the mountains where warmer temperatures led to more mixing and plain old rain.

The higher snow totals were captured pretty well for the most part, especially along the southern edges of the 2-4 inch and 4-8 inch contours. The pink indicates areas that received 0.1-0.25+ inches of sleet and/or freezing rain (which was a bit trickier to contour due to the nature of the reports).

I knew the snow was a bit of a risk in the CAD region, but I didn’t pull the trigger on it and ended up paying for it. I’m going to give this forecast a grade of B-… the northern areas were quite good, but the southern areas suffered a bit.

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I have a new map design that I will roll out during the next snow event. On top of being a larger image, it also has county lines and interstates for easier interpretation.

Snowfall Verification for Dec 7-8

 
Quite a trying forecast, but overall it wasn’t a complete loss. Verified the mountain areas and highest totals fairly well, but the more heavily populated areas left much to be desired. Looking back, I could have been less generous with the 2-4 inch range in northern MD and southeastern PA, but other than that and bringing the 1 inch cut-off further north in MD I don’t see much that I could have done to change my overall thinking for this event.

The changeover from rain to snow was fairly messy east of the mountains, and most did not even transition to 100% snow. On top of that, the snowfall ended more abruptly and sooner than I had expected, which prevented the stronger cooling to make it to the surface in tandem with the back edge of the heavier precipitation. That slightly warmer boundary layer is what turned 1-4 inches into little to no accumulation.

Going to be a little generous and give myself a C- overall, though it wouldn’t take much convincing to push that to a D+ considering the bust in south-central/southeastern PA and MD and the western edge of the snowfall.

Snowfall Verification for Oct 29

 
I’d give that a B+ …probably the best verification yet!

The WV/VA mountains and western PA contouring was off, especially along the southern edge of the mountains, but from central VA and south-central PA and points northeast verification was excellent. Virtually nailed the rain/snow line and sharp gradient along the eastern edge.

GFS actually did better than the NAM regarding the contouring along the western edge (not sure about the actual totals).

Summer 2011 forecast verification

Overall I’d give my summer 2011 forecast a B+, a grade worthy of a forecast that used one of the hottest summers on record as its main analog to forecast what ended up being yet another record-setting summer of heat. On a month-to-month scale, I’d give June an A-, July a C and August a B. The one thing that really hurt this forecast was just the sheer extent of the heat, especially over Texas and Oklahoma where extreme drought occurred. Otherwise, the pattern was recognized fairly well, with warm anomalies across the eastern two-thirds of the country and a cooler West Coast.

Summer 2011 (based off of 1971-2000 30-year normals):

The monthly breakdown:

June

July

August

And here’s summer 2010 (left) next to summer 2011 (right)… what I would consider a grade A forecast:

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I also must remember to do something like this for last winter, as I managed to completely forget about doing the winter verification.

Winter 2011-2012 (DJF) precipitation forecast

The Mid-Atlantic will struggle to get to near normal, but most should be able to edge into that category as the southeastern Mid-Atlantic goes drier than normal again.

As for snowfall, I expect the Mid-Atlantic to be near normal to slightly above normal (90-125%) throughout the region. I think the storm tracks will be similar to last winter, but the winter storms that hit the Southeast and brought anomalously-large snowfall totals to that region will be further north this year due to a weaker trough (and weaker -NAO). That would put the tracks through, or just south of, the Mid-Atlantic. These storms that we didn’t get last year will help boost the region’s snowfall totals, though each individual event may only drop 1-3 inches in most non-mountainous areas.

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This was last year’s DJF forecast and verification:

Snowfall Verification for Feb 21-22

I’ve procrastinated long enough…

 
Overall not too shabby. The orientation and majority placement of the higher totals were generally correct, though the cut-off on the southern edge left a good amount of room for improvement. My first forecast was much better in that regard. The area of highest snowfall was off, but the idea of having the 8-12″ in western PA was certainly worth applauding despite the questionable positioning. The northern edge of the 2-4″ was also overdone.

This forecast gets a B- from me… general orientation and position of the more significant snowfall totals was good, but the southern edge and some of the northern edge of the higher totals definitely needed to be scaled back. A blend of my first and final forecasts would have probably yielded a B/B+ rating.

Snowfall Verification for Feb 9-10

Overall, this storm was an under-performer in the middle of the region compared to my forecast. The models actually did a good job in capturing this “snow hole” in central VA and central NC. Totals in those areas generally ranged from 0.25″-0.5″ and there was some mixing in southern and eastern NC.

 
Totals in WV maxed out at 2-3″, and there was a small area of 2-4″ in the mountains of NC. The snow in the eastern NC/VA area almost over-performed, with several reports of 4.0″ and even one report of 4.2″ in east-central NC. One area of more persistent banding within the first shot of snow helped a small area of southern MD to just edge into the 1.0″ category, with other reports of 0.5″-0.8″ in the area. This first shot of snow also helped parts of western VA hit 1.0″-1.5″, but those areas were also somewhat isolated.

Overall grade for this one is a C-. The storm underperformed in general, but my key target area of 2-4″ (i.e. the area that seemed like it would get the most) in eastern NC and southeastern VA verified well.