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Central PA & The Fringes - January 2014 Pt II


PennMan

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So I just did an analysis of the 15z SREF's 21z temperatures at various sites, specifically ORD, LAF, GRR, DTW, CMH, CLE, ERI, and IPT to get a sample on both sides of the "Arctic front". The idea was to see how the different members are handling the front. The members with the best temperature forecasts (average error below 3.0°F) are...

ARW3/ARN2

ARW4/ARP1

ARW5/ARP2

ARW6/ARN3

NMM3/NMN2

NMM4/NMP1

NMM6/NMP3

NMB1/MBCN

NMB4/MBP1

NMB7/MBP3

 

The members with the worst temperature forecasts (average error at or above 4.0°F) are...

ARW7/ARP3

NMM2/NMN1

NMM5/NMP2

NMB2/MBN1

NMB3/MBN2

NMB6/MBN3

 

The bold ones are doing exceptionally poorly, with average errors at or above 6.0°F.

 

attachicon.gifSREFanalysis.png

 

 

 

For fun, I also gave each member a weight based on how well they are doing and calculated a weighted mean precip and snow forecast for PSB (nearest to KUNV). That method gives a mean precip of 0.19", and a mean snowfall of 6.2".

 

What I found very odd/interesting is how extreme of snow ratios the SREFs are generally forecasting. Of the 17 members that forecast any snow at PSB, only three members have ratios of less than 25:1 (8, 16, and 20). Four have ratios of 40:1 or better (40, 40, 44, 45). The weighted-mean ratio turned out to be 32:1.

 

Good analysis. It's pretty clear the SREF is out to lunch with the snow-liquid ratios. Here is a graphic showing the climatological distribution of snow ratios for the CTP CWA.

 

ctp.GIF

 

Even 25:1 ratios are exceptionally rare, forget anything above 30:1. I don't see anything that supports ratios above 15:1 for UNV, especially with the best lift above where temperatures are in the dendritic snow growth zone. It may be slightly higher farther south where the lift is stronger and a bit lower in the atmosphere where temperatures will be around -15C.

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Good analysis. It's pretty clear the SREF is out to lunch with the snow-liquid ratios. Here is a graphic showing the climatological distribution of snow ratios for the CTP CWA.

 

 

Even 25:1 ratios are exceptionally rare, forget anything above 30:1. I don't see anything that supports ratios above 15:1 for UNV, especially with the best lift above where temperatures are in the dendritic snow growth zone. It may be slightly higher farther south where the lift is stronger and a bit lower in the atmosphere where temperatures will be around -15C.

 

Ya, the ratios seemed pretty wacky to me.

 

Still, the average of all the members with <3.0°F average error at those cities gives 0.25" for State College... I'd be more than happy with 0.25" liquid equivalent (3-4 inches of snow). :)

 

Of course, for now, I'm going to stick with the global models and expect around 1".

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Yupp! I'll be chatting with you guys while the 00z's come in! As you can imagine, things around here get crazy when snow is in the forecast.

Good talk at 6:20 about snow bands setting up and people may overperform or underperform. So many people think a forecast  is a bust if they get an inch or two less then someone 10 miles from them in these type of systems.

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Good talk at 6:20 about snow bands setting up and people may overperform or underperform. So many people think a forecast  is a bust if they get an inch or two less then someone 10 miles from them in these type of systems.

 

Thanks! I agree. Those meso-banding structures will be able to tap into some awesome SLR's which could result in some pretty good lollipops

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Someone just posted on FB that this storm is looking like a bust because there is nothing on radar to our south yet... man people are clueless. 

its like when people start asking where the snow is when a warning or advisory starts at say 4:00 and it is not precipitating at 4:01

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