NYC vs. BOS vs. DCA Snow Climo

[A-L-E-X]

My only question is, are you using 30 year averages? Is there any way you could expand all of these stations to 50 or 60 year averages?

[psuhoffman]

My only question is, are you using 30 year averages? Is there any way you could expand all of these stations to 50 or 60 year averages?

Nope those are the full averages for the period of record for those airports. I would argue 30 year avg's are more accurate for current climo but that is another argument and not relavant since I did not use the 30 year avg's.

[A-L-E-X]

Nope those are the full averages for the period of record for those airports. I would argue 30 year avg's are more accurate for current climo but that is another argument and not relavant since I did not use the 30 year avg's.

Probably, but I have another question in that case. When you use different full averages for each station you run the risk of contaminating the dataset because some stations' period of record is much longer than others. In that case, it would really be better to use 30 yr (or 60 yr) averages for another reason-- to maintain the same period of record for all stations.

This might actually help you out with your debate lol -- Im just pointing this out because it's something I consider when comparing different sets of data.

[NorthShoreWx]

From the NCDC source (http://lwf.ncdc.noaa...d/snowfall.html) cited above:

DCA: 16.6"

NYC: 28.4" (+71%)

BOS: 42.2 (+ 49%)

These are the three stations closest to their respective city centers with the longest period of records. This comparison is also consistent with the thread title.

All three cities are near sea level and surrounded by areas that get more snow, particularly further inland and higher in elevation. DCA is farther from the ocean than NYC or BOS but is just as low lying.

Disclaimer: I do not live in any of the three mentioned cities.

NYC is the closest to here (50 miles on a compass bearing of 248 degrees; i.e., wsw)

DC is 246 miles / 237 degrees (sw)

BOS is 150 miles / 48 degrees (ne)

If someone wants to take the time to normalize the records from the 3 stations to the least common denominator (i.e., the same POR) that would be an appropriate update to the above. This would involve pulling records from NYC and BOS and averaging the past 59 years to match the DCA POR.

[RU848789]

New York Area

JFK: 22.7

Laguardia: 26.0

Newark: 27.6

Regional AVG 25.4

DC Area

DCA: 16.6

IAD: 22.3

BWI: 20.8

Regional Avg: 19.9

Mathmatical Difference 22%

Caveats: We all know airports are notoriously low in reporting snowfall so before anyone yells about me not including central park that was the reason not some bias. If you want to include central park fine but then find some coop station in DC and include that to even out the statistics. There are several that range between 20-23". Trust me it wont change the math much, possibly from 22 to 23%.

As far as airports go 3 in each metro area, each metro area having 1 in a NW location from the main city.

This was as "fair" and statistically accurate a comparison as could be possible. Anything else is just conjecture. If someone wants to make a case otherwise fine but do so with facts and statistical evidence to back it up please. No more "my gut feels like, I remember a time when, or I just know" kind of arguments.

Source: http://lwf.ncdc.noaa...d/snowfall.html

PSU - good points that people should be precise and use data and clearly outline the assumptions when making arguments like this, rather than imprecise, relative words, such as more, less, etc. Having said that, one minor point in your comparison. You might want to make it clear that in your data set, NYC averages 27% more snow than DC, while DC averages 22% less snow than NYC and that both are correct (the 27% number is the difference divided by the DC avg, while the 22% number, which you reported is the difference divided by the NYC average), as long as the basis for the calculation is included.

This type of comparison produces much larger % differences on the 28" CPK and 16" DCA long term averages (28" is 75% more than 16", while 16" is only 43% less than 28"). Again, precision and clearly stated assumptions are critical in any data analysis.

[psuhoffman]

You are taking the highest station of record in the entire NYC metro area and comparing it with the lowest station of record in the entire DC metro area. On top of that you are comparing an airport reporting station with a non airport station when it is known airports have low snowfall bias. Right there you have already made your statistically comparison invalid.

Furthermore you are changing the peramiters of the argument. I originally engaged in this discussion because of the statement made by someone that the NYC area recieves 500 percent more snowfall then the DC area. This was later amended to 40-50%, better but still a gross exageration. The debate I am engaged in is that the NYC metro area does not recieve 40-50% more snowfall on average then the DC metro area. If you want to win the argument that Central Park averages 71 percent more snowfall then some runway on an island in the potomac river south of DC then yay you win. No one was arguing with you about that. However, the stats you just cited are useless for the purposes of the argument I was engaged in. I could compare IAD and JFK (our regions highest official reporting station and your regions lowest) and make the statement that DC and NYC recieve basically the same avg snowfall. That would be statistically correct in the narrow scope I framed it but it would be misleading and just as innacurate as what you just did.

I guess I should qualify one more thing for this debate. If you want to site statistics you can not be selective in what data you use and o not use. If we are talking about comparing the entire NYC area and the DC area one location can not be used against another location. If you want to compare airports it must be all airports in both regions. If its non airport reporting stations and coops fine but then look up all the statistics for all coop stations in the 2 metro areas and run the numbers. Either way what you are trying to prove is not backed up by statistical data and evidence.

From the NCDC source (http://lwf.ncdc.noaa...d/snowfall.html) cited above:

DCA: 16.6"

NYC: 28.4" (+71%)

BOS: 42.2 (+ 49%)

These are the three stations closest to their respective city centers with the longest period of records. This comparison is also consistent with the thread title.

All three cities are near sea level and surrounded by areas that get more snow, particularly further inland and higher in elevation. DCA is farther from the ocean than NYC or BOS but is just as low lying.

Disclaimer: I do not live in any of the three mentioned cities.

NYC is the closest to here (50 miles on a compass bearing of 248 degrees; i.e., wsw)

DC is 246 miles / 237 degrees (sw)

BOS is 150 miles / 48 degrees (ne)

If someone wants to take the time to normalize the records from the 3 stations to the least common denominator (i.e., the same POR) that would be an appropriate update to the above. This would involve pulling records from NYC and BOS and averaging the past 59 years to match the DCA POR.

[psuhoffman]

PSU - good points that people should be precise and use data and clearly outline the assumptions when making arguments like this, rather than imprecise, relative words, such as more, less, etc. Having said that, one minor point in your comparison. You might want to make it clear that in your data set, NYC averages 27% more snow than DC, while DC averages 22% less snow than NYC and that both are correct (the 27% number is the difference divided by the DC avg, while the 22% number, which you reported is the difference divided by the NYC average), as long as the basis for the calculation is included.

This type of comparison produces much larger % differences on the 28" CPK and 16" DCA long term averages (28" is 75% more than 16", while 16" is only 43% less than 28"). Again, precision and clearly stated assumptions are critical in any data analysis.

You have a good point about the difference in how to calculate the %. Perhaps splitting the difference is fair for the purpose of this debate. Comparing Central Park to DCA is comparing apples and oranges though. One is an airport known for having low snowfall bias located on a river south of DC. The other tends to always be one of the highest reporting stations in the NYC area. It is also not as statistically significant because you are using one site instead of multiple sites so that alone makes it less valid when making assumptions for the entire region as the original debate was about.

[psuhoffman]

One last thing about this, if there is really anyone in the NYC area that thinks DCA is indicative and a "fair" estimate of what snowfall climo for the DC area is then that right there is the problem and why there is a disconnect in this argument. DCA is to our region what JFK is to your region. Its a local minimum, due partially to bad location and partially to problems with reporting. No other reporting station in the area is even close to being as low as DCA. Most coop stations in the immidiate DC area average between 20-23". Some of the locations slightly further northwest average 23-28". That said I still see posts from time to time throwing 16" around as the DC snow climo and even that is wrong as DCA avg is 17" rounded off. Do people in your area really use that 16" as a baseline for what they think DC snowfall avg is? No one in this area does. DCA is considered a joke here, literally. If anyone is in this debate because they think the DC area averages 16" of snow then we are at an impasse because you are using skewed data to make an assumption about a region that is not accurate. The truth is the NYC area averages 25.5" and the DC area averages 20". That is calculated by averaging all official reporting stations in the DC and NYC metro areas. If anyone wants to debate that NYC averages 5000000 percent more snowfall then DCA fine go ahead I dont care, this started as a debate about the NYC area and the DC area but somehow DCA keeps being used to verfify snowfall for this entire region.

[real]

And correct me if I am wrong, but DC is also farther west than either Philadelphia or New York. DC is about 30 miles from the Chesepeake Bay and 100 miles or so from the Atlantic Ocean. Occassionaly, storms ride up the coast in such a position that DC proper stays all snow while New York ends up with mixing issues. Its not common - just as its not common that DC has rain and New York/Philly have all snow - but it does happen from time to time.

[real]

If someone made me decide based exclusively on the NESIS snowfall maps whether I wanted to live in Westchester County NY or Montgomery County Maryland for big snow, I would have a hard time deciding between the two just looking at snowfall from all the top rated storms. Frankly, I think Baltimore is often the place to be in Cat 3,4 or 5 storms for some reason. They seem to be just far enough north to often catch a storm bombing out while far enough south to also catch snow from those that run to the south.

http://www.ncdc.noaa...is.php#rankings

[psuhoffman]

If someone made me decide based exclusively on the NESIS snowfall maps whether I wanted to live in Westchester County NY or Montgomery County Maryland for big snow, I would have a hard time deciding between the two just looking at snowfall from all the top rated storms. Frankly, I think Baltimore is often the place to be in Cat 3,4 or 5 storms for some reason. They seem to be just far enough north to often catch a storm bombing out while far enough south to also catch snow from those that run to the south.

http://www.ncdc.noaa...is.php#rankings

correct Baltimore has the most 20" snowstorms of any of the east coast cities, including Boston.

[psuhoffman]

correct Baltimore has the most 20" snowstorms of any of the east coast cities, including Boston.

Now if you wanted to live anywhere on the east coast for simply big snowstorms I would say go with Worcester area. Where I live about 30 miles NW of Baltimore is a good location for 10" plus snowfalls and we avg almost 40" a year here but I am in a snowfall max area and would not throw that into the DC area mix.

[easternsnowman]

I believe the philly average is 22 inches from 1981-2010 and overall average is the same. . If you look at chester county and area around the city with 400 ft or more elevation the average is close to 30 or more.

[NorthShoreWx]

You are taking the highest station of record in the entire NYC metro area and comparing it with the lowest station of record in the entire DC metro area.

I do not know what you mean by this. If you are referring to the period of record (POR) then I agree that they should be normalized to the same length. That is what I was referring to in my previous post.

On top of that you are comparing an airport reporting station with a non airport station when it is known airports have low snowfall bias. Right there you have already made your statistically comparison invalid.

I would not categorize this as a "known" bias as it remains a contentious point in every discussion that I have seen. The same has been debated endlessly about the Central Park "zookeepers". It certainly not a basis for invalidating the statistical comparison. I do however share your belief that there are problems with a lot of airport measurements, particulary airports in urban areas. Is there another valid climo record in DC that we can use?

Furthermore you are changing the peramiters of the argument. I originally engaged in this discussion because of the statement made by someone that the NYC area recieves 500 percent more snowfall then the DC area.

The 500% statement was rediculous. That seemed to get under your skin, but I ignored it because it was too over the top to take seriously. If that was the only thing this discussion was about, it would have ended very quickly.

This was later amended to 40-50%, better but still a gross exageration. The debate I am engaged in is that the NYC metro area does not recieve 40-50% more snowfall on average then the DC metro area. If you want to win the argument that Central Park averages 71 percent more snowfall then some runway on an island in the potomac river south of DC then yay you win. No one was arguing with you about that. However, the stats you just cited are useless for the purposes of the argument I was engaged in. I could compare IAD and JFK (our regions highest official reporting station and your regions lowest) and make the statement that DC and NYC recieve basically the same avg snowfall. That would be statistically correct in the narrow scope I framed it but it would be misleading and just as innacurate as what you just did.

40 - 50% is an accurate representation of the climatological snowfall difference between Washington DC and New York City. There is no way around that. If you want to compare IAD to JFK or EWR or SWF, the numbers will be different, but that is a major change from the topic of NYC vs. BOS vs. DCA Snow Climo. For the record, I felt that your attempt to compile a regional average snowfall for the two areas, while a noble idea, did not yield a scientifically accurate or useful result.

I guess I should qualify one more thing for this debate. If you want to site statistics you can not be selective in what data you use and o not use. If we are talking about comparing the entire NYC area and the DC area one location can not be used against another location. If you want to compare airports it must be all airports in both regions. If its non airport reporting stations and coops fine but then look up all the statistics for all coop stations in the 2 metro areas and run the numbers. Either way what you are trying to prove is not backed up by statistical data and evidence.

I disagree. I thought we were comparing the climo of 3 cities (really 2...how did BOS get mixed up in this?). The three sites used represent the best record closest to the downtown/ center city areas. If there is a better climo record to use for DC, then we should use it. Once we start talking about regions, the gerrymandering of data begins and the arguments can go on indefinitely. I firmly believe that the 50% rule also applies overall to the regions. Climatologically there is good reason for it. It even extends south. DC gets 42% more snowfall than RIC.

I believe that one of the positions you were arguing earlier was that the amount of the difference due to snow events in NYC being rain events in DC was trivial. This discussion is still very much on the table because no one has provided more than anecdotal data for or against the hypothesis. I am undecided because I am unaware of any related stats. It happens both ways, but it also snows in NYC and DC sometimes when it is raining at CAR...that obviously is not an indicator of climate.

One last item...if I conceded that the average snowfall in the District of Columbia was 20" (not 16.6) and used that as a basis for calculating a 40% difference, would that seem reasonable to you, or do you feel that DC gets more than 20" annually?

[psuhoffman]

The first point was that there are 3 official reporting stations in the DC metro area. DCA is an "outlier" in its low snowfall measurements and not indicative of the region. If you honestly think DCA is a good measurement for the DC area this debate is at an impasse because I honestly do not even consider DCA at all indicative of the DC area snowfall climo. I wish they would stop keeping records there and many in this area have pushed the same point because of this problem. Places south and east of DCA always report more snowfall then they do. I do not know what the problem is just that it is a problem. I know NYC has the same issues with some reporting stations and that is why I did include DCA in the statistical averages for the region.

Second point about using one station. The original argument was clearly between the NYC AREA and the DC AREA..... this is important because you are trying to frame this now as comparing DCA to Central Park. That is apples and oranges and I have clearly stated why. One is an airport located south of DC on a river. The other is in the park away from immediate water and a non airport reporting station. One is the lowest regional station and the other the highest.

Third point... I would accept 20" as fair for the DC area. I think overall if we are looking at the DC metro 22 is probably more accurate but there are some places right along the river and near the Mall that are just under 20". Besides I have no statistical data to support this because DCA skews the data low. I could remove DCA but that would be subjective and biases do I will not. With DCA in the mix it brings our average to 20. What I do not understand is why you want to use 28" as the NYC area average. You have 4 official reporting stations in the NYC metro area, and the average of those is not 28". 28" is the average for the highest reporting station of the 4. If you want to use 28 then you must use 22.3 as the number you compare it to (our highest reporting station). It seems like you want to compare the highest average you can come up wtih for the NYC region, with the lowest average you can come up with from the DC region.

Finally you said we are comparing NYC and DCA? That was not the original discussion. Again you kind of picked up the torch for others that started this fire, but the original debate was the NYC area versus the DC area. NOT NYC versus DC National Airport. If I had known this was going to become a comparison of Central Park and DCA I would not have bothered. Read my earlier post about DCA and my views on its accuracy. If you are basing your entire theory on DCA as the avg for DC then that right there is why we can not agree. I do not use DCA or consider it indicative of DC snow climo. If you are using that as what you consider DC snow climo we are two ships passing in the night.

I do not know what you mean by this. If you are referring to the period of record (POR) then I agree that they should be normalized to the same length. That is what I was referring to in my previous post.

One last item...if I conceded that the average snowfall in the District of Columbia was 20" (not 16.6) and used that as a basis for calculating a 40% difference, would that seem reasonable to you, or do you feel that DC gets more than 20" annually?

[NorthShoreWx]

Actually taking this back a few steps, the point I was originally interested in supporting was that the 1.9 degrees in latitude between the two cities makes a significant difference given similar elevation. Do you agree with this?

The difference in snowfall was one of the outcomes of that difference in lattitude, but you have bucked the conventional wisdom by finding ways to show that there is not a material difference in the snowfall between NYC and DC (and their respective regions). I still maintain that there is a 40 - 50% difference, not only between the cities, but between the regions on average, and you still maintain that there is not.

I don't see this progressing any further without better data, and even then I doubt that you would accept any contrary to your position, but its been an interesting discussion.

[nj2va]

I can't believe anyone thinks DCA is a good reporting location for DC proper (DC/Arlington/Alexandria) - not talking about the NW 'burbs like Montgomery County, MD or Loudoun County, VA. Take Dec 19 '09 for example - DCA had 16.4" IIRC. I live in Arlington as well and I recorded just over 19" - less than 5 miles from DCA. Places in NW DC recorded 19-20".

Now, that's simply one storm but its indicative of snowstorms around here.

[NorthShoreWx]

Too much frozen testosterone and not enough reason in this thread. May you all be blessed with copious snowfall. I'm done.

[ORH_wxman]

I'm not from either region, but I think I would put the difference between NYC area and DC area snowfall at a value between psuhoffman and northshorewx...probably in the 30-35% range. In NYC metro you basically have as low as 20-22" avg (near JFK and other unfavorable spots on the south facing shores) to as high as 32-34" on the north shore of Long Island and a few northern burbs as you approach White Plains. I think a number around 27" would be a fair value to approximate the region as a whole.

I think for DC, 16" at Reagan is obviously the low outlier and you can increase it to 23" or so when you get out by IAD. I think roughly 20" would be a fair value for the metro region as a whole. 27" vs 20" is about a 35% difference...if you tweak these average by an inch or so in either direction for either or both airports, you can generate differences as low as 20% (26 vs 21) and as high as 50% (28 vs 19).

[EastBayWx]

Since Boston was mentioned in this thread, I'll make things simple and will try to find a pattern in total snowfall.

Portland ME > Boston > Providence > NYC > Philadelphia > Baltimore > Washington DC > Richmond > Raleigh > Savannah.

Travel south along I-95 from Maine and snowfall drops off in an almost linear fashion from 75"/year to nil by the time one gets to Savannah.

[EastBayWx]

Long Island Far Ahead of District of Columbia:

2000-01 - 2009-10 Snowfall:

Upton, on L.I. and 60 miles east of NYC, also known as Brookhaven National Laboratory or OKX, measured 419.8" of snow during the last decade.

Dulles Airport measured 216.5" during that span.

Reagan National Airport measured 167.5" during that span.

Note that Upton sits under the 100 foot elevation contour and is not the snowiest location on Long Island, sitting about midway between the Sound and the Atlantic.

Here is the Upton snow chart:

http://www.bnl.gov/w...hlySnowfall.htm

That north central portion of LI north of the LIE in Suffolk County west of Riverhead has a climate so similar to SNE that it should be considered an honorary part of New England. 40-45" average, at least over the past decade, appears very valid. Variability from decade to decade is large however.

[ChescoWx]

This is true...here in the nearby NW Philadelphia Suburbs (27 nm NW of PHL airport) in Chester County the 30 year average is 34" of snow (this is 55%) more than PHL airport. During the last decade we have averaged over 37" of snow.

This pattern continues up and down the coast. I believe Worcester which is (40+ miles West of BOS) has a similar sharp increase vs. Boston. I think in Chester County and in Worcester's case it is a combination of inland location and elevation that combine to deliver the significant difference. However, traveling an additional 48 miles west of my location to Harrisburg (MDT) at a lower elevation delivers an almost identical snow total as Chester County. All in all however latitude trumps elevation as Boston still receives 20% (43" vs 34") more snow than here in Chester County .

Paul

www.chescowx.com

I believe the philly average is 22 inches from 1981-2010 and overall average is the same. . If you look at chester county and area around the city with 400 ft or more elevation the average is close to 30 or more.

[ORH_wxman]

This is true...here in the nearby NW Philadelphia Suburbs (27 nm NW of PHL airport) in Chester County the 30 year average is 34" of snow (this is 55%) more than PHL airport. During the last decade we have averaged over 37" of snow.

This pattern continues up and down the coast. I believe Worcester which is (40+ miles West of BOS) has a similar sharp increase vs. Boston. I think in Chester County and in Worcester's case it is a combination of inland location and elevation that combine to deliver the significant difference. However, traveling an additional 48 miles west of my location to Harrisburg (MDT) at a lower elevation delivers an almost identical snow total as Chester County. All in all however latitude trumps elevation as Boston still receives 20% (43" vs 34") more snow than here in Chester County .

Paul

www.chescowx.com

Yes there is a sharp increase just west of Boston...ORH (Worcester) averages 69" to BOS 43" which is a 60% increase.

[NorthShoreWx]

I'm not from either region, but I think I would put the difference between NYC area and DC area snowfall at a value between psuhoffman and northshorewx...probably in the 30-35% range. In NYC metro you basically have as low as 20-22" avg (near JFK and other unfavorable spots on the south facing shores) to as high as 32-34" on the north shore of Long Island and a few northern burbs as you approach White Plains. I think a number around 27" would be a fair value to approximate the region as a whole.

I think for DC, 16" at Reagan is obviously the low outlier and you can increase it to 23" or so when you get out by IAD. I think roughly 20" would be a fair value for the metro region as a whole. 27" vs 20" is about a 35% difference...if you tweak these average by an inch or so in either direction for either or both airports, you can generate differences as low as 20% (26 vs 21) and as high as 50% (28 vs 19).

Blessed are the peace makers. Now if you can make a piece of that potential Norlun dump down this way, we will elevate you from honorary Long Islander to full fledged dual citizenship

[NorthShoreWx]

I remember a rule of thumb that a 1000 foot gain inelevation is roughly equivalent to a 100 mile increase in latitude, most often with the example that the summit of Mt Washington has the climate of someplace 600 miles further north; i.e., sub-arctic northern Quebec.

I'm sure there's a lot of variation, but it seems like a decent quick and dirty way to gage climate by elevation.

[NorthShoreWx]

Long Island Far Ahead of District of Columbia:

2000-01 - 2009-10 Snowfall:

Upton, on L.I. and 60 miles east of NYC, also known as Brookhaven National Laboratory or OKX, measured 419.8" of snow during the last decade.

Dulles Airport measured 216.5" during that span.

Reagan National Airport measured 167.5" during that span.

Note that Upton sits under the 100 foot elevation contour and is not the snowiest location on Long Island, sitting about midway between the Sound and the Atlantic.

Here is the Upton snow chart:

http://www.bnl.gov/w...hlySnowfall.htm

FYI, I took a stroll yesterday at a hair over 400 feet on the north shore. You know where that would be.

[snywx]

I wish more snow for you, but the 40% is accurate in an apples to apples comparison...and we have been through this exercise quantitatively in the past with these results. Its nothing personal...its about where you live and climatology.

You should compare the high ground NW of Baltimore to Orange County NY, not to a southwestern suburb of NYC.

If it makes you feel any better, the old rule of thumb was that avg snowfall increases about 50% from DC to NYC and then another 50% from NYC to BOS. All three towns see more to their north and west.

There is no comparison there..

[rgwp96]

Yes there is a sharp increase just west of Boston...ORH (Worcester) averages 69" to BOS 43" which is a 60% increase.

you can also add the hills of nw jersey . westmilford-highland lake areas probably avg about 50+ and are only 40 or so miles from nyc

[Zelocita Weather]

FYI, I took a stroll yesterday at a hair over 400 feet on the north shore. You know where that would be.

If you take NYC as the center of this region and give a radius of 30-35 miles on all sides you would get the following averages:

Immediate NYC Metro (Suburbs within 10-15 miles, all boroughs, etc.) average 27-28".

C/E LI average 28-30"

C NJ coast/E C NJ average 24-27"

N/C NJ /N NJ/ S NY State average 30-38"

Average all sections within the 35 miles radius= 29 inches

If you take DC as the center of this region and give a radius of 30-35 miles on all sides you would get the following averages:

DC Metro (and immediate burbs on all sides) average 18"

Far SE/E burbs 17"

Far W burbs 22-24"

Far N burbs 22-24"

Far NE/SW burbs 20-22"

Average all sections within the 35 miles radius= 20 inches

45% more on average when comparing regions

[ORH_wxman]

If you take NYC as the center of this region and give a radius of 30-35 miles on all sides you would get the following averages:

Immediate NYC Metro (Suburbs within 10-15 miles, all boroughs, etc.) average 27-28".

C/E LI average 28-30"

C NJ coast/E C NJ average 24-27"

N/C NJ /N NJ/ S NY State average 30-38"

Average all sections within the 35 miles radius= 29 inches

If you take DC as the center of this region and give a radius of 30-35 miles on all sides you would get the following averages:

DC Metro (and immediate burbs on all sides) average 18"

Far SE/E burbs 17"

Far W burbs 22-24"

Far N burbs 22-24"

Far NE/SW burbs 20-22"

Average all sections within the 35 miles radius= 20 inches

45% more on average when comparing regions

If you are going out as far as 35 miles...DC's far northern burbs average more than 22-24"...probably more like 24-28". You are starting to get into the central MD hills.