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December obs/disco/short range


Ian

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Been snowing off and on all evening but I've noticed the snow has no correlation to radar. At times it's snowing with nothing on radar and then when under good returns it's not snowing. It's not usually like this but I have noticed it a few times here. Weird.

During the heaviest snow today, I was only under about 5 dbz when the better returns were south of me. I don't know if it's because of the wind or something, but it was strange.

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BWI's official seasonal total for last winter was 39 inches. Pretty sure most close by areas received close to 50. They also had those weird adjustments to the Feb. 2010 blizzards.

even last year, they adjusted down for the feb 12-13 event. It was weird and I don't remember seeing any official explanation for it.
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Yeah, not really sure why they have adjusted down for some events. For snow total reference, here's the CWG article with mappys snow map along with the supporting data. I don't see Mitch or dailylurkers numbers in there....they may not have provided them, but photoguy is in there a few inches higher than me, so there is some support for areas surrounding bwi having larger numbers.

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/05/08/how-much-snow-fell-in-your-backyard-mapping-the-2013-2014-winter-snow-totals-in-the-mid-atlantic/

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even last year, they adjusted down for the feb 12-13 event. It was weird and I don't remember seeing any official explanation for it.

I do remember something about that. I guess that what cost them from recording 40 plus for the year. I'd really like to know the process they use to measure because it sure seems they make it way more difficult than it should be.

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I do remember something about that. I guess that what cost them from recording 40 plus for the year. I'd really like to know the process they use to measure because it sure seems they make it way more difficult than it should be.

It's straight-forward what initiated the change, but what goes into the current BWI totals is indeed obscure. During the 09/10 changes, LWX finally noticed that the FAA observer's data at BWI could not represent the official Baltimore numbers since reporting by-the-hour would violate the 6-hr rule for snowfall reports. But instead of actually trying to arrive at a reasonable snowfall total for the first two major storms of 09/10, LWX settled on just using snow depth, which doesn't make sense at all for the 24+hr duration events. 

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It's straight-forward what initiated the change, but what goes into the current BWI totals is indeed obscure. During the 09/10 changes, LWX finally noticed that the FAA observer's data at BWI could not represent the official Baltimore numbers since reporting by-the-hour would violate the 6-hr rule for snowfall reports. But instead of actually trying to arrive at a reasonable snowfall total for the first two major storms of 09/10, LWX settled on just using snow depth, which doesn't make sense at all for the 24+hr duration events. 

That's interesting to know. You may remember they also had trouble settling on a final number for PDII. If I recall they were not sure initially if the front running snow that occurred Saturday morning should be included in the final total for the event.

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BWI revised or added more snow in the evening batch.  Either way, they were on the board.

 

000

NOUS41 KLWX 120255
PNSLWX
DCZ001-MDZ003>007-009>011-013-014-016>018-501-502-VAZ025>031-
036>040-042-050>057-501>504-WVZ050>053-055-501>506-121455-

PUBLIC INFORMATION STATEMENT
SPOTTER REPORTS
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
955 PM EST THU DEC 11 2014

THE FOLLOWING ARE UNOFFICIAL OBSERVATIONS TAKEN DURING THE PAST 23
HOURS FOR THE STORM THAT HAS BEEN AFFECTING OUR REGION. APPRECIATION
IS EXTENDED TO HIGHWAY DEPARTMENTS...COOPERATIVE OBSERVERS...SKYWARN
SPOTTERS AND MEDIA FOR THESE REPORTS. THIS SUMMARY IS ALSO AVAILABLE
ON OUR HOME PAGE AT WEATHER.GOV/BALTIMORE

********************STORM TOTAL SNOWFALL********************

LOCATION STORM TOTAL TIME/DATE COMMENTS
SNOWFALL OF
/INCHES/ MEASUREMENT

MARYLAND

...ANNE ARUNDEL COUNTY...
BWI AIRPORT 0.2 700 PM 12/11 AIRPORT

...BALTIMORE COUNTY...
2 NW LONG GREEN 0.2 730 PM 12/11 TRAINED SPOTTER

...BALTIMORE CITY...
PIMLICO 0.2 701 PM 12/11 PUBLIC

...CARROLL COUNTY...
3 WSW LINEBORO 0.1 550 PM 12/11 TRAINED SPOTTER

...HARFORD COUNTY...
2 E NORRISVILLE 0.5 637 PM 12/11 TRAINED SPOTTER
BEL AIR 0.4 1249 PM 12/11 PUBLIC
WHITEFORD 0.2 353 AM 12/11 TRAINED SPOTTER

...HOWARD COUNTY...
2 N COLUMBIA 0.2 1245 PM 12/11 TRAINED SPOTTER
1 SSE SIMPSONVILLE 0.2 130 PM 12/11 TRAINED SPOTTER

VIRGINIA

...ARLINGTON COUNTY...
REAGAN NATIONAL AIRP T 414 PM 12/11 AIRPORT

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It's straight-forward what initiated the change, but what goes into the current BWI totals is indeed obscure. During the 09/10 changes, LWX finally noticed that the FAA observer's data at BWI could not represent the official Baltimore numbers since reporting by-the-hour would violate the 6-hr rule for snowfall reports. But instead of actually trying to arrive at a reasonable snowfall total for the first two major storms of 09/10, LWX settled on just using snow depth, which doesn't make sense at all for the 24+hr duration events. 

 

You left out the final step- they took the snow depth measurement and adjusted it upwards, which was supposed to represent what the total would have been had it been measured every 6 hours. After several revisions, they settled on a total of 25 inches for 2/5-6/2010, revised up from the initial snow depth measurement of 24.7. Of course they never explained their methodology for how they came up with that number though. Also that year they went back and revised 2/2-3/2010, 1/30/2010, and 12/18-19/2009. The Dec. '09 one hurt the most as they went from 21.1 inches down to 18, which took away our snowiest Dec. ever record. I had a problem with these revisions as they all ended up being nice, tidy whole numbers, which makes me think they were just guessing rather than applying some derived formula.

 

There was talk of revising other previous big storms between 1998- Feb. 2010 but it never happened. To be fair, I do think some storms during that time period had measurements that seemed too high (like Feb. 11-12, 2006), but I do think the 09/10 storms were adjusted too low.

 

This is an old article that mentions some of it: http://weblogs.marylandweather.com/2010/02/no_snow_total_for_bwi.html

 

even last year, they adjusted down for the feb 12-13 event. It was weird and I don't remember seeing any official explanation for it.

 

This is something I've seen them do a lot too starting with the 10/11 winter- most of the time the revisions are small (for example, they revised 1/26/11 down from 7.8 to 7.6 inches) but in the case of Feb. 12-13, 2014, its was relatively larger. I don't remember the exact total but it was initially over 13 inches, and the final total now is 11.5 inches.

 

BWI revised or added more snow in the evening batch.  Either way, they were on the board.

 

 

 

Maybe they read this thread and saw us all complaining. :-) This happened because I speculated on a Dec. shutout- you all can thank me later.

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You left out the final step- they took the snow depth measurement and adjusted it upwards, which was supposed to represent what the total would have been had it been measured every 6 hours. After several revisions, they settled on a total of 25 inches for 2/5-6/2010, revised up from the initial snow depth measurement of 24.7. Of course they never explained their methodology for how they came up with that number though. Also that year they went back and revised 2/2-3/2010, 1/30/2010, and 12/18-19/2009. The Dec. '09 one hurt the most as they went from 21.1 inches down to 18, which took away our snowiest Dec. ever record. I had a problem with these revisions as they all ended up being nice, tidy whole numbers, which makes me think they were just guessing rather than applying some derived formula.

 

There was talk of revising other previous big storms between 1998- Feb. 2010 but it never happened. To be fair, I do think some storms during that time period had measurements that seemed too high (like Feb. 11-12, 2006), but I do think the 09/10 storms were adjusted too low.

 

This is an old article that mentions some of it: http://weblogs.marylandweather.com/2010/02/no_snow_total_for_bwi.html

 

 

This is something I've seen them do a lot too starting with the 10/11 winter- most of the time the revisions are small (for example, they revised 1/26/11 down from 7.8 to 7.6 inches) but in the case of Feb. 12-13, 2014, its was relatively larger. I don't remember the exact total but it was initially over 13 inches, and the final total now is 11.5 inches.

 

 

Maybe they read this thread and saw us all complaining. :-) This happened because I speculated on a Dec. shutout- you all can thank me later.

 

I believe BWI recorded 13" in February 2006... it seems reasonable to me and I don't think it was too high, especially since there were suburbs not too far away in Howard county that received over 20". 

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I believe BWI recorded 13" in February 2006... it seems reasonable to me and I don't think it was too high, especially since there were suburbs not too far away in Howard county that received over 20". 

my recollection of that event was that I had no complaints with their measurement

but it was already melting before the last flakes stopped falling thanks to the warm ground       lol

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I believe BWI recorded 13" in February 2006... it seems reasonable to me and I don't think it was too high, especially since there were suburbs not too far away in Howard county that received over 20". 

 

13.1 to be exact... but it always seemed too high to me.  It could be like mitchnick said though- it melted so fast by the time it was over the total may have already been lower. But comparing Howard County to Glen Burnie is apples to oranges. They got about 38 inches from 2/5-6/10? They're always much higher.

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Updated:  

 

000

NOUS41 KLWX 121536
PNSLWX
DCZ001-MDZ003>007-009>011-013-014-016>018-501-502-VAZ025>031-
036>040-042-050>057-501>504-WVZ050>053-055-501>506-130336-

PUBLIC INFORMATION STATEMENT
SPOTTER REPORTS
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1036 AM EST FRI DEC 12 2014

THE FOLLOWING ARE UNOFFICIAL OBSERVATIONS TAKEN DURING THE PAST 24
HOURS FOR THE STORM THAT HAS BEEN AFFECTING OUR REGION. APPRECIATION
IS EXTENDED TO HIGHWAY DEPARTMENTS...COOPERATIVE OBSERVERS...SKYWARN
SPOTTERS AND MEDIA FOR THESE REPORTS. THIS SUMMARY IS ALSO AVAILABLE
ON OUR HOME PAGE AT WEATHER.GOV/BALTIMORE

********************STORM TOTAL SNOWFALL********************

LOCATION STORM TOTAL TIME/DATE COMMENTS
SNOWFALL OF
/INCHES/ MEASUREMENT

MARYLAND

...ANNE ARUNDEL COUNTY...
2 NNE FORT MEADE 0.5 500 AM 12/12 COCORAHS
1 WSW ODENTON 0.4 700 AM 12/12 COCORAHS
3 E LAUREL 0.2 700 AM 12/12 COCORAHS
2 SE DAVIDSONVILLE 0.2 700 AM 12/12 COCORAHS
BWI AIRPORT 0.2 700 PM 12/11 AIRPORT

...BALTIMORE COUNTY...
1 NNE UPPER FALLS 1.0 700 AM 12/12 COCORAHS
2 NW LONG GREEN 0.2 730 PM 12/11 TRAINED SPOTTER

...BALTIMORE CITY...
1 N HAMILTON 0.5 600 AM 12/12 COCORAHS
PIMLICO 0.2 701 PM 12/11 PUBLIC
1 NE PIMLICO 0.2 700 AM 12/12 COCORAHS

...CARROLL COUNTY...
1 SE ELDERSBURG 0.3 700 AM 12/12 COCORAHS
3 NNW GAITHER 0.2 700 AM 12/12 COCORAHS
3 WSW LINEBORO 0.1 550 PM 12/11 TRAINED SPOTTER

...HARFORD COUNTY...
PLEASANT HILLS 1.0 700 AM 12/12 COCORAHS
2 E NORRISVILLE 0.7 800 AM 12/12 TRAINED SPOTTER
BEL AIR 0.4 1249 PM 12/11 PUBLIC

...HOWARD COUNTY...
2 W ELKRIDGE 0.2 700 AM 12/12 COCORAHS
1 SSE SIMPSONVILLE 0.2 130 PM 12/11 TRAINED SPOTTER
2 N COLUMBIA 0.2 700 AM 12/12 COCORAHS
2 N COLUMBIA 0.2 1245 PM 12/11 TRAINED SPOTTER
2 SE GAITHER 0.2 700 AM 12/12 COCORAHS

...PRINCE GEORGES COUNTY...
1 E BOWIE 0.1 700 AM 12/12 COCORAHS

VIRGINIA

...ARLINGTON COUNTY...
REAGAN NATIONAL AIRP T 700 PM 12/11 AIRPORT

$

JACKSON

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