Deck Pic Posted February 17, 2015 Share Posted February 17, 2015 DC has a pretty legit shot at the Friday record min which is a really old one.. 8 in 1896. DC does ok in an airmass situation, but in a clear snowcover driven radational situation UHI will hurt it...I spoke with OrhWxman about the -16/-18 at IAD in 1984...ORH under the same air mass had nothing close to that....IAD is in a perfect radiational bowl...which now has been mitigated by UHI...I have 4" on the ground, but the streets are plowed, the sidewalks are shoveled, and the sides of the buildings don't have snow on them...How the hell is UHI going to be offset by snow on the grass and piles of snow on the sides of the street... Link to comment Share on other sites More sharing options...
WVclimo Posted February 17, 2015 Share Posted February 17, 2015 I like looking at MRB because it has a fairly long period of record, 89 years, and hasn't been as impacted by UHI as the major airports. But it's not a good comp to DC and Baltimore, because it doesn't have records from the cold period of the late 1800's. Most of its weighting for daily record lows is skewed toward the 1960's for obvious reasons. Looking at pre- and post 1970, which is roughly the mid-point of the 89 years, 135 record lows are from after 1970, while 231 are pre-1970. Link to comment Share on other sites More sharing options...
J.Mike Posted February 17, 2015 Share Posted February 17, 2015 For those of your with yards outside the beltway, there will be tremendous damage to broadleaf evergreens, hydrangeas, figs, and other deciduous plants. Link to comment Share on other sites More sharing options...
Ian Posted February 17, 2015 Share Posted February 17, 2015 DC does ok in an airmass situation, but in a clear snowcover driven radational situation UHI will hurt it...I spoke with OrhWxman about the -16/-18 at IAD in 1984...ORH under the same air mass had nothing close to that....IAD is in a perfect radiational bowl...which now has been mitigated by UHI...I have 4" on the ground, but the streets are plowed, the sidewalks are shoveled, and the sides of the buildings don't have snow on them...How the hell is UHI going to be offset by snow on the grass and piles of snow on the sides of the street... Yes that's all true. Tho the air mass is at least as good as the last if not a smidge colder it appears. Snow can't hurt. I think winds probably stay up thru Thursday night as well.. maybe not ripping but moving. MEX is 10... the raw numbers are probably too cold all close to 0 on either side.. def more possible west. I'd probably go about 7 for now. Link to comment Share on other sites More sharing options...
MN Transplant Posted February 18, 2015 Share Posted February 18, 2015 Minneapolis is also a bad UHI spot. Only 2 winter low records since 1983, both in '96. Link to comment Share on other sites More sharing options...
AvantHiatus Posted February 18, 2015 Share Posted February 18, 2015 Minneapolis is also a bad UHI spot. Only 2 winter low records since 1983, both in '96. It's 50/50 UHI and AGW, come on now. Link to comment Share on other sites More sharing options...
StudentOfClimatology Posted February 18, 2015 Share Posted February 18, 2015 It's 50/50 UHI and AGW, come on now. It's predominantly UHI. You're talking about an ~ 1.5F shift in the observed temperature baseline due to climate change over the measurement period. That's not nearly enough to account for the observed disparities. Link to comment Share on other sites More sharing options...
RodneyS Posted February 18, 2015 Share Posted February 18, 2015 ^lol I do wonder on the old v new location I kinda doubt the old is much if any colder now. These issues are everywhere. Yes, but one thing that seems puzzling is the recent shift toward a greater DCA/IAD daily temperature differential after a narrowing of that differential from the second decade to the fifth decade of IAD's existence. Here is the average daily differential that DCA has been warmer than IAD, decade by decade: 1963-72: 3.6 degrees; 1973-82: 4.7 degrees; 1983-92: 3.5 degrees; 1993-2002: 3.4 degrees; 2003-12: 2.6 degrees However, the daily temperature differential increased to 3.4 degrees in 2013 and to 5.4 degrees last year. An aberration, or is there a logical reason for that increase? Link to comment Share on other sites More sharing options...
mitchnick Posted February 18, 2015 Share Posted February 18, 2015 0Z NAM just knocked another degree off at BWI for Friday 7AM dropping it to -4F ouch G&E bill Link to comment Share on other sites More sharing options...
dailylurker Posted February 18, 2015 Share Posted February 18, 2015 0Z NAM just knocked another degree off at BWI for Friday 7AM dropping it to -4F ouch G&E billSome serious ice out there on the lakes and bay/backwater. By Friday I would think the lakes will be safe to go on. I'm sure I'll end up on one. Link to comment Share on other sites More sharing options...
Bob Chill Posted February 18, 2015 Share Posted February 18, 2015 Some serious ice out there on the lakes and bay/backwater. By Friday I would think the lakes will be safe to go on. I'm sure I'll end up on one. My local skating pond is 3" thick. I checked it out this evening. Nobody has broomed it yet. Lazy kids nowadays. lol Link to comment Share on other sites More sharing options...
WEATHER53 Posted February 18, 2015 Share Posted February 18, 2015 I consider it to be factually impossible that with 95% snow coverage of everything-ground, lots, roofs, sidewalks; that with the Potomac and Chesapeake bay at 32, that an observation station located on a sliver of parkland, can run 5-10 degrees warmer that it's surrounds. Now, put the measurement devices inside of a masonry compound on top of a roof(or in Times Square) and that might be a different matter, out on a solid frozen tarmack=IMPOSSIBLE. Link to comment Share on other sites More sharing options...
Ellinwood Posted February 18, 2015 Share Posted February 18, 2015 Let's be a bit more realistic here... DCA typically runs 2-5 degrees warmer on a given night when there's discrepancies between it and nearby stations (I'm talking other "urban" sites in and around DC, no just comparing to IAD and BWI). Link to comment Share on other sites More sharing options...
Deck Pic Posted February 18, 2015 Share Posted February 18, 2015 I consider it to be factually impossible that with 95% snow coverage of everything-ground, lots, roofs, sidewalks; that with the Potomac and Chesapeake bay at 32, that an observation station located on a sliver of parkland, can run 5-10 degrees warmer that it's surrounds. Now, put the measurement devices inside of a masonry compound on top of a roof(or in Times Square) and that might be a different matter, out on a solid frozen tarmack=IMPOSSIBLE. we know you do...but you're wrong...not sure where you get 95% coverage anyway...I'm looking outside the window of my 14 story heated building and all the streets and sidewalks are clear...just piles on the sides......let us know when IAD hits -18 and -16 on back to back nights again...it will never ever happen...On a random radiational night in 1984, IAD gets colder than Boston has ever gotten on record dating back to 1872. Link to comment Share on other sites More sharing options...
snowfan Posted February 18, 2015 Share Posted February 18, 2015 Some serious ice out there on the lakes and bay/backwater. By Friday I would think the lakes will be safe to go on. I'm sure I'll end up on one. Yeah, this was the bay earlier today from Terrapin Park. Lots of ice from the bridge north. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 18, 2015 Share Posted February 18, 2015 Let's be a bit more realistic here... DCA typically runs 2-5 degrees warmer on a given night when there's discrepancies between it and nearby stations (I'm talking other "urban" sites in and around DC, no just comparing to IAD and BWI). we've been down this road before...I'm not sure why I get baited lol...facts are absolutely irrelevant to Tenman...I have fact checked him and proven him wrong dozens of times and it doesn't matter to him...I know I am right though... Link to comment Share on other sites More sharing options...
Deck Pic Posted February 18, 2015 Share Posted February 18, 2015 Created before last yr which had two but yeah.. proof positive that Tennman is wrong..we've had massive storms and cold outbreaks in the last 20 years Link to comment Share on other sites More sharing options...
Ian Posted February 18, 2015 Share Posted February 18, 2015 Let's be a bit more realistic here... DCA typically runs 2-5 degrees warmer on a given night when there's discrepancies between it and nearby stations (I'm talking other "urban" sites in and around DC, no just comparing to IAD and BWI).It usually seems in line more or less tho it is in about the worst spot possible. Some of the wxbugs in the city like Nats Park appear to run cool. Link to comment Share on other sites More sharing options...
dailylurker Posted February 18, 2015 Share Posted February 18, 2015 Yeah, this was the bay earlier today from Terrapin Park. Lots of ice from the bridge north. Very nice. I'm planning on going there on Friday for sunset. I got some beautiful shots of the South River today at sunset. I'm thinking I'll be able to walk out onto the bay where the water is very shallow along the shore there. *Disclaimer* do not walk on bay unless your sure the water is very shallow. Link to comment Share on other sites More sharing options...
WEATHER53 Posted February 18, 2015 Share Posted February 18, 2015 I have some good quality Taylor liquid bulbs. Doing an experiment. I have put the Taylor flush up against a single pane window in my basement. This is an old, wooden, double hung, single pane. Not energy efficient. The window is located on the south side of the house so the bricks that surround the window do have a change to absorb any sun warmth that might occur. At the 8:50ish obs DCA was 25, my heat induced Taylor liquid bulb 19.5. DCA got more snow than me and still has it. The Potomac is all but frozen, and as usual Annapolis is not having the same issue. In my advancing age I am actually going back to being less trusting of government. People get in place, dont want to make any waves, or they have an agenda. My other two Taylors properly located for accurate temperature measurements were reading 14 and 14.7 at 8;50 I am not going to talk about this for quite a while now. There is no more to be said. A fellow who I have no knowledge of but sure seemed like a statistical expert to me stated here a while back that DCA should not be used, and would not, in valid statistical work. He said, and I am paraphrasing, that it's numbers were not supportable by the other numbers of the other stations and the homogeny of those stations is valid and the stand alone of DCA is not. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 18, 2015 Share Posted February 18, 2015 I have some good quality Taylor liquid bulbs. Doing an experiment. I have put the Taylor flush up against a single pane window in my basement. This is an old, wooden, double hung, single pane. Not energy efficient. The window is located on the south side of the house so the bricks that surround the window do have a change to absorb any sun warmth that might occur. At the 8:50ish obs DCA was 25, my heat induced Taylor liquid bulb 19.5. DCA got more snow than me and still has it. The Potomac is all but frozen, and as usual Annapolis is not having the same issue. In my advancing age I am actually going back to being less trusting of government. People get in place, dont want to make any waves, or they have an agenda. My other two Taylors properly located for accurate temperature measurements were reading 14 and 14.7 at 8;50 I am not going to talk about this for quite a while now. There is no more to be said. A fellow who I have no knowledge of but sure seemed like a statistical expert to me stated here a while back that DCA should not be used, and would not, in valid statistical work. He said, and I am paraphrasing, that it's numbers were not supportable by the other numbers of the other stations and the homogeny of those stations is valid and the stand alone of DCA is not. DCA is a bad place to record data...perhaps even a little wonky at times...but UHI is not going to be completely mitigated when the number one contributor to UHI - asphalt - is plowed....anyway...Annapolis is currently 20 and DCA is 22..not sure why you just make stuff up....it doesn't help you Link to comment Share on other sites More sharing options...
Ellinwood Posted February 18, 2015 Share Posted February 18, 2015 It usually seems in line more or less tho it is in about the worst spot possible. Some of the wxbugs in the city like Nats Park appear to run cool. Yeah, the Nats stadium is sited at an elevated spot, but we have ways of calibrating sites to adjust to 2mt. Not perfect, but it's fine most of the time. DCA can be in-line with other stations at any given time (like at this exact moment), but during periods where it should be colder, it's often an average of 3F warmer than the surrounding wxbug sites (like, all of them). It would be one thing if it was just compared to one or two sites that aren't cited right at 2m, but it's literally all of them. Take this morning's lows for example... As for official sites... you've got Andrews (KADW) running at 12 and College Park (KCGS) at 16 for the lows, while DCA was 17. I've been casually observing this phenomenon on a semi-regular basis since late last summer, and it is a fairly consistent issue in the overnight hours when steady cooling is occurring in addition to the actual low. I'm not here to call DCA out and say it's measurements are wrong, but I did want to provide some objective data that shows that DCA does have a tendency to run warm in certain situations. Link to comment Share on other sites More sharing options...
RIC Airport Posted February 18, 2015 Share Posted February 18, 2015 Local TV station going with -5F for Richmond. If that happens, it will be the first subzero temperature since January 2000 and coldest temperature since January 1985. Also look to shatter some record lows and record low maximum several days in a row. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 18, 2015 Share Posted February 18, 2015 Yeah, the Nats stadium is sited at an elevated spot, but we have ways of calibrating sites to adjust to 2mt. Not perfect, but it's fine most of the time. DCA can be in-line with other stations at any given time (like at this exact moment), but during periods where it should be colder, it's often an average of 3F warmer than the surrounding wxbug sites (like, all of them). It would be one thing if it was just compared to one or two sites that aren't cited right at 2m, but it's literally all of them. Take this morning's lows for example... 20150217_DClows.PNG As for official sites... you've got Andrews (KADW) running at 12 and College Park (KCGS) at 16 for the lows, while DCA was 17. I've been casually observing this phenomenon on a semi-regular basis since late last summer, and it is a fairly consistent issue in the overnight hours when steady cooling is occurring in addition to the actual low. I'm not here to call DCA out and say it's measurements are wrong, but I did want to provide some objective data that shows that DCA does have a tendency to run warm in certain situations. not doubting you about DCA...it is a weird animal...but wxbugs in the city can tend to run too cold...I usually tack on a degree to pepco during a storm, because it clearly is too cold sometimes...last night when I gave my obs, I went a degree higher than pepco....the 12 at Children's hospital is cute....right now pepco is 25, and Andrews is 8 which is a huge outlier...I realize there are localized areas that radiate well so temps will be weird....the 25 at pepco actually makes sense to me...all the streets are plowed..other wxbugs are in the low 20s Link to comment Share on other sites More sharing options...
yoda Posted February 18, 2015 Share Posted February 18, 2015 12z GFS has -25c 850s (hr 42 for DCA) Thursday night Link to comment Share on other sites More sharing options...
LongRanger Posted February 18, 2015 Share Posted February 18, 2015 contest-worthy cold? Link to comment Share on other sites More sharing options...
BristowWx Posted February 18, 2015 Share Posted February 18, 2015 12z GFS has -25c 850s (hr 42 for DCA) Thursday night And yet we will still manage rain only couple days later....I still am surprised sometimes how bad we are at winter Link to comment Share on other sites More sharing options...
Ian Posted February 18, 2015 Share Posted February 18, 2015 Lows this morning from Weatherbug/Mark.. yeah DCA is totally not representative. Link to comment Share on other sites More sharing options...
MN Transplant Posted February 18, 2015 Share Posted February 18, 2015 Lows this morning from Weatherbug/Mark.. yeah DCA is totally not representative. It jumped 18 degrees in an hour this morning at Andrews. I think they may have dug that station into a iron ore pit. Link to comment Share on other sites More sharing options...
clueless Posted February 18, 2015 Share Posted February 18, 2015 There was a three degree difference for lows at two different wxbugs in the Burg. Not very fear from each other. The one to the north and west was at 6 while the other was at 3. I was surprised. Normally it's the other way around. I just need to get my own station. Link to comment Share on other sites More sharing options...
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