MN Transplant Posted September 2, 2015 Share Posted September 2, 2015 famartin - does LWX keep long-term records of the min/max at the office? That would be an easy tell whether IAD has wavered over the past couple of years or whether it is all meteorological. Link to comment Share on other sites More sharing options...
MN Transplant Posted September 2, 2015 Share Posted September 2, 2015 I do think a fair amount of it is just the pattern. Esp the cold winters lately. Was reading how the wind energy companies are struggling this year because of a lack of wind... Link to comment Share on other sites More sharing options...
Ian Posted September 2, 2015 Share Posted September 2, 2015 Was reading how the wind energy companies are struggling this year because of a lack of wind...Interesting haven't seen that. Good point on LWX temps. Link to comment Share on other sites More sharing options...
MN Transplant Posted September 2, 2015 Share Posted September 2, 2015 Ok, went to the Utah St climate center and downloaded the IAD temps and the Sterling coop/ghcn data. The Sterling data is in rough shape right now, but you can do a comparison after correcting for missing, bad (August 11/12th?), or days where highs may have been corrupted by time of day (early June murk). During June, IAD ran almost 0.5° higher than Sterling During July, IAD ran less than 0.1° higher During August, IAD ran lower than Sterling by a bit over 0.3° Of course, that doesn't help at all. But I did the work, so there it is. Link to comment Share on other sites More sharing options...
MN Transplant Posted September 2, 2015 Share Posted September 2, 2015 Another interesting tidbit - IAD and Sterling both have 14 90° days, but they aren't the same list. There are actually 17 days where one or the other hit 90. (not including Sept) Link to comment Share on other sites More sharing options...
Ian Posted September 2, 2015 Share Posted September 2, 2015 Ok, went to the Utah St climate center and downloaded the IAD temps and the Sterling coop/ghcn data. The Sterling data is in rough shape right now, but you can do a comparison after correcting for missing, bad (August 11/12th?), or days where highs may have been corrupted by time of day (early June murk). During June, IAD ran almost 0.5° higher than Sterling During July, IAD ran less than 0.1° higher During August, IAD ran lower than Sterling by a bit over 0.3° Of course, that doesn't help at all. But I did the work, so there it is. Is LWX right at IAD? I guess I should know that. Does seem generally close enough to be about the same. Tho do they do 12z to 12z reporting there? I guess so if it's listed as a coop. Link to comment Share on other sites More sharing options...
famartin Posted September 2, 2015 Share Posted September 2, 2015 We had some issues with our office thermometer lately. Should be fixed now I think. Link to comment Share on other sites More sharing options...
famartin Posted September 2, 2015 Share Posted September 2, 2015 Is LWX right at IAD? I guess I should know that. Does seem generally close enough to be about the same. Tho do they do 12z to 12z reporting there? I guess so if it's listed as a coop. The office is about 5 miles from the ASOS and a little lower in elevation. My house is actually closer than the office. Link to comment Share on other sites More sharing options...
Inverted_Trough Posted September 3, 2015 Author Share Posted September 3, 2015 When doing the comparisons, I'd be wary of incorporating the daily minimums for IAD and DCA. The reason I only looked at daily maximums for my comparison is because the atmosphere is better mixed in the afternoon, mitigating the impact of UHI somewhat. Daily minimums have wide variance and the difference between minimums could fluctuate greatly even month to month. In other words, it's much harder to "separate the signal from the noise" if you're comparing minimums. I don't think there's a way to quantify with any certainty what the warm bias was with the old sensor. I've believed for quite some time that DCA was reading a couple degrees too warm - based on a lot of other evidence besides the subject of this topic - but I guess there's no way to know for sure. Link to comment Share on other sites More sharing options...
RodneyS Posted September 3, 2015 Share Posted September 3, 2015 When doing the comparisons, I'd be wary of incorporating the daily minimums for IAD and DCA. The reason I only looked at daily maximums for my comparison is because the atmosphere is better mixed in the afternoon, mitigating the impact of UHI somewhat. Daily minimums have wide variance and the difference between minimums could fluctuate greatly even month to month. In other words, it's much harder to "separate the signal from the noise" if you're comparing minimums. I don't think there's a way to quantify with any certainty what the warm bias was with the old sensor. I've believed for quite some time that DCA was reading a couple degrees too warm - based on a lot of other evidence besides the subject of this topic - but I guess there's no way to know for sure. Even comparing only daily DCA/IAD maximum temperatures, there have been significant historical month-to-month fluctuations with respect to differentials. For example, in June 1976 the daily maximum DCA/IAD differential averaged 5.00 degrees, but it fell to 3.48 degrees in July 1976 and only 1.06 degrees in August 1976. Of course, in view of analyses questioning the reliability of both the DCA and IAD sensors in recent months, one might now ask: Did they change both sensors in mid-July of that year? Link to comment Share on other sites More sharing options...
famartin Posted September 3, 2015 Share Posted September 3, 2015 Even comparing only daily DCA/IAD maximum temperatures, there have been significant historical month-to-month fluctuations with respect to differentials. For example, in June 1976 the daily maximum DCA/IAD differential averaged 5.00 degrees, but it fell to 3.48 degrees in July 1976 and only 1.06 degrees in August 1976. Of course, in view of analyses questioning the reliability of both the DCA and IAD sensors in recent months, one might now ask: Did they change both sensors in mid-July of that year? There was a paper from the 80s regarding problems with the DCA thermometer around that time. I think it was linked from a blog that was linked from the original CWG article on the recent discrepancies. Link to comment Share on other sites More sharing options...
WEATHER53 Posted September 4, 2015 Share Posted September 4, 2015 Its been nice to see DCA highs tempered lower by the correction. Still warmer than IAD and BWI as it should be. This recent streak DCA and surrounds have been couple degrees apart but not the 4/5/6 that had become commonplace. This fall and winter when we radiate out nice let's see what happens. Link to comment Share on other sites More sharing options...
famartin Posted September 4, 2015 Share Posted September 4, 2015 Its been nice to see DCA highs tempered lower by the correction. Still warmer than IAD and BWI as it should be. This recent streak DCA and surrounds have been couple degrees apart but not the 4/5/6 that had become commonplace. This fall and winter when we radiate out nice let's see what happens. You don't need to wait. There have already been some strong radiational nights where the difference was over 10 degrees in August, after the sensor was replaced. Which is to be expected. Link to comment Share on other sites More sharing options...
GramaxRefugee Posted September 4, 2015 Share Posted September 4, 2015 There was a paper from the 80s regarding problems with the DCA thermometer around that time. I think it was linked from a blog that was linked from the original CWG article on the recent discrepancies.I apologize if it's already posted, but I didn't notice, so.... http://www.nwas.org/digest/papers/1986/Vol11-Issue3-Aug1986/Pg18-Andrews.pdf Don't know if this is the paper, but I've read it a few times and often thought of TenMan J. when I did. Link to comment Share on other sites More sharing options...
WEATHER53 Posted September 4, 2015 Share Posted September 4, 2015 You don't need to wait. There have already been some strong radiational nights where the difference was over 10 degrees in August, after the sensor was replaced. Which is to be expected. How does a 15'x15 measure by station area achieve such a warming factor? How would that occur in total snow cover for the region. If you went 200 feet from the site in any direction I bet the vales would be 5 degrees cooler on a strong radiating at night. Back in the late 70's when airport security was vastly different Stanley R did exactly that and found a difference of -4 average on the three thermometers that he set up Vindication is sweet and if I am still a nut then so is the Post and several state climatologists and mets. Lot of pushback on getting this done and got a feeling that more will be revealed Link to comment Share on other sites More sharing options...
Ian Posted September 4, 2015 Share Posted September 4, 2015 http://bfy.tw/1dgM Link to comment Share on other sites More sharing options...
famartin Posted September 4, 2015 Share Posted September 4, 2015 How does a 15'x15 measure by station area achieve such a warming factor? How would that occur in total snow cover for the region. If you went 200 feet from the site in any direction I bet the vales would be 5 degrees cooler on a strong radiating at night. Back in the late 70's when airport security was vastly different Stanley R did exactly that and found a difference of -4 average on the three thermometers that he set up Vindication is sweet and if I am still a nut then so is the Post and several state climatologists and mets. Lot of pushback on getting this done and got a feeling that more will be revealed Ummm... What? Link to comment Share on other sites More sharing options...
RodneyS Posted September 5, 2015 Share Posted September 5, 2015 I apologize if it's already posted, but I didn't notice, so.... http://www.nwas.org/digest/papers/1986/Vol11-Issue3-Aug1986/Pg18-Andrews.pdf Don't know if this is the paper, but I've read it a few times and often thought of TenMan J. when I did. Thanks for posting -- very interesting article, which again points to the need for a second sensor at official NWS stations. I note however, that the Summer 1976 DCA temperature numbers were not called into question. So, if the IAD sensor was also accurate during that season, it would seem that the DCA/IAD average daily maximum differential may have truly fallen from 5.00 degrees in June 1976 to 1.06 degrees in August 1976. Link to comment Share on other sites More sharing options...
AvantHiatus Posted September 5, 2015 Share Posted September 5, 2015 http://bfy.tw/1dgM http://bfy.tw/1ePX Link to comment Share on other sites More sharing options...
CAPE Posted September 5, 2015 Share Posted September 5, 2015 http://bfy.tw/1dgM Seems he does not want to acknowledge that there is really no mystery here. UHI in DC often results in dramatic contrasts in temps between the city itself and close by outying areas. This is not a seasonal thing. And I really doubt the sensor itself or the measuring circuit was the cause of any significant errors. Link to comment Share on other sites More sharing options...
WEATHER53 Posted September 5, 2015 Share Posted September 5, 2015 Seems he does not want to acknowledge that there is really no mystery here. UHI in DC often results in dramatic contrasts in temps between the city itself and close by outying areas. This is not a seasonal thing. And I really doubt the sensor itself or the measuring circuit was the cause of any significant errors. And you do not correctly comprehend the relationship between the atmosphere, the overall geography, and a tiny patch of ground. Were the thermometer located next to the Williard in an entire asphalt environment that would be a different matter. Other than the airport building itself DCA is surrounded by water and a parklike environment Several hundred yards to the west is extensively urbanized. There will be more changes coming it was just that the only way to get this first step done was to ease in gradually. Link to comment Share on other sites More sharing options...
AvantHiatus Posted September 5, 2015 Share Posted September 5, 2015 Elevation is king, it often remains overlooked in accounting for temperature differentials. DCA is somewhat locked in a coastal valley, there is way more to the story than UHI. It's a brutal combination of AGW heated water, asphalt, elevation, and southern location relative to IAD. Link to comment Share on other sites More sharing options...
Ian Posted September 5, 2015 Share Posted September 5, 2015 Several hundred yards isn't much. The airport is surrounded by big urbanization and the predominant wind during hot days is off the hotness a few hundred yards away. Again look at the city temps at night basically the same. Link to comment Share on other sites More sharing options...
CAPE Posted September 6, 2015 Share Posted September 6, 2015 Elevation is king, it often remains overlooked in accounting for temperature differentials. DCA is somewhat locked in a coastal valley, there is way more to the story than UHI. It's a brutal combination of AGW heated water, asphalt, elevation, and southern location relative to IAD. Its mostly UHI in this case. Tenman even complained about Annapolis temps during good radiating nights in winter being significantly colder than DC. Not King Elevation in that case. And not a faulty sensor either. Link to comment Share on other sites More sharing options...
famartin Posted September 6, 2015 Share Posted September 6, 2015 Its mostly UHI in this case. Tenman even complained about Annapolis temps during good radiating nights in winter being significantly colder than DC. Not King Elevation in that case. And not a faulty sensor either. And Annapolis is closer to the bay than DCA is to the river. Link to comment Share on other sites More sharing options...
AvantHiatus Posted September 6, 2015 Share Posted September 6, 2015 All I know is that KWWD has very similar climatology. Take it for what it's worth. Link to comment Share on other sites More sharing options...
AvantHiatus Posted September 6, 2015 Share Posted September 6, 2015 And Annapolis is closer to the bay than DCA is to the river. Does the difference vary on a seasonal basis? Figured it would be less during the winter. Link to comment Share on other sites More sharing options...
CAPE Posted September 6, 2015 Share Posted September 6, 2015 And Annapolis is closer to the bay than DCA is to the river. Exactly. But Annapolis lacks significant UHI, and also during cold periods in winter where we get good radiational cooling nights, the winds are often very light and from the NW, so the bay has less impact on temps there. Link to comment Share on other sites More sharing options...
CAPE Posted September 6, 2015 Share Posted September 6, 2015 All I know is that KWWD has very similar climatology. Take it for what it's worth. Well, you are on the same latitude, as am I. My location is at the same latitude as the very northern tip of DC. But, I am on the interior of the upper eastern shore, away from any effects from UHI, or proximity to water(unlike you). So even though I lack elevation, around 60 feet, my temps are almost always cooler than DC, as well as places like Annapolis, and Dover, and anywhere along the bay really. On cold winter mornings it is very common for temps imby to be 5 to as much as 10 degrees colder than Easton MD, where I work. And of course there is no hint of urban anything near me, other than the tar and chip road. Link to comment Share on other sites More sharing options...
WEATHER53 Posted September 6, 2015 Share Posted September 6, 2015 Its mostly UHI in this case. Tenman even complained about Annapolis temps during good radiating nights in winter being significantly colder than DC. Not King Elevation in that case. And not a faulty sensor either.Ten man did not complain about Annapolis and that sort of falsehood is what turns legitimate discussion into food fights. Get your shi$ straight. I use Annapolis as the example of why Dca proximity to water does not work because Annapolis is located due west also of a much bigger body of water. You out of area guys are clueless and Ian's comment No better as dca is 70% surrounded by water marsh and extensive tree scape. The very idea that Nothing was wrong at dca has already been squashed with more adjustments likely on the way Link to comment Share on other sites More sharing options...
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