Damage In Tolland Posted September 26, 2014 Share Posted September 26, 2014 Seems like a lot of conjecture and speculation. Until someone produces a study that shows that Davis wx stations over measure Dewpoints and undermeasure rainfall and are too cold on temperature calibrations.. I'll continue to know I am reporting pinpoint accurate data for my locale Link to comment Share on other sites More sharing options...
CoastalWx Posted September 26, 2014 Share Posted September 26, 2014 They don't over measure Dewpoints. The argument has been that evapotranspiration near the surface gives TDs that aren't representative. Link to comment Share on other sites More sharing options...
Zeus Posted September 26, 2014 Share Posted September 26, 2014 So now I under report rain, over report snow amounts and Dewpoints , report too low temperatures..let's see if I can come up with falsified fog reports That would be the smoke you blow up your own ass. Link to comment Share on other sites More sharing options...
CT Rain Posted September 26, 2014 Share Posted September 26, 2014 I have my Davis rain gauge and 4" CoCoRaHs gauge on the same 4x4 post in the backyard. The Davis does under report a bit compared to the 4" gauge. Maybe 3 or 4%? The other issue is that having been to Kevin's house with those giant trees around... I bet ANY gauge would underreport. You're supposed to have the gauge away from trees/obstructions at 2 times the height of any obstruction if I remember correctly. So a 70' tree would need the gauge mounted 140' away from said tree. Link to comment Share on other sites More sharing options...
powderfreak Posted September 26, 2014 Share Posted September 26, 2014 Oh Zeus, lol. An easy way to test it is to stick one of the CoCoRAHS approved stratus rain gauges next to the Davis. We've discussed it several times in the NNE thread. Ask Eek, I think he compares his Davis with a manual gauge and finds it is lower sometimes. Link to comment Share on other sites More sharing options...
powderfreak Posted September 26, 2014 Share Posted September 26, 2014 They don't over measure Dewpoints. The argument has been that evapotranspiration near the surface gives TDs that aren't representative. Yeah it's just the siting not the actual reading. It's like if you were looking for the dew point in your house, but put one instrument in the living room with a fire going in the hearth, and another instrument in the bathroom with the hot shower running. They both measure correctly what they are supposed to, it's just you can't compare them because the environment is different. Link to comment Share on other sites More sharing options...
radarman Posted September 26, 2014 Share Posted September 26, 2014 I have my Davis rain gauge and 4" CoCoRaHs gauge on the same 4x4 post in the backyard. The Davis does under report a bit compared to the 4" gauge. Maybe 3 or 4%? The other issue is that having been to Kevin's house with those giant trees around... I bet ANY gauge would underreport. You're supposed to have the gauge away from trees/obstructions at 2 times the height of any obstruction if I remember correctly. So a 70' tree would need the gauge mounted 140' away from said tree. I think it's actually half... http://www.nws.noaa.gov/om/coop/standard.htm "The height of the protection should not exceed twice its distance from the gauge" If I parse that correctly, a 70 foot tree, 35 feet from the gauge would be ok. Link to comment Share on other sites More sharing options...
CT Rain Posted September 26, 2014 Share Posted September 26, 2014 I think it's actually half... http://www.nws.noaa.gov/om/coop/standard.htm "The height of the protection should not exceed twice its distance from the gauge" If I parse that correctly, a 70 foot tree, 35 feet from the gauge would be ok. Interesting - that makes sense. Check out the CoCoRaHS training pdf... some good stuff in here. http://cocorahs.com/media/docs/CoCoRaHS_Training_8.1.pdf Info on pg 19 re: siting Link to comment Share on other sites More sharing options...
MainePhotog Posted September 26, 2014 Share Posted September 26, 2014 Oh Zeus, lol. An easy way to test it is to stick one of the CoCoRAHS approved stratus rain gauges next to the Davis. We've discussed it several times in the NNE thread. Ask Eek, I think he compares his Davis with a manual gauge and finds it is lower sometimes. Which is fine, if sited properly. If there are trees/building/obstructions too close to the guage, then it will need to be resited or the guages will continue to under report. Link to comment Share on other sites More sharing options...
radarman Posted September 26, 2014 Share Posted September 26, 2014 Interesting - that makes sense. Check out the CoCoRaHS training pdf... some good stuff in here. http://cocorahs.com/media/docs/CoCoRaHS_Training_8.1.pdf Info on pg 19 re: siting Hmmm. Definitely conflicts with the info from the coop site. Cocorahs seems to err on the side of greater distance from the obstructions. As an aside, I get a kick out of meteorology slide decks, always replete with 3-5 corny jokes.... Link to comment Share on other sites More sharing options...
CT Rain Posted September 26, 2014 Share Posted September 26, 2014 Hmmm. Definitely conflicts with the info from the coop site. Cocorahs seems to err on the side of greater distance from the obstructions. As an aside, I get a kick out of meteorology slide decks, always replete with 3-5 corny jokes.... lol of course! Link to comment Share on other sites More sharing options...
dendrite Posted September 26, 2014 Share Posted September 26, 2014 The tippers underreport with heavy rainfall and wind. Some of the liquid is lost as it "tips" during +RA. Then you have turbulent undercatch during strong winds. I calibrate mine to my cocorahs gauge as well. Link to comment Share on other sites More sharing options...
powderfreak Posted September 26, 2014 Share Posted September 26, 2014 I've always heard with measuring snow that the hole in the forest canopy needs to have a radius equal to or more than the height of the surrounding trees...I'd assume it's the same with rain. IE...you need to be 40ft away in all directions of 40ft tall trees. Link to comment Share on other sites More sharing options...
dryslot Posted September 26, 2014 Share Posted September 26, 2014 I don't even use what my tipper reports, I only use my CoCorahs gauge as it is dead nuts on and my tipper constantly under reports by at least 10%, Plus pretty tough taking a core sample of snow flipping the tipper bucket upside down.............. Link to comment Share on other sites More sharing options...
HIPPYVALLEY Posted September 26, 2014 Share Posted September 26, 2014 Stunning day. 70F in Northampton, full sun. Link to comment Share on other sites More sharing options...
Ginx snewx Posted September 26, 2014 Share Posted September 26, 2014 I've always heard with measuring snow that the hole in the forest canopy needs to have a radius equal to or more than the height of the surrounding trees...I'd assume it's the same with rain. IE...you need to be 40ft away in all directions of 40ft tall trees. does your 2500 station conform? How about the stake? from your pics seems to catch tree fall? Link to comment Share on other sites More sharing options...
radarman Posted September 26, 2014 Share Posted September 26, 2014 The tippers underreport with heavy rainfall and wind. Some of the liquid is lost as it "tips" during +RA. Then you have turbulent undercatch during strong winds. I calibrate mine to my cocorahs gauge as well. Post from you on eastern in '06... good stuff: My Davis is rarely far off from the manual 4" cans. The problem with the tipper is that the higher the rainfall rates you have the more splashover (lost rain) you will experience. This is especially true once you get into the 1.5-2"/hr rates...even if they are short lived. You can calibrate the Davis tipping bucket by slowly pouring 544mL of water into the cone. Davis I believe does this over a 45 minute span. The result should be 1.00" reported by the gauge. If you can't measure out exactly 544mL you can do what I did. I found the volume of 1" of rain for the 4" diameter can and related that to the Davis gauge. After you do the calculations, you'd find that 1" of water in the 4" diameter gauge would equal ~0.38" reported by the Davis gauge. Of course, the Davis gauge uses the weight of water for reporting while the manual gauges use the volume of water...so there may be a bit of a discrepancy there. Someone else would have to figure out the consequences of doing it this way. That said, my amounts are still pretty much in line with the manual gauge and KMHT. Link to comment Share on other sites More sharing options...
weathafella Posted September 26, 2014 Share Posted September 26, 2014 I'm enjoying the return to warmth. Never minded it prior to November. Link to comment Share on other sites More sharing options...
CT Rain Posted September 26, 2014 Share Posted September 26, 2014 Euro is a soaker on Tuesday. Link to comment Share on other sites More sharing options...
CoastalWx Posted September 26, 2014 Share Posted September 26, 2014 What a horrific 4 months this has been weather wise. Link to comment Share on other sites More sharing options...
CT Rain Posted September 26, 2014 Share Posted September 26, 2014 Euro/GFS not exactly on the same page Tuesday through Thursday next week. Link to comment Share on other sites More sharing options...
weathafella Posted September 26, 2014 Share Posted September 26, 2014 Euro is a soaker on Tuesday. We've heard this song before.... Link to comment Share on other sites More sharing options...
Damage In Tolland Posted September 26, 2014 Share Posted September 26, 2014 If Euro soaks plan on a dry day. That's like the 3rd or 4th time it's done that over the last few weeks only to have us go into drought and everything miss south Link to comment Share on other sites More sharing options...
Modfan Posted September 26, 2014 Share Posted September 26, 2014 If Euro soaks plan on a dry day. That's like the 3rd or 4th time it's done that over the last few weeks only to have us go into drought and everything miss south Time to raise the Red Flag warnings! lol Link to comment Share on other sites More sharing options...
CoastalWx Posted September 26, 2014 Share Posted September 26, 2014 I have about 15" of day 5-7 QPF this summer. Link to comment Share on other sites More sharing options...
ineedsnow Posted September 26, 2014 Share Posted September 26, 2014 Its always 5 days away have to get lucky once in awhile though. Bought a 5 dollar scratch ticket this morning and hit for 1000 so I guess anything is possible lol Link to comment Share on other sites More sharing options...
Ginx snewx Posted September 26, 2014 Share Posted September 26, 2014 the answer to the every year foliage by stress , temp weather questions. Link to comment Share on other sites More sharing options...
Ginx snewx Posted September 26, 2014 Share Posted September 26, 2014 If Euro soaks plan on a dry day. That's like the 3rd or 4th time it's done that over the last few weeks only to have us go into drought and everything miss south we enjoyed the .5 to 2 inches of rain from Storrs Ct to Woodstock to Nantucket, the we drought has a problem you are familiar with, shrinkage Link to comment Share on other sites More sharing options...
Nittany88 Posted September 26, 2014 Share Posted September 26, 2014 the answer to the every year foliage by stress , temp weather questions. Great info. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted September 26, 2014 Share Posted September 26, 2014 we enjoyed the .5 to 2 inches of rain from Storrs Ct to Woodstock to Nantucket, the we drought has a problem you are familiar with, shrinkage Storrs didn't get that much and I'm pretty sure you didn't either Link to comment Share on other sites More sharing options...
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