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WxChallenge 2013-14


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Still no response from the Gray NWS office.

Did you try Mike Ekster? He works there. I know a few others from a presentation I did there. I believe Mike is on the forums, but I'm not positive with his id. Could be Arnold219. If gray doesn't get back to you maybe you can pm him.

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Did you try Mike Ekster? He works there. I know a few others from a presentation I did there. I believe Mike is on the forums, but I'm not positive with his id. Could be Arnold219. If gray doesn't get back to you maybe you can pm him.

 

Ya, I've met Mike before. Is he at the Gray office now? I thought he was at the Taunton office before...

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Ya, I've met Mike before. Is he at the Gray office now? I thought he was at the Taunton office before...

I think he's been at the Gray office for a few years now. Don't know if he moved recently to the Taunton office if you think he did. But I just spoke to a friend still at LSC and he confirms that Mike is still working at the Gray, Maine office. 

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I think he's been at the Gray office for a few years now. Don't know if he moved recently to the Taunton office if you think he did. But I just spoke to a friend still at LSC and he confirms that Mike is still working at the Gray, Maine office. 

 

No it would have been a while ago. I think I vaguely remember hearing he was gonna move to the Gray office now that you mention it.

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Hey Max. I am a little confused how HYSPLIT is calculated.

So when doing backward trajectories for any station, you need to pick a model that goes far enough out in time if you are trying to figure out the high temperature. Then select backwards for trajectories, input the date and time for when you think the high will be reached. Also make sure the hours the trajectories run for is correct or you will get an error. Afterwards input 3 parcel heights above ground level and it means above the station so if KCON is 103m, it doesn't add 103 meters to your inputs, it starts from 0. So once you have given HYSPLIT the model input, the time input, set the trajectory to backwards, and also picked 3 parcel heights, and those parcel heights are the ending heights keep in mind, then press start and you will get a gif image. So the 3 parcel heights need to be close to what you think the boundary layer height could be or else the calculation you do won't be correct. And usually I pick 1 of the 3, but sometimes if I'm not sure what the BL will reach I do an average of all 3. It's simply taking the parcel start and end heights, taking the difference, and adding that to the approximate surface temperature at the time the trajectory is over a certain point. So for example, if the parcel started over St. Louis, MO at 500m at the start of the model run and ended up over KCON at the end of the model run at 200m. Then using the dry adiabatic lapse rate you'd need to add 3C to the surface temperature at St. Louis to approximate the KCON temperature x hours later. This method doesn't work all the time because sometimes the parcel is over a sparse data region, or its not a straight line, or even simply its not going to be clear and sunny the next day. Lots of different things make this method not an exact science, but sometimes it works. 

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So we have to pick areas other than kcon?

No. Using this page link: http://ready.arl.noaa.gov/hypub-bin/trajtype.pl you leave the default settings alone and just click next. Then on this page link: http://ready.arl.noaa.gov/hypub-bin/trajsrc.pl you select one location using any of the ways listed. I just simply use the airport code, which for kcon, is con. Also select which model you want to use using the scroll down at the top. After that just click next. This link: http://ready.arl.noaa.gov/hypub-bin/trajsrcm.pl brings you to the model run, again use the scroll down and then click next. Lastly on this page link: http://ready.arl.noaa.gov/hypub-bin/traj1.pl Make sure to select backward, and then everything else should be self explanatory. And also make sure to keep maximum # of trajectories to 3. KCON is the end point to all 3 so you don't have to pick any other locations other than KCON.  

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OK, but in reading this output isn't it the same thing from extrapolating from a sounding? What does the ending trajectory mean? Does it mean where a person can extrapolate from a sounding? What does the red, blue and green lines mean? Thanks.

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OK, but in reading this output isn't it the same thing from extrapolating from a sounding? What does the ending trajectory mean? Does it mean where a person can extrapolate from a sounding? What does the red, blue and green lines mean? Thanks.

Those are the 3 different ending parcel heights. And soundings can't tell you where parcels are coming from. The jist of the HYSPLIT is finding where air parcels are going and coming from. It's kind of like saying if x parcel was at y and then ended at z 24 hours later without changing the temperatures at y and z 24 hours apart should be exactly the same if the parcel did not change. And also if the top of boundary layer for example was at 400m and you wanted to see where a parcel that ends up at 400m came from you can using the backwards trajectory function of the HYSPLIT. Hope this clears it up a bit more for you. I gotta go now so I won't be on until probably tomorrow. A

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43/9/9/0

 

The low for tonight will be interesting...they fell 5 degrees in the last hour and are already decoupled. Although most guidance is anywhere from 12 (NAM MOS) to 13 (USL) to the mid teens (GFS MOS), to go along with most raw models struggling to drop things below 20, things should be just about perfect for a good radiational cooling night in a bit of a valley. The NWS had 9 and after much thought decided to go all in with that number. The mean for tonight is 16F so anyone who went cold may really make up some ground...at least I hope so.

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46/9/8 I strayed from consensus to try to pick up some serious ground. Definitely nervous about the low with the dew point creeping up and I tore my hair out over the high. I could see it being lower but I feel like this is similar to last Thursday where the high was about 5 degrees higher than modeled. In this case, the NAM is on my side, at least until 00z MOS. :lol:

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