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About isohume

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  • Birthday October 16

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  1. True, computing skills are necessary, but computers will also take over forecasting in the not too distant future. Therefore, strong comm skills will be essential in order to inform folks what the computers are saying/doing.
  2. If you're contemplating a career in the NWS, I'd take additional communication and speech classes. The NWS future is focused on Decision Support Services (DSS), meaning more embedded face-to-face, GoTo meetings, and Skype. Less emphasis is put on science and more on meeting our customer's wants and needs. I feel this is all a justification for our existence and has a lot to do with "dumbed-down" hand-holding and spectacle, but that's where things are headed and not just in the NWS.
  3. I know what you're saying, but there is never a confidence of greater than 50% in any of the periods. PoP periods are not additive. Another confusing way to look at it is: If you fcst'd a PoP of 100% covering the next 7 days during the summer, you'd most likely be correct based on climatology. However, if you fcst a 100% PoP for a specific 12-hr period, say 144 hrs out, you'd likely be wrong based on inherent uncertainty with time. You'd most likely be right in betting your car over a 5-day fcst of measurable precip during this time of year. However, extremely long fcst periods add little to no value over climo. That's why official NWS PoPs are defined by separate 12-hr periods, with higher confidence normally occurring within the first 1-3 days depending on the pattern.
  4. Nope, for the today period you'd have a 50% chance and for the tonight period a 50% chance. For the 24-hr period you'd also have a 50% chance.
  5. Your highest 12-hr PoP btw the 6am-6pm window is the PoP for today. From 6pm-6am the highest 1-hr PoP is the 12-hr PoP for tonight. Just look at the 12-hr PoPs: https://graphical.weather.gov/sectors/midatlanticWeek.php#tabs
  6. Outlooks issued --> Outlooks bust. Model chasing --> Models bust. Wishcasting --> Wishcasting busts. Winter grade --> Bust.
  7. Those grids are produced by local WFOs. Notice only a few locations have fcsts. Eventually all WFOs will be participating. Eventually. They've been saying this since 2005.
  8. That's a good procedure, but the level where temp stops cooling dry adiabatically is often not the mixing height. BL mixing often continues into the cloud layer.
  9. I've never heard of derviving maxT from mixing heights. Mixing heights are calculated from maxT. The general method is fcst maxT then lift a parcel dry adiabatiacally until it reaches the sounding temp curve. That height is your mixing height, which can be well above or below the LCL. If you really want to fcst maxT from a sounding, I suggest using an old Air Force technique listed below. (This method has seasonal variations and isn't good near a large body of water. It also doesn't account for terrain, sfc-type albedo/absob, or adv effects.) If no inversion is present between 4-6 kft above the surface: 1. From the morning sounding, find the temp at 850 mb. 2. Clear/scattered clouds: Proceed from 850 temp dry adiabatically to the surface to get maxT. 3. Broken clouds/overcast: Proceed from 850 temp moist adiabatically to the surface to get maxT. If an inversion is present between 4-6 kft above the surface: 1. Find the temperature at the warmest point (top) of the inversion. 2. From that point, proceed dry adiabatically to the surface for maxT. There are many reasons why each model has different solns, but the main reasons are what and how they parameterize various atmos variables, initialization schemes, and resolution (sigma levels). Here are some of the variables which are parameterized by the models:
  10. Ideally the uncertainty should fall out of the spread, but it can't. We're actually working on a way to normalize the uncertainty, given the base and the spread. This would then highlight areas on a map in shades of grey indicating low-high uncertainty. Doubt our customers will like it tho as they always want our deterministic "best guess".
  11. So if the NWS would have said 8" in stead of 12" at the last hr in an uncertain fcst, how would that have benefited the civic actions already in play? They did actually lower their numbers on the evening shift to 8", which accounted for no change in the the em response already decided on hours earlier. The thing they should have done, IMO, is relay their uncertainty better, which is hard to do and not necessarily heard. The NWS needs a way to quantify uncertainty where it is understood by the general public. This will be an arduous task to say the least and will take years.
  12. Independent service assessments are performed on major events warranting review, which this one likely will due to the publicity involved. Additionally, each office performs local case studies and root cause analyses for significant events and/or forecast challenges/issues. http://www.weather.gov/publications/assessments
  13. CWG is hung up on snow totals and trying to make it a big deal. Warning criteria was well met, almost doubled in NYC, and severe impacts occured. The NWS up there was correct in not downplaying the event, imo.
  14. Is this the banter thread? Just bantering along with everyone else!