Alright, TON of uncertainty leading up to the severe weather Thursday-Sunday...
Starting with Saturday a very strong jet will be located over the southern plains with an impressive 120 knot jet. When looking long range, a good indicator for severe weather, as I have noticed for the past couple of years is where the winds change direction coming out of the trough. This has little proof, but holds some merit, blow in the highlighted region is where this wind shift occurs. Often times this is where the upper level support is maximized with upward vertical motion through the jet axis due to the 4 quadrant jet model and curvature.
The GFS has sped up the entire pattern, which has decreased my confidence. The biggest question mark and least confidence I have is how far north the 60+ surface dewpoints reach. As was the case this past week the models way over did the surface dew points resulting in mostly a hail and wind show. Below are the sfc dew points valid at 0z Sun.
...and Sunday
Again, this is all based on the 12z run, I would expect the pattern to lag behind what is currently shown by the GFS and influenced where I put out Day 4 and 5 "Go Zones". The models will probably show little consistency and all this analysis will blow up in my face!!!
And a little humor with a NWS fail...
Croix we should talk about that NWS post from Denver. I was there on Sunday and it was 71 degrees at my dads house around 9am and then the temperature dropped with the cold front to below freezing not too long after leaving around 1:00pm. While that looks wrong and utterly stupid, the high was set late morning and then several inches of snow already on the ground before sunset. It goes to show that the Weather in Denver is absolutely nuts and its one of the toughest places to forecast for anywhere in the country.
ReplyDeleteWhile I agree with you Dan, at the same time, notice how the forecast is for "This Afternoon." So if the high occurred at 9am, shouldn't they still adjust the afternoon temperature then?
ReplyDeleteIn short yes, but they don't write those point forecasts. They are generated by the GFE software and it doesn't deal well with certain situations like this. I've asked my fellow employees about this kind of thing before and now that I've been here I've been able to see how these point forecasts get generated. You guys are right in the fact that someone should have just manually adjusted to cover for this situation, but at the NWS WFOs that's not considered baseline. At set times they go into GFE and manipulate gridded data, then forecasts get generated by software and info gets pushed to the web page. In case you were wondering and because our main active NWS forecaster Author...ahem....ahem....doesnt seem to comment in here. He probably would have a much more eloquent answer to this.
ReplyDeleteoh and here is another link to some of the ECMWF output from Penn State: If you combine this with what you get from College of Dupage you can get the gist of what the model is going for
ReplyDeletehttp://www.meteo.psu.edu/~gadomski/ewall.html
ECMWF data can be found on left side under model extras. At least its some more data
You are correct Dan, its how the data is generated that, at times, makes the NWS look incorrect. Paging Jake, where are you Jake???
ReplyDeleteHere is another source for ECMWF,direct from their webpage.
http://www.ecmwf.int/products/forecasts/d/charts/medium/deterministic/msl_uv850_z500!Geopotential%20500%20hPa%20and%20Temperature%20at%20850%20hPa!240!North%20America!pop!od!oper!public_plots!2011030612!!/
Also, if the short term forecaster had the afternoon trends correct for temperatures, it should of still accurately displayed an "afternoon high" with falling temps. I was shown this at MKE, cause I asked the exact question, how do you deal with falling temperatures post cold front.
ReplyDelete