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The March 25-March 32 HECS potential


Ji

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they are being overly cautious based on the march 6th bust and the backlash......

 

not sure there are any new reasons today to raise it. in this situation no real reason to go big yet. there may be a greater than 2 in 10 shot of .1"+ .. but most people don't take the digit as defined. not sure it's really totally useful with that current definition anyway.

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not sure there are any new reasons today to raise it. in this situation no real reason to go big yet. there may be a greater than 2 in 10 shot of .1"+ .. but most people don't take the digit as defined. not sure it's really totally useful with that current definition anyway.

Is that what 2 means?

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lol...no

 

it wont be in range until 2:15-2:30.....go to bed...you can see the 0.35" and warm BL when you wake up

Lol it's a sickness even though I have to be up at 6:30 in the morning, I am dying to see if it goes the way of the other globals tonight. Hopefully either Ian or Bob will be up then.

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Jason has been spooked by march 6th a bit I think....it's too bad since the detractors are some of the stupidest people on earth....

 

If they are going to use the SPI as defined it should be a 4 at a minimum and probably a 5 or 6.....if they think the SPI is going to be misconstrued then just dont use it

even earlier in the year i gave a 9 on a day where every airport got accum and people were all freaking out it was a 9. so.. im not sure it's the greatest scale ever.

 

but camden went with a two.. he asked about it. based on jason's post earlier with wes' comments.. didn't see a need to up it based on anything new (which is all arguably worse than earlier runs despite QPF or snowmaps) so i left it.

 

but if you were just giving probability straight up, your odds are seemingly fine.

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If the CWG isn't sticking to the original definition of the SPI, I think they should redefine it, then. It's really confusing people who actually know what it means.

 

The WPC has about an 80% chance of 2" or more for DC, by the way (though I think they rely too heavily on the GFS/NAM). Also, it probably doesn't take the 6z into account as it was issued at around 2 am.

http://www.hpc.ncep.noaa.gov/pwpf_48hr/prb_48hsnow_ge02_2013032212f072_sm.gif

 

prb_48hsnow_ge02_2013032212f072_sm.gif

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If the CWG isn't sticking to the original definition of the SPI, I think they should redefine it, then. It's really confusing people who actually know what it means.

The WPC has about an 80% chance of 2" or more for DC, by the way (though I think they rely too heavily on the GFS/NAM). Also, it probably doesn't take the 6z into account as it was issued at around 2 am.

http://www.hpc.ncep.noaa.gov/pwpf_48hr/prb_48hsnow_ge02_2013032212f072_sm.gif

prb_48hsnow_ge02_2013032212f072_sm.gif

I don't place any faith on those maps, but I do give credence to the forecaster maps. They were issued after the Euro and are pretty bullish.

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They had nothing for Richmond, either. And areas down there got a few inches... just saying.

I'll take the bet if you think they will be wrong on this event

you guys had the 5H low right over you, a meso feature that a global will rarely see

iow, you got lucky because the Wunderground Euro snow maps have been more right than wrong thru the season

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If the CWG isn't sticking to the original definition of the SPI, I think they should redefine it, then. It's really confusing people who actually know what it means.

The WPC has about an 80% chance of 2" or more for DC, by the way (though I think they rely too heavily on the GFS/NAM). Also, it probably doesn't take the 6z into account as it was issued at around 2 am.

http://www.hpc.ncep.noaa.gov/pwpf_48hr/prb_48hsnow_ge02_2013032212f072_sm.gif

prb_48hsnow_ge02_2013032212f072_sm.gif

These probabilities are 3/4 SREF weighted, and are auto generated once the WWD forecaster sends his deterministic guidance out to the field internally (WFOs and RFCs).

http://www.wpc.ncep.noaa.gov/pwpf/about_pwpf_products.shtml

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These probabilities are 3/4 SREF weighted, and are auto generated once the WWD forecaster sends his deterministic guidance out to the field internally (WFOs and RFCs).

http://www.wpc.ncep.noaa.gov/pwpf/about_pwpf_products.shtml

 

Brian,

 

My own perception is that more often then not, the product has the probabilities too high for the various thresholds. I'm not sure my perceptions are true or not.   Has Keith verified them so users can check to see how well they are  calibrated?  Wes

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Hi Wes,

Yes, they have verified with a high bias over the years, but the perception is they will probably show better verification after this season given all the big events (particularly in the NE). I think overall they suffer more in the marginal events, given 1) the NAM's tendency (and thus the NMB members that make up 1/3 of the SREF) to be too wet into the cold air, and 2) when there are boundary layer concerns. Ironically, the WPC final 10/40/70% probabilities historically have shown little if any improvement over these prelim ones. Often times we see a 50% threshold and while that seems high, it would also indicate that 5/10 or 50/100 of such events would not verify statistically.

We have learned quite a bit over the past couple weeks via post analyses and collaboration with EMC in terms of the model's calculation of snowfall. It's actually kind of scary, honestly, during marginal BL events. I actually had an opportunity to present our (WPC's) perspective of the 3/6 event at EMC's weekly MEG meeting yesterday, highlighting these very issues. There are events as we've discovered on March 6th that there is a huge difference in marginal BL conditions between snow "fall" and the actual snow "depth". The models struggle with this...or as I should say (and concluded after the 3/6 storm)...WE as forecasters struggle sometimes with interpretating and differentiating between the various model snow accumulation output via various algorithms and techniques when the SFC and BL temps are so marginal. It's as if some of these maps represent snow that "would have" accumulated had the BL been sufficiently cold. The 'ol snow that melts once it falls dilemma.

We have seen much success with some of the experimental percent of frozen precip and rime-filtered SLR output from the NAM this past season. Again though, it's still the NAM, so if the NAM is too cold, then even these products will struggle as on 3/6. At least it can raise some red flags though when the BL is marginal, and/or when there is an elevated warm layer. Hopefully next year we can get this into the GFS, but right now it only works with Ferrier microphysics (i.e. NAM).

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Ohv transfers are bad. Bad for models. Bad for weenie nerves. And bad for dc snow. I'll stick with 1-3 for 95 West but now with daytime snow, elevation has gained a big upper hand. This doesn't include my yard.

Models are far from done. It can still go either way. History of events like this + calendar spring means the wrong way is favored.

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