Winter Weather Polygons?

[Charles L.]

This thought came to my mind yesterday. At first, I was not a big fan of the polygon warning system, but if it is used right it is a great tool and better than warning the entire county.

Question I have, have they ever thought about going polygon warning style with winter weather warnings and advisories?

I bring it up because for some of the higher elevations on the Rim and Plateau.

During a winter event, we "normally" do not see as much snow here as they do in Red Boiling Springs which is in the far eastern part of Macon County. And when they put the advisory out for say 2", it could snow 2" there while we get left with only a dusting or 1/2".

Cookeville to Monterey is another example...

The only downside to this would be that it would make it harder for forecasters because they would have to "pinpoint" where the higher totals would be in those specific counties.

Anyone else got any thoughts?

[Adam]

This thought came to my mind yesterday. At first, I was not a big fan of the polygon warning system, but if it is used right it is a great tool and better than warning the entire county.

Question I have, have they ever thought about going polygon warning style with winter weather warnings and advisories?

I bring it up because for some of the higher elevations on the Rim and Plateau.

During a winter event, we "normally" do not see as much snow here as they do in Red Boiling Springs which is in the far eastern part of Macon County. And when they put the advisory out for say 2", it could snow 2" there while we get left with only a dusting or 1/2".

Cookeville to Monterey is another example...

The only downside to this would be that it would make it harder for forecasters because they would have to "pinpoint" where the higher totals would be in those specific counties.

Anyone else got any thoughts?

That is the way it is with Lawrenceburg and Summertown, they are higher up in elevation so most of the time they get more snow.

[ST1]

MRX has broken up a few counties so that the higher elevations can be warned while the lower parts are not. For example, South East Greene County can be under a Winter Storm Warning while Northwest Greene Co. can be under an advisory, etc. Cocke county is divided into Northwest Cocke and Cocke Smoky Mountains.

[Thundersnow]

Polygon warnings only make sense for very localized events, county by county.  Usually, winter weather will affect a whole row of counties at the very least.  And, the NWS already issues advisories for groupings of counties.

I can't imagine many cases when winter weather would only affect a single county, as a severe thunderstorm would, unless that county happens to contain a much higher elevation than surrounding counties or in cases where the rain/snow line is right at the cut-off of that county, where it's on the edge of the CWA, which might create a situation where only a very small part of the CWA is affected.

This might make most sense in Lake Effect Snow counties where LES bands affect small areas downwind from the Great Lakes.  But, it would be pretty unusual around here, I would think.

[Kevin]

This would probably be pretty tough...IMO...because of the type of warnings that WSWs...and NPWs for that matter...are. They are what is referred to in the NWS as "long-fused" warnings...meaning they can be in effect for hours or even days at a time...and also are issued hours or even a day or two ahead of time...also having large areal coverage. Getting accuracy in a county-based format in these events is hard enough sometimes...putting it into a sub-county context is even more difficult.

What is an easier solution in your example case with higher elevations is what is applied in the Western Region...where the NWS specifically mentions what the expected snow level will be in the text of the product...sometimes even in the warning bullet...such as "...Winter Storm Warning above 1000 Feet through Thursday..." As ST1 also says...MRX for instance...and other offices as well...will break up the official zones among the counties to account for elevation too...so you can have a warning differentiated within the county...but have a significant enough forecast or geographical difference to justify such.

Its contemplating applying that on a nationwide scale where you may be considering simple rain/snow lines or so forth (imagine trying to polygon an area of 58+ mph winds for a High Wind Warning) that seems a bit unfeasible to me...when there can be workarounds implemented. Perhaps though sometime in the future the technology and ability will make that a reality...I can't see it yet (now waiting of course for next week's PNS that says polygon WSW and NPW products are coming this Fall )

[Adam]

They also use those kind of warnings in the mountains out west.

[Charles L.]

Ok, thanks for the replies. I was asking because I know that when they call for 3" or so, people my think (IMBY) but really it is for the higher elevations, like Putnam County for instance, and when it doesn't pan out for them (lower elevation people) who do you think they blame?

[Coach B]

I think I've seen HUN use elevation specific forecasts during winter events for some of their counties.  Don't recall OHX or MEG doing it though.

[Tom23]

As ST1 mentioned, MRX breaks it up sometimes when its reasonable. We have mountains/Plateau in East TN along with the valley, so they are forced to do so. This is a very good idea, but it would be hard to do during Storm season until it actually happens in a particular spot, which by then would be already too late.