PSWO for a slight risk?!

[Jeff Snyder]

OK, so I know there was a change in issuance criteria for the Public Severe Weather Outlook product a few years ago (see this thread from 2004-2005 -> PWO for MDT risk days?), but it's always been my impression that this is a high-end product intended for EMs, media, and the general public (i.e. those who don't understand the technical discussion of SWODYs and MCDs) to bring attention to a widespread or particularly sig-severe event. In other words, the PSWO used to be issued for HIGH risk events, though the threshold was dropped to include some MDT risk events in the past few years.

However, issuing a PSWO for a slight risk seems like a bit watering-down of a previously high-end product. Sure, there's a 10% hatched tor risk for the eastern Carolinas, but such probs are still only in the SLT category. If the risk really necessitated the issuance of a PSWO, then why only a SLT risk? Certainly, if one expects a risk of strong and/or long-track tornadoes to be great enough to pull the trigger on a PSWO, then it seems like it'd be great enough to warrant a MDT, at least. I know we're talking about an overnight risk, during an apparent "off-season" (December) with fast-moving storms, but this still seems to be a bit of stretch IMO. Note that, as with many southeastern US potential events this time of year (e.g. often a low-CAPE, high-shear setup that seem to be notoriously difficult to forecast well), very little in the way of verification has been received. I'm not being critical of the actual forecast/SWODY (hey, it was SLT for a reason), but I am being a bit critical of the PSWO issuance.

Anyone from SPC want to chime in on this apparent policy change? I know there was some concern that this rarely-used product may be foreign to the intended audience as a result of its very own rarely-used nature, but such is often the case for high-end products (e.g. "tornado emergencies", etc.).

 

[Fred Gossage]

http://www.srh.noaa.gov/bmx/?n=spcproducts

 

[Jeff Snyder]

http://www.srh.noaa.gov/bmx/?n=spcproducts

Wow, one and done! That links explains it all. This all comes down to determining how high of a PoD one is aiming for at the expense of a higher FAR. Certainly, it looks like it has been determined that dropping the threshold for PSWOs effectively increases the PoD, but it's also very likely that the FAR will also increase (heck, we're batting 0-1 so far).

 

[rdale]

I think the errant PDS also caused one station's web director to post this image... I hope it wasn't the met's who declared this a possible tornado on radar:

http://www.wtsp.com/news/local/story.aspx?storyid=119160&catid=8

 

[Mike Johnston]

The PDS Watch was for the eastern Carolinas, so I doubt it motivated the story on the waterspout radar image off the Florida coast - at least I hope not.

Only 1 tornado report yesterday, but I would not be surprised if a few of those wind reports are later reclassified. If you read through the wind reports, there are several, including 1 with injuries, that sound descriptive of a tornado. So, [the forecasts] may not end up being a complete bust afterall. Visibility was terrible here in Charleston yesterday; it doesn't surprise me at all that visual confirmations of any tornadoes would be lacking.

Re: the PSWO issue, I think the overall effectiveness of this product depends on dissemination through the local media - especially drive-time radio. When this happens, it seems it at least puts a thought in the back of the casual listener's mind as he goes about his daily business.

Another aspect of yesterday's weather forecasts was the multitude of marine and flood forecast products for the coastal zones, which have the effect of drowning out the potentially more serious severe weather forecast products, but I guess that's a separate issue unto itself.