It's time to do away with severe thunderstorm warnings

[Dan Robinson]

I still take issue with this statement. It may verify most of the time in your location, but the truth of the matter is, ice on roads won't develop until the ground temperature reaches freezing. Period.

Bridges cool rapidly to the air temps. I don't have an exact time value, but I have viewed graphs on the Kentucky road sensor network that show bridges 15-20 minutes or less behind the air temp plots when temperatures are dropping. This correlates well with what I have observed in reality, as I've never seen a bridge not icing when temps were below freezing. The KY data can be found here (not all of these sensors are at bridges):

http://transportation.ky.gov/RWIS/index.htm

So, it is reasonable to expect that bridge temperatures will match local obs in the vast majority, if not all, cases. As for the rest of the roads, the NWS already considers ground temps when other winter products are issued. I can find examples if needed, but I've read many an SPS/WWA/FRA where forecasters took into account how long freezing temperatures had been present in the area and what the expected road surfaces temps would be as a result. Exact, realtime road surface sensor data would be good for verification, but hasn't been necessary to accurately evaluate the hazard.

So now we're only going to issue products for the start of an event?

Again, this would be a discretionary matter on a case-by-case basis, left up to the individual WFO. The product should be in effect until the primary threat passes. This can vary from situation to situation, but normally should follow the convention of any FRA, WWA or SPS that would have existed in its place.

 

[rdale]

Rain does not pond on road surfaces equally yet it is common practice for the NWS to issue flash flood warnings across and entire CWA

FFW's are issued by county, so I'm not sure you'd find too many cases where a FFW would cover the whole CWA. And I'll admit up front that I'm only speaking of areas I've dealt with in the Great Lakes - but a FFW never covers every roadways in the whole county. Water doesn't pop up in unexpected places -- we all know what roads flood and what rivers come out of their banks. When it is an extreme event, the same old FFW has text in there saying so. There's no need for a "Super Flash Flood Warning" or an "Historic Recordsetting Flash Flood Warning."

Yes but notice how we often see the inclusion of a Wind Chill Advisory

Pretty sure these are never issued during a Blizzard Warning.

Special Weather Statement

SPS's are only issued to give additional updates to the existing Blizzard Warning. It's not a warning product, it's just a "here is what is happening with the Blizzard Warning right now" product.

Hazard Weather Outlook

The HWO is a daily forecast product issued 365 times per year at a minimum --- it's nothing but a general overview of any hazardous weather. It is not a warning product.

If a RIW product was out there, I'm confident that scores of intelligent, dedicated and well meaning OCM's would pick up on it for use in their broadcasts even if it was a clear night under a chilly dome of high pressure and radiational cooling was quietly undoing the work that the sun had begun.

If they are intelligent, dedicated and well meaning OCMs, they don't need to wait for a RIW to tell people that "temps are dropping into the 20's and roads are wet, so they'll ice up." If they are also intelligent, dedicated and well meaning, they aren't going to take Survivor off the air to do wall-to-wall "don't go out and drive" cut-ins.

This isn't a product intended to make people go hide under their beds

Then you missed what Dan has posted about his proposed RIW, as telling everyone to stay off the roads or they might die seems to be intended to do just that...

Again - sociology. In the past we told people what not to do - "Don't drive into flooded roadways, don't hide in the closet during a fire, don't panic." Then research showed that actually was bad because it put the thoughts into their heads that they may not have otherwise had. Now we say "turn around, don't drown" and "stay somewhere that a fireman will find you" and "remain calm." The difference may seem nonexistant for those of us using "common sense" - but "real research" says it is truly there. So until we see "real research" on the RIWs impact, I think it's hard to continue a meaningful discussion.

(On the other hand, this is the most civil debate I've seen on the forum since the pre-lightbar days )

 

[rdale]

...and just a reminder so that everyone is on the same page, WDTB put together an excellent set of training on this very topic at http://wdtb.noaa.gov/courses/winterawoc/IC3/index.html

 

[Terry Tyler]

I agree with Dan. Hes been doing Icy Roads for a long time and knows what hes talking about. I could see Polygonal Ice Warnings issued similar to how Flash Flood Warnings are issued. I think they should do an over the air EAS and let people know whats up. Rural areas are the ones that need these warnings the most. Places with winding roads and varying elevations are particularly deadly. They issue FFWs almost every time it rains, and I dont think it would be that far-fetched to do a Polygonal Road-Ice Warning for mornings such as 12-7. Having drove on both Icy and Wet roadways. I can tell you, Its a Clear and Present danger. If your not Gripping your wheel and have a good set of tires. You could wreck easily, especially if your caught off guard or are not paying attention to the hazard.

With that said, I agree that it all comes down to the Individual as far as heeding the warning and being aware. 8 out of 10 chases, I see a terrible wreck caused by Hydroplaning. Most people know better then to drive fast when its pouring rain, but some just dont. I guess you could chalk it up to poor driving, not paying attention or being un-aware to the present hazards. The bottom line is, Yes. I think they should do Icy Road Warnings. When you compare the Deaths from Icy Roads to Tornadoes, the comparison is staggering. This arguement, However is much like arguing about Alcohol vs Pot deaths. This is how the Man runs things, and its not going to change over a thread on some forum. Whether it makes since or not, thats just how it is and how its going to be.

 

[John Farley]

I am generally inclined to think the RIW is not a good idea, although I do think that some situations where the roads ice up from very small amounts of snow or freezing precipitation that are not now covered under any kind of headline should be. Some data questions that strike me as useful for this discussion include the following:

1. How much greater is the number of traffic deaths during icing events than the number of traffic deaths in the same area in fair weather? (I remember some discussion of this point earlier in this thread, but not numbers. If there were numbers, I apologize for asking this.)

2. Of the 475 or so deaths in a year (don't recall the exact number Dan cited, but I believe it was in that ballpark), how many occurred when a winter storm warning, ice storm warning, blizzard warning, heavy snow warning, etc. was in effect? How many during advisories (e.g. winter weather advisory, freezing rain advisory, snow or blowing snow advisory, etc.)? And how many when no advisory of any kind was in effect?

3. Finally, sort of a combination of the above two - of the excess mortality during ice compared to no ice, how much can be attributed to each of the conditions mentioned in question 2?

I think these would be useful data items to have - not sure how much of this if any can be derived from Dan's data, but the cases that concern me are the ones that represent excess mortality in a situation in which no warning or advisory was in effect. IMHO, a winter warning or advisory of any kind should serve as an alert that roads are icy and one should either stay off them or take extra care in driving. So the cases that worry me are ones where people head out with no warning or advisory of potentially hazardous winter driving conditions. If those are a lot, probably some change should be made. If they are few, maybe not.

In all this, an unfortunate reality is that many people will not really have a choice not to drive - most workplaces are not likely going to find it economically feasible to close any time there is a small amount of ice or snow. Additionally, I continue to believe that many of these fatalities are caused by poor driving. Granted, there are some conditions where safe driving is nearly impossible, but there are many more where a modicum of care and winter driving skill will usually keep most people safe. One could argue that efforts to improve these might be a more effective way of reducing winter driving fatalities and injuries, although I do agree that however many hazardous situations that now occur with no warning or advisory should be covered by some kind of winter weather warning or advisory.

 

[Dan Robinson]

Rob, those courses are excellent resources - thanks for posting.

Driver awareness is a major factor in mitigating the human impact. Most of the public doesn't currently understand precisely how much they are at risk when they decide to venture out in many of these lower-end events without a major change in driving behavior. To that end, support in the realm of communication from the NWS - the authoritative source - is critical. Most everyone understands the travel impacts from major snowstorms and ice storms, and lower per-mile, per-hour death rates in those events (particularly with snowstorms) correlate well with that. But a dusting of light snow, for example, doesn't appear as sinister as it actually is. Countless drivers interviewed in news reports attest to the fact that they didn't expect it to be as slick as it was.

All low-end precip-in-progress winter weather products issued by the NWS are already primarily or exclusively concerned with road icing (See here). Since that is the case, why not simply call those products what they actually are to better communicate the inherent hazard being addressed?

When a tornado warning is issued, the "end result" hazard is the one that is being communicated to the public. We wouldn't use "Strong Mesocyclone Warnings" and expect the public to immediately make the mental connection to a tornado as the "end result", even though the process would seem patently obvious to us 'weather geeks'. Similar to calling Flash Flood Warnings "Heavy Rain Warnings". Likewise, Winter Weather Advisories, Freezing Rain Advisories, SPSs, Snow Advisories, etc are all addressing the travel impact, but don't explicity say so unless one chooses to read the entire text. There is at least a two-step mental connection that the public must make to realize that a WWA/FRA = hazardous roads. Again, what may seem obvious to us in the weather community often slips by people who don't regularly think about it.

 

[John Farley]

St. Louis Christmas 09 snow/icing event - a case study

This is going to be a rather long post, so please bear with me if you are interested in this issue. Yesterday's (Christmas '09) snow/icing event in the St. Louis area seems to be exactly the kind of event to which this discussion is most relevant. From a meteorological standpoint, this was a low-end event, with snow accumulations of a half inch or less in most areas. But from a human-impact standpoint, it was a high-end event, with, tragically, the death of a Missouri state trooper and numerous freeway closures and pileups in the St. Louis area. News story from Post-Dispatch:

http://www.stltoday.com/stltoday/ne...15E011ABF8AC552D86257698000B8679?OpenDocument

In accordance with NWS policy and practice of not issuing advisories for snowfalls of less than an inch, no advisory or warning was issued for this event. Yet, the NWS was clearly aware of the risk and did attempt to communicate that risk through special weather statements and short term forecasts. Here are two examples of several such statements that were issued for various areas; I choose these two because they focus on the STL area where the impacts were greatest:

[FONT=lucida sans typewriter, lucida console, courier]SPECIAL WEATHER STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE ST LOUIS MO
432 AM CST FRI DEC 25 2009

ILZ058-059-079-095>102-MOZ036-052-061-063>065-074-075-085-251515-
GREENE IL-MACOUPIN IL-RANDOLPH IL-ADAMS IL-BROWN IL-PIKE IL-
CALHOUN IL-JERSEY IL-MADISON IL-ST. CLAIR IL-MONROE IL-PIKE-
LINCOLN-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY-JEFFERSON-
ST. FRANCOIS-STE. GENEVIEVE-MADISON-
INCLUDING THE CITIES OF...CHESTER...QUINCY...EDWARDSVILLE...
BELLEVILLE...BOWLING GREEN...ST CHARLES...ST LOUIS...FARMINGTON
432 AM CST FRI DEC 25 2009

...RAPID FREEZING OF WATER ON ROADS LIKELY AS STRONG COLD FRONT
MOVES THROUGH THE AREA...

A VERY STRONG COLD FRONT IS MOVING THROUGH THE AREA. TEMPERATURES
ARE FALLING AT A RATE OF 10 DEGREES OR MORE PER HOUR. THIS WILL
LIKELY CAUSE RAPID FREEZING OF ANY WATER WHICH HAS ACCUMULATED ON
AREA ROADS...BRIDGES...OVERPASSES...SIDEWALKS...AND OTHER EXPOSED
SURFACES. THIS WILL CAUSE BLACK ICE CONDITIONS...AND COULD MAKE
DRIVING EXTREMELY HAZARDOUS. BE PREPARED FOR RAPIDLY CHANGING ROAD
CONDITIONS. WATCH FOR WET ROADS WHICH WILL LIKELY FREEZE VERY
RAPIDLY AS TEMPERATURES DROP. ALLOW FOR EXTRA STOPPING DISTANCE AND
SLOW DOWN APPROPRIATELY FOR TURNS AND CURVES IN THE ROAD.
[/FONT]

[FONT=lucida sans typewriter, lucida console, courier]SHORT TERM FORECAST
NATIONAL WEATHER SERVICE ST LOUIS MO
923 AM CST FRI DEC 25 2009

ILZ098>102-MOZ051-052-059>065-072-073-251730-
CALHOUN IL-JERSEY IL-MADISON IL-ST. CLAIR IL-MONROE IL-MONTGOMERY-
LINCOLN-GASCONADE-WARREN-ST. CHARLES-FRANKLIN-ST. LOUIS-
ST. LOUIS CITY-JEFFERSON-CRAWFORD-WASHINGTON-
INCLUDING THE CITIES OF...EDWARDSVILLE...BELLEVILLE...
ST CHARLES...UNION...ST LOUIS
923 AM CST FRI DEC 25 2009

NOW

SNOW CAN BE EXPECTED ACROSS THE AREA THIS MORNING. MOST OF THE
SNOW WILL BE LIGHT...BUT THERE COULD BE AN OCCASIONAL BURST OF
MODERATE INTENSITY SNOWFALL. GUSTY SOUTHWEST WINDS OF 20 TO 30 MPH
WILL FURTHER REDUCE THE VISIBILITY AT TIMES. SNOWFALL
ACCUMULATIONS WILL RANGE FROM A DUSTING UP TO AN INCH. MOTORISTS
SHOULD BE CAUTIOUS AS THE SNOW WILL LIKELY ACCUMULATE ON ROADS.
[/FONT]
These products indicate that there was an awareness of the risks and an effort, within the constraints of current NWS policies and practices, to communicate them. In other words, the STL NWS office did exactly what it was supposed to do under current policies and practices.

The problem, IMHO, is that these products generally reach very little of the public. In this particular case, several circumstances came together to make the situation particularly hazardous:

1. Although there was not very much snow, much of what did fall came in quick bursts that quickly covered the roads. Strong winds contributed to the situation by reducing visibility in blowing snow, and likely making skids harder to prevent/control in areas with strong crosswinds.

2. There was a rapid drop in temperature after a prolonged period of heavy rainfall. Any salt that may have been on the roads from treatment earlier in December was washed away, and more important, the rapid drop in temperature led to some flash freezing of wet areas and assured that the snow would accumulate or turn to ice.

3. Although there had previously in the month been some light dustings of snow and predictions of snow that did not materialize, this was the first hazardous winter driving situation of the season in St. Louis, so a lot of people were out of practice.

Combine all that with the fact that most people heard no advisory or warning and probably did not hear the statements about possible hazardous conditions, and the result was a real mess. As I mentioned in another thread, I was coming back from my daughter's house in Hamel, IL to my house in Edwardsville on I-55 just after noon. This is a distance of seven or eight miles. When I left Hamel, there was a half-inch or less of snow on the ground and snow falling lightly. When I first got on I-55, there was snow blowing across the road but the road was not particularly icy. Still, I proceeded cautiously around 50-55 mph while others barreled by at 70. Two or three miles before the Edwardsville exit, I encountered an intense snow squall with visibility down under 1/2 mile, maybe as low as 1/4. The road quickly became snow and ice covered, and from there to the Edwardsville exit there were at least 3 cars off the road. I am sure the suddenness with which the hazardous conditions developed was a contributing factor, though greater caution and situational awareness could, I would think, have prevented some of the slide-offs.

Would it have made a difference if some kind of warning or advisory had been issued? I don't know, but I would think if it had been it would at least alert people to consider postponing their trip for a couple hours or to drive with greater caution and situational awareness. Then at least people would be making their own informed choices and could not legitimately say they were caught by surprise.

I'm not sure we need another category of warning/advisory, or that use of a warning as opposed to an advisory wouldn't further confuse people about low-end vs. high-end meteorological events. But I do think that, at the least, winter weather advisories should be routinely issued for snow events under 1 inch if conditions are otherwise favorable for road icing/hazardous driving conditions. This is a case where this condition applied, and it was clearly understood before the event that they applied. I think that the NWS policy should probably allow for issuance of some kind of advisory in this situation. In general, advisories and warnings are much more widely disseminated than the kinds of products (special weather statements and short-term forecasts) that were issued for this event.

 

[Brian Barnes]

It was earlier brought up whether or not the NWS should be worrying about non-meteorological events, I recently saw "Child Abduction Emergency" on EAX's NWS map. So, if that's going to be on weather maps, or an issued product - then why not road icing. Makes sense to me.

 

[rdale]

So, if that's going to be on weather maps, or an issued product - then why not road icing. Makes sense to me.

It already does... NWS GRR issued a winter weather advisory for flurries today - but the concern was icing of the roadways. It showed up on the map.

 

[Patrick Marsh]

It was earlier brought up whether or not the NWS should be worrying about non-meteorological events, I recently saw "Child Abduction Emergency" on EAX's NWS map. So, if that's going to be on weather maps, or an issued product - then why not road icing. Makes sense to me.

No one has said it shouldn't be on the map. We've argued they shouldn't be issuing these products. Child Abduction Emergencies, Civil Emergencies, etc are not *issued* by the NWS. They are *issued* by other agencies and relayed via the NWS. An employee at a WFO cannot randomly choose to issue a Child Abduction Emergency.

If the DOT wants to issue a Road Ice Warning and they ask the NWS to relay it via their products stream (which includes the NOAA All Hazards Radio) that's a different story.

 

[Rich Long]

I really think the campaign here should be on the broadcast mets. Lets face it, not a lot of people get their info from the NWS directly. IMHO we should be working with the bradcast mets and raise thier awareness to the situation.

What was said on the news the day of the rain/ice event? Did the broadcast mets raise any sort of awareness? If not, some of the responsibility falls on them. They are Mets too and products from NWS or not they are capable of making these calls too.

 

[Jason Boggs]

Any Met worth a crap will raise awareness when the roads are possibly slick. I know the Mets here always talk about the roads when they might be slick.

When I came to my parents house on Wed, it was snowing, and the roads had just a tiny bit of snow on them in places. I went no faster than 55-60mph while being passed by people going as fast as 75 or 80. Again, it's ultimately up to nobody else but the people on the road to determine their own safety.

 

[Dan Robinson]

What is the primary hazard being addressed by WWAs, FRAs, Snow Advisories, Heavy Snow Warnings, and snow/ice SPSs?

Road icing.

So, why not:

A. Call those products what they really are.

B.) Expand criteria to include high-impact, sub-advisory events.

C.) Add public awareness wording to those products in the same spirit of 'Turn Around, Don't Drown'.

 

[rdale]

This week's Weatherbrains featured Dan as their special guest... Take a listen at http://weatherbrains.com/weatherbrains/?p=1026

 

[Chris Allington]

Heres another special example... I really dont think we need more than this.

...WINTER WEATHER ADVISORY IN EFFECT UNTIL MIDNIGHT CST TONIGHT...

THE NATIONAL WEATHER SERVICE IN OMAHA/VALLEY HAS ISSUED A WINTER
WEATHER ADVISORY FOR SNOW AND BLOWING SNOW...WHICH IS IN EFFECT UNTIL
MIDNIGHT CST TONIGHT.

* TIMING: LIGHT SNOW WILL CONTINUE THROUGH THE EVENING. SOME
MODERATE SNOW IS POSSIBLE FROM TIME TO TIME.

* SNOW ACCUMULATIONS: MOST SPOTS WILL SEE UP TO AN INCH OF SNOW.

* ICE ACCUMULATIONS: WHILE ICE ACCUMULATIONS ARE NOT EXPECTED...A
THIN LAYER OF ICE UNDER THE SNOW HAS DEVELOPED FROM INITIAL
MELTING THEN REFREEZING OF THE SNOW.

* WINDS: NORTHWEST WINDS OF 20 TO 30 MPH WILL CAUSE BLOWING SNOW
AND REDUCED VISIBILITIES.

* IMPACTS: VERY SLICK ROADS HAVE BEEN REPORTED AND WILL CONTINUE
THROUGH THE EVENING. VISIBILITIES BELOW A HALF MILE ARE
LIKELY...WITH SOME OPEN AREAS SEEING BRIEF WHITEOUT CONDITIONS.
MOTORISTS ARE URGED TO SLOW DOWN. WHILE THE AMOUNT OF SNOW
APPEARS TO BE FAIRLY LIGHT...YOU WILL ENCOUNTER VERY SLICK ROADS.