Blog Fiasco

July 23, 2012

Disseminating storm-based warnings

Filed under: Musings,Weather — Tags: , , — bcotton @ 10:54 pm

Earlier this month, I wrote about the format and wording of severe weather warnings, and how to effectively shape those warnings. In those previous posts, we came to the conclusion that county sections are pretty lousy ways to define warnings. Defining warnings based on counties leads to over-warning, and using county subsections are ambiguous to the public. Storm-based polygon warnings are the most accurate way to define warnings, but they come with their own problems. First, as I previously discussed, there’s the issue of having to shape around county boundaries. Secondly, they present some challenges in dissemination.

Storm-based warnings are easily transmitted visually (though they still require a basic level of geographical knowledge that I’m not sure we can assume), so they work well on TV, Internet images, and smartphone apps. They are really poor in text or audio formats. Warnings disseminated through audio or text must still reference vaguely-defined county regions. As a result, storm-based warnings lose some of their benefit immediately.

NOAA All-Hazards Radio’s Specific Area Message Encoding (SAME), which is used to selectively activate weather radio receivers, works on a county basis. As a result, the NWS obsoleted its own technology when it switched to storm-based warnings in 2007. On the other hand, county-based warning distribution like SAME has one distinct advantage: the ability to pre-warn. A common recommendation when programming weather radios is to have the radio activate for warnings for your own county and also the surrounding counties. This allows additional lead time in some events. The current warning paradigm does not allow for such a setup.

The future of warning dissemination will be hitting people in the pocket. Mobile phones are the best way to reach a large (and growing) portion of the population. The Wireless Emergency Alert system is a good start. WEA will automatically send warnings to cell phones in affected areas (this also helps to address the issue of people driving, especially through areas they wouldn’t normally be), but it has some room for improvement. The character limit of WEA messages is 90, which is just over half the length of a traditional text message, resulting in a very information-sparse alert. In addition, it will be based on the tower‘s location, not the phone’s. This means that people will receive warnings that do not include them (or worse, will not receive warnings that do include them). Of course, it also requires that people have a WEA-capable device.

In the end, a multi-layered approach is required. Broadcast media must continue to remain a valuable partner. WEA and third-party smartphone apps should continue to get warnings to people’s phones. Weather radio technology should either be upgraded to support location-based alerting or be gracefully retired. Warning siren systems should be upgraded so that they can be sounded selectively (most systems still sound county-wide), or better yet scrapped entirely.

July 8, 2012

Effectively shaping warnings

Filed under: Musings,Weather — Tags: , , — bcotton @ 8:19 pm

Earlier this week, I wrote about the format and wording of severe weather warnings in order to most effectively communicate the necessary information to the public. In that post (and the excellent discussion that took place in the comments), I referred several times to the problems that can arise from the shape of warnings. Before I let loose on that, let’s set some historical context. From 1953-2005, the National Weather Service issued warnings on a by-county basis. This lead to over-warning unaffected areas.

In 2005, the NWS began a pilot program to issue warnings with a forecaster-defined polygon shape. In this way, the warnings could be issued such that they reflect actual threats and not political boundaries. All forecast offices began using these “storm-based warnings” in 2007, but the system still isn’t perfect.

Radar image showing two separate polygon warnings side-by-side

Sample polygon warning from WFO Indianapolis. Source: http://www.crh.noaa.gov/ind/?n=polywarn

Even though forecasters can issue warnings that are based on the atmosphere, they still must consider the political boundaries. Many warning dissemination systems (more on this in a future post) don’t support polygon warnings, so if a warning would normally clip a corner of a county, the forecaster must consider whether or not to cut a notch out of the warning. (I asked for clarification from a friend who is an NWS forecaster. He said there’s a setting that optionally excludes tiny slivers of counties. “We try to do our best to serve two masters between county based communication systems and scientifically based warnings. The main focus at all times, however, is getting information to people who are threatened as fast as possible and in as useful a manner as possible.”)

The problem is further compounded when a storm exists along the boundary between the County Warning Areas (CWAs) of two forecast offices. Current NWS practice does not allow a warning to extend outside an office’s CWA. Since CWAs edges are determined by the county borders, they are frequently uneven. A storm may clip a small portion of another office’s CWA, and the issuing forecaster must shape the polygon to avoid that portion. In order to include said portion, the other office must issue its own warning. While offices will often coordinate when storms are near a CWA boundary, I seriously doubt that any forecasters will take the time to make sure their polygons match precisely. The resulting discontinuity can be confusing to the public and makes absolutely no sense from a threat perspective. The storm does not respect political boundaries.

Radar image with severe thunderstorm warning polygons. The shape of the middle polygon is influenced by the boundary between county warning areas

A recent severe weather event in central Indiana. The warning in the middle of the image was issued by the NWS office in Northern Indiana. The southern extent of the warning is defined by the boundary between the Northern Indiana and Indianapolis county warning areas.

Removing the county-border issues from the polygon system still doesn’t lead to perfection. Polygons themselves suffer from some issues. Notably, they’re ripe for being over-large in order to improve verification scores, as Patrick Marsh posted earlier this week. The other key concern is that, as I mentioned above, some warning systems have no concept of polygons. NOAA All-Hazards Radio (also known as “weather radio”) is a prime example., as are outdoor warning sirens (some locations have the ability to sound sirens selectively, but it is by no means ubiquitous). Until these systems are modernized, even the best polygons will still lead to over-warning.

July 1, 2012

Effectively communicating to the public

Filed under: Musings,Weather — Tags: , , — bcotton @ 8:20 pm

One of the main challenges a meteorologist faces (and this is true for many professions. I eagerly await a post from Matt Simmons drawing a parallel in systems administration) is effectively getting a message to the public. This becomes especially important in times of severe weather when the timeliness and clarity of the message can literally be the difference between life and death. While the National Weather Service and the media do a good job, there’s a lot of room for improvement. Let’s consider the three questions a person needs answered:

  1. Am I threatened?
  2. If so, what do I do about it?
  3. When am I in the clear?

Now compare this to an actual warning.

027
WUUS53 KIND 011733
SVRIND
INC015-023-157-011830-
/O.NEW.KIND.SV.W.0131.120701T1733Z-120701T1830Z/

BULLETIN – IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
133 PM EDT SUN JUL 1 2012

This is just header information. The public rarely encounters it directly.

THE NATIONAL WEATHER SERVICE IN INDIANAPOLIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR…
CARROLL COUNTY IN NORTH CENTRAL INDIANA…
NORTHWESTERN CLINTON COUNTY IN CENTRAL INDIANA…
NORTHEASTERN TIPPECANOE COUNTY IN WEST CENTRAL INDIANA…

Okay, so let’s assume I know what county I’m in. Am I in the right part of the county?

* UNTIL 230 PM EDT

The first question to be definitively answered is the third one.

* AT 131 PM EDT…NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL…AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED 6 MILES
SOUTHEAST OF BROOKSTON…OR 8 MILES NORTHEAST OF LAFAYETTE…AND
MOVING EAST AT 40 MPH.

There’s some town names here and a description of the threat. Maybe I can figure out if I’m threatened by this or not.

* LOCATIONS IMPACTED INCLUDE…
DELPHI…
YEOMAN…
ROSSVILLE…
CAMDEN…
FLORA…
BURLINGTON…

THIS INCLUDES INTERSTATE 65 BETWEEN MILE MARKERS 173 AND 181.

Oh, okay! My city isn’t listed, so I’m probably in the clear. Folks in Delphi know that they are threatened. The first question is answered.

PRECAUTIONARY/PREPAREDNESS ACTIONS…

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR…DESTRUCTIVE HAIL…DEADLY LIGHTNING…AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM…AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

And here, basically at the end of the warning, is the answer to question 2.

LAT…LON 4073 8652 4070 8652 4069 8637 4063 8636
4034 8641 4045 8693 4057 8689 4057 8678
4066 8678 4067 8676 4073 8676 4074 8675
4074 8663
TIME…MOT…LOC 1733Z 280DEG 19KT 4052 8679
WIND…HAIL 60MPH 1.00IN

The latitude/longitude pairs define the shape of the warning (more on that in a bit). This can be used to provide really good answers to question 1.

Your typical severe weather warning answers all three of the questions we base our discussion on, but in the wrong order. Arguably, question 1 gets answered first, although it relies greatly on the geographical awareness of the public. I suspect many adults are aware of what county they live in (due to school districts, libraries, property taxes, etc), but if they work in a different county, do they know that county’s name? Can they name the surrounding counties (this is useful for preparedness. If the county to your west is under a warning, chances are good you might be soon)? The fact that subsections of counties (e.g. “northeastern Tippecanoe County”) are variable and undefined only add to the confusion.

The fact that the “call to action statement” (what NWS meteorologists call the answer to question 3) comes at the tail end of the warning means that a full minute may pass until it’s made clear what actions someone should take. In many cases, the lead time is sufficient that this additional time is acceptable, but in short-lead-time situations (for example, the Joplin, MO tornado of 2011) every second counts.

It’s not bad to give people more information than they need, especially when it reinforces your point. One example comes from a derecho that hit Louisville, KY on July 13, 2004. This storm caused widespread damage through southern Indiana and central Kentucky. In order to make it clear that this was an exceptionally dangerous storm, one of the forecasters at the NWS office in Louisville made mention of “hurricane force winds” in the warnings. Although this wasn’t strictly necessary, it helped to make the danger more clear in the mind of the public. Extra information can be valuable, but it should never get in the way of the main point.

So how would I re-format warnings?

<headers>

THE NATIONAL WEATHER SERVICE HAS ISSUED A <threat> WARNING FOR

<counties>, including <cities>

<call to action, don’t die, etc.>

<THIS WARNING EXPIRES AT <expiration time>

<More explanation, supporting info>

The media has an advantage here, as they can format their presentation of the warning however they’d like. The NWS is stuck with a defined format. It’s worth noting that decades ago, the public did not receive NWS products directly; they were filtered through the broadcast media first. In modern times, All-Hazards Radio, weather websites, and mobile apps are putting more NWS products directly in front of the public. So far, the NWS has not updated warning text to fit this new model.

One thing you may have noticed is that my version doesn’t mention the office issuing the warning. I had this discussion with a recent meteorology graduate last week. What use is knowing what office issued the warning? Most people probably don’t know what NWS office serves them. Furthermore, a warning may be issued by a backup office if the primary office is unavailable (e.g. if the office staff is taking shelter because they’re about to get hit by a tornado). Adding the issuing office does nothing to answer or reinforce the three questions. It’s not extra information, it’s extraneous.

Note: I was going to add some comments about the shape of warnings, but this post is long enough and that rant won’t be short. Look for it in the next few days.

Powered by WordPress