The source field is a credibility ranking, it has thirty-one values, and two of the things people assume are on the list are not.

In this lesson you will

  • Explain why the source field exists and how it functions as a credibility signal.
  • Recognize valid source values and identify two common invalid ones.
  • Describe how a report can change a warning while it is running.
  • Explain how a report feeds warning verification.

What module 7 already covered

Module 7 lesson 1 owns the lifecycle and this lesson assumes it: the five stages from you to the national archive, the fact that a Local Storm Report is preliminary while Storm Data is the certified record, the fields an LSR carries, and the measured or estimated tag. Go back to it if any of that is hazy.

What module 7 did not do is open up the source field, and that is this lesson, because it is where the whole idea of a trained spotter turns into something mechanical.

A credibility ranking, written into the format

Every report carries a source, chosen from a fixed national list. It is not a courtesy field. A forecaster reading two conflicting reports uses it to decide which to act on, and the list is ordered in their head even though it is alphabetical on the page.

Roughly how a forecaster weighs itValues
StrongestNWS STORM SURVEY, NWS EMPLOYEE, OFFICIAL NWS OBS, ASOS, AWOS, MESONET, BUOY
Trained and accountableTRAINED SPOTTER, AMATEUR RADIO, EMERGENCY MNGR, LAW ENFORCEMENT, FIRE DEPT/RESCUE, 911 CALL CENTER, COUNTY OFFICIAL, CO-OP OBSERVER, COCORAHS
SituationalBROADCAST MEDIA, STORM CHASER, AIRPLANE PILOT, SHIP, COAST GUARD, DEPT OF HIGHWAYS, UTILITY COMPANY, PARK/FOREST SRVC, POST OFFICE, OTHER FEDERAL, INSURANCE CO, NEWSPAPER, C-MAN STATION
WeakestPUBLIC, UNKNOWN

Thirty-one values in total. The grouping here is this course explaining how the field is used; the directive itself lists them alphabetically and assigns no ranking. That a forecaster ranks them anyway is the point of the lesson.

This is what "trained spotter" buys you
It is two words in a fixed field, and they are the difference between a report that is acted on and one that waits for corroboration. Say you are a trained spotter when you report, as module 7 lesson 6 instructed, because it is the only way the field gets filled in correctly. Nobody can infer it from your wording.

Two things that are not sources

SOCIAL MEDIA is not a source value. Neither is MPING.
Where a report reaches an office through social media, the underlying source is what gets recorded, PUBLIC or LAW ENFORCEMENT or whatever the person actually is, and the channel goes in the remarks: "via Twitter". This is exactly right, and it is worth understanding why. Social media is a pipe, not a person. The question the field answers is "who saw this", and the answer is never "a website".

Which is a useful test for any report you relay: the source is the human being who observed it, not the last link in the chain. Lesson 4 returns to this, because a relayed report that records the relayer as the source has lost the only thing that made it worth relaying.

What your report can change, while it is still running

Module 7 lesson 5 gave the reasons to report during an active warning. Here is the mechanism, which is more concrete than people expect.

  1. A new or upgraded warning. A severe thunderstorm warning becomes a tornado warning on the strength of an observation. The office does not need to wait for radar to agree.
  2. A severe weather statement. The follow-up product that updates a running warning: it can narrow the area, extend the time, or carry your confirmation out to everybody already inside the polygon.
  3. A damage threat tag. Module 7 lesson 5 had the ladder. A measured hail size can move a storm onto the rung that reaches phones.
  4. A storm survey. After the fact, and your report is often what tells the office there is something to go and look at.
And the one that is invisible to you
Verification. Whether a warning was right is decided almost entirely by whether reports came in. A warned event with no report looks like a false alarm in the record, forever, and the office carries that in its statistics. Your report is how a correct warning gets counted as correct, and nothing about the process shows that back to you.

Remarks

The last field, and the one people waste. It takes a few hundred characters of plain English and it is where everything the fixed fields cannot hold goes: what the damage actually looked like, that the size was measured with calipers, that the water was still rising when you left, that the report came via a relay.

Write it in full sentences for somebody reading it in five years with no context, because that is who reads it. Module 7 lesson 1 explained that Storm Data is the version that still exists in thirty years. The remarks are the only part of it that sounds like a person was there.

Check yourself

You see a photograph on social media of hail from your county, posted by a member of the public, and you relay it to the office. What source should the report carry?

  1. PUBLIC, with the social media channel noted in the remarks
  2. SOCIAL MEDIA, since that is where the report came from
  3. TRAINED SPOTTER, since you are one and you passed it along
  4. UNKNOWN, since you cannot verify who took the photograph
Hint

The field answers one question: who observed it?

Answer

PUBLIC, with the social media channel noted in the remarks

The source is the person who saw the hail, which is a member of the public, and the channel goes in the remarks. SOCIAL MEDIA is not a valid value. And the third option is the serious error: relaying something does not make you its observer, and recording yourself as the source would upgrade the credibility of a report you did not make.

Sources

  1. NWS Instruction 10-517, multi-purpose weather products specification
  2. NWS Instruction 10-1605, Storm Data preparation
  3. NWS, local storm reports and severe weather statements