Most observers will use National
Weather Service form B-91 (WS B-91) for reporting their daily observations. Quality
control of these forms has indicated that some confusion exists on how to properly log the
reports, as well as the station information entries.
Station Header block:
STATION (Climatological) -- This is the name assigned to your station.
Include the distance and direction from the main post office, if this has been assigned,
or any other identification (used if there is more than one observing site in the same
town). For example, "Avon 5NE", "Springfield 2", and "Lincoln"
are valid.
RIVER STATION -- For those of you who read river data at a location
different than your normal observing site, you would put the assigned name in this
block. Otherwise, leave it blank.
MONTH -- This is the 3 letter identifier for the month (JAN,
FEB, MAR, etc.)
YEAR -- If your form is pre-printed with "19__", please
cross out the "19" part and write the 4 digit year. If it is pre-printed with
"20__", fill in the last two digits of the year.
STATE -- Use the two-letter postal identifier for the state
("IL").
COUNTY -- Name of the county where the station is located.
In some cases, this may be a different county than the "parent" town listed as
the station name. For example, Pana is in Christian County, but Pana 3E is in Shelby
County.
RIVER -- Only if you report river stages, write the river
name in this block. Otherwise, leave it blank.
TIME OF OBSERVATION RIVER, TEMP, PRECIPITATION -- All 3 of these
use the same basic conventions. For example, if you take your observations at 6:00 AM,
then you would write "6a" in the box, 6:00 PM would be "6p", etc.
Midnight is coded as "12m", and noon is coded as "12n".
STANDARD TIME IN USE -- For Illinois observers, there are only
two valid entries: C (Central) is to be used from November to March, and DC
(Daylight Central) is to be used from April to October. (Observations are taken at the
same clock time, regardless of CST or CDT being used.) We have seen many incorrect
entries, e.g. "CST", "Central", "DCST", "Yes"
(assuming this was a yes/no question), and leaving the box blank.
TYPE OF RIVER GAGE, ELEVATION OF GAGE ZERO, FLOOD STAGE, NORMAL POOL
STAGE -- If you take river readings, the NWS will tell you what to write in these
boxes. If you do not take river readings, please leave these boxes blank.
At the bottom right of the observation form, there are 3 blocks that also need to be
filled out:
OBSERVER -- Please sign or write your name in this block.
If your station is a business, where several people take the observations, you may put
"STAFF". We are not allowed to write in your name if the box is
blank.
SUPERVISING OFFICE -- If this box is not already stamped when the
B-91 booklet is sent to you, please write "ILX" in this box.
STATION INDEX NUMBER -- If your form has not already been stamped
with your index number, please write it in this box. It is in the form 11-xxxx-d,
where "11" is the code for Illinois, "xxxx" is the station number, and
"d" is the climate district.
Common Errors
For example, say on your 6 am observation on the 5th, you register a high
temperature of 61, a low of 25, and a current temperature of 26. These are marked down in
the row labeled "5". Then on the 6th, your high is 70, the low is 26, and the
current temperature is 40. Even though the temperature on the morning of the 6th may have
only dropped to 40, for the 24-hour period ending at 6 am, the coldest temperature was 26
(the "at-observation" temperature from the previous day). Therefore, you log the
low temperature on the 6th as 26 degrees. If you wish, you may put a comment such as
"AM low 40" in the remarks line for the 6th.
The "at-observation temperature" must be included when
determing the high and low. For example, let's say you reported a high of 68, a low of
54, and an at-observation temperature of 50. Your low temperature in this case would
actually be 50. (This relates to the example above.)
Precipitation totals should be logged for the day that the
observation was taken, not the day that it actually occurred. On your 7 am observation
on the 15th, you read 0.56 inches of rain in the gage, but you know that all of it fell
the evening before. You would still log the 0.56 inches in the box for the 15th, because
it is a 24 hour total for the period from 7 am on the 14th, to 7 am on the 15th. On the
B-91 forms, there is also a space to mark the times the precipitation fell (if known).
This is logged on the day it actually fell. For example, if it rained from 7 to 10 pm on
the 5th, it would be marked on the 5th, even though the actual total will be written on
the 6th.
Report precipitation using the correct number of digits. Liquid
precipitation totals use two digits to the right of the decimal point; 24-hour snowfall
uses 1 digit to the right of the decimal point, and current snow depth is rounded to the
nearest inch (i.e., no decimal point). If any of these values is considered a trace, enter
"T". If none occurred, please put in a "0", instead of leaving
the box blank. (This clarifies that there was actually no precipitation, instead of saying
that no observation was taken.) For example, the precipitation total may be reported as
"T", "0.02", "1.10", etc. Snowfall is in the format
"T", "0.2", "1.1", etc. A snow depth of 1.1 inches
would be logged as "1", 0.5 inches as "1", and 0.3 inches as
"T".
For precipitation less than 0.01 inch, snowfall less than 0.1 inch,
and snow depth (rounded) less than an inch, put a "T" in the box. Do not use
"Trace", "Tr", "0.001", etc. You may include remarks such as
"snow flurries", "few sprinkles", etc., but these actually do count
toward the precipitation totals, and thus should be reflected in the 24-hour
precipitation/snowfall totals.
Do not change your observation time without consulting with us!
Minor changes, such as routinely taking the observation an hour earlier, may be
permissible (after discussing the situation with us), but going from evening observations
to morning observations (and vice versa) are not permitted. (If you are simply taking the
observation slightly earlier or later than usual, put the actual observation time in the
column labeled "Time of observation if different from above".)
Transmitting Observations
Several techniques are available for you to send your daily observations. (For those
of you who currently do not do this, we would greatly appreciate it if you would begin.
Daily reports are used for river forecasting, and for composing summaries for
external distribution.)
IV-ROCS is an automated telephone system that
allows you to enter your observed data. The system codes the observations, and
they are transmitted to the NWS for relay around the network.
WXCODER uses a computer with Internet access for
entering data onto a special home page. This system also has quality control to
avoid observation errors (e.g. low temperature warmer than high temperature).
Future upgrades to the WXCODER system will allow you to print your
B-91 form directly from the WXCODER page.
If observers do not have access to any of the above, they may phone
their observations to us using our 800 number.
Regardless of how you send your observations, there are some things to
keep in mind:
Do not send in your observation more than 1/2 hour before your coded
observation time. If you do, then your observation will not be recognized by our
computer.
Please use the correct value for "trace". For
IV-ROCS, press the * (star) key at the prompt. For WXCODER,
enter a "T" at the appropriate prompt.
Please use the correct value for below zero temperatures. For
IV-ROCS users, this is coded by pressing the star key before the number (e.g. *18 for
a temperature of -18 degrees). In WXCODER, enter the value using a negative sign.
If no precipitation is reported, do not include a precipitation type
code.
However, go ahead and send the precip amount of "0.00".
Report the precipitation type code. (Applies to
IV-ROCS.) If more than two precipitation types are observed, you will be
asked one at a time. Any code values of 5 through
9 will prompt the system to ask you to enter a snowfall value.
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