This chapter prescribes procedures and practices for making entries on various observational forms. The main emphasis is on Meteorological Form 1M-10C (MF1M-10C). At all manual FAA facilities, including LAWRS, all observations shall be recorded on Form MF1M-10C. NWS stations typically use Meteorological Form 1M-10A/B (MF1M-10A/B) which is a more comprehensive form required at those stations. The two forms, MF1M-10A/B and MF1M-10C, are similar in that the column numbers for recording the various types of data are the same. However, form MF1M-10C contains fewer columns in accordance with the reduced requirement for certain types of data at FAA facilities. In this chapter, only the columns that are on the MF1M-10C will be described. Many of the instructions in this chapter that are related to MF1M-10C are duplicated from Chapter 15, Coding and Dissemination. References to other chapters are noted where applicable.

Certified observers shall normally complete all entries on MF1M-10C. Non-certified trainees/ observers may make entries on the form under the immediate supervision of a certified observer who assumes responsibility for the validity of the entries by initialing in column 15. Non-certified observers may initial the observation, but the certified observer shall initial first. Initials shall be separated by a solidus (/).

The same type of writing instrument shall be used throughout the form. To ensure legible copies and ample contrast for reproduction, the observer shall use a black-inked fine ball-point pen.

Data entered in columns 3 through 14 of Form MF1M-10C that are not intended to be transmitted shall be enclosed in parentheses.

See paragraph 15-5, Coding Missing Data in METAR and SPECI Reports. When using Form MF1M-10C, the observer shall explain briefly the reasons for any missing data in block 65, Remarks, Notes, and Miscellaneous Phenomena.

When a METAR observation is taken late, but within 15 minutes of the standard time of observation, and no appreciable changes have occurred since the standard time, the observer shall record the observation and transmit it using the actual time of observation. If conditions have changed appreciably or the observation is more than 15 minutes late, the observer shall skip a line and record and transmit a SPECI observation containing all the elements in a METAR observation. After transmitting the SPECI, using the actual time of observation, the observer shall estimate the conditions probable at the standard time using recording instruments whenever possible. The observer shall record this data on the skipped line using the standard time in column 2. The estimated observation shall not be transmitted. The observer shall make note in column 65 referencing the actual time of observation that the estimated observation was recorded.

To make a correction on Form MF1M-10C, the observer shall draw a single line through the erroneous entry. The observer shall not erase or otherwise obliterate entries. The observer shall record corrected data in the appropriate blocks on the same or next line appropriately identified.

At LAWRS, the observer shall enter the official station name and state abbreviation in the block labeled STATION. The four-letter Airport ID shall be included in the SID block. Also in the blocks provided, the observer shall enter the date and time (in Coordinated Universal Time (UTC)) and the conversion factor used to convert Local Standard Time (LST) to UTC. The observer shall check after UTC to indicate that the times used in column 2 of the form are in UTC. In the blocks labeled LATITUDE and LONGITUDE, enter the station’s latitude and longitude to the nearest minute of a degree. In the block labeled STATION ELEVATION, enter the station’s elevation (H_p) to the nearest foot.

In the block labeled STATION, the observer shall enter the type of station, the official station name and state abbreviation. The four-letter Airport ID shall be included in the SID block. Also in the blocks provided, the observer shall enter the date and time (in LST), and conversion factor used to convert LST to UTC. In the blocks labeled LATITUDE and LONGITUDE, enter the station’s latitude and longitude to the nearest minute of a degree. In the block labeled STATION ELEVATION, enter the station’s elevation (H_p) to the nearest foot.

The column number corresponds to the column number on the form MF1M-10A/B. Many of these columns do not appear on Form MF1M-10C. The procedures and practices given below are only for those columns applicable at FAA facilities. In addition, some of the columns may only be applicable at designated stations.

16-11.   TYPE OF OBSERVATION (COLUMN 1)

M shall be recorded to designate a METAR observation, S shall be recorded to designate a SPECI observation.

At LAWRS, the observer shall record the actual time of the observation in Coordinated Universal Time (UTC). At all other stations, the observer shall record the actual time of observation in Local Standard Time (LST).

The observer shall record the true wind direction from which the wind is blowing in tens of degrees using three figures. Directions less than 100 degrees shall be preceded with a 0. When the wind is calm, the observer shall enter 000 for the direction. When the wind speed is 6 knots or less, the direction may be recorded as VRB.

The observer shall record the wind speed in whole knots using the hundreds digit (if not zero), and the tens and units digit. The observer shall record speeds of less than 10 knots with a leading zero. For example, a wind speed of 5 knots shall be logged as 05. A wind speed of 105 knots shall be logged as 105. Calm winds shall be recorded as 00.

When gusts have been recorded or observed during the 10 minutes prior to the actual time of observation, the observer shall enter the peak speed.

When wind direction fluctuates by 60 degrees or more during the 2-minute evaluation period and the wind speed is greater than 6 knots, the observer shall enter the range of variability. A wind direction fluctuating between 260 degrees and 40 degrees shall be entered as 260V040.

The observer shall record the surface prevailing visibility (column 7a) determined from the weather station's usual point(s) of observation using the nearest reportable value listed in Figure 15-3, Reportable Visibility Values. The observer shall record tower visibility if either the surface prevailing visibility or the tower visibility is less than 4 miles. Tower visibility (column 7b) shall be determined from the air traffic control tower using the nearest reportable value listed in Figure 15-3, Reportable Visibility Values.

At designated stations, the observer shall record the RVR to match the coding in paragraph 15-13, Runway Visual Range Group.

Record weather and obscurations occurring at the station using the order described in paragraph 11-6, Order for Reporting Multiple Types of Weather and Obscurations. Weather intensity symbols and codes are shown in Figure 11-1, Present Weather. Only record obscurations if the visibility is reduced to less than 7 miles, except for volcanic ash, which is always recorded.

The procedures for reporting sky condition are given in Chapter 12, Sky Condition. The observer shall record sky cover data according to paragraph 15-15, Sky Condition Group. The observer shall record data for each layer of clouds and obscuring phenomena visible from the station regardless of amount. The observer shall make entries in ascending order of height for bases of each layer. An additional line can be added if more space is needed.

a.  Sky Cover. The observer shall record any sky cover which is visible from the station using the appropriate contractions or combination of contractions from Figure 12-1, Reportable Contractions for Sky Cover. If the sky cover is variable, see paragraphs 12-33, Variable Sky Cover, and 15-37, Variable Sky Condition.

b.  Height of Sky Cover. Heights of layers shall be reported and rounded to the nearest reportable increment listed in Figure 12-3, Increments of Reportable Values for Layer or Ceiling Heights. When a value falls halfway between two reportable increments, the lower value shall be reported. When a layer is 50 feet or less above the surface, the height reported is 000. If the ceiling height is variable, see paragraph 12-36, Variable Ceiling Height, and paragraph 15-35, Variable Ceiling Height, for reporting procedures.

The observer shall record the dry-bulb temperature to the nearest whole degree Celsius (see paragraph 3-9, Rounding Off Numbers). Sub-zero temperatures shall be prefixed with a minus sign (-). An "M" shall be prefixed to sub-zero temperatures in the transmitted observation. The observer shall add a leading zero to temperatures of only one digit (2 is recorded as 02.).

The observer shall record the dew point temperature to the nearest whole degree Celsius. Sub-zero dew point temperatures shall be prefixed with a minus sign (-). An "M" shall be prefixed to sub-zero dew point temperatures in the transmitted observation. When the dry-bulb temperature is -34°C (-30ºF) or below, the dew point is considered to be statistical data. In such cases, the observer shall leave column 12 blank and not transmit a value. The observer shall add a leading zero to temperatures of only one digit (4 is recorded as 04). If dew point temperature is unavailable, leave the column blank.

The observer shall record the altimeter setting in inches of mercury using only the tens, units, tenths, and hundredths digits (without a decimal point). For example, record 29.94 as 2994. Altimeter settings shall never be estimated, however, if the altimeter setting is missing, column 13 is left blank.

The observer shall record all remarks in column 14 according to the procedures in Chapter 15, Coding and Dissemination. The procedures for coding remarks are the same procedures for entering the data into column 14, MF1M-10C. The observer may use additional lines of the form, if required.

For each hourly observation, the observer shall record the eighths of sky hidden by surface-based obscuring phenomena and sky covered (not necessarily hidden) by all clouds and obscuring phenomena aloft that are visible from the station. For example, record 1 for any clouds up to one-eighth sky cover, 5 for five-eighths, 8 for eight eighths.

The observer shall record the dry-bulb temperature in degrees and tenths of degrees Celsius if psychrometric data are obtained from other than a hygrothermometer or an equivalent system. At part-time stations, the observer shall record hourly temperatures in whole degrees from the thermograph for the hours when observers are not on duty. If a thermograph is not available, the observer shall make no entry in this column. Sub-zero temperatures shall be prefixed with a minus sign (-).

The observer shall record the wet-bulb temperature in degrees and tenths of degrees Celsius if psychrometric data are obtained from other than a hygrothermometer or an equivalent system. Sub-zero temperatures shall be prefixed with a minus sign (-).

The observer shall record the station pressure in this column to the nearest 0.005 inches of mercury. Part-time stations should record the corrected station pressure from the barograph at the time of the 3-hourly or 6-hourly observation prior to the station reopening. This is needed in determining the 3-hour pressure change (ppp).

The certified observer responsible for the observation shall initial this column.

The observer shall record the beginning time of the first 6-hourly observation scheduled after 0000 LST on the line captioned "MID TO" and the following line captioned "1" from column 27. On the following three lines, the observer shall record in chronological order the beginning times of the subsequent 6-hourly observations. The observer shall record entries in hours and minutes (4 digits) to the nearest minute. At stations in the time zone where midnight LST corresponds to the time of a 6-hourly observation, the lines captioned "MID TO" and "MID" shall not be used. Observers at stations not open for the full 24 hour calendar day shall follow these same instructions.

The observation number identifies the first, second, third, and fourth 6-hourly observations of the day. No entry is required.

The observer shall record the maximum temperature in column 31 and the minimum temperature in column 32 in tenths of degrees Celsius, using 3-digits that occurred: between midnight and the first 6-hourly observation, in the six hours prior to each 6-hourly observation, and between the last 6-hourly observation and midnight, in the lines labeled "MID TO," "1," "2," "3," "4," and "MID," respectively. The temperature recorded on the last METAR observation of the previous day, having a standard time 0000 LST of the current day, shall be considered when determining the maximum and minimum temperature from midnight to the first 6-hourly. At part-time stations that do not have a thermograph, the loss of data can be avoided by using base temperature extremes for the 24-hour period beginning when the station closes to the time the station closes the next day. If the station is open at midnight, temperature extremes should be maintained from midnight to midnight. Otherwise, the observer shall do as follows:

a.  Reset the maximum and minimum displays or thermometers at the time of the last 6-hourly taken before the station closes.

b.  At the time of the first 6-hourly after the station opens, record the extremes on the appropriate line of columns 31 and 32 that correspond to the 6-hour time frame. Record in block 65, the period during which the temperature extremes were recorded; e.g., COL31-32 0645 12HR TEMP EXTREMES.

c.  Use the extremes that occurred during the 24 hours before the station closes to complete the summary of the day temperature data. Record in block 65, the column numbers and the temperature period covered; e.g., COL66-67 TEMPERATURE DATA FROM 1800 TO 1800.

d.  If a thermograph is used, the observer shall follow paragraph 16-33, Precipitation, to enter the 6-hourly synoptic times that occur from midnight to midnight in column 26. The observer shall do this even if the station is not open for the full 24 hour calendar day. From the thermograph, the observer shall determine the maximum temperature to record in column 31 and the minimum temperature for column 32. The observer shall use these values to determine the summary of the day information required in columns 57 and 58.

At 6-hourly observation times, the observer shall record the amounts of precipitation that occurred during the periods as indicated below. The observer shall record amounts to the nearest hundredth of an inch except that "T" shall be recorded for amounts less than 0.005 inch and "0" shall be recorded if no precipitation occurred.

a.  At stations taking midnight observations, the observer shall record the amount of precipitation that occurred between midnight LST and the first 6-hourly observation time on the line captioned "MID TO."

b.  On lines "1," "2," "3," and "4" (as indicated in column 27), the observer shall record the amount of precipitation that occurred in the previous six hours.

c.  When midnight observations are taken, the observer shall record the amount of precipitation that occurred between the last 6-hourly observation time and the midnight observation on the line captioned "MID."

d.  Whenever the water equivalent of solid precipitation cannot be measured by melting or weighing of the sample or core sampling, the observer shall estimate the water equivalent on the basis of a 1/10 ratio method unless a different ratio is more appropriate for the individual storm or station. The observer shall record in block 65, the column number, the time of the observation, and the ratio used; e.g., COL33 1245 1/2 RATIO USED.

At 6-hourly observation times, the observer shall record the amount of solid precipitation that fell in the six hours prior to the observation on the lines numbered (in column 27) "1," "2," "3," and "4." At stations taking midnight observations, the observer shall record the snowfall between midnight and the first 6-hourly observation on the line captioned "MID TO." On the line captioned "MID", the observer shall record the amount of snowfall that occurred between the last 6-hourly observation and midnight. "Snow" as used in this and the following snow depth sections includes all types of solid precipitation; e.g., SN, GS, SG, PL, IC, and GR. The observer shall make entries as follows:

a.  If there is no solid precipitation, record a "0."

b.  A trace, but less than 0.05 inch, record a "T."

c.  A measurable amount occurred, record the maximum depth of solid precipitation to the nearest 0.1 inch. If solid precipitation occurred several times during the period, and each fall melted either completely or in part before the next fall, record the total of the maximum depths of each fall.

d.  If an amount consists entirely of hail, record in block 65, the column number, the time of the observation, and HAIL; e.g., COL34 0045 HAIL.

e.  In order to preserve climatological snowfall records at stations operating under reduced hours, the following guidelines are presented. It is important that you exercise your acquired skills to make this estimate. If it is reasonable to assume that all new precipitation which fell was frozen and the conditions were rather consistent throughout the period, various methods may be used to estimate the snowfall for the period; e.g., basis of 1/10 ratio method unless a different ratio is more appropriate for the individual storm or station, or measurements in protected areas. The estimate should be based upon your best judgment. Record in block 65, the column number, the time of the observation, and ESTIMATED. The reason for the estimation may also be included; e.g., COL34 0045 ESTIMATED DUE TO STATION CLOSURE.

f.  If an estimated amount cannot be reasonably made, (e.g., several days of closure, mixed precipitation, etc.) missing (M) should be recorded in column 34 and column 60 for the day.

g.  It is assumed that if an estimated amount is explained in block 65 for column 34, the summary of the day (column 61) is also considered to be estimated. A second remark to denote that column 61 is estimated is not required. Any estimated amounts in column 34 should be explained in block 65. Record the column number, the time of the observation, and the reason for the estimation; e.g., COL34 1244 ESTIMATED DUE TO MELTING.

The observer shall record the depth of solid precipitation and ice on the ground at the time of each 6-hourly observation and, if taken, at the time of the midnight observation on the lines identified as "1," "2," "3," "4," and "MID," respectively. Entries shall be as follows:

a.  No snow or ice on the ground in exposed areas (snow may be present in surrounding forested or otherwise protected areas), record a "0."

b.  A trace, but less than 0.5 inch, on the ground in representative areas, record a "T."

c.  If there is a measurable amount on the ground, record the depth to the nearest whole inch.

d.  When solid precipitation has occurred in the past six hours and because of melting or sublimation, the current depth is less than at some time during the six hours (reportable value), record the current depth in column 35. In block 65, record the maximum snow depth and the approximate time (LST) of the occurrence. Record the column number, the time of the observation, and the approximate time of the occurrence; e.g., COL35 1846 MAX SNOW DEPTH 1 AT 1530.

e.  If the depth consists entirely of hail, record in block 65, the column number, the time of the observation, and HAIL; e.g., COL35 1844 HAIL.

f.  Snow depth is entered in column 35 at the main synoptic times (00, 06, 12, and 18 UTC) when measured by observing personnel. When observing personnel are not on duty the entry shall be an "M."

16-36.   STATION PRESSURE (COLUMN 36) (NA LAWRS)

a.  Mercury Barometer. If a mercury barometer is used to determine station pressure, the observer shall record in this column the sum of the barometer reading (to the nearest thousandth [0.001] inch) and the value obtained from the Total Correction Table (or the value obtained by addition of the sum of corrections given on the Barometer Correction Card and the temperature correction to the nearest thousandth of an inch.)

b.  Precision Aneroid Barometer or Altimeter Setting Indicator. If a precision aneroid barometer or altimeter-setting indicator is used to determine station pressure, the observer shall record the reading to the nearest 0.005 inch (or 0.1 hectopascal).

The observer shall record the observed barograph reading to the nearest 0.005 inch (or 0.1 hectopascal).

The observer shall subtract column 37 from column 36 and record the difference to the nearest 0.005 inch (or 0.1 hectopascal) with the proper sign in column 38. If column 37 is higher than column 36, the correction in column 38 shall be preceded by a minus sign. If this difference is greater than 0.05 inch (or 1.5 hPa), the observer shall precede the entry with an asterisk "*" and reset the barograph to a zero correction. In block 65, the observer shall record the reason for the asterisk and the time (LST); for example, *BAROGRAPH RESET TO ZERO CORRECTION AT 1458.

The observer shall record the maximum temperature recorded in column 57 for the day to the nearest tenth of a degree Celsius. Any temperature below 0C shall be preceded by a minus (-). The observer shall disregard the entry in column 57 on the line captioned "1" if the midnight observation is taken. The observer shall record "M" if any data are missing.

The observer shall record the minimum temperature recorded in column 58 for the day to the nearest tenth of a degree Celsius. Any temperature below 0C shall be preceded by a minus (-). The observer shall disregard the entry in column 58 on the line captioned "1" if the midnight observation is taken. The observer shall record "M" if any data are missing.

The observer shall record the total precipitation for the 24 hours ending at midnight (LST) as follows:

a.  No precipitation, record a "0."

b.  A trace (less than 0.005 inch), record a "T." A trace amount includes the sum of any number of "T" observations, unless a recording or totalizing gauge indicates 0.005 inch or more.

c.  A measurable amount has occurred, record the amount (water equivalent) to the nearest 0.01 inch.

d.  Where the 24-hour precipitation is derived from entries in column 33, disregard the entry in column 33 on the line captioned "1" if the midnight observation is taken. Record "M" if any data are missing.

e.  If the station is closed and unless measurable precipitation has occurred, record "0."

f.  If any entries in column 33 are missing, the entry in column 59 will also be missing (M).

g.  If any entries in column 33 are estimated (block 65 remark), the entry in column 59 shall also be considered estimated. A remark in block 65 is not required to denote an estimated amount in column 59 since a remark is already noted for column 33.

The observer shall record the total amount (unmelted) of solid precipitation that fell in the 24 hours ending at midnight (LST) as follows:

a.  No 6-hour solid precipitation, record a "0."

b.  A trace (less than 0.05 inch), record a "T."

c.  A measurable amount occurred, record the total amount that fell in inches and tenths. Note that it is the total amount of fall that is entered. Therefore, the amount entered shall be the amount that accumulated in the past 24 hours adjusted for any melting or evaporation that has taken place.

d.  Where the 24-hour precipitation is derived from entries in column 34, disregard the entry in column 34 on the line captioned "1" if the midnight observation is taken. Record "M" if any data are missing. The sum of all trace entries is a trace.

e.  If any entries in column 34 are estimated (block 65 remark), the entry in column 60 will also be considered estimated. A remark in block 65 is not required to denote an estimated amount in column 60 since a remark is already noted for column 34.

f.  If any entries in column 34 are missing, the entry in column 60 will also be missing (M).

The observer shall record the depth of solid precipitation or ice on the ground at 1200 UTC. In areas outside the contiguous United States, enter a modified time at the top of the column as necessary to meet regional needs. The observer shall make entries to the nearest whole inch, or as follows:

a.  No snow or ice on the ground in exposed areas (snow may be present in surrounding forested or otherwise protected areas), record a "0."

b.  For a trace (less than 0.5 inch), in exposed areas, record a "T."

c.  Use the 1200 UTC value in column 35, if appropriate.

d.  If personnel are not on duty at 1200 UTC, enter the depth measured as near 1200 UTC as practicable and indicate the time (UTC) in block 65; e.g., COL70 OBSERVED AT 1120 UTC.

The observer shall use this block to record data considered significant, but not recorded elsewhere along with information in the following subsections.

a.  The observer shall record the Local Standard Time (LST) of occurrence with all entries unless otherwise specified.

b.  The observer shall make entries to report:

(1)  Conditions affecting the representativeness or accuracy of the recorded data. For example, the possible effect of construction on instrument readings, accumulation of ice or snow on sensors.

(2)  Outages, changes in instruments, reasons for change, times of change or outage.

(3)  Reasons for omission of mandatory data.

(4)  Change in hours of station operation, effective dates, if temporary, or date if permanent.

(5)  Estimated data.

(6)  Miscellaneous items; e.g., when a Basic Weather Watch or Continuous Weather Watch began or ended; approximate date/time and location of an aircraft mishap, when notified by the FAA (FSS/TWR) of an aircraft mishap.

(7)  Separate individual remarks by a single solidus (/); e.g. COL34 0245 ESTIMATED DUE TO HIGH WINDS/COL45 LAST OF SEVERAL OCCURRENCES/
GLAZE 1155-1405.

(8)  The clock designated as the station standard shall be checked at intervals as stated in paragraph 3-4g, Accuracy of Time in Observations. At least one time check daily shall be recorded and annotated. If a facility has another procedure for taking and recording time checks, the time check block may remain blank.

During hours of operation, the observer shall make entries on MF1M-10C according to the instructions in this order. Entries on MF1M-10C shall only be made to record data transmitted by observing personnel. The observer shall record missing (M) for unknown data.

At stations equipped with a gust recorder, and where less than 24 METAR observations are taken daily, the observer shall enter the 2-minute wind speed in the left hand margin of MF1M-10C. The observer shall enter a time next to it in parentheses to indicate the minute used for the wind speed. The observer shall use the same minute for each hour the station was closed. If the fastest recorded 2-minute wind should occur while the station was closed, the observer shall enter missing (M) for the wind direction.

Although the observer may make entries on the form to suit the data available, all data transmitted shall be in accordance with the instructions in this order. Each character encoded and transmitted in the 3- and 6-hourly observations additive data groups has a meaning as specified in Chapter 15, Coding and Dissemination, and shall not be changed to meet the station's available data.

Columns 26 and higher were designed for stations that operate continuously. Part-time stations shall also record data for a 24-hour period, but because many part-time stations are not open at midnight, and do not have continuous recording instruments, their 24 hour day (or their station day) begins when the station closes and ends 24 hours later. Although the station day begins on the previous calendar day, the times entered in column 26 shall be the times (LST) of the main 6-hourly synoptic reports made during the calendar day entered in the heading of the form. In column 26, the observer shall disregard the "MID TO" and "MID" lines and on the line captioned "1," record the time of the first 6-hourly of the day. The precipitation and temperature extremes entered on that line cover the period from the last 6-hourly observation taken before the station closed (the previous day) to the current 6-hourly observation. The observer shall reference the time of observation (column 26) and in block 65, record the number of hours, 12 or more since the last 6-hourly; e.g., COL42 0645 12HR DATA. The times on the following lines shall be 6 hours apart and the entries shall cover the previous 6 hours.

a.  Snowfall, Column 34 (NA LAWRS). The entry on line "1" for snowfall, column 34, during the period when observing personnel were not on duty can be either "0," an amount, or missing (M). The observer shall record "0" if, from conditions before the station closed until it opened, it is reasonably certain that no solid precipitation occurred. If the observer is unsure, because of mixed precipitation or several days of station closure, the observer shall record "M" (missing) in this column and also in column 60. If any amount in column 34 is missing, the M shall be carried in column 60. The observer shall estimate snowfall if conditions were generally consistent throughout the period and all new precipitation was considered to be frozen. If any amount in column 34 is estimated, the observer shall reference the column number and the time of observation in block 65, and shall record that the data was estimated; e.g., COL34 0644 ESTIMATED. The observer may also indicate why the data was estimated. If any amount in column 34 was estimated, and none was considered missing, column 60 shall also be considered as estimated.

b.  Station Day, Columns 57 through 61 (NA LAWRS). The observer shall use the entries in columns 31 through 35 to complete the summary of day columns 57 through 61 for the "station" day. The observer shall line out "MIDNIGHT TO MIDNIGHT" and shall record the 24-hour period covered unless recording instruments are used for precipitation or temperature. For example, if the station's hours of operation are from 0600 to 1800, the station day is from 1800 the previous day to 1800 the current day (remember the first 6-hourly observation contained data for a 12-hour period).

The accuracy of weather observations is important after the fact since the National Climatic Data Center (NCDC) utilizes this information to update climatological records for the U.S. If a station discovers that erroneous weather information was transmitted long-line, they are encouraged to send the corrected weather data using WS Form B-14, or, if the form is not available, by letter to the address provided below. (See Figure 16-1, WS Form B-14.)

NCDC Services Center
Image Entry
465 Industrial Blvd.
London, KY 40741

Figure 16-2, Example of Entries on MF1M-10C, presents an example of a filled-in MF1M-10C form.

Figure 16-2. Example of Entries on MF1M-10C