Weather Reports¶
Weather Report Types¶
APRS is an ideal tool for reporting weather conditions via packet. APRS is also ideally suited for the Skywarn weather observer initiative.
APRS supports three types of Weather Report:
-
- Raw Weather Report (not recommended - sending system should reformat data into Complete Weather Report format)
- Positionless Weather Report (not recommended - sending system should reformat data into Complete Weather Report format)
- Complete Weather Report
Data Type Identifiers¶
The following APRS Data Type Identifiers are used in Weather Reports containing raw data:
! Ultimeter 2000
# Peet Bros U-II
$ Ultimeter 2000
* Peet Bros U-II
_ Positionless weather data (not recommended)
In addition, where the raw data has been post-processed (for example, by the insertion of station location information), the four position Data Type Identifiers !, =, / and @ may be used instead. In this case, the Weather Report is identified with the weather symbol /_ or \_ in the APRS Data.
Raw Weather Reports (not recommended)¶
Raw weather data from a stand-alone weather station is contained in the Information Field of an APRS AX.25 frame.
Raw Weather Formats are not recommended. Sending stations should convert to complete format on RF.
Bytes:
| Raw Weather Report Format - Not recommended | |
|---|---|
| ! or # or $ or * | Raw Weather Data |
| 1 | n |
| Examples !!006B005803500000----03E9--------002105140000005D Ultimeter 2000 #50B7500820082 Peet Bros U-II $ULTW0031003702CE0069----000086A00001----011901CC00000005 Ultimeter 2000 *7007600000000 Peet Bros U-II |
Positionless Weather Reports (not recommended)¶
Generic raw weather data from a stand-alone weather station is contained in the Information Field of an APRS AX.25 frame.
The WinAPRS "positionless" weather format is not recommended.
Bytes:
| Positionless Weather Report Format - Not recommended | ||||
|---|---|---|---|---|
| _ | Time MDHM | Weather Data | APRS Software S | WX Unit uuuu |
| 1 | 8 | n | 1 | 2-4 |
| Example _10090556c220s004g005t077r000p000P000h50b09900wRSW report derived from Radio Shack WX station data. |
APRS Software Type¶
A Weather Report may contain a single-character code S for the type of APRS software that is running at the weather station:
d = APRSdos
M = MacAPRS
P = pocketAPRS
S = APRS+SA
W = WinAPRS
X = X-APRS (Linux)
Weather Unit Type¶
A Weather Report may contain a 2–4 character code uuuu for the type of weather station unit. The following codes have been allocated:
= Davis
| Dvs | |
|---|---|
| HKT | |
| PIC | |
| RSW | |
| U-II | |
| U2R | |
| U2k | |
| U2kr | |
| U5 | |
| Upkm |
= Heathkit
= PIC device
= Radio Shack
= Original Ultimeter U-II (auto mode)
= Original Ultimeter U-II (remote mode)
= Ultimeter 500/2000
= Remote Ultimeter logger
= Ultimeter 500
= Remote Ultimeter packet mode
O = Otracker
K = Kenwood
B = Byonics
Y = Yaesu
Users may specify any other 2–4 character code for devices not in this list.
Weather Data¶
The format of weather data within a Weather Report differs according to the type of weather station unit, but generically consists of some or all of the following elements:
Bytes:
| Weather Data | ||||||||
|---|---|---|---|---|---|---|---|---|
| Wind Direction cccc | Wind Speed ssss | Gust gggg | Temp tttt | Rain Last Hr rrrr | Rain Last 24 Hrs pppp | Rain Since Midnight PPPP | Humidity hhh | Barometric Pressure bbbbbb |
| 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 6 |
where: c = wind direction (in degrees).
s = sustained one-minute wind speed (in mph).
g = gust (peak wind speed in mph in the last 5 minutes).
t = temperature (in degrees Fahrenheit). Temperatures below zero are expressed as -01 to -99.
r = rainfall (in hundredths of an inch) in the last hour.
p = rainfall (in hundredths of an inch) in the last 24 hours.
P = rainfall (in hundredths of an inch) since midnight.
h = humidity (in %. 00 = 100%).
b = barometric pressure (in tenths of millibars/tenths of hPascal).
Other parameters that are available on some weather station units include:
L = luminosity (in watts per square meter) 000 to 999.
l (lower-case letter “L”) = luminosity (in watts per square meter) 1000 and above. (Actual value is 1000 more than 3 digit number.)
(L is inserted in place of one of the rain values).
s = snowfall (in inches) in the last 24 hours. 3 digits.
A decimal point is allowed for non-integer values.
# = raw rain counter
Note: The weather report must include at least the MDHM date/timestamp, wind direction, wind speed, gust and temperature, but the remaining parameters may be in a different order (or may not even exist).
Note: Where an item of weather data is unknown or irrelevant, its value may be expressed as a series of dots or spaces. For example, if there is no wind speed/direction/gust sensor, the wind values could be expressed as:
c...s...g... or c˽˽˽s˽˽˽g˽˽˽
For example, Jim’s rain gauge may produce a report like this:
_10090556c...s...g...t...P012Jim
(The date/timestamp, wind direction/speed/gust and temperature parameters must be included, even though they are not meaningful).
Location of a Raw and Positionless Weather Stations¶
APRS cannot display weather data on a map until it knows the location of the sending station. In the case of a station transmitting Raw or Positionless Weather Reports, the station has to occasionally send an additional packet containing its position (using any of the legal lat/long and compressed lat/long position formats described earlier).
Raw Weather Formats not recommended. Microprocessors should convert to complete format on RF.
Symbols with Raw and Positionless Weather Stations¶
Because Raw and Positionless Weather Reports do not contain a display symbol in the AX.25 Information field, it is possible to specify the symbol in a generic APRS destination address (e.g. GPSHW or GPSE63) instead.
Alternatively, if the weather station is on a balloon, the SSID –11 may be used in the source address (e.g. N0QBF-11).
Raw Weather Formats not recommended. Sending stations should convert to complete format on RF.
See Chapter 20: APRS Symbols for more detail on the usage of symbols.
Complete Weather Reports with Timestamp and Position¶
An APRS Complete Weather Report can contain a timestamp and location information, using any of the legal lat/long and compressed lat/long position formats described earlier. An APRS Object may also have weather information associated with it.
Examples of report formats are shown below. Note that the Symbol Code in every case is the _ (underscore). Also, the 7-byte Wind Direction and Wind Speed Data Extension replace the cccc and ssss fields of a Positionless Weather Report.
| Complete Weather Report Format — with Lat/Long position, no Timestamp | ||||||||
|---|---|---|---|---|---|---|---|---|
| ! or = | Lat | Sym Table ID | Long | Symbol Code _ | Wind Directn/ Speed | Weather Data | APRS Software S | WX Unit uuuu |
| 1 | 8 | 1 | 9 | 1 | 7 | n | 1 | 2-4 |
| Examples !4903.50N/07201.75W_220/004g005t077r000p000P000h50b09900wRSW !4903.50N/07201.75W_220/004g005t077r000p000P000h50b. wRSW |
Bytes:
Bytes:
| Complete Weather Report Format — with Lat/Long position and Timestamp | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| / or @ | Time DHM / HMS | Lat | Sym Table ID | Long | Symbol Code _ | Wind Directn/ Speed | Weather Data | APRS Software S | WX Unit uuuu |
| 1 | 7 | 8 | 1 | 9 | 1 | 7 | n | 1 | 2-4 |
| Example @092345z4903.50N/07201.75W_220/004g005t-07r000p000P000h50b09900wRSW |
| Complete Weather Report Format — with Compressed Lat/Long position, no Timestamp | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| ! or = | Sym Table ID | Comp Lat YYYY | Comp Long XXXX | Symbol Code _ | Comp Wind Directn/ Speed | Comp Type T | Weather Data | APRS Software S | WX Unit uuuu |
| 1 | 1 | 4 | 4 | 1 | 2 | 1 | n | 1 | 2-4 |
| Example =/5L!!<*e7>_7P[g005t077r000p000P000h50b09900wRSW |
Bytes:
| Complete Weather Report Format — with Compressed Lat/Long position, with Timestamp | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| / or @ | Time DHM / HMS | Sym Table ID | Comp Lat YYYY | Comp Long XXXX | Symbol Code _ | Comp Wind Directn/ Speed | Comp Type T | Weather Data | APRS Software S | WX Unit uuuu |
| 1 | 7 | 1 | 4 | 4 | 1 | 2 | 1 | n | 1 | 2-4 |
| Example @092345z/5L!!<*e7_7P[g005t077r000p000P000h50b09900wRSW |
Bytes:
| Complete Weather Report Format — with Object and Lat/Long position | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| ; | Object Name | * | Time DHM / HMS | Lat | Sym Table ID | Long | Symbol Code _ | Wind Directn/ Speed | Weather Data | APRS Software S | WX Unit uuuu |
| 1 | 9 | 1 | 7 | 8 | 1 | 9 | 1 | 7 | n | 1 | 2-4 |
| Examples ;BRENDA˽˽˽*4903.50N/07201.75W_220/004g005t077r000p000P000h50b09900wRSW ;BRENDA˽˽˽*092345z4903.50N/07201.75W_220/004g005b0990 |
Bytes:
Storm DataAPRS reports can contain data relating to tropical storms, hurricanes and tropical depressions. The format of the data is as follows:
| Storm Data | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Direction | / | Speed | Storm Type /ST | Sustained Wind Speed /www | Peak Wind Gusts ^GGG | Central Pressure /pppp | Radius Hurricane Winds >RRR | Radius Tropical Storm Winds &rrr | Radius Whole Gale %ggg |
| 3 | 1 | 3 | 3 | 4 | 4 | 5 | 4 | 4 | 4 |
Bytes:
where: ST = TS (Tropical Storm)
HC (Hurricane)
TD (Tropical Depression).
www = sustained wind speed (in knots).
GGG = gust (peak wind speed in knots).
pppp = central pressure (in millibars/hPascal)
RRR = radius of hurricane winds (in nautical miles). rrr = radius of tropical storm winds (in nautical miles). ggg = radius of “whole gale” (i.e. 50 knot) winds (in
nautical miles). Optional.
Storm data will usually be included in an Object Report, but may also be included in a Position Report or an Item Report.
The display symbol will be either:
\@ Hurricane/Tropical Storm (current position)
/@ Hurricane (predicted future position)
For example, the progress of Hurricane Brenda could be expressed in Object Reports like these:
;BRENDA*092345z4903.50N**07202.75W@**088/036/HC/150^200/0980>090&030%040
;BRENDA*100045z4905.50N/07201.75W@101/047/HC/104^123/0980>065&020%040
National Weather Service Bulletins¶
APRS supports the dissemination of National Weather Service bulletins. See Chapter 14: Messages, Bulletins and Announcements.