jdc 22-jun-2007
METAR data can be obtained from http://www.noaa.org/ using ftp. This package can query data from the NOAA server and parse METAR data (obtained with this package or otherwise). Use the code below or try it with a GUI like tclMetarGui
KPV See also TclWeather and A Very Simple Weather App both of which download and parse METAR data.
package provide tclmetar 0.1
package require ftp
namespace eval ::tclmetar {
variable ftpsock
variable metar_keys {abbrev raw year month day hour minute corrected winddir winddirstr windspeed windgust windvarfrom windvarfromstr windvarto windvartostr temperature dewpoint airpressure cloudstype cloudsheight toweringcumulus cumulonimbus weather visibility}
}
proc ::tclmetar::get_winddirstr { winddir } {
if { [string is integer -strict $winddir] } {
set wsi [expr {int(($winddir+11.25)/22.5)}]
return [lindex {N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW N} $wsi]
}
return $winddir
}
proc ::tclmetar::parse_wind { f wd winddirnm winddirstrnm ws windspeednm wg windgustnm wu } {
upvar $winddirnm winddir
upvar $winddirstrnm winddirstr
upvar $windspeednm windspeed
upvar $windgustnm windgust
set winddir [string trimleft $wd "0"]
if { [string length $winddir] == 0 } {
set winddir 0
}
set windspeed [string trimleft $ws "0"]
if { [string length $windspeed] == 0 } {
set windspeed 0
}
set windgust [string trimleft [string range $wg 1 end] "0"]
if { [string length $windgust] == 0 } {
set windgust 0
}
switch -exact -- $wu {
"KT" {
set windspeed [expr {round($windspeed * 1.852)}]
set windgust [expr {round($windgust * 1.852)}]
}
"MPS" {
set windspeed [expr {round($windspeed * 3.6)}]
set windgust [expr {round($windgust * 3.6)}]
}
"KMH" {
}
}
set winddirstr [get_winddirstr $winddir]
return
}
proc ::tclmetar::parse_wind_variability { wvf windvarfromnm windvarfromstrnm wvt windvartonm windvartostrnm } {
upvar $windvarfromnm windvarfrom
upvar $windvartonm windvarto
upvar $windvarfromstrnm windvarfromstr
upvar $windvartostrnm windvartostr
set windvarfrom [string trimleft $wvf "0"]
if { [string length $windvarfrom] == 0 } {
set windvarfrom 0
}
set windvarfromstr [get_winddirstr $windvarfrom]
set windvarto [string trimleft $wvt "0"]
if { [string length $windvarto] == 0 } {
set windvarto 0
}
set windvartostr [get_winddirstr $windvarto]
return
}
proc ::tclmetar::parse_temperature { f tempnm } {
upvar $tempnm temp
if { [string match "M*" $f] } {
set temp -[string trimleft [string range $f 1 end] "0"]
if { [string equal $temp "-"] } {
set temp "0"
}
} else {
set temp [string trimleft $f "0"]
if { [string length $temp] == 0 } {
set temp "0"
}
}
}
proc ::tclmetar::parse_air_pressure { pv airpressurenm pu } {
upvar $airpressurenm airpressure
switch -exact -- $pu {
"A" {
set airpressure [string trimleft [string range $pv 0 1] "0"].[string range $pv 2 3]
set airpressure [expr {$airpressure * 0.033864}]
}
"Q" {
set airpressure [expr {[string trimleft $pv "0"] / 1000.0}]
}
}
return
}
proc ::tclmetar::parse_clouds { ct cloudstypenm ch cloudsheightnm cbtcu toweringcumulusnm cumulonimbusnm } {
upvar $cloudstypenm cloudstype
upvar $cloudsheightnm cloudsheight
upvar $toweringcumulusnm toweringcumulus
upvar $cumulonimbusnm cumulonimbus
switch -exact -- $ct {
SKC -
CLR -
NSC {
if { [string equal $cloudstype "<unknown>"] } {
set cloudstype SKC
} else {
lappend cloudstype SKC
}
}
FEW -
SCT -
BKN -
OVC {
if { [string equal $cloudstype "<unknown>"] } {
set cloudstype $ct
} else {
lappend cloudstype $ct
}
}
}
set ch [string trimleft $ch "0"]
if { [string length $ch] == 0 } {
set ch "0"
}
if { [string equal $cloudsheight "<unknown>"] } {
set cloudsheight [expr {$ch * 30.48}]
} else {
lappend cloudsheight [expr {$ch * 30.48}]
}
switch -exact -- $cbtcu {
CB {
set toweringcumulus 0
set cumulonimbus 1
}
TCU {
set toweringcumulus 1
set cumulonimbus 0
}
default {
set toweringcumulus 0
set cumulonimbus 0
}
}
return
}
proc ::tclmetar::parse_weather { int vic desc wea weathernm } {
upvar $weathernm weather
set wl [list $int $vic $desc $wea]
if { [string equal $weather "<unknown>"] } {
set weather [list $wl]
} else {
lappend weather $wl
}
return
}
proc ::tclmetar::parse_international_visibility { m visibilitynm } {
upvar $visibilitynm visibility
set visibility [string trimleft $m "0"]
if { [string length $visibility] == 0 } {
set visibility 0
}
return
}
proc ::tclmetar::parse_american_visibility { v1 v2 prevf visibilitynm } {
upvar $visibilitynm visibility
if { ([string length $v2] == 0) || [string equal $v2 "0"] } {
set v2 1
}
append v2 ".0"
if { ![string is integer -strict $prevf] } {
set prevf 0
}
set visibility [expr {($prevf + $v1/$v2) * 1609.34}]
return
}
proc ::tclmetar::parse { metarl mi_abbrev } {
set ar(abbrev) $mi_abbrev
set ar(raw) $metarl
set ar(year) "<unknown>"
set ar(month) "<unknown>"
set ar(day) "<unknown>"
set ar(hour) "<unknown>"
set ar(minute) "<unknown>"
set ar(corrected) "<unknown>" ;# bool
set ar(winddir) "<unknown>" ;# 0 = north, 90 = east
set ar(winddirstr) "<unknown>"
set ar(windspeed) "<unknown>" ;# in km/h
set ar(windgust) "<unknown>" ;# in km/h
set ar(windvarfrom) "<unknown>" ;# 0 = north, 90 = east
set ar(windvarfromstr) "<unknown>" ;# 0 = north, 90 = east
set ar(windvarto) "<unknown>" ;# 0 = north, 90 = east
set ar(windvartostr) "<unknown>" ;# 0 = north, 90 = east
set ar(temperature) "<unknown>" ;# in degrees Celcius
set ar(dewpoint) "<unknown>" ;# in degrees Celcius
set ar(airpressure) "<unknown>" ;# in bar
set ar(cloudstype) "<unknown>" ;# list of SKC (sky clear) | FEW | SCT (scattered) | BKN (broken) | OVC (overcast) | CAVOK
set ar(cloudsheight) "<unknown>" ;# list of heights in meter | CAVOK
set ar(toweringcumulus) "<unknown>" ;# bool
set ar(cumulonimbus) "<unknown>" ;# bool
set ar(weather) "<unknown>" ;# in metar abbreviations
set ar(visibility) "<unknown>" ;# in meter
set prevf ""
set mi_abbrev_found 0
foreach f $metarl {
ach f $metarl {
if { [string equal $mi_abbrev $f] } {
set mi_abbrev_found 1
continue
}
}
if { !$mi_abbrev_found && [regexp {([0-9]{4})/([0-9]{2})/([0-9]{2})} $f m y m d] } {
set ar(year) [string trimleft $y "0"]
set ar(month) [string trimleft $m "0"]
set ar(day) [string trimleft $d "0"]
} elseif { !$mi_abbrev_found && [regexp {([0-9]{2}):([0-9]{2})} $f ma h m] } {
set ar(hour) [string trimleft $h "0"]
if { [string length $ar(hour)] == 0 } {
set ar(hour) 0
}
set ar(minute) [string trimleft $m "0"]
if { [string length $ar(minute)] == 0 } {
set ar(minute) 0
}
} elseif { !$mi_abbrev_found } {
continue
} elseif { [string match "RMK*" $f] || [string match "TEMP*" $f] || [string match "NOSIG*" $f] } {
break
} elseif { [regexp {([0-9][0-9])([0-9][0-9])([0-9][0-9])Z} $f ma d h m] } {
# Date/time field
set ar(day) [string trimleft $d "0"]
set ar(hour) [string trimleft $h "0"]
if { [string length $ar(hour)] == 0 } {
set ar(hour) 0
}
set ar(minute) [string trimleft $m "0"]
if { [string length $ar(minute)] == 0 } {
set ar(minute) 0
}
} elseif { [string equal "COR" $f] } {
set ar(corrected) 1
} elseif { [string equal "AUT" $f] } {
set ar(corrected) 0
} elseif { [string match {R[0-9][0-9][LCR]*} $f] } {
# Runway visibility still to be added
} elseif { [regexp {([0-9]{3}|VRB)([0-9]{2,3})(G[0-9]{2,3})?(KT|KMH|MPS)} $f m wd ws wg wu] } {
# Wind field
parse_wind $f $wd ar(winddir) ar(winddirstr) $ws ar(windspeed) $wg ar(windgust) $wu
} elseif { [regexp {([0-9]{3})V([0-9]{3})} $f m wvf wvt] } {
# Wind variability
parse_wind_variability $wvf ar(windvarfrom) ar(windvarfromstr) $wvt ar(windvarto) ar(windvartostr)
} elseif { [regexp {^(M?[0-9][0-9])/+(M?[0-9][0-9])$} $f m temp dewp] } {
# Temperature field
parse_temperature $temp ar(temperature)
parse_temperature $dewp ar(dewpoint)
} elseif { [regexp {(A|Q)([0-9]{4})} $f m pu pv] } {
# Altimeter settings field
parse_air_pressure $pv ar(airpressure) $pu
} elseif { [regexp {(SKC|FEW|SCT|BKN|OVC|CLR|NSC)([0-9]{3})?(CB|TCU)?} $f m ct ch cbtcu] } {
# Clouds field
parse_clouds $ct ar(cloudstype) $ch ar(cloudsheight) $cbtcu ar(toweringcumulus) ar(cumulonimbus)
} elseif { [string equal $f "CAVOK"] } {
set ar(cloudstype) "CAVOK"
set ar(cloudsheight) "CAVOK"
set ar(cumulonimbus) 0
set ar(toweringcumulus) 0
set ar(visibility) 9999
} elseif { [regexp {([\+\-]?)(VC)?(MI|BC|PR|TS|BL|SH|DR|FZ)?(DZ|RA|SN|SG|IC|PI|GR|GS|UP|BR|FG|FU|VA|SA|HZ|PY|DU|SQ|SS|DU|PO|FC|\+FC)} $f m int vic desc wea] } {
# Weather field
parse_weather $int $vic $desc $wea ar(weather)
while { 1 } {
set f [string range $f [string length $m] end]
if { ![regexp {([\+\-]?)(VC)?(MI|BC|PR|TS|BL|SH|DR|FZ)?(DZ|RA|SN|SG|IC|PI|GR|GS|UP|BR|FG|FU|VA|SA|HZ|PY|DU|SQ|SS|DU|PO|FC|\+FC)} $f m int vic desc wea] } {
break
}
parse_weather $int $vic $desc $wea ar(weather)
}
} elseif { [regexp {[0-9]{4}} $f m ] } {
# International visibility field
parse_international_visibility $m ar(visibility)
} elseif { [regexp {^([0-9]{1,2})/?([0-9]{0,2})SM$} $f m v1 v2] } {
# American visibility field
parse_american_visibility $v1 $v2 $prevf ar(visibility)
}
# Visibility directions still to be added
set prevf $f
}
return [array get ar]
}
proc ::tclmetar::get_time { arnm } {
upvar $arnm ar
set y $ar(year)
while { [string length $y] < 4 } {
set y "0$y"
}
set M $ar(month)
while { [string length $M] < 2 } {
set M "0$M"
}
set d $ar(day)
while { [string length $d] < 2 } {
set d "0$d"
}
set h $ar(hour)
while { [string length $h] < 2 } {
set h "0$h"
}
set h "T$h"
set m $ar(minute)
while { [string length $m] < 2 } {
set m "0$m"
}
set s "00"
set mt [clock scan "$y$M$d$h$m$s" -gmt true]
return $mt
}
proc ::tclmetar::ftpopen { ftpserver ftpuser ftppassword ftpdir } {
variable ftpsock
set ftpsock [ftp::Open $ftpserver $ftpuser $ftppassword]
ftp::Cd $ftpsock $ftpdir
return
}
proc ::tclmetar::ftpget { mfile } {
variable ftpsock
set mdata ""
set rt [ftp::Get $ftpsock $mfile -variable mdata]
if { [string length $rt] && $rt } {
set mdata [string map {\n " " \r " " \t " "} [string trim $mdata]]
return [eval list [split $mdata]]
} else {
return -code error "Could not download file '$mfile'"
}
}
proc ::tclmetar::ftpclose { } {
variable ftpsock
ftp::Close $ftpsock
}
proc ::tclmetar::get_metar_data { mi_abbrev } {
set ftpserver tgftp.nws.noaa.gov
set ftpdir data/observations/metar/stations
set ftpuser anonymous
set ftppassword anonymous
set tVerbose $ftp::VERBOSE
set ::ftp::VERBOSE 0
::log::lvSuppress error
tclmetar::ftpopen $ftpserver $ftpuser $ftppassword $ftpdir
set rt [catch {tclmetar::ftpget $mi_abbrev.TXT} mi_data]
tclmetar::ftpclose
set ::ftp::VERBOSE $tVerbose
if { $rt } {
return -code error $mi_data
}
if { [catch {tclmetar::parse $mi_data $mi_abbrev} rl] } {
return -code error $rl
}
return $rl
}After a
package require tclmetar
the package is ready for use.
| abbrev | METAR station abbreviation |
| raw | Unparsed METAR data as obtained from the NOAA server |
| year | Year part of date on which METAR data was collected |
| month | Month part of date on which METAR data was collected |
| day | Day part of date on which METAR data was collected |
| hour | Hour part of date on which METAR data was collected |
| minute | Minute part of date on which METAR data was collected |
| corrected | Indication if METAR data was correct before upload to NOAA server by METAR Station of not |
| winddir | Wind direction, 0 = north, 90 = east, ... |
| winddirstr | String representation of wind direction (N, NNE, NE, ENE, E, ESE, SE, SSE, S, SSW, SW, WSW, W, WNW, NW, NNW, N) |
| windspeed | Wind speed, in km/h |
| windgust | Wind gusts, in km/h |
| windvarfrom | Variable wind direction from this direction, 0 = north, 90 = east, ... |
| windvarfromstr | String representation of wind variability from |
| windvarto | Variable wind direction to this direction, 0 = north, 90 = east, ... |
| windvartostr | String representation of wind variability to |
| temperature | Temperature, in degrees Celcius |
| dewpoint | Temperatur, in degrees Celcius |
| airpressure | Air-pressure, in bar |
| cloudstype | Clouds-type, list of SKC (sky clear), FEW (few), SCT (scattered), BKN (broken), OVC (overcast), CAVOK (ceiling and visibility OK) |
| cloudsheight | List of clouds-heights in meter or CAVOK |
| toweringcumulus | Boolean indicating if this type of clouds is present near the METAR station |
| cumulonimbus | Boolean indicating if this type of clouds is present near the METAR station |
| weather | Weather in METAR abbreviations |
| visibility | Horizontal visibility at ground level, in meter |
Command:
::tclmetar::get_metar_data metarStationCode
This command will query the METAR data for the specified metarStationCode and return the parsed result as a list of key/value pairs suitable for use with array set.
The following script will query METAR data for all METAR stations specified on the command line:
package require tclmetar
foreach m $argv {
if { [catch {::tclmetar::get_metar_data $m} wl] } {
puts "Could not get METAR info for '$m'"
} else {
puts "Weather for $m:"
array set a $wl
parray a
unset a
}
}> tclsh test.tcl EBBR KJFK
Weather for EBBR:
a(abbrev) = EBBR
a(airpressure) = 1.008
a(cloudsheight) = 1158.24
a(cloudstype) = SCT
a(corrected) = <unknown>
a(cumulonimbus) = 0
a(day) = 22
a(dewpoint) = 10
a(hour) = 11
a(minute) = 20
a(month) = 6
a(raw) = 2007/06/22 11:20 EBBR 221120Z 20011KT 170V240 9999 SCT038 20/10 Q1008 TEMPO 5000 SHRA FEW020CB BKN030
a(temperature) = 20
a(toweringcumulus) = 0
a(visibility) = 9999
a(weather) = <unknown>
a(winddir) = 200
a(winddirstr) = SSW
a(windgust) = 0
a(windspeed) = 20
a(windvarfrom) = 170
a(windvarfromstr) = S
a(windvarto) = 240
a(windvartostr) = WSW
a(year) = 2007
Weather for KJFK:
a(abbrev) = KJFK
a(airpressure) = 1.01016312
a(cloudsheight) = 3657.6
a(cloudstype) = FEW
a(corrected) = <unknown>
a(cumulonimbus) = 0
a(day) = 22
a(dewpoint) = 11
a(hour) = 10
a(minute) = 51
a(month) = 6
a(raw) = 2007/06/22 10:51 KJFK 221051Z 30016KT 10SM FEW120 19/11 A2983 RMK AO2 SLP102 T01890111 {$}
a(temperature) = 19
a(toweringcumulus) = 0
a(visibility) = 16093.4
a(weather) = <unknown>
a(winddir) = 300
a(winddirstr) = WNW
a(windgust) = 0
a(windspeed) = 30
a(windvarfrom) = <unknown>
a(windvarfromstr) = <unknown>
a(windvarto) = <unknown>
a(windvartostr) = <unknown>
a(year) = 2007weather data