How NDFD Treats wwaHazards

wwaHazards(Watch, Warning, Advisory Hazards) in NDFD is handled by including a wwaHazard string table in the local use section of the GRIB2 message. The grid cell values in the data part of the GRIB2 message are numbers(Codes) which refer to that entry in the wwaHazard string table. The entries consist of ASCII wwaHazard strings which have up to 5 wwaHazards separated by '^'.  Simple wwaHazards are of the form "AA.B^CC.D" where AA and CC are a two letter descriptor unique to each Hazard, and B and D are either a "W" for Warning, an "A" for Watch, a "Y" for Advisory or a "S" for statement.


Simple Hazard code

In order to create graphical images of wwaHazards, NDFD needed a way to combine the various possibilities of wwaHazards into a discrete number of colors. So they came up with NDFD simple wwaHazards codes. degrib currently (as of 3/2017) recognizes four iterations of simple wwaHazards codes, as follows:

      1 = initial version of NDFD Simple Hazard(WWA) Code
      2 = 9/2008 version of NDFD Simple Hazard(WWA) Code
      3 = 7/2009 version of NDFD Simple Hazard(WWA) Code
      4 = 3/2017 version of NDFD Simple Hazard(WWA) Code(default)

Note: If there are more than one wwaHazards at a certain grid point, degrib will always pick up on the lowest Code value of a wwaHazard. The lower the Code the higher the priority. For example, what if we have a wwaHazard of "TO.W^EH.W"? See the Simple Hazard(WWA) Code Table below. Tornado Warning has a Code of "2", and Excessive Heat Warning has a Code of "44", so degrib will pick up on the TO.W and ignore the EH.W. 

Please see Handling wwaHazard in Degrib(below), or our man page, for instructions on how to work with wwaHazards in degrib. 


 

Current(version 4) Simple Hazard(WWA) Code Table:

wwaHazard Code Label 1
None 0 None
TS.W 1 Tsunami Warning
TO.W 2 Tornado Warning
EW.W 3 Extreme Wind Warning
SV.W 4 Severe Thunderstorm Warning
FF.W 5 Flash Flood Warning
- 6 Shelter In Place Warning
- 7 Evacuation - Immediate
- 8 Civil Danger Warning
- 9 Nuclear Power Plant Warning
- 10 Radiological Hazard Warning
- 11 Hazardous Materials Warning
- 12 Fire Warning
- 13 Civil Emergency Message
- 14 Law Enforcement Warning
HF.W 15 Hurricane Force Wind Warning
HI.W 16 Hurricane Wind Warning
SS.W 17 Storm Surge Warning
HU.W 18 Hurricane Warning
HU.W 19 Hurricane Warning
TY.W 20 Typhoon Warning
TY.W 21 Typhoon Warning
MA.W 22 Special Marine Warning
MA.W 23 Marine Weather Statement (follow up to SMW)
BZ.W 24 Blizzard Warning
IS.W 25 Ice Storm Warning
TI.W 26 Tropical Storm Wind Warning
HS.W 27 Heavy Snow Warning
WS.W 28 Winter Storm Warning
HW.W 29 High Wind Warning
TR.W 30 Tropical Storm Warning
TR.W 31 Tropical Storm Warning
SR.W 32 Storm Warning
TS.A 33 Tsunami Watch
- 34 Avalanche Warning
- 35 Earthquake Warning
AF.W 36 Ashfall Warning
CF.W 37 Coastal Flood Warning
LS.W 38 Lakeshore Flood Warning
FA.W 39 Flood Warning (areal)
FL.W 40 Flood Warning (for forecast points)
SU.W 41 High Surf Warning
IP.W 42 Sleet Warning
LE.W 43 Lake Effect Snow Warning
EH.W 44 Excessive Heat Warning
DS.W 45 Dust Storm Warning
TO.A 46 PDS - Tornado Watch
TO.A 47 Tornado Watch
SV.A 48 PDS - Severe Thunderstorm Watch
SV.A 49 Severe Thunderstorm Watch
FF.A 50 Flash Flood Watch
TO.W 51 Severe Weather Statement
SV.W 52 Severe Weather Statement
FF.W 53 Flash Flood Statement
GL.W 54 Gale Warning
FA.W 55 Flood Statement (follow-up to areal Flood Warning)
FL.W 56 Flood Statement (follow-up to point Flood Warning)
TS.Y 57 Tsunami Advisory
WC.W 58 Wind Chill Warning
EC.W 59 Extreme Cold Warning
HZ.W 60 Hard Freeze Warning
FZ.W 61 Freeze Warning
FW.W 62 Red Flag Warning
SS.A 63 Storm Surge Watch
HU.A 64 Hurricane Watch
HU.A 65 Hurricane Watch
TY.A 66 Typhoon Watch
TY.A 67 Typhoon Watch
HU.S 68 Hurricane Local Statement
TY.S 69 Typhoon Local Statement
SB.Y 70 Snow and Blowing Snow Advisory
ZR.Y 71 Freezing Rain Advisory
- 72 Freezing Drizzle Advisory
IP.Y 73 Sleet Advisory
WW.Y 74 Winter Weather Advisory
LB.Y 75 Lake Effect Snow and Blowing Snow Advisory
LE.Y 76 Lake Effect Snow Advisory
WC.Y 77 Wind Chill Advisory
HT.Y 78 Heat Advisory
FA.Y 79 Urban and Small Stream Flood Advisory
FA.Y 80 Small Stream Flood Advisory
FA.Y 81 Arroyo and Small Stream Flood Advisory
FA.Y 82 Flood Advisory
FL.Y 83 Flood Advisory (for forecast points)
FA.Y 84 Hydrologic Advisory
LS.Y 85 Lakeshore Flood Advisory
CF.Y 86 Coastal Flood Advisory
SU.Y 87 High Surf Advisory
BS.Y 88 Blowing Snow Advisory
SN.Y 89 Snow Advisory
UP.W 90 Heavy Freezing Spray Warning
SM.Y 91 Dense Smoke Advisory
MS.Y 92 Dense Smoke Advisory
SW.Y 93 Small Craft Advisory For Hazadous Seas
RB.Y 94 Small Craft Advisory for Rough Bar
SI.Y 95 Small Craft Advisory for Winds
SC.Y 96 Small Craft Advisory
BW.Y 97 Brisk Wind Advisory
SE.W 98 Hazardous Seas Warning
FG.Y 99 Dense Fog Advisory
MF.Y 100 Dense Fog Advisory
LW.Y 101 Lake Wind Advisory
WI.Y 102 Wind Advisory
DU.Y 103 Blowing Dust Advisory
FR.Y 104 Frost Advisory
AF.Y 105 Ashfall Advisory
MH.Y 106 Ashfall Advisory
ZF.Y 107 Freezing Fog Advisory
UP.Y 108 Freezing Spray Advisory
AS.Y 109 Air Stagnation Advisory
LO.Y 110 Low Water Advisory
- 111 Local Area Emergency
- 112 Avalanche Watch
BZ.A 113 Blizzard Watch
RP.S 114 Rip Current Statement
BH.S 115 Beach Hazard Statement
TI.A 116 Tropical Storm Wind Watch
HF.A0 117 Hurricane Force Wind Watch
HI.A 118 Hurricane Wind Watch
TR.A 119 Tropical Storm Watch
TR.A 120 Tropical Storm Watch
SR.A 121 Storm Watch
GL.A 122 Gale Watch
WS.A 123 Winter Storm Watch
SE.A 124 Hazardous Seas Watch
UP.A 125 Heavy Freezing Spray Watch
CF.A 126 Coastal Flood Watch
LS.A 127 Lakeshore Flood Watch
FA.A 128 Flood Watch (areal)
HW.A 129 High Wind Watch
EH.A 130 Excessive Heat Watch
EC.A 131 Extreme Cold Watch
WC.A 132 Wind Chill Watch
LE.A 133 Lake Effect Snow Watch
HZ.A 134 Hard Freeze Watch
FZ.A 135 Freeze Watch
FW.A 136 Fire Weather Watch
- 137 Extreme Fire Danger
- 138 Child Abduction Emergency
- 139 911 Telephone Outage
CF.S 140 Coastal Flood Statement
LS.S 141 Lakeshore Flood Statement
MA.S 142 Marine Weather Statement
- 143 Special Weather Statement
- 144 Hazardous Weather Outlook
- 145 Short Term Forecast
- 146 Administrative Message
TR.S 147 Tropical Storm Local Statement
- 148 Test

 


 

Handling wwaHazards in Degrib

Handing wwaHazards: Degrib -P Option

Degrib has several different ways of handling wwaHazards. Starting with the "degrib -P" option, it can:

  1. Output the wwaHazards string:
    degrib ds.wwa.bin -P -pnt 35,-76 -WxParse 0
  2. Convert the wwaHazards string to english:
    degrib ds.wwa.bin -P -pnt 35,-76 -WxParse 1
  3. Convert the wwaHazards string to an NDFD simple wwaHazards code:
    degrib ds.wwa.bin -P -pnt 35,-76 -WxParse 2

Handling wwaHazards: Degrib -C Option

Continuing to the "degrib -C" option, it is limited in some respects by the file formats that it writes to.

The -C -Flt option

  1. degrib ds.wwa.bin -C -Flt -Met -msg 1 => convert the message to a NxM 4 byte float file where each cell contains the number in the wwaHazards string lookup table contained in the .txt file (created with the default -Met option)
  2. degrib ds.wwa.bin -C -Flt -nMet -msg 1 -SimpleWWA 4=> convert the message to a NxM 4 byte float file using simple wwaHazards scheme 4 (see Table above).

The -C -Csv option

  1. degrib ds.wwa.bin -C -Csv -msg 1 => convert the message to an ASCII comma delimited file with a x, y, lat, lon, and wwaHazards value for each cell. In this case the wwaHazards value is the wwaHazards string.
  2. degrib ds.wwa.bin -C -Csv -msg 1 -WxParse 1 => convert the message to an ASCII comma delimited file with a x, y, lat, lon, and wwaHazards value for each cell. In this case the wwaHazards value is the wwaHazards string converted to english.
  3. degrib ds.wwa.bin -C -Csv -msg 1 -WxParse 2 => convert the message to an ASCII comma delimited file with a x, y, lat, lon, and wwaHazards value for each cell. In this case the wwaHazards value is the wwaHazards string converted to an NDFD simple wwaHazards code (see Table above).