WAFS Grids

1
WAFS Grids

• Jesse Sparks
• Aviation Weather Center
• Kansas City, MO

2
World Area Forecast System

• Established by ICAO and WMO
• Improve the quality and consistency of en route
  guidance provided for international aircraft
  operations
• 2 World Area Forecast Centers
• WAFC Washington (AWC, EMC, NWSTG)
• WAFC London (Exeter, UK)
• Each operates its own satellite-based broadcast
  system to distribute global weather data to
  airports all over the world
• Work in duplicate in a case of failure
• Provide each other backup
• Issue upper air significant weather forecasts to
  support global Flight Operations

3
World Area Forecast System

• High Level SIGWX (FL630-250)
• 4 times daily
• 24-hour forecast
• 16-17 hour lead time
• Mid Level SIGWX (FL450-100)
• 4 times daily
• 24-hour forecast
• 16 hour lead time
• Format
• BUFR
• PNG

4
WAFS High Level SIGWX00z, 06z, 12z, 18z

• Thunderstorms/CB
• Tropical Cyclones
• Mod/Sev CAT
• Tropopause Heights
• Jetstreams (80kt and above depicted)
• Jet Depth
• Volcanic Eruptions
• Widespread Sand/Dust storms
• Release of Radioactive Materials

5
WAFS Mid Level SIGWX 00z, 06z, 12z, 18z

• Thunderstorms/CB
• Tropical Cyclones
• Mod/Sev Turb (CAT or IC)
• Mod/Sev Icing
• Tropopause Heights
• Jetstreams (80kt and above depicted)
• Jet Depth
• Volcanic Eruptions
• Widespread Sand/Dust storms
• Release of Radioactive Materials

6
WAFS High Level SIGWXPacific Chart

• Collaborators
• London
• WEG
• HFO
• BOM
• TAMC
• KIWI
• GUM
• AAWU
• ZAN

7
Use of SIGWX Forecasts

• Used directly by airline dispatchers for flight
  planning and weather briefing before departure,
  and by flight crew members during flight
• Pre-Flight Information Bulletin
• International Flight Documentation
• Pre-flight air traffic routing decision-making
• Recommended use for flights from 3 hours before
  to 3 hours after SIGWX validity

8
WAFS Gridded Forecasts

• Model-derived global forecasts
• Washington (GFS)
• London (UKMET)
• 3-hour time intervals
• T6, 9, 12, 15, 18, 21, 24, 27, 30, 33, and 36
  hours
• Recommended use 1 hour 30 minutes before and
  after each time step
• Automatically updates and cancels the
  corresponding forecast issued six hours earlier

9
WAFS Gridded Forecasts

• Base fields (existing GRIB-1)
• Upper-air wind
• Upper-air temperature
• Direction, speed, and flight level of max wind
• Humidity data
• Geopotential altitude
• Derived fields (new - GRIB-2)
• Clear Air Turbulence (CAT)
• In-Cloud Turbulence (IC TURB)
• Icing
• Cumulonimbus (CB) extent
• CB top/base

10
New WAFS Grids
CAT IC Turb ICE CB Extent CB Tops/ Bases
Algorithm Ellrod (VWS 50hPa Layer Deformation) Brunt Vasalia Frequency ( ??e/?z Gravity ?e ) FIP (Cloudy areas with supercooled water) 3-hr ConvectivePCPN rate CB Min/max pressure converted to std height
Levels 150, 200, 250, 300, 400 hPa 300, 400, 500, 600, 700 hPa 300, 400, 500, 600, 700, 850 hPa gt FL240 300 hPa deep gt FL240 300 hPa deep TOPS (min) BASES (max)
Max/Avg 70 km (h) 70 km (h) 50 hPa (v) 70 km (h) 50 hPa (v) 70 km (h) (Avg only) 70 km (h) (Avg only)
Interpolate (GFS 0.3 to WAFS 1.25) Linear Linear Linear Nearest Neighbor Nearest Neighbor
11
WAFS CAT

• Valid 12z May 11 Valid 12z May 11

12
WAFS CB

• Valid 00z May 11 Valid 00z May 11

13
WAFS Grids - Advantages

• Increased temporal resolution
• Valid for operations at all time scales (T6
  through T36) in 3-hourly increments
• Extends forecast for later portions of long-haul
  flights
• All forecasts updated every 6 hours
• Users dont have to use old data for short-haul
  flights
• Users dont have to combine model runs for
  long-haul flights

14
WAFS Grids - Advantages

• Increased consistency
• Common forecast algorithms minimizes differences
  between WAFC London and WAFC Washington
• Eliminates model run-to-run inconsistencies
• Available sooner than current SIGWX
• Part of WAFC global model output
• 3 hours prior to current SIGWX

15
WAFS Grids - Advantages

• Greater detail
• CB
• Grids contain all convective clouds
• SIGWX contains only significant areas of
  ISOL/OCNL EMBD or FRQ CB
• TURB
• Grids contain all TURB CAT, IC TURB, Convective
• SIGWX contains only areas of jet stream CAT and
  IC for only ICAO area NAT (Mid-level SIGWX)

16
WAFS Grids - Advantages

• Greater detail
• ICE
• Grids contain all icing potential for the entire
  globe
• SIGWX contains only non-convective icing for only
  ICAO area NAT (Mid-level SIGWX)
• Level-specific information for gridded ICE and
  TURB forecasts
• For a general global forecast, the forecaster
  SIGWX cannot compete with WAFS Gridded forecasts

17
WAFS Grids - Timeline

• By November 2013
• Transition WAFS grids from GRIB-1 to GRIB-2
  format
• WAFS product vendors transition from BUFR format
  to GRIB-2 format on WAFC workstation
• WAFCs make available web-based WAFS grids
• Test/verify/refine WAFS gridded forecasts
• Eliminate forecaster-produced WAFS SIGWX

18
WAFS Grids - Timeline
Now Sept 2009 WAFCs develop and test WAFS grids in GRIB-2 form
Now Dec 2009 WAFCs develop and test WAFS web-based grids from GRIB-2 data Verification studies of web-based products
Sept 2009 Nov 2011 Develop software for displaying WAFS grids in GRIB-2 on WAFC workstation
Dec 2009 WAFCs make available web-based WAFS grids (experimental)
Nov 2010 WAFS grids become operational co-exist with SIGWX
Nov 2011 Nov 2013 WAFC workstations upgraded to accept GRIB-2
Nov 2013 Cessation of WAFS SIGWX and WAFS grids in GRIB-1
19
WAFS Grids - Demo

• http//aviationweather.gov/testbed/globalgrids/

20
(No Transcript)