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Experimental Aviation Grids at National Weather Service Marquette, Michigan. Steven Fleegel NWS Marquette, MI. Great Lakes Operational Meteorology Workshop Webinar Series. May 14, 2013. Overview. Started as a part of experimental Fire Weather grid creation in February 2012

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experimental aviation grids at national weather service marquette michigan

Experimental Aviation Grids at National Weather Service Marquette, Michigan

Steven Fleegel

NWS Marquette, MI

Great Lakes Operational Meteorology Workshop Webinar Series

May 14, 2013

  • Started as a part of experimental Fire Weather grid creation in February 2012
    • Creating Ceiling and Visibility grids
  • Tools and Procedures were modified and created in Graphical Forecast Editor (GFE) to use a consensus approach
    • Averaged the derived model ceilings and explicit model visibilities
    • Completely hands off for forecasters
overview cont
Overview - cont.
  • This proved useful to the forecasters in giving a rough idea on potential ceiling/visibilities across the County Warning Area (CWA)
    • Very helpful with timing
  • Created hourly through first 12 hours and then every 3 hours after that through 72 hours
    • Originally created every 3 hours through 60 hours
what was done in gfe
What was done in GFE
  • Added Ceiling and Visibility (Vsby) grids to the Forecast (Fcst) database
    • Originally, the ceiling grids were derived on the fly and calculated based off model RH
  • Ceiling grids were converted to background processing (smartInits) with the transition to calculations based on RH with respect to Ice (March 2013)
    • Vsby grids were also converted to smartInits at this time
  • This conversion allowed the consensus calculations to be enhanced
    • Hourly calculations in the first 12 hours
      • Hourly model data when available and interpolated 3 or 6 hour model data.
    • Weights to increase emphasis on preferred models
models included
Models Included




MET Guidance

NAM 4km Nest

MAV Guidance (Beyond 12-hours)

WRF-ARW (local 20km and 5km)


HRRR (Previous)

Gridded LAMP

Gridded LAMP (Previous)



  • NAM12
  • MET Guidance
  • GFS40
  • MAV Guidance (beyond 12-hours)
  • RAP X2
  • RAP (Previous)
  • WRF-ARW (local 5km) X2
  • RuMM1/2 (3 hourly local 3km WRF-ARW initialized off RAP)
  • Gridded LAMP
  • Gridded LAMP (Previous)

GFE and AWIPS data limitations exclude using GEM (NH and Regional), ECMWF, NCEP WRFs Ceiling data

how the forecasters see the data
How the Forecasters see the Data
  • Example of a Ceiling grid in GFE
  • Uses a color table to match Categorical Amendment Criteria (CAC)
    • Help forecasters quickly see areas of concern
what was done in avnfps
What was done in AvnFPS
  • The data is also available to the Aviation forecasters through the AvnFPS TAF Editor
  • Forecaster feedback has been positive to this addition
    • Helps them with timing for TAFs
  • Did have to make minor background adjustments due to local labeling
    • Will likely be transitioning towards more consistent labeling with AWIPS 2




case study march 11 2013
Case Study – March 11, 2013

Low pressure system moving northeast through the Great Lakes region

march 11 2013 00z
March 11, 2013 – 00Z



Surface Chart

march 11 2013 06z
March 11, 2013 – 06Z



Surface Chart

march 11 2013 12z
March 11, 2013 – 12Z



Surface Chart

quick verification background
Quick Verification Background

Categorical Amendment Criteria (CAC)

march 11 2013 verification
March 11, 2013 - Verification

KSAW – Sawyer International Airport

3/10 – 18Z

3/11 – 00Z

3/10 – 06Z

24hrs Out

12hrs Out

6hrs Out

MVFRMust File AlternateIFRAlternate Landing MinsAirfield Landing Mins

kcmx march 19 th 2013 snow
KCMX – March 19th, 2013 Snow

KCMX – Houghton County Memorial Airport

March 17, 2013 – 18Z Forecast

  • Low pressure system moving east out of the Northern Plains and across Lake Superior
  • Hit alternate landing minimum visibilities within an hour or two at 30 hours out
    • Extremely useful for Outlook portion of TAF forecast
shallow moisture case 03 08 2013
Shallow Moisture Case – 03/08/2013

Light winds and lingering moisture trapped below subsidence associated with high pressure over the Great Lakes

shallow moisture case cont
Shallow Moisture Case – cont.

Model initial conditions – March 08, 2013 00Z




shallow moisture cont
Shallow Moisture – cont.
  • With the reliance on model data, the Aviation Grids struggled
    • Forecasters also struggled with timing of wind becoming offshore
      • Forecaster Aviation discussion mention timing uncertainty on clouds
      • 00z TAF had conditions scattering out at 02Z
    • But at least the TAF forecast had the right idea
  • In order to quantify the biases and identify areas of improvement, verification was started in February 2013
  • Caveats
    • Local NDFD Verification
      • Only Hourly obs at the top of the hour
      • Looks at ceiling height with no restriction by cloud cover
      • Looked at 2 of our 3 TAF sites
        • Left out KIWD (Ironwood, MI) due to inconsistent observations
    • Stats on Demand (NWS Verification)
      • 5min obs and calculation
      • Has in-between obs (Specials)
aviation grids performance
Aviation Grids – Performance
  • Positives
    • Synoptic systems
      • As long as there is model consistency
    • Visibility
      • Values and timing
      • Model derived data versus calculated like ceilings
    • Recently improved ceilings in lake effect areas
      • Due to relative humidity calculations with respect to ice
aviation grids shortcomings
Aviation Grids - Shortcomings
  • Shallow Moist Layers
    • Models have same issue
    • Plus, with GFE only having data every 25mb, it is easy for those shallow layers to be missed
  • Timing the end of lake effect snow and clouds
    • Models have same issue
  • Very low ceilings
    • Due to the way the consensus is averaged
      • One model showing 20,000 foot ceilings can quickly raise the other models consensus of 500 feet
    • Doesn't represent lower ceilings or vertical visibility (VV) due to Blowing Snow (BLSN) or heavy snow (+SN)
      • Potential improvement based off Forecast
        • Tool could use BLSN or +SN to adjust ceiling values to increase consistency with the forecast
cac category distribution ksaw
CAC Category Distribution - KSAW
  • Issue with lack of lower ceilings can be seen in frequency comparisons
    • Biased towards VFR conditions
      • Misses IFR and lower
    • Visibility has a fairly even distribution in all categories
recent improvements
Recent Improvements
  • Changes made at the beginning of March have improved lower ceiling errors
    • RH with respect to Ice
    • Hourly Calculations in the first 12 hours
  • Has greatly reduced the high bias for MVFR and lower Ceilings
future work
Future Work
  • Main focus will be improving Ceiling forecasts for IFR and lower conditions
  • Perform Summertime convection verification
  • Incorporate some influence of the Forecast to visibility and ceiling
  • Generate experimental TAFs like some NWS Eastern Region offices
    • Would help simplify verification, since it would be incorporated into Stats on Demand
future work cont
Future Work – cont.
  • Expand Gridded Database to web for aviation customers
    • Point and Click and Forecast Graphics
      • Similar to Jackson, KY, Charleston, WV, etc.
  • Visibility Grids – Definitely shows skill
    • Verification over last two months indicates that it is as good or slightly better than our TAFs
  • Ceiling Grids – Showing improvement
    • But still struggles with IFR and lower values
  • A good start
    • Believe that using this as a starting point and then adding forecaster intervention would create a superior product for the TAF sites and our CWA as a whole
contact information
Contact Information
  • Steven Fleegel – steven.fleegel@noaa.gov
  • NWS Marquette, MI