Experimental Aviation Grids at National Weather Service Marquette, Michigan

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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
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Overview

• 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

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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

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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

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Models Included

• Ceiling

• Visibility

• NAM12
• MET Guidance
• NAM 4km Nest
• MAV Guidance (Beyond 12-hours)
• WRF-ARW (local 20km and 5km)
• HRRR
• HRRR (Previous)
• Gridded LAMP
• Gridded LAMP (Previous)
• NCEP WRF-ARW East
• NCEP WRF-NMM East

• 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
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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

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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

Vsby Sky Ceiling
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Case Study March 11, 2013

• Low pressure system moving northeast through the
  Great Lakes region

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March 11, 2013 00Z
Ceiling
Visibility
Surface Chart
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March 11, 2013 06Z
Ceiling
Visibility
Surface Chart
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March 11, 2013 12Z
Ceiling
Visibility
Surface Chart
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Quick Verification Background

• Categorical Amendment Criteria (CAC)

Flight Category Impact
lt 3000 ft (914.4 m) and/or lt 5 sm (8.05 km) MVFR
lt 2000 ft (609.6 m) and/or lt 3 sm (4.83 km) Must File Alternate
lt 1000 ft (304.8 m) and/or lt 3 sm (4.83 km) IFR
lt 600 ft (182.88 m) and/or lt 2 sm (3.22 km) Alternate Landing Minimums
lt 200 ft (61 m) and/or lt 1/2 sm (0.8 km) Airfield Landing Minimums
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March 11, 2013 - Verification
KSAW Sawyer International Airport
3/10 18Z
3/11 00Z
3/10 06Z
24hrs Out
12hrs Out
6hrs Out
MVFR Must File Alternate IFR Alternate
Landing Mins Airfield Landing Mins
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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

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Shallow Moisture Case 03/08/2013

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

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Shallow Moisture Case cont.
Model initial conditions March 08, 2013 00Z
RAP
GFS
NAM
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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

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Verification

• 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)

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KSAW 0-6hr Verification
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KCMX 0-6hr Verification
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KSAW 6-24hr Verification
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KCMX 6-24hr Verification
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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

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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

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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

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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

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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

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Future Work cont.

• Expand Gridded Database to web for aviation
  customers
• Point and Click and Forecast Graphics
• Similar to Jackson, KY, Charleston, WV, etc.

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Conclusion

• 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

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Contact Information

• Steven Fleegel steven.fleegel_at_noaa.gov
• NWS Marquette, MI