Experimental Aviation Grids at National Weather Service

Marquette, MichiganSteven 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– 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.

• 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• 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

Ceiling• 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)

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

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

VsbySky

Ceiling

Case Study – March 11, 2013

Low pressure system moving northeast through the Great Lakes region

March 11, 2013 – 00Z

Ceiling

Visibility

Surface Chart

March 11, 2013 – 06Z

Ceiling

Visibility

Surface Chart

March 11, 2013 – 12Z

Ceiling

Visibility

Surface Chart

Quick Verification Background

Categorical Amendment Criteria (CAC)

Flight Category Impact

<= 3000 ft (914.4 m) and/or <= 5 sm (8.05 km)

MVFR

< 2000 ft (609.6 m) and/or < 3 sm (4.83 km)

Must File Alternate

< 1000 ft (304.8 m) and/or < 3 sm (4.83 km)

IFR

< 600 ft (182.88 m) and/or < 2 sm (3.22 km)

Alternate Landing Minimums

< 200 ft (61 m) and/or < 1/2 sm (0.8 km)

Airfield Landing Minimums

March 11, 2013 - Verification

24hrs Out 12hrs Out 6hrs Out

KSAW – Sawyer International Airport

MVFR Must File Alternate IFR Alternate Landing Mins Airfield Landing Mins MVFR Must File Alternate IFR Alternate Landing Mins Airfield Landing Mins

3/10 – 06Z 3/10 – 18Z 3/11 – 00Z

KCMX – March 19th, 2013 Snow

• 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

KCMX – Houghton County Memorial AirportMarch 17, 2013 – 18Z Forecast

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.

RAPModel initial conditions – March 08, 2013 00Z

GFS

NAM

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

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)

KSAW – 0-6hr Verification

KCMX – 0-6hr Verification

KSAW – 6-24hr Verification

KCMX – 6-24hr Verification

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

• 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

• 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• 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

• 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.

• Expand Gridded Database to web for aviation customers– Point and Click and Forecast

Graphics• Similar to Jackson, KY,

Charleston, WV, etc.

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

Contact Information

• Steven Fleegel – steven.fleegel@noaa.gov• NWS Marquette, MI