Transcript Presentation/Poster

The LAMP/HRRR MELD FOR
AVIATION FORECASTING
Bob Glahn, Judy Ghirardelli, Jung-Sun Im, Adam Schnapp,
Gordana Rancic, and Chenjie Huang
Meteorological Development Laboratory,
National Weather Service, NOAA
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OUTLINE
• LAMP forecasts
• HRRR forecasts
• Ceiling and Visibility Meld
– Method
– Verification
– Example
• Conclusions
• Plans
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CEILING HEIGHT AND VISIBILITY FORECASTS
• Ceiling height and visibility forecasts are
contained in weather forecast products for the
aviation community, including the TAFs.
– Ceiling in hundreds (hds) ft above ground.
– Visibility in miles.
• Guidance based partly on numerical models is
needed to produce the final forecasts.
• LAMP provides forecasts for aviation products
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LAMP
(LOCALIZED AVIATION MOS PROGRAM)
• LAMP Guidance Products:
– Forecasts produced
• each hour,
• for most weather elements contained in aviation and
public weather products, including ceiling and visibility,
• in hourly increments out to 25 hours.
– Forecasts of convection and lightning potential.
• Forecasts are available in text and gridded
forms.
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LAMP
• LAMP Forecasts are statistically produced as a
combination of:
– current observations,
– simple advective models, and
– MOS forecasts (based on NCEP’s Global Forecast
System).
• Ceiling and visibility forecasts are in terms of:
– categories (e.g., ceiling 400-900 ft) and
– the probability of each category.
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LAMP CEILING HEIGHT FORECAST, 7-H PROJECTION FROM
APRIL 11, 2013, 1200 UTC
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SEA LEVEL PRESSURE AND FRONTS
APRIL 11, 2013, 1200 UTC
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HRRR MODEL
(HIGH RESOLUTION RAPID REFRESH MODEL)
• HRRR is a 3-km dynamic model
– Forecasts produced
• each hour,
• for a variety of weather elements, including
ceiling and visibility,
• in hourly increments out to 15 hours.
• Ceiling in terms of meters above sea level.
• Visibility in meters.
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HRRR CEILING HEIGHT FORECAST FOR APRIL 11, 2013,
8-H PROJECTION FROM 1100 UTC
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CEILING AND VISIBILITY AS A MELD
OF LAMP AND HRRR
• Both LAMP and HRRR produce ceiling and
visibility forecasts
– LAMP in terms of categorical forecasts and the
probability of each category (e.g., ceiling 400-900 ft;
visibility 3-5 mi) at 1552 specific sites (stations).
– HRRR in terms of specific values of ceiling in meters
above sea level and visibility in meters on a grid.
• Ceiling (Visibility) Meld forecasts are produced as
a combination of LAMP and HRRR ceiling
(visibility) forecasts.
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DATA AVAILABLE
• LAMP has a long archive
• Two warm seasons of HRRR data were
available (April-September, 2013, 2014)
– 8 months used for development
– 4 months used for independent verification
• April 2013, August 2013, June 2014, September 2014
• Previous work used 1 season of cool season
data (not reported here)
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REEP USED FOR PRODUCING MELD
(REGRESSION ESTIMATION OF EVENT PROBABILITIES)
• REEP predictors for ceiling (visibility):
– LAMP Probability of each of 7 (6) categories at the 1552
LAMP stations
• Probabilities better than categorical values as predictors
– HRRR forecasts in binary form, total of 12 (11),
interpolated to the LAMP stations
• Small spots removed/coalesced before making binaries
– Observations (obs) in binary form, total of 15 (15) at the
LAMP stations
• REEP predictands in binary form, total of 24 (16)
categories at the LAMP stations (ground truth)
– More definition than original LAMP
• Generalized development—All points grouped together
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REEP PREDICTOR SELECTION
• Forward selection of predictors
– > 0.5% reduction of variance cutoff
• for any projection
• for any predictand category
• For ceiling (visibility) 15 (14) predictors were
selected:
– All 7 (6) LAMP probabilities
– 5 (3 ) HRRR binaries
– 3 (5 ) Obs binaries
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REEP EQUATIONS
• REEP produces 24 X 25 = 600 (16 X 25 = 400)
equations, one for each of 24 (16) categories of
ceiling (visibility) for each of the 25 projections.
– Each equation has the same predictors, except that
the LAMP and HRRR forecasts match the predictand
projections.
– The same-cycle HRRR is not available in time to be
used, so the 1-h old forecast is used.
– Beyond 14 hours, the 14-h HRRR is continued for all
predictand projections.
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VERIFICATION ON INDEPENDENT DATA
• Primary performance metrics
– Threat score for < categories
– Bias for categories
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IMPLEMENTATION STRATEGY
• Development was done at points
• Implementation was done on the 2.5-km
NDFD grid
– Analyze LAMP probabilities to the grid
– Analyze obs to the grid
– Apply the HRRR forecasts on the grid
– Apply the REEP equations at each gridpoint
• Other implementation strategies possible
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LAMP/HRRR MELD CEILING HEIGHT FORECAST FOR
APRIL 11, 2013, 7-H PROJECTION FROM 1200 UTC
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LAMP CEILING HEIGHT FORECAST, 7-H PROJECTION FROM
APRIL 11, 2013, 1200 UTC
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HRRR CEILING HEIGHT FORECAST FOR APRIL 11, 2013,
8-H PROJECTION FROM 1100 UTC
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CONCLUSIONS
• The Meld of LAMP and HRRR for one cycle
(start time) has produced ceiling and visibility
forecasts generally superior to LAMP and
especially to HRRR.
• It is MDL’s intention to implement a
LAMP/HRRR Meld built on the work shown
here with possible improvements.
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REFERENCE
• Glahn, B., A. D. Schnapp, and J.-S. Im, 2015: The LAMP and
HRRR ceiling height and visibility meld. MDL Office Note 15-1.
Meteorological Development Laboratory, National Weather
Service, NOAA., U.S. Department of Commerce, 28 pp.
Can be found at:
http://www.nws.noaa.gov/mdl/lamp/publications/
lamp_hrrr_office_note_ON_15-1_7_31_15_final.pdf
The general LAMP web site URL:
http://www.nws.noaa.gov/mdl/lamp/index.shtml
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