lightning forecasting at the storm prediction center
DESCRIPTION
Lightning Forecasting at the Storm Prediction Center. Joe Schaefer with help from Phillip Bothwell, David Bright and Russell Schneider. Current uses of the NLDN by the SPC. First strike detection – convective initiation Subjective measure of convective intensity & trend - PowerPoint PPT PresentationTRANSCRIPT
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Lightning Forecasting
at theStorm Prediction
CenterJoe Schaefer with help from
Phillip Bothwell, David Brightand
Russell Schneider
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Current uses of the NLDN by the SPC
• First strike detection – convective initiation• Subjective measure of convective intensity & trend• Verification and validation of thunderstorms• Detection of convection in regions of sparse radar coverage
(esp. for Fire Weather)
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Lightning (CG) & Fire Starts
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SPC Lightning Forecasts
• General Thunder in Convective Outlook• “Enhanced Thunder”
– Presently experimental on Internet– Operational Product next year
• Fire Weather Outlook
Two types of Internal Thunderstorm Guidance
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Enhanced Thunder19 July 2005
200000Z – 201200Z
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Ensemble Forecasts
• Current SPC SREF processing– All operational computations on NOAA CCS
• SREF products specialized for the national mission of the SPC
• 16 member SREF (1 time-lagged Eta member)– Include the -3 hr operational Eta in all calculations
• Add the +3 hr operational Eta to spaghetti plots
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F15 SREF PROBABILITY F15 SREF PROBABILITY CLOUD PHYSICS THUNDER CLOUD PHYSICS THUNDER PARAMETER >= 1PARAMETER >= 1
SREF MEAN CPTP = 1 (DASHED)
SREF PROB CPTP >= 1SREF PROB CPTP >= 1 (SOLID & FILLED)(SOLID & FILLED)
CLOUD PHYSICS THUNDER PARAMETER Percent of members with appreciable CAPE in the 0oC to -20oC layer
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F15 SREF 3-hr COMBINEDF15 SREF 3-hr COMBINEDPROBABILITY OF LIGHTNINGPROBABILITY OF LIGHTNING
- Pr (CPTP) >= 1 x Pr (PCPN) >= .01”
Uncalibrated probabilityof lightning
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F15 SREF 3-hr COMBINED PROBABILITY F15 SREF 3-hr COMBINED PROBABILITY OF LIGHTNING (Calibrated)OF LIGHTNING (Calibrated)& LIGHTNING STRIKES& LIGHTNING STRIKES
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Statistical Forecasts Based on Phillip Bothwell’s Dissertation work
• Perfect Prog Forecast TechniquePrincipal Component Analysis determines predictorsLogistic regression
• 40 km grid resolution at 3 hour time intervals• Uses Lightning Climatology (no knowledge of ongoing
activity
Forecasts• Probability of 1 or more CG flashes• Probability of 100 or more CG flashes.
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OBJECTIVES
• Technique applicable to ANY analysis or gridded data set (i.e., forecast for the next 3 hours… 57 to 60 hours,
or any time period in between)
• System can run on data fromANY forecast model. inter-model comparisons (different models…e.g., RUC and ETA)
intra-model comparisons (different cycles of same model).
• Distinguish low lightning producers from high producers
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LTG CLIMATOLOGY:
Probability of one or more CG flashes / 40x40 km grid box / 3 hrs.
Centered on July 22
12-15UTC 15-18UTC
18-21 UTC 21-00UTC
Relative minimum
during daytime hours
Relative maximum
during daytime hours
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LTG CLIMATOLOGY:
Probability of one or more CG flashes / 40x40 km grid box / 3 hrs.
Centered on July 22
00-03UTC 03-06UTC
06-09UTC 09-12UTC
Relative maximum
during overnight
hoursRelative
minimum during
overnight hours
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57-60 Hour Lightning Forecast
12Z July 13, 2004
Forecast Observed
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There can be a big difference between storms that produce only one flash and…
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NOAA Photo Library
NWS Historical Collection
… those that have large numbers of flashes!
Previous attempts at predicting events with significant flash rates have not met with much success!
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Significant CG Lightning Events100 or more CG flashes/40x40 km/3 hrs
• Kempf and Krider (2003) as well as others have found a strong connection between daily rain volumes and corresponding counts of CG lightning
• Intense areas of CG lightning can often be associated with strong to severe storms
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Probability of 100 or more CG Flashes9-12 hour Forecast18Z Sep. 18, 2004
Solid Probability 21,%, 2%, 5%Dashed Observed 100,200,399 Flashes
Climatology03 Z – 06Z
5 Days Centered on Sep. 20
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Future use of Lightning Data
• Become more quantitative • Track development & evolution of total lightning
within individual thunderstorms• Prediction of critical lightning characteristics
– Positive CG Strokes – Fire Weather (house fires?)
– Forecasts of severe lightning events• We need to learn more …
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