John Saltenberger NWCC Lightning Prediction Oregon AMS Feb

NWCC Predictive Services Decision Support Fire Workload –Mobilization –Logistic Planning –GMAC support Prioritizing Pre-positioning 3-5 day planning window is crucial!

Number of Reported Fires Observed Fire Danger Observed Lightning Level Map Type Number of Large Fires Synoptic Wind Index Lapse Rates Does analysis of the historical record reveal relationships between lightning and wildfire frequency and/or size?

Lightning Ignition facts Roughly half of Oregon & Washington wildfires result from lightning. However, up to 75% of large wildfires are from lightning in some areas. …but only 7% of thunderstorm outbreaks result in large fires (3 to 4% west side). NWCC strives to identify those few critical lightning events.

Lightning Forecasting Phase 1 Map typing

Clustering 500mb map types 500mb hgt grid GFS 500mb init

Clustering to identify map types 500mb hgt grid

mb hgt grid Create a column for each daily 500mb hgt grid

Clustering to identify map types mb maps 500mb hgt grid

Record 500mb map type for every day in fire season. Record if any lightning occurred in each PSA during those same days. N Y Y Y N Y N N Y Y N Y

PSA E4: Total days with map type 1: 36 Total days with map type 1 and any lightning: 6 Historical probability: 16%

E4

Lightning Most problematic More frequent lightning

Lightning Forecasting Phase 2 GIS support

Use GIS to count how many strikes in each PSA on every day of fire season. (categorized into 10 decile bins based on strike count history)

PSA E4: Total days with map type 1: 36 Total days with map type 1 and Lightning Level 5: 3 Historical probability: 8%

E4

Lightning Forecasting Phase 3 Logistic Regression

Fine tuning the forecast Smaller 20 pt grid Archive daily 00Z and 12Z initialized GFS variables at each gridpoint

DAILY ARCHIVES OF INITIALZED GFS DATA 850, 700, 500mb heights and thickness mb and mb Lapse Rates 500 mb Temperature, Dew Pt & RH 700 mb Temperature, Dew Pt & RH Column Precipitable Water U and V components of 700 mb and 500 mb wind CAPE, LI, Totals, 700mb Theta-e Historical PSA lightning prob for each map type Perfect Prog method!

Logistic regression Best predictors occurrence & amount Map Type probability mb Lapse Rt 500 mb Temperature Precipitable Water 700 mb Rel Hum quadratic/cubic bias

2011 PSA Probability and Amount Each PSA was assigned a value of probability and LL weighted from nearby grid boxes known to be significant 45% 25%30% 0%

E4

Lightning Forecasting Phase 4 Logistic Regression applied to forecasting

Probability Forecasts of a Binary (Yes or No) Event At what confidence of probability percentage do I commit to saying an binary event is going to happen? 40%?50%? 60%?

POD Probability of Detection (how many cases correctly forecast?) FAR False Alarm Rate (how many cases forecast …but did not occur?)

As POD increases, so does FAR …or… As FAR decreases, so does POD

GOAL: Define the confidence percentage to maximize POD until FAR becomes unacceptable 40%?50%? 60%?

40%?50%? 60%? POD: FAR:

NWCC’s GOAL: Experiment with defining the (Y/N) confidence percentage until… POD rises to 67% …or… FAR falls to 49%...

Lightning Best predictors at each gridpoint are populated from the 00Z or 06Z GFS via a perfect prog type scheme to objectively forecast: – Lightning YES/NO – Mostly likely LL (percentile rank bin)

Large Fire Probability Significant fire probability during lightning events (for each PSA) is determined by: –The forecasted lightning amount (decile) –A pro-rated likely number of ignitions –The fraction of those ignitions that become historically have become “large” –Forecasted fluctuation in the Fire Danger

3 ignitions 5 ignitions 19 ignitions 21 ignitions 47 ignitions Historical Large Fire Probability From Multiple Ignitions

Historical Large Fire Probability From Multiple Ignitions LOW FIRE DANGER

Historical Large Fire Probability From Multiple Ignitions HIGH FIRE DANGER

5-Day Forecasted Fire Activity High Risk Event Forecasted ActivityTodayWedThuFriSat PSA C2 Large Fire Probability 0%1%52%1%10% 5-Day Total Forecasted Ignitions to 10 Day Outlook based on Historical Fire Occurrence ClimatologySunMonTueWedThu PSA C2 Large Fire Probability 0% 1%2% 5-Day Total Climo Ignitions Lightning Unstable Fire Activity Forecast 2012

Initial Attack Overwhelmed by: Sheer number of ignitions R U W Severity of atmosphere

Thank You!