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TRANSCRIPT
3/6/2019
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National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Oklahoma CityMarch 4-6, 2019
Waterlogged: A Record Year in RainA look at the latest products and strategies that are being developed by the National Weather Service to inform decision makers and help mitigate losses from extreme rainfall and flash flooding.
Greg Carbin, Chief of Forecast OperationsAlso: Patrick Burke, Alex Lamers, David Novak, and WPC Staff
NWS Weather Prediction Center (WPC)College Park, Maryland
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
WPC MissionProvide precipitation and medium range forecasts to enable national readiness for hazardous weather.
Actionable information that is scientific, probabilistic, & impact-based.
National Weather Situational Awareness
Heavy Rainfall
Winter Weather
Medium Range
Hazards
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Historical Context and Change
WPC has a 60 year legacy of QPF, and over 30 years of experience issuing Excessive Rainfall Outlooks.
QPF Threat Scores (1”)Days 1, 2, and 3
QPF asAnnual Exceedance Probability
WPC: A Unique National Resource
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Extreme Rainfall Prediction Process/Products
Performed at each gridpoint
NWM
FFG
Hi-res rain rates
Day 1 Excessive Rainfall Outlook
QPF
Forecaster expertise......analyzed in context with a host of atmospheric and hydro data...
...combined with ensembles for a quantifiable, probabilistic approach...
...result in probability-based and verified extreme rainfall forecasts.
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
The Challenges of Flash Flood Forecasting
6” in 3 hours
3 feet in four days!
California Burn Scars... Vulnerable Basins... and Tropical Cyclone Landfalls
Winter Spring Summer Fall
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
The Challenges of Flash Flood ForecastingCalifornia Burn Scars... Vulnerable Basins... and Tropical Cyclone LandfallCalifornia Burn Scars... Vulnerable Basins... and Tropical Cyclone Landfalls
Winter Spring Summer Fall
Michael Owen Baker/AP
Kenneth Song/Santa Barbara News-Press @BKMovie2018 #EllicottCity Evening Standard/AP
3/6/2019
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National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Why Probabilistic Forecasts?
10th Percentile“At least this much”
50th Percentile“Most Likely”
90th Percentile“Worst Case”
Deterministic forecasts never verify perfectly everywhere. Probabilistic forecasts can inform us about a range of possible outcomes and can incorporate sophisticated statistical post-processing.
• Best used as a point-based tool○ Storm unlikely to verify at given percentile across
the board
• Tropical rainfall amounts tend to verify closer to worst case scenarios
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Products and Services Timelines (Ellicott City)Mesoscale Precip Discussion
1735Z, SundayMay 27, 2018
Day 3 Excessive Rainfall Outlooks Issued
Fri. May 25, 2018
Day 2 Excessive Rainfall Outlooks Issued
Sat. May 26, 2018
Day 1 Excessive Rainfall Outlooks Issued
Sun. May 27, 2018
Day 1-2 Quantitative Precipitation Forecast Issued Sat. May 26, 2018
10”
Issue time: 0825Z
Issue time: 2023Z
Issue time: 0819Z
Issue time: 2005Z
Issue time: 0824Z
Issue time: 1459Z
Issue time: 0832Z
Flash Flood Watch Issued0825Z, SundayMay 27, 2018
FLASH FLOODING POSSIBLE
FLASH FLOOD WARNING2147Z SundayMay 27, 2018
T-48 hours … T-36 hours … T-24 hours … T-12 hours T-3 hours
Flash flood potential over the Mid-Atlantic was briefly highlighted by WPC on a Sunday morning special NWS Leadership call related to Alberto. A WPC//WFO QPF collaboration call at 1800Z, Sunday afternoon, included WFO LWX.
Ellicott City, Maryland
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Products and Services Timelines (Florence)
MPD #845 issued 5:32 pm EDT Sep 15 Rainfall bands east of Florence will continue to produce torrential rainfall rates, exacerbating the already catastrophic/ life-threatening flooding conditions that exist across portions of southeastern NC.
Record-breaking rainfall of potentially 30-40 inches in North Carolina Carolina...
First tropical cyclone QPF graphic created
Day 3 High Risk
Key messages begin highlighting catastrophic flash flooding likely
Day 1-3 High Risks
Cat 1 Hurricane Florence makes landfall...
MPD #832 issued 11:37 pm EDT Sep 13 first to message flash flooding likely
WPC takes over tropical advisories...
T-120 hours … T-72 hours … T-48 hours* … T-24 hours * Flash Flood Watches issued
New NC state rainfall record set
Coordinated key messages highlight the potential for life-threatening flooding
WPC briefs FEMA & partners2x daily QPF collaboration calls with ER-ROC/WFOs/RFCs
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Excessive Rainfall Outlook Categories Explained
Flooding “coverage” as afunction of risk area
HIGH
MDT
SLGT
MRGL
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Excessive Rainfall Outlook Categories Explained
Flooding “coverage” as afunction of risk area
A SLGT Risk Day
HIGH
MDT
SLGT
MRGL
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Excessive Rainfall Outlook Categories Explained
Flooding “coverage” as afunction of risk area
A MDT Risk Day
HIGH
MDT
SLGT
MRGL
3/6/2019
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National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Excessive Rainfall Outlook Categories Explained
Flooding “coverage” as afunction of risk area
A HIGH Risk Day
HIGH
MDT
SLGT
MRGL
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Why HIGH Risk Days Matter
Slide courtesy of Matthew Green, FEMA Liaison to NHC
* These statistics DO NOT includelosses from Hurricane Harvey.
*
*
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Why HIGH Risk Days Matter
Slide courtesy of Matthew Green, FEMA Liaison to NHCSlide courtesy of Matthew Green, FEMA Liaison to NHC
* These statistics DO NOT includelosses from Hurricane Harvey.
* *
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Why HIGH Risk Days Matter
Jan. 9, 10Mar. 22, 23
Feb. 25
May 29
Jul. 26
Sep. 9
Sep. 14, 15, 16, 17Oct. 9
Oct. 12
2018 NWS Storm Data Statistics
52 of 101 2018 flood-related fatalities occurred within a Day 1 High Risk.
Property damage in the High Risk areas in 2018 was estimated in excess of $1B.
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Frequency of ERO High Risks, 2015-2018*
* Currently, official policy must be waived for the issuance of a High Risk in the WPC Day 3 Excessive Rainfall Outlook. This has only occurred for two events, Hurricane Harvey in 2017 and Hurricane Florence in 2018. The Department of Commerce and NOAA are tracking an “Agency Priority Goal” to improve the lead time and messaging ahead of catastrophic flash flood events. As rainfall forecasts continue to improve and provide greater confidence ahead of some of these events (not just tropical), approval for the routine issuance of Day 3 High Risk Outlooks will likely be granted by 2020. (Frequency maps courtesy of Mike Erickson, WPC).
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
As Rainfall Forecasts Continue to Improve...
3/6/2019
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National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
...Risk Messaging and Understanding Need to Follow WPC Day X (1, 2, or 3)
Excessive Rainfall Outlook *
* Outlooks are forecasts! Similar to SPC Outlooks, marginal or no risk days do not always mean zero risk and High Risk days are not always the most severe.
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Increases in Heavy Precipitation and Vulnerability
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
● Much-above-average to record-high precipitation fell across much of the contiguous U.S. east of the Rockies.● 2018 was the 6th consecutive year with a nationally averaged precipitation total greater than the 20th century average.
○ Since 1895, total annual precipitation across the contiguous U.S. has increased at an average rate of close to 2-inches per century.
Waterlogged: A Record Year in Rain
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
● West Virginia’s statewide total of 65.13” broke its previous record (59.42” in 2003) by nearly 6”. North Carolina’s annual total of 68.36” was more than 5” greater than the previous state record (63.16” in 2003).
● Several locations in coastal North Carolina and the Southern Appalachians observed annual totals of 100” or more of precipitation for the first time in their observational history.
Waterlogged: A Record Year in Rain2018 State Precipitation Annual Rankings, 124-years, 1895-2018
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma
Thank You!Questions & Contact Info
Greg Carbin, Chief of Forecast Operations
@NWSWPC
NWS Weather Prediction Center (WPC)College Park, Maryland
National Weather ServiceWeather Prediction CenterNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
National Tornado Summit, March 4-6, 2019 Oklahoma City, Oklahoma