Shawn - PowerPoint Presentation

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Shawn DeVinny, Forecastershawn.devinny@noaa.gov

NWS Forecasts And Warnings

August 11, 2015

Todd Krause, Warning Coordination Met

Todd.krause@noaa.gov

National Weather Service Twin Cities/Chanhassen, MNSlide2

Our Mission“the protection of life and property and the

enhancement of the national economy”Slide3

Accomplishing The Mission…ForecastingObserving

AnalyzingCommunicationWarningsWatchesVarious Text ProductsNOAA Weather RadioWebsite(s)Social MediaSlide4

Building A Weather-Ready NationFirst goal: Improve Weather

Decision Services for Events that Threaten Lives and LivelihoodsUser engagement: “Increase engagement with users and core partners…” Slide5

Times Are Changing In The NWSScientific understanding and weather model accuracy has improved over the years

In some well forecast high-impact weather events, communication was found to be a shortcoming when the public was underprepared, despite a good forecastSlide6

Weather-Ready Nation

Shift from product-focused service to interpretation and consultationNWS will evolve from the forecaster generating products based on static definitions toward a services modelSlide7

Products And Services Available To Public WorksHow Public Works Agencies Can Contact The NWS For Questions And More Information

Call Us! Please! We answer the phone 24 hours a day. Remember, we are a 24/7/365 operation! Don’t ever worry about “bugging” us, this is why we’re hereSocial Media- Facebook/TwitterUtilize

NWSChatSlide8

Products And Services Available To Public WorksFinding Weather Data

Snowfall DataTemperature DataEvent SummariesHistorical Weather InformationTop News Archives On Our WebsiteThe MN State ClimatologistSlide9

Products And Services Available To Public Works

Warnings/Advisories/WatchesHow are they defined?Pros/ConsStatisticsAdditional Useful ResourcesMobileHourly Weather GraphAFD- Area Forecast DiscussionGraphical Forecasts

Radar BasicsSlide10

Watch, Warning, Advisory

WATCH: Weather having a significant impact on society is possible but details are uncertain.WARNING: Weather having a

SIGNIFICANT impact on society is imminent or highly likely. Dangerous conditions expected.ADVISORY: Weather having a MODERATE impact on society is imminent or highly likely. Hazardous conditions expected, but should not be dangerous if precautions are taken.Slide11

NWS Warning Criteria (discretion)

Ice Storm: ¼” ice or moreWind Chill: -35High Wind: 40 mph sustained, 58 mph gusts Heat: 105 heat indexFlood: river reaches flood stage or long-term arealFlash Flood: life threateningSevere Tstm: 58 mph and/or 1” hailTornado: radar or spotter

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NWS ProductsWinter Storm Warning

Snow of 6” or more in 12 hours Or Snow of 8” or more in 24 hoursOr ½” or more of sleetOr a combination of heavy snow, sleet, significant wind, or freezing rainSlide13

NWS ProductsWinter Storm Watch/Blizzard Watch

Watches are issued once the forecaster reaches 50% confidence in an event reaching the criteria.We continue to move to forecaster discretion based on impactsThe process is evolving… “NWS will evolve from static definitions toward a services model”Slide14

Pros/Cons Of Watch ProductsPros

Provides you with a “heads up” 36+ hours ahead of timeWell communicatedArea and time definedConsCan be misinterpretedWatches = 50% in criteria being reached. What does this mean to the user?In theory, up to 50% of watches will NOT be converted to a WarningMany expect a Watch to become a Warning. This is a misinterpretation of the productSlide15

January 30th, 2014

Heavy snow occurred across the metro from 6AM-9AM on a Thursday morning.Amounts were generally under 6”, but a Winter Storm Warning was issued the night before due to expected societal impacts from the timing and intensity of the snow.Slide16

January 30th, 2014Slide17

January 30

th, 2014Slide18
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NWS ProductsWinter Weather Advisory

Snow of 3-6”Blowing Snow causing significant visibility restrictionsSleet of less than ½”Exceptions to these guidelines exist based on forecaster judgmentImpactsSlide20
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NWS ProductsBlizzard Warning

35+ mph (sustained or frequent gusts)Visibility frequently < ¼ mileWhat’s Missing?Considerable falling OR blowing snowMajor Misconception: blizzard = heavy snowA “Blizzard” has nothing to do with snowfall amountsA “Blizzard” has everything to do with wind and visibility. No falling snow necessary!Slide22
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Pros/Cons Of Warning ProductsPros

Clearly defines an area and time when impacts will occurClearly defines the hazardCommunication of these productsWell advertised- easy for you to get this information ConsistencyCredibilitySlide25

Pros/Cons Of Warning ProductsConsCounty based- we are limited to county borders

Difficult to get away from issuing based on static definitions Often lacks a description of forecaster confidenceCan be difficult to interpret large blocks of textSlide26

Winter Storm Warning StatsPOD- Probability Of Detection (county-by-county analysis)

92% accuracyAverage Lead Time For You To Prepare21.2 hoursSlide27

Products And Services Available To Public WorksWarnings/Advisories/Watches

How are they defined?Pros/ConsStatisticsAdditional Useful ResourcesMobile DevicesHourly Weather GraphAFD- Area Forecast DiscussionGraphical Forecasts

Radar BasicsSlide28

http://innovation.srh.noaa.gov/NWSwidget

Mobile Devices – NWS Info

Detailed forecast for your location

Hourly forecast for first 12 hours

Radar

Satellite

Forecast DiscussionsSlide29

Useful ResourcesThe Hourly Weather GraphAn interactive graph showing hourly details for weather elements for any location

A great tool in aiding decision-makingWhen will the snow be the heaviest?Slide30

The Hourly Weather GraphSlide31

Useful ResourcesHow To Get To The Hourly Weather Graph

Go to our national website: weather.govSlide32

Useful ResourcesHow To Get To The Hourly Weather Graph

2) Submit you local city or zip code in the box in the upper left hand cornerSlide33

Useful ResourcesHow To Get To The Hourly Weather Graph

Or go to our local website: weather.gov/twincitiesSlide34

Useful ResourcesHow To Get To The Hourly Weather Graph

2) Submit your local city or zip code in the box in the upper left hand cornerSlide35

Useful ResourcesHow To Get To The Hourly Weather Graph

3) Your local forecast comes up, find the “hourly weather graph” on the right hand sideSlide36
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The Hourly Weather GraphWhat if this forecast was for your location?Slide38

Area Forecast DiscussionThis product explains the thinking behind the forecast and is generated by the forecaster after they’ve completed their forecast

The AFD is updated at least 2x per dayTypically updated ~4 AM and ~4PMWill include scientific terminologySlide39

Area Forecast DiscussionHow is this product useful to Public Works?Portraying confidence

To get a sense of high or low forecaster confidence may influence decision-makingIf confidence is low, an explanation to why will be offered. Is it a timing issue? Uncertainty concerning precipitation type?Can explain details you simply can’t get from the local forecastSlide40

Area Forecast DiscussionSlide41

Area Forecast DiscussionGo to our local website: weather.gov/

twincitiesHover over “Forecasts” on the top center, and click on “Forecast Discussion”Slide42

Weather GraphicsWe produce a “Weather Story” updated every evening and early morning

Instead of (or in addition to) reading various text products, you may find these very beneficial ahead of a winter stormYou can find the weather story on our home page and we also post all updates to our Facebook and Twitter accountsSlide43

Weather Graphics During Winter WeatherBefore The Storm

TimingSlide44
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Weather Graphics During Winter WeatherBefore The Storm

TimingUncertaintySlide47
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Weather Graphics During Winter WeatherBefore The Storm

TimingUncertaintyCommunicating how mixed precipitation events will unfoldGraphics best demonstrate where to expect snow, sleet, freezing rain, rain…etc.Slide49
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Bringing It All TogetherSlide52

Radar BasicsThe difference between rain and snowBe careful when viewing radar that displays snow, rain, and mix

Radar doesn’t actually detect precipitation type directlyAlgorithms convert the reflectivity to a precipitation type (not always accurate)Snow bandingA band of snow is usually prominent during most snow storms. There is often a narrow band of heaviest reflectivity within this. This heavy narrow band will pivot at some point, which typically produces the highest snowfall amountSlide53

Rain vs. Snow

Rain

SnowSlide54

Snow BandingSlide55

Base vs Composite ReflectivityBase ReflectivityThe lowest radar scan

Helpful in seeing as low to the ground as possibleWon’t fool you as easily because you are seeing the lowest scanComposite ReflectivityDisplays the maximum return at any levelWill always look worse than base reflectivityCan fool you in to thinking it should be snowing (evaporation is common at the onset of a storm)

Recommendation: Use base reflectivity onlySlide56

Products And Services Available To Public WorksFinding Past Weather Data

Snowfall DataTemperature DataEvent SummariesHistorical Weather InformationTop News Archives On Our WebsiteThe MN State ClimatologistSlide57

MN State ClimatologistAnother resource for climatological weather dataIncludes climate data for the Twin Cities back to the 1800’s

http://climate.umn.edu/Slide58

Finding Past Weather DataHover over “Climate and Past Weather,” then click on “Local”Slide59
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Monthly Climate Data (An Example)Slide61
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Event SummariesAfter a winter weather event, we’ll post a summaryTable of snowfall amounts

Map of snowfall amountsCheck our website for these“Top News of the Day”Typically posted to social media as wellNeed snowfall amounts during the storm? Check the “Public Information” statementSlide66
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Public Information StatementSlide68
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Products And Services Available To Public WorksHow Public Works Agencies Can Contact The NWS For Questions And More Information

Call Us! Please!We answer the phone 24 hours a day. Remember, we are a 24/7/365 operation! Don’t ever worry about “bugging” us, this is why we’re hereSocial Media- Facebook/Twitter

Utilize NWSChatFeel free to contact us with questionsSlide70

Warning Reception: iNWS

Interactive National Weather ServiceWeather alerts to your mobile deviceSelect your alert area and which alerts you wantPublic safety officials

http://inws.wrh.noaa.govSlide71

Find us on FacebookSlide72

Follow us on TwitterSlide73

TwitterSlide74

NWS ChatYou can sign up for NWS ChatMust first request access via the website

https://nwschat.weather.gov/live/Our office identifer is “MPX”Join the “MPX Chat” roomWe monitor this chat room 24/7We respond to questions and often post more and quicker updates concerning the weatherYou can also see a feed of our products as they are publishedSlide75
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Shawn DeVinnyshawn.devinny@noaa.govNational Weather Service Twin Cities/Chanhassen, MN

Thank You!