Winter Weather Spotter Winter Weather Spotter CourseCourseNational Weather Service Northern National Weather Service Northern

IndianaIndiana

Course OutlineCourse Outline

Introduction to NWS Winter Weather Introduction to NWS Winter Weather Advisories/Watches/WarningsAdvisories/Watches/Warnings

Snow Spotters – our network todaySnow Spotters – our network today Reporting real time information – Reporting real time information –

what do we need to know about?what do we need to know about? What to report after the storm is overWhat to report after the storm is over How to measure snowHow to measure snow How to report your informationHow to report your information

DefinitionsDefinitions

Freezing RainFreezing Rain – Rain falls as – Rain falls as liquidliquid and and then then freezes on contactfreezes on contact

SleetSleet – Rain drops freeze into ice pellets – Rain drops freeze into ice pellets priorprior to reaching ground. to reaching ground.

SnowSnow – An aggregation of many ice crystals – An aggregation of many ice crystals GraupelGraupel – Snowflakes which have been – Snowflakes which have been

heavily rimed. Also called snow pellets, soft heavily rimed. Also called snow pellets, soft hail, and hominy snow. Looks like uncooked hail, and hominy snow. Looks like uncooked white grits.white grits.

Definitions (cont.)Definitions (cont.)

SnowfallSnowfall – Amount of new snow – Amount of new snow which has fallen. Measured to the which has fallen. Measured to the nearest tenth of an inch.nearest tenth of an inch.

Snow DepthSnow Depth – Total amount of snow – Total amount of snow on the ground (old and new). on the ground (old and new). Measured to the nearest inch.Measured to the nearest inch.

Precipitation Type DiagramPrecipitation Type Diagram

Dec 5, 2002 Raleigh, NCDec 5, 2002 Raleigh, NC

Jan 30, 2002 North Webster, Jan 30, 2002 North Webster, ININ

NWS Winter Weather NWS Winter Weather ProductsProducts

Watches/Warnings/Watches/Warnings/AdvisoriesAdvisories

Hazardous Weather OutlookHazardous Weather Outlook Winter Storm WatchWinter Storm Watch Winter Storm WarningWinter Storm Warning Lake Effect Snow WarningLake Effect Snow Warning Blizzard WarningBlizzard Warning Winter Weather AdvisoryWinter Weather Advisory

Hazardous Weather OutlookHazardous Weather Outlook

Issued each day between 5am and Issued each day between 5am and 6am6am

Outlines potential weather hazards Outlines potential weather hazards expected over the next 7 daysexpected over the next 7 days

The potential for major storms The potential for major storms beyond 2 days will be discussed in beyond 2 days will be discussed in the HWOthe HWO

Winter Storm WatchWinter Storm Watch

Typically issued Typically issued 24 to 36 hours in 24 to 36 hours in advanceadvance of the storm of the storm

Issued when potential exists for:Issued when potential exists for: 66 inchesinches or more of snow in or more of snow in 12 hours12 hours 88 inchesinches or more of snow in or more of snow in 24 hours24 hours Significant mixed precipitationSignificant mixed precipitation

Winter Storm WarningWinter Storm Warning

Typically issued Typically issued 6 to 12 hours in 6 to 12 hours in advanceadvance of the storm of the storm

Issued when the following are likely:Issued when the following are likely: 6 inches6 inches or more of snow in or more of snow in 12 hours12 hours 8 inches8 inches or more of snow in or more of snow in 24 hours24 hours 0.25 inches0.25 inches or more of freezing rain or more of freezing rain

Lake Effect Snow WarningLake Effect Snow Warning

Same criteria as a Winter Storm Same criteria as a Winter Storm WarningWarning

6 inches in 12 hours6 inches in 12 hours 8 inches in 24 hours8 inches in 24 hours Lake effect snow warning implies the Lake effect snow warning implies the

localized nature of the heavy snow – in localized nature of the heavy snow – in most cases not everyone in a county most cases not everyone in a county will receive warning criteria snowfallwill receive warning criteria snowfall

Blizzard WarningBlizzard Warning

Wind speeds of Wind speeds of 35 mph35 mph or greater or greater ANDAND Visibility of Visibility of ¼ mile¼ mile or less in blowing or less in blowing

snowsnow Conditions must persist for at least Conditions must persist for at least 3 3

hourshours Blizzards may or may not be Blizzards may or may not be

accompanied by falling snow (Ground accompanied by falling snow (Ground Blizzard)Blizzard)

Winter Weather AdvisoryWinter Weather Advisory

Typically issued Typically issued 6 to 12 hours in 6 to 12 hours in advanceadvance of storm of storm

Issued when the following are likely:Issued when the following are likely: 4 to 5 inches4 to 5 inches of snow in of snow in 12 hours12 hours Light accumulation of freezing rain Light accumulation of freezing rain

(less than 0.25 inches)(less than 0.25 inches)

Where We are TodayWhere We are Today

Existing Snow Spotter Existing Snow Spotter Network Network

AtAt

NWS Northern IndianaNWS Northern Indiana

Existing Coop SpottersExisting Coop Spotters

2002 Snow Spotters2002 Snow Spotters

Need for More SpottersNeed for More Spotters

Existing COOP network is evenly spread Existing COOP network is evenly spread over our County Warning Area (CWA)over our County Warning Area (CWA)

We need to fill in the gaps between We need to fill in the gaps between COOP and official NWS observing sites – COOP and official NWS observing sites – as you well know, snowfall can vary as you well know, snowfall can vary widely within the same county, especially widely within the same county, especially in areas which receive lake effect snowin areas which receive lake effect snow

This is where YOU come in!This is where YOU come in!

Reporting Real time Reporting Real time InformationInformation

What type of Information can What type of Information can be useful to us?be useful to us?

Real Time InformationReal Time Information

Heavy SnowHeavy Snow – for example, snow falling at – for example, snow falling at the rate of 1 inch per hourthe rate of 1 inch per hour

Precipitation type changePrecipitation type change – snow to rain, – snow to rain, rain to snow, freezing rain, etc.rain to snow, freezing rain, etc.

Is the precipitation causing problems on Is the precipitation causing problems on roads?roads?

Significant Blowing and Drifting SnowSignificant Blowing and Drifting Snow – Is – Is drifting making travel difficult (or drifting making travel difficult (or impossible)?impossible)?

Freezing RainFreezing Rain

Is there a Is there a glaze accumulationglaze accumulation on roads on roads and sidewalks or only on elevated and sidewalks or only on elevated surfaces, such as trees and power lines?surfaces, such as trees and power lines?

How much ice has accumulated on How much ice has accumulated on surfaces. This can be difficult to measure surfaces. This can be difficult to measure directly, but can be easily estimated.directly, but can be easily estimated.

Measuring trickMeasuring trick – Crack a piece of ice off a – Crack a piece of ice off a railing and measure the thickness.railing and measure the thickness.

What to Report After the What to Report After the StormStorm

When the Snow Lets UpWhen the Snow Lets Up

Get a final measurement.Get a final measurement. Report your Report your total snowfall for the total snowfall for the

eventevent, and , and how long it was snowinghow long it was snowing.. For example: 7 inches in 10 hours.For example: 7 inches in 10 hours. In the case of freezing rain, also In the case of freezing rain, also

report the report the total amount of glazetotal amount of glaze on on surfaces.surfaces.

What Do We Use Your Reports What Do We Use Your Reports For?For?

Update forecasts, warnings, and Update forecasts, warnings, and advisories to better match conditions advisories to better match conditions being reportedbeing reported

Our updated forecasts and warnings Our updated forecasts and warnings in turn allow local officials to make in turn allow local officials to make better decisionsbetter decisions

We use storm total snowfall and ice We use storm total snowfall and ice accumulation data to verify forecasts accumulation data to verify forecasts and warningsand warnings

How to Measure SnowHow to Measure Snow

Yes, that says 54 inches!Yes, that says 54 inches!

Before the Snow FliesBefore the Snow Flies

Place a snowboard outside. Choose a Place a snowboard outside. Choose a location away from trees, shadows, location away from trees, shadows, and known drifting areas.and known drifting areas.

A snowboard can be any light colored A snowboard can be any light colored board, about board, about 2 feet by 2 feet2 feet by 2 feet. A piece . A piece of plywood painted white works great!of plywood painted white works great!

Mark the snowboard locationMark the snowboard location with a with a stake so you can find it easily in the stake so you can find it easily in the snow.snow.

Typical Snow BoardTypical Snow Board

Measuring the SnowMeasuring the Snow

If it is windy, it can be more accurate If it is windy, it can be more accurate to to take several measurementstake several measurements on the on the board and board and take an averagetake an average. .

After you measure, sweep the snow After you measure, sweep the snow board clean. board clean.

You can clean the snow board off up You can clean the snow board off up to 4 times in 24 hours, but no more to 4 times in 24 hours, but no more than once in 6 hours.than once in 6 hours.

Take a Measurement Take a Measurement

Sweep the Snow BoardSweep the Snow Board

Special CasesSpecial Cases

If snow falls and accumulates, then If snow falls and accumulates, then melts, the total snowfall will be the melts, the total snowfall will be the maximum maximum measured measured before the snow before the snow meltsmelts

If snow falls and If snow falls and melts on contactmelts on contact, , never reaching 0.1 inch depth, a never reaching 0.1 inch depth, a tracetrace of snow is recorded. of snow is recorded.

Sleet counts towards the snowfall Sleet counts towards the snowfall total, but freezing rain does not.total, but freezing rain does not.

Let the Snow Fly!Let the Snow Fly!