How to win “Forecaster of the How to win “Forecaster of the Year”Year”

OrOrHow to be more like me.How to be more like me.

If you really want to.If you really want to.REALLY want to.REALLY want to.

What is forecasting?What is forecasting?

AnalysisAnalysis DiagnosisDiagnosis PrognosisPrognosis

What is What is notnot forecasting? forecasting?

Rules of thumbRules of thumb Following the model blindlyFollowing the model blindly

– ““Meteorological cancer”Meteorological cancer”

FeelingsFeelings

So what do we do?So what do we do?

Forecast (in the mind, on a screen, or on Forecast (in the mind, on a screen, or on paper) the motion of large-scale featurespaper) the motion of large-scale features– LowsLows– HighsHighs– FrontsFronts– Vorticity centresVorticity centres– MoistureMoisture– Jet streams / streaksJet streams / streaks

Keeping in mindKeeping in mind

Geography / climatology of the areaGeography / climatology of the area– Valleys, upslope areasValleys, upslope areas– TreelineTreeline

Recent events and surface conditionsRecent events and surface conditions– SnowpackSnowpack– Recent rainfallsRecent rainfalls

Now we have a handle on the Now we have a handle on the large-scale featureslarge-scale features

Let’s get down to the nitty grittyLet’s get down to the nitty gritty(but not the dirt band)(but not the dirt band)

Temperature forecastingTemperature forecasting

Think process – what affects the Think process – what affects the temperature?temperature?– Cloud cover / sunshineCloud cover / sunshine– PrecipitationPrecipitation– AdvectionAdvection

What works for temperatureWhat works for temperature

Analysis (tephis, surface, upper plots)Analysis (tephis, surface, upper plots) Gerlyand curvesGerlyand curves Temperature trendsTemperature trends 850 850 ΔΔT/T/ΔΔt superimposed on yesterday’s t superimposed on yesterday’s

valuesvalues BarthrumBarthrum Synoptic correlationSynoptic correlation

Cloud cover forecastingCloud cover forecasting

Once more, think process – what causes Once more, think process – what causes cloud?cloud?– Cloud shows ascent – so the focus is on what is Cloud shows ascent – so the focus is on what is

causing that ascentcausing that ascent FrontsFronts TroughsTroughs Vorticity centresVorticity centres Outflow boundariesOutflow boundaries Jet streaksJet streaks

What works for sky conditionWhat works for sky condition

Analysis (tephis, surface, upper plots)Analysis (tephis, surface, upper plots) PersistencePersistence Satellite images (visible, 4 Satellite images (visible, 4 μμm, blended)m, blended) Water vapour imagesWater vapour images

Precipitation forecastingPrecipitation forecasting

This is the trickiest, but it boils down to the This is the trickiest, but it boils down to the same thing – think processsame thing – think process

Precipitation tells you there is significant lift Precipitation tells you there is significant lift occurring along with ample moistureoccurring along with ample moisture– So this is essentially the same as for cloud So this is essentially the same as for cloud

cover forecastingcover forecasting

What works for precipitationWhat works for precipitation

Analysis (tephis, surface, upper plots)Analysis (tephis, surface, upper plots) RADARRADAR Satellite imagerySatellite imagery

– Looking for convectionLooking for convection– Looking for vort centresLooking for vort centres– Looking for subsidenceLooking for subsidence

What works for windWhat works for wind

SCRIBESCRIBE– Also analysis (tephis, surface, upper plots)Also analysis (tephis, surface, upper plots)

How do I put it all together?How do I put it all together?

3 primary steps3 primary steps– AnalysisAnalysis– DiagnosisDiagnosis– PrognosisPrognosis

I end up with a forecastI end up with a forecast

And thenAnd then

AfterAfter I have my forecast I have my forecast

Shocker!Shocker!

I look at what the model saysI look at what the model says

I compare SCRIBE to my forecastI compare SCRIBE to my forecast

I look for areas where the model is known I look for areas where the model is known not to fare wellnot to fare well– Boundary layer cloudBoundary layer cloud– Convective precipitationConvective precipitation– Strongly curved flowStrongly curved flow

And make changes accordinglyAnd make changes accordingly

Keep in mindKeep in mind

This important techniqueThis important technique

BE LAZYBE LAZY

(when manipulating SCRIBE)(when manipulating SCRIBE)

What do you mean, be lazy?What do you mean, be lazy?

Verification has shown us thatVerification has shown us that– When we make small changes, we’re right When we make small changes, we’re right

about 50% of the timeabout 50% of the time– When we make big changes, we usually don’t When we make big changes, we usually don’t

make a make a big enoughbig enough change change

So……………..So……………..

““If I’ve ever been sure of anything If I’ve ever been sure of anything in my life, I’m sure of this”in my life, I’m sure of this”

(This change will be a good one)(This change will be a good one)

Only make big changesOnly make big changes

What is a big change?What is a big change?

Temperature changes of Temperature changes of at leastat least 2 degrees 2 degrees Sky condition changes of Sky condition changes of at leastat least 2 2

conditionsconditions Wind changes of Wind changes of at leastat least 20 km/h and 90 20 km/h and 90

degreesdegrees– And then onlyAnd then only

When it’s windy and SCRIBE calls for calm, and vice-When it’s windy and SCRIBE calls for calm, and vice-versaversa

In highly curved flowIn highly curved flow

What is a big change, continuedWhat is a big change, continued

PrecipitationPrecipitation– By 1 POP categoryBy 1 POP category– By 1 phaseBy 1 phase

Points to rememberPoints to remember

Analysis, diagnosis, prognosisAnalysis, diagnosis, prognosis Make up your forecast Make up your forecast beforebefore checking checking

SCRIBESCRIBE Be lazy – only make significant changesBe lazy – only make significant changes