Short-Range Ensemble Forecast Objectives
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Transcript of Short-Range Ensemble Forecast Objectives
National Weather Service
The Short-Range Ensemble Forecast: The Short-Range Ensemble Forecast: Applying Uncertainty and Probabilistic Applying Uncertainty and Probabilistic
Forecasts of Winter Storms Forecasts of Winter Storms
Matt Steinbugl, NOAA/NWS Des Matt Steinbugl, NOAA/NWS Des MoinesMoines
Rich Grumm, NOAA/NWS State Rich Grumm, NOAA/NWS State CollegeCollege
National Weather Service
Short-Range Ensemble Forecast Short-Range Ensemble Forecast ObjectivesObjectives
• ConveyConvey and and applyapply uncertainty to the uncertainty to the forecast processforecast process• RecognizeRecognize and and assignassign probabilities to probabilities to crucial winter weather forecast crucial winter weather forecast parametersparameters
This will allow forecasters:This will allow forecasters:• To To increase overall confidenceincrease overall confidence within within each individual forecast through a each individual forecast through a probabilistic approachprobabilistic approach• To To make better decisionsmake better decisions while allowing while allowing users better decision making capabilitiesusers better decision making capabilities
National Weather Service
Why Ensembles?Why Ensembles?
•Uncertainty in initial conditions Uncertainty in initial conditions and model calculations can alone and model calculations can alone lead significant outcome changes lead significant outcome changes (run-to-run)(run-to-run)
•Need to account for non-linear Need to account for non-linear processesprocesses
•Atmosphere is chaotic in natureAtmosphere is chaotic in nature
National Weather Service
Why Ensembles?Why Ensembles?
•Needed to deal with inherent forecast Needed to deal with inherent forecast uncertaintyuncertainty
•Improve significant winter weather Improve significant winter weather forecastsforecasts
•Recognize high uncertainty/high Recognize high uncertainty/high probability outcomes and relate these probability outcomes and relate these to each phase of the forecast processto each phase of the forecast process
National Weather Service
What is the SREF?What is the SREF?
Multi-model based ensemble Multi-model based ensemble prediction system (EPS) with each prediction system (EPS) with each member having different dynamical member having different dynamical cores and physics packages.cores and physics packages.
21 individual members:21 individual members:
5 ETA (BMJ) + 5 ETA (KF) + 5 RSM 5 ETA (BMJ) + 5 ETA (KF) + 5 RSM ++6 WRF NMM/ARW (BMJ/KF) = 6 WRF NMM/ARW (BMJ/KF) = 21 21 membersmembers
-3 hourly output out to 87hrs-3 hourly output out to 87hrs-Produced at NCEP 03Z, 09Z, 15Z -Produced at NCEP 03Z, 09Z, 15Z and 21Z and 21Z
National Weather Service
Deterministic (GFS) vs. Deterministic (GFS) vs. Probabilistic (SREF)Probabilistic (SREF)
ModelModel Initial Initial ConditionCondition
s (ICs)s (ICs)
Model Model corescores
RemarksRemarks
GFSGFS 1 IC1 IC 1 model 1 model corecore
run-to-run-to-run run
(jumpine(jumpiness)ss)
SREFSREF Multiple Multiple ICsICs
Multiple Multiple corescores
More More consistenconsisten
cycyComparing deterministic models is a 50/50 Comparing deterministic models is a 50/50
proposition!!!proposition!!!
National Weather Service
Case Study DataCase Study Data
•Examine 3 significant winter Examine 3 significant winter weather events across the weather events across the Eastern United StatesEastern United States
•We need to extract the We need to extract the following from the data:following from the data:
-Amounts/timing of pcpn?-Amounts/timing of pcpn?-PYTPE?-PYTPE?-Temps for Snow vs. Ice?-Temps for Snow vs. Ice?-Pattern Recognition?-Pattern Recognition?-Atypical/typical event?-Atypical/typical event?
National Weather Service
SpaghettiSpaghetti//Probability charts - 0° Probability charts - 0° isothermisotherm
Mean Mean and and probabilprobabilityity
sprespreadad
22mm
850850mbmb
National Weather Service
Mixed/Conditional Probability Mixed/Conditional Probability charts PYTPEcharts PYTPE
RaiRainn
Ice Ice PelletsPellets
SnoSnoww
FZRFZRAA
National Weather Service
Probability/Mean charts – Probability/Mean charts – 0.50/1.00” QPF0.50/1.00” QPF
National Weather Service
Mixed/Conditional Probability Mixed/Conditional Probability charts PYTPEcharts PYTPE
RaiRainn
Ice Ice PelletsPellets
SnoSnoww
FZRFZRAA
National Weather Service
SummarySummary EPSs are an important means of:EPSs are an important means of:•Explicitly conveying and applying uncertainty Explicitly conveying and applying uncertainty through a probabilistic approachthrough a probabilistic approach
•Visualizing and quantifying uncertainty Visualizing and quantifying uncertainty within the forecast processwithin the forecast process
Using ensembles will allow forecasters to Using ensembles will allow forecasters to relate probabilities to each phase of the relate probabilities to each phase of the warning decision processwarning decision process
In turn, this will allow forecasters to make In turn, this will allow forecasters to make better decisions and users to have better better decisions and users to have better decision making capabilitiesdecision making capabilities
National Weather Service
SpecialSpecial ThanksThanks
Rich Grumm, SOO CTPRich Grumm, SOO CTP
Karl Jungbluth, SOO DMXKarl Jungbluth, SOO DMX
Peter Manousos, SOO NCEPPeter Manousos, SOO NCEP
Jun Du, NCEP/EMCJun Du, NCEP/EMC
Steve Wiess, SPCSteve Wiess, SPC
Jeremy Grams, SPCJeremy Grams, SPC
David Bright, SPCDavid Bright, SPC
National Weather Service
ReferencesReferences
http://http://www.hpc.ncep.noaa.gov/ensembletrainingwww.hpc.ncep.noaa.gov/ensembletraining//
http://wwwt.emc.ncep.noaa.gov/mmb/SREF/WMO06_full.pdfhttp://wwwt.emc.ncep.noaa.gov/mmb/SREF/WMO06_full.pdf
http://wwwt.emc.ncep.noaa.gov/mmb/SREF-Docs/http://wwwt.emc.ncep.noaa.gov/mmb/SREF-Docs/
AWOC Winter IC 6.3: Using Ensembles in Winter Weather AWOC Winter IC 6.3: Using Ensembles in Winter Weather Forecasting Forecasting
http://mcc.sws.uiuc.eduhttp://mcc.sws.uiuc.edu
http://nws.met.psu.edu/severe/index.jsphttp://nws.met.psu.edu/severe/index.jsp
http://nws.met.psu.edu/severe/2006/11May2006.pdfhttp://nws.met.psu.edu/severe/2006/11May2006.pdf
SREF Exploitation at NCEP’s Hydrometeorological Prediction Center SREF Exploitation at NCEP’s Hydrometeorological Prediction Center (HPC) (HPC) http://nws.met.psu.edu/severe/2005/23April2005.pdfhttp://nws.met.psu.edu/severe/2005/23April2005.pdf
Dealing with uncertainties in forecasts – M Steven Tracton Dealing with uncertainties in forecasts – M Steven Tracton NWS/NCEP/EMCNWS/NCEP/EMC
http://weather.unisys.com/archive/index.htmlhttp://weather.unisys.com/archive/index.html
http://eyewall.met.psu.edu/plumes/Plume.pdfhttp://eyewall.met.psu.edu/plumes/Plume.pdf
http://eyewall.met.psu.edu/plumes/PlumeDisplay.htmlhttp://eyewall.met.psu.edu/plumes/PlumeDisplay.html
http://eyewall.met.psu.edu/ensembles/java/ModelDisplay.htmlhttp://eyewall.met.psu.edu/ensembles/java/ModelDisplay.html