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Forecast Toolkit


Overview


This page is a collection of web-based forecast tools that focuses several questions:
    • Should I believe this solution (is this a predictable pattern)?
    • What is the range of possible solutions?
    • Should I pay attention to this pattern?
    • What is significant in the forecast?
    • What are the potential impacts in terms of sensible weather?
Browser Issues: Some links on the STID Google Sites (Atmospheric River section) have not been showing the graphics recently when you click on them with certain browsers. It appears that this is related to new behavior between Google Sites and some java/scripts. Click here for more info.

YouTube Suggestions: The small YouTube videos on this page may appear grainy or are otherwise too small to be helpful.  You should be able to make the video larger (depending on your browser) or open in YouTube and select a higher resolution (720p should be fine). 

Large Scale Patterns

Ensemble Situational Awareness Table

http://ssd.wrh.noaa.gov/satable/#

Anomaly Table Demo


The Benefits
  • Provides a framework for quickly identifying significant events in the forecast.
  • NAEFS ensemble mean fields are compared to the 1979-2009 CFSR reanalysis climatology to highlight potentially significant features in the forecast.
  • The NAEFS ensemble consists of a control run and 20 perturbed members from each of the Canadian and GEFS models.
The Drawbacks
  • Only presents the ensemble mean-- no explicit confidence information. 
  • Large anomalies in an ensemble mean at long lead times suggest a higher likelihood of significant events, but not if the model is underdispersive or "overconfident"

Probabilistic QPF and EFI

http://ssd.wrh.noaa.gov/satable/esrl/
The Benefits
  • The PQPF represent high resolution (1/8 degree) probabilistic forecasts at various thresholds. Raw (and frequently biased) ensemble forecasts from the GEFS are transformed into reliable predictive probability distributions for various precipitation accumulations.
  • The Extreme Forecast Index (EFI) is an index designed to identify situations where the GEFS mean forecast is predicting an extreme solution relative to a reference climatology. The percentile shown represents where the current forecast value falls within quantiles created from the reforecast database climatology. Values toward 0 and 100 are very near or beyond the reference climate distribution.;
The Drawbacks
  • GEFS is under-dispersive
  • EFI Temperatures are significant near 0 and 100 (cold/warm). The EFI "T" column will only show whichever percentile (cold/warm) is most significant
  • A "-" symbol in the table indicated data is not available for that time.

GEFS Ensemble Graphics

The Benefits
  • Gathers several confidence tools (normalized spread, GFS deterministic versus GEFS ensemble, model climate QPF, ensemble IVT) in one place.
The Drawbacks
  • Normalized spread is especially tricky to interpret, and can highlight strong gradients or pattern changes rather than low predictability.

GFS Comparison Graphics 


The Benefits
  • Easy to use web page that compares the GFS to the Parallel GFS.
  • Plots standard levels and several precip fields.
  • Includes a dProg/dt function to see how the guidance has changed over the prior few runs.
The Drawbacks
  • None really.

Relative Measures of Predictability (RMOP)

http://www.emc.ncep.noaa.gov/gmb/yluo/html_pqpf/rmop.html

The Benefits
  • RMOP in a given region indicates how much spread the GEFS emseble members have relative to spread over the last 30 days.
  • Example... 90% RMOP: current GEFS at this forecast hour is more tightly clustered than 90% of forecasts at this hour over the past 30 days.  55% probability: 55% of GEFS forecasts at this hour with 90% RMOP have verified close to observations.
  • High values of RMOP: ensemble has narrowed in on a solution.  High values of probability: that solution might actually occur.
  • High values of both RMOP and probability should increase confidence.
The Drawbacks
  • Only the ensemble mean is plotted, which will wash out smaller scale features when there is timing/spatial uncertainty.
  • High values of RMOP with low probabilities indicate that the GEFS is confident but you should not be!

FSU Confidence in Surface Fields

http://moe.met.fsu.edu/confidence/


The Benefits
  • Can help to establish confidence in localized sensible weather from a large-scale ensemble.
  • Compares de-biased climatological GEFS spread to spread in the current GEFS forecast
  • Similar to normalized spread plots, but spread is compared to climatology rather than last 30 days of forecasts.
  • Plan-view and point-based plots for 2-m temperature, wind speed and other surface variables.
The Drawbacks
  • Low-resolution fields, no post-processing.
  • Low spread does not always imply high skill.

Climate Forecast System Ensemble

http://hopwrf.info/CFS/AnomAveAve500hgt_AllTimes.html

The Benefits
  • 20-member CFS ensemble contains 00,06,12,18 UTC runs for the last 5 days.
  • Some of the only operational guidance available beyond week 2.
The Drawbacks
  • Limited verification data available.  The CFS output is something to start looking at and evaluating, but be careful not to take these (or any) long-range forecasts at face value until we know more about the biases and skill of the forecast system.

Atmospheric River Plots

http://ssd.wrh.noaa.gov/naefs/?type=ivt

The Benefits
  • Provides depictions of the GEFS ensemble mean and the GFS deterministic IWV transport for the western US


Analogs and Surface Sensible WX

GEFS Reforecast Analogs

http://www.esrl.noaa.gov/psd/forecasts/reforecast2/analogs/index.html

The Benefits
  • Reforecast analogs are used to calibrate the real-time GEFS forecast, which shows considerable skill over raw ensemble probabilies.
  • Uses a GEFS reforecast dataset covering 1984 to 2012 at ~50km (~70 km) resolution for days 1-8 (8-16).
The Drawbacks
  • Precipitation forecasts are subject to the quality of the NARR reanalysis precipitation (32-km resolution).
Also Check out: 

CIPS Analogs

http://www.eas.slu.edu/CIPS/ANALOG/analog.php

Also Check out:
The Benefits
  • Identifies 15 past NARR analyses that are similar to the current NAM and GFS forecast.
  • Initial page shows the list of dates sorted by how well they match the forecast pattern.
  • Plots show the probabilties of exceeding various precipitation, snowfall and temperature thresholds.  Example: 50% probability of >12" snowfall at a point means that on more than half of the 15 past dates with similar patterns, at least 12" of snow fell at that point (based on COOP data).
  • Western US domain moves based on the pattern.
The Drawbacks
  • Based on deterministic NAM/GFS solutions.  Builds confidence in the impacts, but only assuming that the model forecast is good.
  • Precipitation/snowfall probabilities use smoothed COOP data, not PRISM.  Terrain is not well represented.

SPC SREF Probability Plots

http://www.spc.noaa.gov/exper/sref/

The Benefits
  • SPC does some post-processing of the 21 SREF members here.
  • Useful fields: calibrated thunderstorm probability, Fire Weather joint probabilities, CAPE/Shear and other combined convective probabilities, PQPF.
  • Click on the forecast hour for d(prog)/dt graphics.
The Drawbacks
  • Basic surface fields are not calibrated or bias-corrected.  16-km resolution is insufficient in complex terrain.

SPC Interactive SREF Plume Diagrams

http://www.spc.noaa.gov/exper/sref/srefplumes/


Also Check Out:
The Benefits
  • Time series plots of all SREF ensemble members at a point
  • Useful fields: 10m winds, precip/snow accumulations
  • The SREF has 21 members that are all variations of the WRF model.  3 different cores, 7 initial condition perturbations each.  16 km resolution.
The Drawbacks
  • This is not MOS and is not bias-corrected.  As such, WRF configurations typically overpredict wind speed and underpredict the diurnal range of temperature, although this varies from event to event.

NOMADS Probability Tool

http://nomads.ncdc.noaa.gov/EnsProb/

The Benefits
  • Show the raw probability of exceeding various thresholds (% of 21 GEFS members).
  • Point-based one-stop shop for raw ensemble mean/spread data and probabilities.
The Drawbacks
  • Use raw ensemble probabilities at your peril. Particularly for high precipitation thresholds, these uncalibrated values are unreliable in complex terrain.
  • Tool takes a short time to run (30 seconds or more)

CFS Severe Weather Guidance Dashboard

http://www.spc.noaa.gov/exper/CFS_Dashboard/


The Benefits
  • Helps identify potential severe weather outbreaks well in advance 
  • Based on the CFS (Coupled Forecast System) 
  • The colored blocks in the table show the number of grid point where the daily-averaged Supercell Composite Parameter (SCP) is > = 1
  • SCP components are found here: http://www.spc.noaa.gov/exper/mesoanalysis/help/help_scp.html
  • Vertical continuity in the grids suggest run to run consistency in the forecast
The Drawbacks
  • This is an experimental product and may not update every model run

UCAR High Resolution Ensemble

http://ensemble.ucar.edu/



The Benefits
  • Provides ensemble based guidance using high resolution models (mainly WRF). 
  • 10 Member, 48 Hour forecast at 3 km run at 00Z.
  • Shows skill in both identifying precipitation locations and magnitudes (has a tendency to overforecast high precipitation rates and underforecast low precipitation rate events)
The Drawbacks
  • This is an experimental quasi-operational product
  • Subjective analysis suggests this system has difficulty maintaining forward-propagating mesoscale convective systems (MCSs) that develop in weakly forced environments

Anomaly Composite Maps




The Benefits
  • Creates map composites of any number of dates (within a one to three month window) and outputs anomaly maps in terms of Standard Deviation (Standardized Anomalies). 
  • Output presents composite anomalies for 500 mb height, PWAT, 850 mb air temp, SLP, 700 mb wind speed and 850 mb wind speed.
  • By compositing using one or three month windows, the output shows anomalies relative to seasonal climatology.  This helps to draw more direct comparisons to the WR Situational Awareness Table.
The Drawbacks
  • Current iteration only shows standard anomalies and not output such as return frequencies or percentiles.
  • Output is image based so there is little direct interaction with the data.
  • Plot regions are limited.
  • Users MUST ensure they enter dates 



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