Rapid Update Cycle Rapid Update Cycle ModelModel

William Sachman William Sachman

and and

Steven EarleSteven Earle

ESC452 - Spring 2006ESC452 - Spring 2006

Primary uses of RUCPrimary uses of RUC►Making short range forecastsMaking short range forecasts

Initialized with very recent dataInitialized with very recent data

►Monitoring hourly conditions with Monitoring hourly conditions with hourly analyseshourly analyses Useful when overlaid with satellite, Useful when overlaid with satellite,

radar and other hourly observationsradar and other hourly observations

►Evaluating trends of longer range Evaluating trends of longer range modelsmodels Used to confirm other modelsUsed to confirm other models

HistoryHistory►With the birth of an increase in With the birth of an increase in

automated observations from automated observations from commercial aircraft and the newly commercial aircraft and the newly developed wind profilers came the developed wind profilers came the means to create short term forecasts means to create short term forecasts based on the frequent observations.based on the frequent observations.

► It was designed to provide accurate 0-It was designed to provide accurate 0-12h forecasts for weather sensitive 12h forecasts for weather sensitive users such as the aviation community.users such as the aviation community.

►Significant weather events occur in Significant weather events occur in such a short time frame, including such a short time frame, including severe weather.severe weather.

RUC ImplementationRUC Implementation► Mesoscale Analyses and Prediction System Mesoscale Analyses and Prediction System

(MAPS) was developed at the Forecast (MAPS) was developed at the Forecast Systems Laboratory (FSL) and began testing Systems Laboratory (FSL) and began testing in 1988 in 1988 used only for research.used only for research.

► RUC-1 was the first short range operational RUC-1 was the first short range operational forecast model, September 1994 at NCEPforecast model, September 1994 at NCEP 3h data assimilation cycle 3h data assimilation cycle 60-km resolution and 25 levels60-km resolution and 25 levels

► RUC-2 developed in April, 1998RUC-2 developed in April, 1998 1h data assimilation cycle1h data assimilation cycle 40-km resolution and 40 levels40-km resolution and 40 levels

► RUC-20 April 16, 2002RUC-20 April 16, 2002► RUC-13 June 28, 2005RUC-13 June 28, 2005

RUC-20RUC-20► Replaces RUC-2.Replaces RUC-2.► 50 hybrid isentropic-sigma levels50 hybrid isentropic-sigma levels► 20-km grid spacing20-km grid spacing

► Model ChangesModel Changes 13-km resolution13-km resolution Still has 50 levelsStill has 50 levels

► New observations in data assimilationNew observations in data assimilation METARMETAR MesonetMesonet Radio Acoustic Sounding System Radio Acoustic Sounding System (RASS)(RASS)

► Improved Post-processingImproved Post-processing precipitation type, CAPE, visibilityprecipitation type, CAPE, visibility

RUC-13RUC-13

RUC-13 now provides a 9 hour forecast every hour, with a 12 hour forecast every third hour

1-hour version of the RUC model1-hour version of the RUC model

RUC-20 Mean OrographyRUC-20 Mean Orography

http://www.meted.ucar.edu/nwp/pcu2/index.htm

http://www.meted.ucar.edu/nwp/pcu2/index.htm

http://maps.fsl.noaa.gov/

February 21, 3005 22z

• More detailed coastline with 13km RUC

http://maps.fsl.noaa.gov/

Soil Moisture (Top 2cm)Soil Moisture (Top 2cm)

Horizontal DomainHorizontal Domain

► Consists of a rectangular mesh (451 by 337 grid Consists of a rectangular mesh (451 by 337 grid points)points)

► Grid length measures 13.545 km at 35Grid length measures 13.545 km at 35ooN and 12.4 N and 12.4 km at 45km at 45ooN N

► Grid length decreased to 10 km at the northern Grid length decreased to 10 km at the northern boundaryboundary

► East-West boundaries are well off the coastline East-West boundaries are well off the coastline providing good coastal forecastsproviding good coastal forecasts

► Local circulation is better resolved including Local circulation is better resolved including differential heating and orographic precipitation differential heating and orographic precipitation patternspatterns

► Very detailed outputVery detailed output Could lead to problems?Could lead to problems?

Vertical DomainVertical DomainSigma Coordinates Isentropic (Theta) Coordinates

Surfaces are terrain following-resolve boundary layer well

May not correctly portray weather events on the lee side of mountains

Increases resolution in baroclinic regions-fronts and tropopause

Incompletely depicts low level adiabatic flow

http://www.meted.ucar.edu/nwp/pcu2/index.htm

RUC-13 Vertical ResolutionRUC-13 Vertical Resolution

Data Type ~ Number Frequency

Rawinsonde 80 12h

Wind Profilers 30 1h

VAD Winds 110-130 1h

Aircraft (V, Temp) 1400-4500 1h

Surface METAR 1500-1700 1h

Buoy/Ship 100-150 1h

GOES Precip. Water 1500-3000 1h

GOES Cloud Winds 1000-2500 1h

GPS Precip. Water 300 1h

Mesonet 5000 1h

METAR cloud-vis-wx 1500 1h

Observations used to initialize RUC Observations used to initialize RUC modelmodel

RUC Diagnosed VariablesRUC Diagnosed Variables

► Relative HumidityRelative Humidity► Surface TemperatureSurface Temperature► Dew PointDew Point► Sea-level pressureSea-level pressure► PrecipitationPrecipitation► Snow accumulationSnow accumulation► Snow depthSnow depth► Precipitation typePrecipitation type► Freezing levelsFreezing levels► 3h Pressure changes3h Pressure changes► CAPE/CINCAPE/CIN► Lifted IndexLifted Index► Precipitable waterPrecipitable water► HelicityHelicity

► Soil MoistureSoil Moisture► Tropopause pressureTropopause pressure► Vertical VelocityVertical Velocity► PBL depthPBL depth► Gust wind speedGust wind speed► Cloud base heightCloud base height► Cloud top heightCloud top height► Cloud fractionCloud fraction► VisibilityVisibility► Pressure of max Theta-E in Pressure of max Theta-E in

columncolumn► Convective cloud top heightConvective cloud top height► Equilibrium level heightEquilibrium level height

Strengths of the RUC modelStrengths of the RUC model

► Initializes every hourInitializes every hour►Hybrid isentropic-sigma vertical Hybrid isentropic-sigma vertical

coordinatescoordinates Eliminates problem of isentropic (theta) Eliminates problem of isentropic (theta)

surfaces intersecting the ground.surfaces intersecting the ground.

►Horizontal DomainHorizontal Domain Finer definition of terrain features which Finer definition of terrain features which

leads to better representation of leads to better representation of topographically induced features.topographically induced features.

Weaknesses of the RUC modelWeaknesses of the RUC model

►Hybrid isentropic-sigma vertical Hybrid isentropic-sigma vertical coordinatescoordinates Difficult to blend coordinates at their interfacesDifficult to blend coordinates at their interfaces

►Horizontal DomainHorizontal Domain Detailed (sometimes noisy) output compared Detailed (sometimes noisy) output compared

to other models.to other models. Resolution still insufficient to depict local Resolution still insufficient to depict local

details of most topographically induced details of most topographically induced circulationscirculations

In Conclusion...In Conclusion...

► Operational forecast model that provides Operational forecast model that provides accurate short range forecasts.accurate short range forecasts.

► The most recent model is the RUC-13 The most recent model is the RUC-13 model, providing a 13km resolution.model, providing a 13km resolution.

► RUC uses hybrid isentropic-sigma vertical RUC uses hybrid isentropic-sigma vertical coordinate system.coordinate system.

► Combines upper air and surface data to Combines upper air and surface data to initialize model.initialize model.

ReferencesReferences

► FSLFSL► NOAANOAA► NCEPNCEP

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