USWRP Multi-Agency Cool-Season QPF Workshop

Co-ChairsMarty Ralph (NOAA/ETL)

Bob Rauber (Univ. Illinois)

Workshop Focus

•Regional differences in precipitation processes and QPF methods

•Precipitation type forecasting and QPF of snow, freezing rain, sleet

QPF for winter flood prone areas such as West Coast and Southern Appalachians

Winter QPF in areas with significant mesoscale forcing (e.g. Atlantic coastal plain, Appalachians, Great Lakes, Front Range, coastal and interior western mountains.

0-48 hour Cool-Season forecast problem

THE END PRODUCT OF THE WORKSHOP

An implementation plan for the USWRP that sets out the scientific

objectives of each component of the cool season QPF problem

Final report is available at: http://box.mmm.ucar.edu/uswrp/implementation/CSQPF.pdf

10” rain

Feb. 25, 2004, SSM/I Integrated Water Vapor (green 1-2 cm, orange 3-4 cm)

GROUP 1: RESEARCH AND FIELD STUDIES

Co-leaders: Ron Stewart, McGill UniversityJeff Waldstreicher, NOAA/NWS Eastern

Region SSD  Recommended Physical Process Studies• 4D structure of systems above the boundary layer (i.e., in the free troposphere)

• The rain-freezing rain-snow transition region

• Regional mesoscale boundary layer forcing (particularly orographic and lake effects)

• Moisture sources and transport into winter systems

• Predictability of cool season precipitation

GROUP 2: DATA ASSIMILIATION AND NWP ADVANCES

Co-leaders: Tom Schlatter, NOAA/FSLBrian Jewett, University of Illinois at

Urbana/Champaign  Recommended parameterization improvements• Cloud microphysics – the thermodynamic conditions and presence of microscopic particulates within a cloud determine the origin and subsequent growth of hydrometeors

• Boundary layer – winds in the sub-cloud layer transport hydrometeors laterally, and changes of phase can strongly alter the sub-cloud temperature and humidity profiles

• Land surface – antecedent conditions at and near the ground affect potential for freezing rain

• Convection – when near-surface temperature is just above freezing the intensity of precipitation can mark the difference between rain and snow.

GROUP 3: OBSERVING SYSTEMS, TEST BEDS

Co-leaders: Dave Reynolds, NOAA/NWSFO MontereyDave Kingsmill, NOAA/ETL

  Key Applications for Observations

• Nowcasting• Data Assimilation• Verification

Required types of observation platforms

• In-situ• Ground-based remote sensors• Space-based remote sensors

GROUP 4: USERS, USER NEEDSCo-leaders: Roy Rasmussen, NCAR

Paul Pisano, Federal Highway Administration

 Steps for development of cool season QPF products:• Determine and validate user needs for cool season QPF products.

• Evaluate the social, environmental and security impacts of the winter QPF product.

• Develop operational concept and prototype(s) based on needs.

• Define science needs, and conduct research to meet them

• Test and evaluate prototypes through the use of testbeds and demonstration projects.

• Revise system based on user response (iterate).

• Transfer technology to operations based on the operational concept defined earlier in the process.

Core Recommendation #1Establish a National Hydrometeorological Test-bed (HMT)

From the working group reports, a consensus emerged that a test-bed approach should be implemented using two long-term regional efforts.

• HMT-East focus on winter storms along the East Coast of the United States, with freezing rain, coastal cyclones (e.g., Nor’easters), heavy snow, and lake effects as priorities

• HMT-West focus on water resource related issues in the West, with flood control, water supply, orographic effects and atmospheric rivers (concentrated regions of strong horizontal water vapor transport) as priorities

• HMT: Linking Research and Operations- Longer-term, continuous activities that are required to optimize operational impacts are the focus of HMT. - The HMT infrastructure then provides a foundation upon which to conduct episodic major field programs that are required to address certain key research and forecasting problems

Cool-season QPF multi-agency workshop report, May 2004

Core Recommendations #’s 2 & 3• Develop Probabilistic Methods

- must address major regional differences- specify the size, position, orientation, timing, and amount of precipitation within regions of snowfall and mixed precipitation,- specify location of boundaries separating precipitation types

• Advance mesoscale data assimilation and modeling - community effort to develop the WRF system should be the focus of work to improve cool season QPF - for the next 2-3 yrs is continue enhancement of 3DVAR while pros & cons of EnKF and 4DVAR are explored - results of assimilation experiments may be strongly scale-dependent, i.e., methods that work well in global models may not work well in mesoscale models with more sophisticated physics

Temporary Oversampling in Testbeds can Provide AOR Data

Candidate Sensors• surface met• GPS receivers• profilers• gap-filling radars• buoys

Testbeds(regional or topical)

Final network

OutcomeImproved Services through NWP and

Nowcasting

Testbed results objectively inform decisions on changing NOAA’s long-term regional observing network.

TemporaryOversamplingObjective testing

and demonstration

Fill gaps throughtargeted sensor development, e.g.,• buoy profilers• precipitation radars