UTILIZING COCORAHS RAINFALL DATA IN OPERATIONAL RIVER FORECAST OPERATIONS AT THE NERFC Ronald S. W. Horwood Meteorologist SR HAS Forecaster National Weather Service Northeast River Forecast Center Taunton MA NROW 2014

OVERVIEW Background on NERFC Operations QPE Assimilation at the NERFC Addition of CoCoRAHS Data Into Operational QPE at the NERFC Case Review Summary Questions

BACKGROUND ON NERFC OPERATIONS One of 13 National Weather Service River Forecast Centers in the U.S. Issue daily forecasts for over 200 forecast points in New England and New York State. – Serving 8 NWS Weather Forecast Offices 3 Hydrometeorological Analysis and Support (HAS) Forecasters and 7 Hydrologists. 1 Hydrologist in Charge (HIC) 1 Development and Operations Hydrologist (DOH) 1 Service Coordination Hydrologist (SCH)

Background on NERFC Operations - cont Run the Sacramento Soil Moisture Accounting Hydrologic Model on a 6-hourly time step. – Inputs to the hydrologic model include: Observed and future precipitation Observed and future temperatures Existing snow water equivalent (SWE) – River forecasts are run out 72 hours daily with 48 hours of QPF and past observed precipitation (QPE).

QPE ASSIMILATION AT THE NERFC The NERFC maintains 2 gridded data sets of 6- hourly observed precipitation (QPE) to drive the hydrologic model. – MPE A radar/gauge combination used to drive the hydrologic model in the warm season ( May – Oct ). – MPE/DailyQC A gauge only dataset used to drive the hydrologic model in the cool season ( Nov – Apr ).

MPE ( Radar/gauge combination )

MPE/DailyQC ( Gauge only )

QPE ASSIMILATION AT THE NERFC - cont Our gauge only dataset (MPE/DailyQC) was comprised of: – NWS Cooperative Observers (COOP) – NWS Automated Surface Observing Systems (ASOS) – United States Geological Survey and other agency automated precipitation gauges. Our network of gauge data continued to have holes especially across northern New York State and northern New England.

MPE/DAILYQC WITHOUT COCORAHS

ADDITION OF COCORAHS DATA INTO OPERATIONAL QPE What is CoCoRAHS????? – Community Collaborative Rain, Hail and Snow Network A unique, non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation (rain, hail and snow). – Originated with the Colorado Climate Center at Colorado State University in – Now Established in all 50 states and the District of Columbia.

COCORAHS AT THE NERFC - cont The NERFC began ingesting CoCoRAHS data into our database in about 2010 but it was not used in QPE. In 2012…a decision was made to assess the feasibility of using this data operationally. – Stations were monitored for quality and reliability. – Up to 5 quality CoCoRAHS stations were added for each county in New England and New York State and defined in the MPE/DailyQC program. Became operational in Spring of 2014.

COCORAHS STATIONS IN MPE/DAILYQC

CASE REVIEW Heavy rainfall event from 12z 16 October – 12z 17 October 2014 Used NERFC MPE/DailyQC ( gauge only ) for QPE estimates – Compared the hydrologic model simulations for 4 river forecast points without and with CoCoRAHS data. NTYV1 NANM1 MERM1 JONV1

NTYV1 without CoCoRAHS

NANM1 without CoCoRAHS Simulation improves by 0.15 feet

MERM1 without CoCoRAHS Simulation improves by 0.18 feet

JONV1 without CoCoRAHS Simulation slightly worse on tail

Summary 3 of the 4 simulations with CoCoRAHS data showed improvement with 1 slightly worse. – Encouraging results…further evaluation is needed since the change to CocoRAHS is relatively recent. Subjectively…QPE has appeared better in data sparse regions with the addition of the CoCoRAHS data.

QUESTIONS???