Weather Prediction Center

National Oceanic and Atmospheric Administration

 

 

 

2024 Flash Flood and Intense Rainfall Experiment (FFaIR)

The 2024 FFaIR experiment will take place the weeks of: June 10-14, June 24-28, July 8-12, July 22-26, July 29-Aug 2, 2024.

 

2023-2024 Winter Weather Experiment (WWE)

The 14th Annual WWE experiment has concluded and a summary is coming in June.

 

2023 Flash Flood and Intense Rainfall Experiment (FFaIR)

The 2023 Flash Flood and Intense Rainfall experiment occurred from June through August 2023. Part 1 of this report focuses on the evaluation of the Rapid Refresh Forecasting System (RRFS). Part 1 of the report is available here.

 

2022-2023 Winter Weather Experiment

The 13th Annual Winter Weather Experiment took place in Feb and March 2024 investigating the National Blend of Models. As a new addition to HMT collaboration efforts, this year’s WWE gained additional personnel from the Leveraging Abilities Needs Talents Energies Resource Network (LANTERN) volunteer program. This program allowed interested WFO forecasters a chance to learn more about HMT, WWE, and be involved in the testbed process. More specifically, the LANTERN volunteers were tasked with selecting and facilitating discussion on operationally relevant cases with forecasting challenges focused on the use of NBMv4.1. The complete report is available here.

 

2022 Flash Flood and Intense Rainfall Experiment (FFaIR)

The 10th annual Flash Flood and Intense Rainfall (FFaIR) Experiment was conducted remotely from June 21 to July 22, 2022 by the Hydrometeorology Testbed at the Weather Prediction Center (HMT WPC). FFaIR used experimental products and guidance in a pseudo-operational setting, evaluating their utility and performance in forecasting heavy rainfall and flash flooding. With the planned implementation of the Rapid Refresh Forecast System (RRPF) fast approaching, FFaIR focused on various deterministic configurations of the system provided by EMC, GSL, and the Center for Analysis and Prediction of Storms (CAPS) group from the University of Oklahoma. In addition to the RRFS evaluation, three GEFS-based machine learning products for the Day 1 ERO provided by Colorado State University (CSU), along with a HRRR-based one, were evaluated. FFaIR participants used these experimental tools and guidance, along with operational ones, to produce a Day 1 ERO and AERO (an ERO-like product based in Average Recurrence Interval exceedances) and the Maximum Rainfall and Timing Product (MRTP) for Day 1, with a Day 2 one created when possible. The complete report is available here.

 

2021-2022 Winter Weather Experiment (WWE)

The 12th annual WWE was conducted over the 2021-2022 winter season through two remote intensive evaluation weeks and the use of retrospective cases were utilized to complete the experiment objectives. This year tasked participants with examining potential updates to the Winter Storm Severity Index (WSSI) and analyze CAM and NBM datasets for snow accumulation and precipitation type forecasting and verification. The WWE also hosted invited presentations throughout the entire WWE season. In addition to the intensive weeks, this years' WWE was responsible for organizing several other winter related activities. The first relates to hosting a series of focus groups where NWS forecasters were invited to provide feedback on: 1) the development of a decision support tool that provides a probability that roads are subfreezing, and 2) The value and utility of different HREF visualizations for snow bands, snow rates, and precipitation types. The complete report is available here.

 

2021 Flash Flood and Intense Rainfall Experiment (FFaIR)

The 9th annual Flash Flood and Intense Rainfall (FFaIR) Experiment was conducted remotely June 21 through July 23, 2021 by the Hydrometeorology Testbed at the Weather Prediction Center (HMT-WPC). Running in a pseudo-operational setting, FFaIR utilized and evaluated experimental models and products in the process of forecasting heavy rainfall and flash flooding. Like last year, the experimental models evaluated in FFaIR focused on various configurations of FV3 convective allowing models (CAMs);three versions from the Environment Modeling Center (EMC), one version from GSL, and four versions from the Center for Analysis and Prediction of Storms (CAPS) group. Additionally, two FV3 convection allowing ensembles were evaluated, one from CAPS, and a collaborative effort between GSL, EMC, and NSSL run in the cloud. In addition to the FV3 CAMs and ensembles, six CAM-based Machine Learning First Guess Fields for the Day 1 ERO were provided by Colorado State University (CSU). Forecasts issued by the FFaIR participants were a Day 1 ERO, the Maximum Rainfall and Timing Product (MRTP), and a new ERO product based on Average Recurence Interval (ARI) exceedances, refered to as the ARI-ERO. The complete report is available here.

 

2020-2021 Winter Weather Experiment (WWE)

The Hydrometeorology Testbed at the Weather Prediction Center (HMT-WPC) remotely conducted the 11th Annual Winter Weather Experiment (WWE) from 1 November 2020 through 15 March 2021. The 11th Annual WWE explored the future of snowfall products and services by providing a large suite of experimental FV3 convection allowing models (CAMs) and operational simulations in the Day 2 and Day 3 time period. This year's experiment aimed to expand by fostering more flexibility and garnering more CONUS-wide participation. The primary avenue of this expansion was the use of a dynamic GIS based website. Participants were asked to explore our experimental data through this interface paired with an online survey which asked for subjective rankings and comments of the data both before and after an event occurred. Another component of interaction involved asking the participants to use an online drawing tool to create polygons of snowfall footprint, maximum snowfall amount, and maximum precipitation rates within their defined snowfall footprint. The full details and results of this experiment activity, as well as the science goals are available here.

 

2020 Flash Flood and Intense Rainfall Experiment (FFaIR)

The 8th annual Flash Flood and Intense Rainfall (FFaIR) Experiment was conducted remotely this year, from June 15 through July 17, 2020 by the Hydrometeorology Testbed at the Weather Prediction Center (HMT-WPC). The HMT partnered with National Weather Service meteorologists and hydrologists and the development and research communities to evaluate the usefulness of various experimental model and ensemble products and guidance in forecasting heavy rainfall and flash flooding threat. This year's experiment focused on the evalution of eight different configurations of the FV3_SAR model (Stand Alone Regional; as of September 2020 the model is now called the FV3-LAM or Limited Area Model). In addition to this three Machine Learning First Guess Fields for the Day 1 ERO were provided by CSU and evaluated. Other guidance analyzed included a Heavy Precipitation Object Tracker (HPOT), the HRRRE, and the SSEF from CAPS-OU. New this year, the participants were tasked with issuing a product refered to as the Maximum Rainfall and Timing Product (MRTP). The MRTP was designed to help evaluate other aspects of rainfall aside from QPF, such as rainfall duration. The complete report is available here.

 

2019-2020 Winter Weather Experiment (WWE)

The Hydrometeorology Testbed at the Weather Prediction Center (HMT-WPC) conducted the 10th Annual Winter Weather Experiment (WWE) from 12 November 2019 through 13 March 2020, and for the third consective year, the experiment was done in a remote format. The 10th Annual WWE focused heavily on the forecast process by introducing an exercise where participants created a snowfall forecast blend using the experimental data sets. There was also a focus on the use of ensemble clustering to assess forecast sensitivity on snowfall footprints, and the identification of precipitation type (p-type) challenges in the forecast process. This year the WWE began exploring the utility of downscaling methodologies in the NAM and GFS over the Western United States for the improvement of snowfall forecasts over higher terrain, and a snow liquid ratio (SLR) tailored to the intermountain west. Convection Allowing Models (CAMs) were also explored in the Day 2 and Day 3 time period. The complete experiment report is available here.

 

2019 Flash Flood and Intense Rainfall Experiment (FFaIR)

The 7th annual Flash Flood and Intense Rainfall (FFaIR) Experiment was conducted at the National Center for Weather and Climate Prediction (NCWCP) from June 17 through July 19, 2019 by the Hydrometeorology Testbed at the Weather Prediction Center (HMT-WPC). The HMT partnered with National Weather Service meteorologists and hydrologists and the development and research communities to evaluate the usefulness of various experimental model and ensemble products. In addition to the model data, various hydological and satellite tools were also used to produce short range (6-36 hour) probabilistic flash flood forecasts. The design of the experiment centered around mimicking operations at WPC and tasked participants each day to produce four experimental probabilistic forecasts utilizing the experimental tools provided by the HMT team. A secondary component of the experiment included analysis of the performance of convection allowing models (CAMs) that use the finite volume cubed-sphere dynamic core, refered to as the FV3 core. The complete report is available here.

 

2018-2019 Winter Weather Experiment (WWE)

The 9th annual Winter Weather Experiment was conducted both remotely and on site at the National Center for Weather and Climate Prediction (NCWCP) from November 13, 2018 through March 15, 2019. The experiment focused on evaluating precipitation-type algorithms applied to both the FV3-GFS and 12-km NAM models during diverse weather events exhibiting precipitation-type transition zones and their use as inputs into a manually-generated experimental forecast blend. Ensemble predictability of winter weather events was also evaluated using an ensemble clustering tool. CAMs snowfall output from both deterministic and ensemble guidance for the Day 1 period were assessed, focusing on Great Lakes lake-effect snowfall and other mesoscale events. The complete report is available here.

 

2018 Flash Flood and Intense Rainfall Experiment (FFaIR)

The sixth annual Flash Flood and Intense Rainfall Experiment (FFaIR) was conducted at the National Center for Weather and Climate Prediction (NCWCP) June 18-July 20, 2018. The 2018 FFaIR Experiment focused on the use of high resolution guidance to synthesize atmospheric and hydrological guidance in an end to end forecast process to produce probabilistic flash flood forecasts in the short range (6-24 hours). To simulate the flow of information that occurs from a national center (i.e. WPC) to the local forecast offices, this years experiment engaged the HMT-Hydro participants and the Science and Operations Officer-Development and Operations Hydrologist (SOO-DOH) community through screen sharing, video, and teleconference to discuss the experimental guidance with the goal of producing a collaborative 6-hour probabilistic flash flood forecast. There was significant emphasis on testing the high-resolution deterministic models and ensembles over the short term, Day 1, period and fusing the atmospheric data with new, experimental output from the National Water Model. The complete report is available here.

 

2017-2018 Winter Weather Experiment (WWE)

The 8th Annual Winter Weather Experiment was executed both remotely and on site at the Weather Prediction Center in College Park, MD by the HMT-WPC from November 14, 2017 through March 9, 2018. The experiment objectives focused on the exploration and testing of multiple microphysical and probabilistic precipitation type methodologies to determine which methods best enhanced the forecast process. Tools and algorithms from NWP guidance, the WPC Winter Weather Desk, the National Blend of Models, and Fuzzy Clustering were evaluated. A complete summary of the experiment is available here.

 

2017 Flash Flood and Intense Rainfall Experiment (FFaIR)

The fifth annual Flash Flood and Intense Rainfall Experiment (FFaIR) was conducted at the National Center for Weather and Climate Prediction (NCWCP) June 19-July 21, 2017. The 2017 FFaIR Experiment focused on the use of high resolution atmospheric and hydrologic guidance to improve flood prediction both in the short range (6-12 hours) and at longer time ranges (48-72 hours). Virtual engagment with the NWS SOO community took place each day to enhance flood situational awareness and collaborate on potential experimental flash flood watches. There was significant emphasis on testing the improvement of the Days 2 and 3 probabilistic Excessive Rainfall Outlook (ERO) with higher resolution data and the fusion with the National Water Model output. A complete summary of the experiment is available here.

 

2016-2017 Winter Weather Experiment (WWE)

The 7th Annual Winter Weather Experiment was hosted by HMT-WPC from January 17 through February 17, 2017. The experiment brought together forecasters, researchers, and model developers from across the weather enterprise to test new data sets, tools, and forecast methodologies. Building on last year's experiment, further testing of hourly snowfall rate data was conducted to assess the diagnosis and predictibility of meso-scale heavy snowfall banding. Several new PWPF methodologies were tested over the CONUS in the Day 2 period, and the experiment was rounded off by exploring the issuance of both leagacy and experimental winter weather watches from the national center. Forecasts and new tools were presented each session via a daily webinar. Here is a comprehensive summary of the 2017 Winter Weather Experiment experiment activities, data sets used, and investigative results.

 

2016 Flash Flood and Intense Rainfall Experiment (FFaIR)

The fourth annual Flash Flood and Intense Rainfall Experiment (FFaIR) was conducted at the National Center for Weather and Climate Prediction (NCWCP) June 20-July 22, 2016. The focus of FFaIR 2016 was to test and apply the use of flash flood tools from a national perspective down to a local Weather Forecast Office (WFO) level. Once again cross test-bed collaboration between HMT-WPC and HMT-Hydro focused on the goal of improving the forecasting of flash flooding. The use of OWP's National Water Model (NWM) coupled with atmospheric CAMs and ensembles were explored to test the issuance of Day 1 and 2 probabilistic flash flood forecasts. A complete summary of the experiment is available here. An addendum to the experiment summary explaining a disparity between versions of HRRR was published in November 2016.

 

2015-2016 Winter Weather Experiment (WWE)

HMT-WPC hosted the 6th Annual Winter Weather Experiment from January 28 through February 19, 2016. The first two days of the experiment were lost due to impact of the recent blizzard on the HMT-WPC team living in the local area. The experiment brought together forecasters, researchers, and model developers from across the weather enterprise to test new data sets and tools, with a focus on the utility of hourly snowfall rate forecasts. The utility of the WPC watch/warning collaboration tool was also explored each day. For the second year, a daily webinar featuring the experiment forecast for the day and the tools being tested was presented. For the first time, participants made a retrospective forecast using an archived event from earlier in the winter. Here is a complete summary of the 2016 Winter Weather Experiment, an addendum to the experiment summary, and a table depicting the R2O progress of experiment activities.

 

2015 Flash Flood and Intense Rainfall Experiment (FFaIR)

The third annual Flash Flood and Intense Rainfall Experiment (FFaIR) was conducted at the National Center for Weather and Climate Prediction (NCWCP) July 6-24, 2015. Cross test-bed collaboration between HMT-WPC and HWT-Hydro focused on the goal of improving the forecasting of flash floods. The utility of several high resolution models and ensembles systems was explored, as well as the Advective-Statistical Forecasts of Rainfall (ADSTAT) and forecast recurrence interval tools. A complete summary of the experiment is available here.

 

2014-2015 Winter Weather Experiment (WWE)

From January 12 - February 13, HMT-WPC hosted it's annual Winter Weather Experiment. Now in it's fifth year, the experiment brought together forecasters, researchers, and model developers from across the weather enterprise to conduct exercises aimed at continuing improvement of winter weather forecasts. This year's focus of the experiment was the continued exploration of micro-physics based snowfall forecasting methods, along with expanding medium range probabilistic winter weather forecasts to include forecasts of heavy snow and freezing rain from Days 4-7. Additionally, this year's experiment featured a daily webinar, where participants shared their forecast thoughts and discussed experimental model data with remote participants. Here is a complete summary of the 2015 Winter Weather Experiment.

 

2014 Flash Flood and Intense Rainfall Experiment (FFaIR)

The second annual Flash Flood and Intense Rainfall Experiment (FFaIR) was conducted July 7-25, 2014. Building off of the success of last year's experiment, participants from across the weather enterprise explored the utility of neighborhood probability techniques and other convection-allowing model guidance to improve short-term flash flood forecasts. In addition to issuing experimental forecasts, participants in FFaIR provided a daily forecast briefing to support the HWT-Hydro experimental flash flood warning activities. FFaIR also featured the debut of a new flash flood verification database. The development of this database represents a significant step forward in our verification capabilities by combining flsh flood information from multiple sources. A complete summary of the experiment is available here.

 

2013-2014 Winter Weather Experiment (WWE)

The fourth annual HMT-WPC Winter Weather Experiment was conducted January 21 - February 21, 2014. Experiment participants included forecasters, researchers, and model developers from a variety of sectors of the weather enterprise, and for the first time remote participation by National Weather Service forecasters from selected offices. The focus of the experment was the continued exploration of micro-physics based snowfall forecasting methods, along with a first time look at the coupling of NAM micro-physics with the Noah Land Surface Model to generate snowfall accumulation forecasts. Another first in this year's experiment was the exploration of medium range probablisitc winter weather forecasts. Participants evaluated several medium range guidance data sets, and generated Day 4-7 forecasts each day. Here is a complete summary of the 2014 Winter Weather Experiment.

 

2013 Flash Flood and Intense Rainfall Experiment (FFaIR)

In collaboration with the National Severe Storms Laboratory (NSSL) and the Earth System Research Laboratory (ESRL), HMT-WPC conducted the inaugural Flash Flood and Intense Rainfall Experiment (FFaIR) July 8 - 26, 2013. During the experiment, forecasters, researchers, and model developers worked together as a collaborative forecast team to explore the challenges associated with issuing short-term QPF and flash flood forecasts. The experiment featured a variety of deterministic and probabilistic high resolution model data and identified several new forecast tools that will be used on WPC's new MetWatch Desk. Here is a complete summary of the 2013 Flash Flood and Intense Rainfall Experiment.

 

2012-2013 Winter Weather Experiment (WWE)

The third annual HMT-HPC Winter Weather Experiment was conducted January 15 - February 15, 2013. The experiment brought together forecasters, researchers, and model developers from across the weather enterprise to explore the use of ensemble systems to help quantify and communicate uncertainty in winter weather forecasts. This year's experiment also highlighted a new snowfall accumulation technique that uses model microphysics information to refine the snowfall forecasts. The experiment highlighted the importance of ensemble guidance for winter weather forecasts and identified several potential ways to improve and expand WPC's current winter weather product suite. Here is a complete summary of the 2013 Winter Weather Experiment.

 

2012 Atmospheric River Retrospective Forecasting Experiment

The first Atmospheric River Retrospective Forecasting Experiment (ARRFEX) was a collaboration between the Earth Systems Research Laboratory (ESRL) and the Hydrometeorological Testbed (HMT)-Hydrometeorological Prediction Center (HPC). The experiment was held September 17-28, 2012 at the new National Center for Weather and Climate Prediction (NCWCP). The experiment brought together forecasters, modelers and researchers from River Forecast Centers (RFC), Weather Forecast Offices (WFO), the Environmental Modeling Center (EMC), ESRL and the University of Utah to identify potential techniques to improve forecasts of atmospheric river (AR) induced extreme precipitation events along the U.S. West Coast. The experiment featured retrospective analysis of 8 pre-selected AR events that resulted in heavy precipitation along the U.S. West Coast during the 2009-2012 cool seasons. Participants were instructed to create a variety of forecast products, in pseudo-real time, for each event using archived operational and experimental numerical model guidance and datasets. Here is a complete summary of the 2012 Atmospheric River Retrospective Forecasting Experiment.

 

2011-2012 Winter Weather Experiment (WWE)

The second annual HMT-HPC Winter Weather Experiment was conducted January 9 - February 10, 2012, and brought together forecasters, researchers and model developers to explore the challenges of probabilistic winter weather forecasting. The experiment focused on the use of ensemble systems to help quantify and communicate uncertainty in winter weather forecasts. The experiment revealed that while probabilistic winter weather forecasting remains a challenge, higher resolution ensembles can provide critical forecast details needed to isolate specific parameters for better depiction of forecast uncertainty. Here is a complete summary of the 2012 Winter Weather Experiment.

 

QPF Component of the 2011 HWT Spring Experiment

Continuing the partnership started in 2010, HMT-HPC staff and HPC forecasters once again traveled to Norman, OK to facilitate the QPF component of the 2011 HWT Spring Experiment. During the experiment, participants evaluated the utility of high resolution deterministic and ensemble guidance for precipitation forecasting. High resolution ensembles were again found to provide skillful forecast guidance, highlighting the potential for this type of guidance to add further skill to warm season QPF in the future. Here is a complete summary of the 2011 QPF component of the experiment.

 

2010-2011 Winter Weather Experiment (WWE)

The inuagural HMT-HPC Winter Weather Experiment was held at HPC during January-February 2011. HPC forecasters as well as visiting scientists from NOAA-HMT, other NCEP centers and NWS field officies participated in the experiment. The primary focus of the experiment was to explore the role of high-resolution model data in improving forecasts of precipitation type, snow and ice accumulation, and meso-scale snow bands. The experiment revealed that the high resolution models were often too slow with the progression of the surface low, which impacted their precipitation and thermal fields. Here is a complete summary of the 2011 Winter Weather Experiment.

 

QPF Component of the 2010 HWT Spring Experiment

HMT-HPC partnered with the Hazardous Weather Testbed to add a QPF component to their 2010 Spring Experiment. During the experiment, participants explored the use of high resolution convection-allowing deterministic and ensemble guidance for potential improvement of warm season QPF. High resolution models were found to have skill in forecasting warm season QPF, which portends well for future forecast improvements. Forecast guidance from the 4km, 26 member Storm Scale Ensemble Forecast system (SSEF) provided by University of Oklahoma's Center for Analysis and Prediction of Storms (CAPS) was particularly impressive. A summary of the QPF Component of the 2010 HWT Spring Experiment was presented at the AMS Annual Meeting in Seattle, WA. In addition to leading the QPF component of the HWT Spring Experiment, HMT-HPC hosted a two week parallel experiment for HPC forecasters.