This morning the National Weather Service (NWS) Operations Proving Ground (OPG) began a 6-week evaluation of 1-minute satellite imagery, a normal operating capability of the Geostationary Operational Environmental Satellite (GOES)-R Series. The overarching goal of the evaluation will be to provide quantitative and qualitative guidance to NWS management and the GOES-R Program Office on how 1-minute satellite imagery impacts NWS forecaster decision making in a variety of weather situations.

In total, eighteen participants from NWS Forecast Offices across the country will each complete seven simulations that were developed using satellite imagery collected during the 2013 and 2014 GOES-14 Imager Super Rapid Scan Operations for GOES-R (SRSOR) experiments. In all simulations, participants will provide feedback on how satellite imagery affects decision making processes, situational awareness, confidence, workflow, and workload. Furthermore, in three of the simulations, the forecasters will be split into two groups where one set is given 1-minute imagery and the other set is 5-minute imagery. This unique dataset will allow the OPG staff to investigate if 1-minute satellite imagery had added value when compared to 5-minute imagery for these cases.

Once completed in early April, OPG staff will write a report summarizing the statistical analysis and forecaster feedback that was gathered during the evaluation. In addition, results will be presented at the upcoming 2015 National Weather Association and 2016 American Meteorological Society Annual Meetings.

On Sunday April 27th, 2014, a moderate risk for severe thunderstorms was forecast by the SPC across eastern Kansas and Oklahoma, most of Missouri and Arkansas, as well as portions of Texas, Louisiana, Mississippi, and Tennessee. Before 12Z on that morning, convection developed along the dryline/Pacific cold front across central Kansas and Oklahoma. These thunderstorms became elevated as they moved east northeast towards Kansas City and western Missouri due to mid to lower tropospheric warm air advection. The early morning convection added uncertainty to the forecast as there was a question whether the atmosphere would recover and destabilize for convective initiation (CI) before the dryline and Pacific cold front moved through across eastern KS and western MO behind the morning convection.

In the image above at 1815 UTC, although there was clearing right ahead of the dryline, extensive cloud cover and cool temperatures were present in the wake of the morning convection across eastern Kansas and western Missouri. Ninety minutes later, at 1945 UTC, temperatures started to rebound into the lower to mid 70s across southeastern Kansas and a cumulus field developed ahead of the dryline across eastern Oklahoma.

One of the GOES-R future capability products, Probability of Convective Initiation, provides probabilistic 0-1 h forecasts of cloud objects achieving convective initiation (35 dBZ or > radar echo). Inputs into the algorithm are convective cloud properties from either GOES-13/GOES-15 and 20 Rapid Refresh model output fields. This fused product is excellent at providing guidance to the mesoanalyst or warning forecaster on which portion of a cumulus field will develop into convection. In the image below at 1945 UTC, there were low probabilities of CI within the newly developed cumulus field across northeastern Oklahoma.

At 2045 UTC, 60 minutes later, the cumulus field developed northward into southeastern Kansas and probabilities increased to 60% within that cumulus field. This indicates a higher likelihood of CI and is starting to provide confidence to the forecaster that the atmosphere is destabilizing enough for the potential of CI.

Another GOES-R future capability is the Convective Cloud-Top Cooling (CTC) product. This algorithm uses GOES-13/GOES-15 imager data and cloud phase information to provide situational awareness on which convective cloud objects are quickly growing vertically (i.e., a proxy for initial updraft strength). A stronger CTC rate is directly correlated with updraft strength and larger hail when compared to the WSR-88D maximum expected hail size algorithm. At 2125 UTC, 40 minutes after the elevated CI probabilities, two thunderstorms were developing across southeastern Kansas and northeastern Oklahoma. This is evident by the strong CTC detections in those areas.

Fifteen minutes later, the first severe thunderstorm warning was issued on the thunderstorm with the northern CTC detection in southeastern Kansas. These two thunderstorms eventually developed into the supercells that produced the two EF2 tornadoes that affected Baxter Springs, KS (southern CTC detection) and Bates/Linn County, KS (northern CTC detection). Although the two products shown are GOES-R future capabilities, they are used today with GOES-13/GOES-15 data to demonstrate the algorithms and provide observational information of the convective environment that is not currently available with other datasets. When these two products are used together with observations forecasters are already comfortable with, situational awareness of the convective environment is elevated and more accurate short-term forecasts of convection may possibly be provided to partners.

~ Chad Gravelle, NWS Operations Proving Ground Satellite Liaison