Weather
Patrick Eriksson speaks about monitoring sea ice in the very heavily trafficked Baltic Sea
The Baltic Sea, a relatively small semi-closed basin with brackish water, is one of the most heavily trafficked sea areas in the world. Thousands of vessels visit ice-infested ports every winter, which requires well organized icebreaking. To support this winter navigation operation, the Ice Service at FMI conducts monitoring and forecasting of the sea ice throughout the winter. An essential source of information is obviously satellite data. Imagery from several satellite platforms is not only processed to serve ice charting and reporting, but is also delivered in near-real-time straight to the bridges of the icebreakers. The dark and cloudy Nordic winter has proven the Synthetic Aperture Radar instruments (SAR) to be the most suitable when analysing the development of the sea ice. Different passive instruments are also used, light and cloudiness permitting. All satellite platforms bring their various strengths and limitations on the ice analyst’s desktop, causing constantly changing challenges to the charting of sea-ice features. So far, the analysis has been predominantly manual work, but the ever-increasing data volumes are setting a demand for AI-based automatic interpretation.
Vojtěch Bližňák presents how the satellite cloud data helps forecasting road surface temperature in Czechia.
The goal of the contribution is to assess an impact of extrapolated cloud cover derived from satellite observations on forecasts of road surface temperature (RST) performed by the road weather model (RWM) FORTE. Based on road weather station measurements and forecasts of the ALADIN numerical weather prediction (NWP) model, which are used as inputs to prepare initial and boundary conditions, the RWM generates a linearly continuous forecast of RST on selected Czech highways. The work will compare the evaluation of RST forecasts generated by two model runs using NWP and satellite-derived cloud cover estimation.
Vesa Nietosvaara showcases how the MTG's FCI instrument will improve the quality of satellite data, especially for users in high latitudes.
The first Meteosat Third Generation (MTG-I) satellite with Flexible Combined Instrument (FCI) was launched at the end of 2022. It will be followed later in 2024 by MTG-S Satellite with Infrared Sounder onboard. MTG will carry novelty instruments – Infrared Sounder, Lightning Imager and Ultraviolet Visible Near-infrared (UVN) Spectrometer - in the GEO orbit. Meteosat Third Generation aims to secure continuity and to increase the capabilities of the Meteosat satellites in response to requirements of the future forecast/nowcast systems. Altogether, the new and enhanced capabilities will allow us to make a huge step in better monitoring of our environment, and allowing development of new applications.
Reima Eresmaa presents how satellite data helps in numerical weather prediction systems to support meteorological applications in Finland and surrounding countries.
MetCoOp is a group devoted to developing and operating rapidly-updating kilometric-scale Numerical Weather Prediction (NWP) systems to support meteorological applications in Finland, Scandinavia and Baltic countries. There are currently two operational NWP systems: The MetCoOp Ensemble Prediction System (MEPS) and the MetCoOp Nowcasting System (MNWC). Forecasts are provided in a limited-area grid in 2.5 km horizontal resolution and on 65 levels.
MetCoOp NWP systems assimilate a variety of satellite-based data provided by polar orbiters of NOAA, EUMETSAT, and CMA. In particular, extensive use is made of radiance measurements in microwave and infrared wavelengths. Via three-dimensional variational data assimilation, such observations help constrain the NWP model state at the initial time of each forecast. The radiance observations provide information on temperature and humidity at different altitudes.
Virve Karsisto shows the road model FMI uses to forecast road conditions.
Finnish Meteorological Institute’s (FMI) road weather model has been in operational use over 20 years. The forecasts help in the road maintenance decision making and give useful information for road users about the driving conditions. Recently, a shadowing algorithm has been implemented to the model to take in to account the shadowing caused by the surrounding objects. This helps to make more localized forecasts, as shadowing can cause great differences in road temperature even between different lanes.
Minna Haikonen explains how FMI collaborates with customers in delivering important warnings.
Finnish Meteorological Institute produces weather services for land traffic and shipping to ensure safety and cost effective planning on everyday decision making for customers and stakeholders. FMI produces wide range of weather services including weather and road weather forecasts, observation services and warnings that can be tailored according to customer needs. One example of these a tailored weather services is a so called pre warning service for rail traffic operation and maintenance which is based on meteorological consultation via email or video conference system all around the year. FMI`s meteorologists monitor weather 24/7 basis and issue pre warnings according to the customer needs. There are several parameters that need to be monitored and the pre warning is issued whenever it seems likely that a predefined threshold will be met. During wintertime these pre warnings are proven to be very important especially before heavy snowfall cases not to mention if there is also low temperatures and hard winds appearing at the same time.
Becky Hemingway present ECMWF's Precipitation Type and Extreme Forecast Index products.
ECMWF produces a vast array of global forecast data on a daily basis. In order to make this data useable a large number of products are created and made available to ECMWF Member and Cooperating States and the wider meteorological community via OpenCharts and ecCharts. This presentation will focus on two products which help forecasters in forecasting extreme precipitation, Precipitation Type and the Extreme Forecast Index (EFI). Both products are generally well liked by forecasters and are seen to verify well. The talk will detail how the products are created using the ECMWF Ensemble Forecast System, discuss how to use the products and provide case studies of cold weather events including from the high-latitude regions.
Marjo Hippi explains how FMI deals with slipperiness during winter.
Icy and snowy sidewalks are very typical phenomena in Finland during winter. Near zero temperatures and slipperiness due to ice and snow on sidewalks increases the pedestrians' slip risk. Almost every second person slips annually in Finland and around 50 000 persons (1 % of Finnish population) are injured needing medical attention. Slip injuries cause huge economic losses, long sick leaves, and human suffering. The Finnish Meteorological Institute (FMI) has developed a numerical weather model that predicts the sidewalk slipperiness from pedestrians' point of view. The model classifies the sidewalk slipperiness into three classes: normal, slippery, and very slippery. Very slippery sidewalk condition mean that the slip risk is increased. Typical situations for very difficult sidewalk situations are packed snow, freezing or ice layer covered by water or snow. The model is a tool for duty meteorologists when issuing warning about slippery sidewalk condition.
Gunnar Noer explains and showcases the nature of polar lows.
Polar lows are small but fairly intense low pressure systems that form in the Arctic marine regions during the winter season. They form in unstable air masses associated with cold air outbreaks from the Arctic ice cap. Polar Lows give rise to gale or storm force winds which, in combination with heavy snowfall, cause widespread traffic disruptions. In recent years, polar lows have caused several fatal incidents with snow avalanches. This lecture focuses on the key processes and the methodology for forecasting polar lows.
Thomas Krennert (ZAMG) talks about the importance of moisture gradients in analysing the possibility of development of deep moist convection.
The exact predictability of convection in the Alpine region in the absence of fronts in weak-surface-pressure-gradient-situations during the warm season remains challenging for forecasters. The development into single-cell deep moist convection SC-DMC under these conditions depends on the availability of well-known ingredients like low level moisture, steep tropospheric lapse rates and sufficient lift. Satellite studies have shown that favourable locations for the first onset of SC-DMC resulting from widespread shallow convection over mountainous terrain are water vapour gradients in the middle or upper troposphere UTMG (upper tropospheric moisture gradients, Krennert, et al., 2003, https://doi.org/10.1016/S0169-8095(03)00067-X). The contributions of the respective ingredients related to UTMG supporting the initiation of DMC are discussed. A focus is set on moist symmetric instability MSI as a possible mechanism for favouring the transition from shallow to deep moist convection.
Wilfried Jacobs (DWD) explains the power of Airmass RGB in estimating the possibility of cold front transforming into a convective line.
Especially, the airmass RGB is a powerful tool for estimating the cold front’s tendency to transform to a convective line. Convective lines are connected with strong gusts, heavy precipitation sometimes with graupel or even hail. During this presentation the indications of convective lines will be outlined by considering the airmass RGB together with other means, e.g., radiosounding. Examples of two succeeding days will be discussed in detail whereas the first case did not lead to a convective line whereas the second example did. Typical differences of patterns in the corresponding airmass RGB and additional data sources will be related to a convective line’s probability.
Andreas Wirth (ZAMG) presents the benefits of analysing the water vapour imagery to diagnose synoptic structures and weather patterns.
Water vapor (WV) imagery is very useful when it comes to visualize zonal and meridional transport of air masses, but it is also suited to get a rapid overview on vertical transport processes. This characteristic makes WV-imagery extremely helpful when it comes to diagnose fronts and cyclogenesis.
The presentation will focus on the dynamics of cyclogenesis and fronts and how they are reflected in WV-imagery. The concept of relative streams will be introduced in the context of cyclogenesis, ana- and kata fronts.
Meteorological products based on WV absorption bands such as the Total Precipitable Water product will be introduced and their usefulness will be demonstrated on case examples.