Data sources

Last updated: 2 November 2026

Summary

"Vremcho" combines numerical weather models, ground measurements and observations, radar and satellite imagery, and other specialised data. Using a combination of sources allows us to provide the most accurate and reliable forecast possible. The information is corrected in real time according to the topology of the respective location and the available radar and satellite data.

1. Core weather forecast

• Some periods overlap because the forecast combines information from more than one model: for each day and each variable we use the highest-resolution model that reaches that day, while GFS and GEFS fill in the days and variables for which the more accurate models do not yet have data.

2. Precipitation nowcasting, radar and satellite imagery

• Nowcast provides a forecast of the precipitation expected over the coming hours. It is used for the expected start, end and intensity of precipitation, and for notifications about approaching precipitation.
• RainViewer provides radar imagery of precipitation from the past few hours.
• The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) provides satellite imagery through EUMETView WMS. We use the mtg_fd:ir105_hrfi layer — Meteosat Third Generation (MTG), Flexible Combined Imager (FCI), High Resolution Fast Imagery (HRFI), IR 10.5 µm — for infrared imagery and indicative cloud cover over Bulgaria.

3. Air quality, pollen and UV index

The data is provided by the Copernicus Atmosphere Monitoring Service (CAMS):

• Atmospheric composition forecast — UV index;
• Air pollution forecast — PM10, PM2.5, NO₂, O₃, SO₂, CO, desert dust and pollen from alder, birch, grasses, mugwort, olive and ragweed.

The overall European Air Quality Index is calculated using the methodology of the European Environment Agency (EEA).

4. Sea water and waves

The water temperature along the Bulgarian Black Sea coast is provided by the Copernicus Marine Service (CMEMS) through the Black Sea Physics Analysis and Forecast product (BLKSEA_ANALYSISFORECAST_PHY_007_001) and the cmems_mod_blk_phy-temp_anfc_2.5km_PT1H-m dataset.

We use the hourly temperature from the analysis and forecast in the shallowest available layer (0.5 m).

Waves are provided by the same service through the Black Sea Waves Analysis and Forecast product (BLKSEA_ANALYSISFORECAST_WAV_007_003).

5. Observations and official warnings

• Official warnings of bad and dangerous weather are received through MeteoAlarm, a service of the European Meteorological Services Network (EUMETNET). Warnings for Bulgaria are issued by the National Institute of Meteorology and Hydrology (NIMH);
• The latest METAR observations for Sofia (LBSF), Burgas (LBBG), Varna (LBWN) and Plovdiv (LBPD) are received through the National Oceanic and Atmospheric Administration / National Weather Service (NOAA/NWS). They support the processing of atmospheric pressure, visibility and current phenomena such as fog, precipitation and thunderstorms.
• Observations from NIMH's synoptic stations support the processing of temperature, humidity and wind in the areas around those stations.

6. Maps and geographic data

• The National Register of Populated Places (NRNM/EKATTE) of the National Statistical Institute (NSI) provides data on populated places and municipalities.
• NUTS 3 administrative boundaries are used to determine whether a given location falls within the region for which an official warning has been issued.
• Natural Earth provides data on Bulgaria's coastline with the Black Sea.
• The relief on the mountain maps comes from the Copernicus DEM elevation model, and the outlines of the mountain ranges from the GMBA Mountain Inventory and OpenStreetMap.

7. Important information

The stated specifications of the numerical weather models may change when the sources are updated. Forecasts and imagery may contain inaccuracies or be received with a delay.

The information in "Vremcho" is of a general informational nature. Do not use it as the sole source for decisions related to life, health, safety or the protection of property.

Attribution and licences

• The core forecast data from the ICON models is provided by Deutscher Wetterdienst (DWD, German Meteorological Service) through DWD Open Data under the CC BY 4.0 licence. The data has been processed and modified by "Vremcho".
• The core forecast data from the GFS and GEFS models is provided by the National Oceanic and Atmospheric Administration / National Centers for Environmental Prediction (NOAA/NCEP) and has been processed by "Vremcho".
• The IFS HRES and IFS ENS forecasts are based on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF), obtained through ECMWF Open Data. Source: www.ecmwf.int, licence CC BY 4.0. The data has been processed by "Vremcho". ECMWF is not liable for any errors or omissions in the data, its availability, or damages arising from its use.
• The short-term precipitation forecast is generated with data from Rainbow.ai.
• The radar imagery uses weather data from RainViewer.
• The satellite imagery and the cloud cover derived from it contain modified data from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) (Meteosat).
• The air quality, pollen and UV index data contains modified information from the Copernicus Atmosphere Monitoring Service (CAMS). Neither the European Commission nor ECMWF is responsible for any use of this information.
• The sea water temperature and waves are generated using information from the Copernicus Marine Service (CMEMS); DOI: 10.48670/mds-00355 and DOI: 10.48670/mds-00360. Source: European Union, Copernicus Marine Service information, © Mercator Ocean.
• Official warnings are provided through MeteoAlarm with data from the members of the European Meteorological Services Network (EUMETNET); warnings for Bulgaria are issued by NIMH. Licence: CC BY 4.0. The content may have been technically processed.
• METAR observations are provided through the National Oceanic and Atmospheric Administration / National Weather Service (NOAA/NWS) (Telecommunications Gateway) and have been processed by "Vremcho".
• Synoptic observations are retrieved from NIMH's information systems and have been processed by "Vremcho".
• Methodology for the European Air Quality Index: European Environment Agency (EEA).
• Populated place data: National Register of Populated Places (NRNM/EKATTE), National Statistical Institute (NSI).
• Natural Earth data is in the public domain and requires no licence.
• Mountain relief produced using Copernicus WorldDEM™-90 © DLR e.V. 2010–2014 and © Airbus Defence and Space GmbH 2014–2018, provided under COPERNICUS by the European Union and ESA. Mountain ranges: GMBA Mountain Inventory v2 (Snethlage et al., 2022), licence CC BY 4.0, and © OpenStreetMap contributors, licence ODbL.