# IFS **URL:** https://forum.ecmwf.int/c/ifs-aifs-and-openifs/ifs/44.md [Latest](https://forum.ecmwf.int/latest.md) · [Categories](https://forum.ecmwf.int/categories.md) · [Tags](https://forum.ecmwf.int/tags.md) --- ## [About the IFS category](https://forum.ecmwf.int/t/about-the-ifs-category/11988)
**Author:** [@Michela](https://forum.ecmwf.int/u/Michela)\ **Replies:** 0\ **Last updated:** [20 March 2025 17:44 UTC](https://forum.ecmwf.int/t/about-the-ifs-category/11988 "2025-03-20T17:44:48Z")
Welcome to the IFS forum! This is your hub for asking questions, and engaging with fellow users of the IFS model. Be sure to check the instructions below to get started! To learn more about ECMWF Integrated System (IFS)… --- ## [snow depth (and density) threshold for 100 % snow coverage: inconsistency between documentation on ECMWF charts and cy49r1 physical processes documentation ?](https://forum.ecmwf.int/t/snow-depth-and-density-threshold-for-100-snow-coverage-inconsistency-between-documentation-on-ecmwf-charts-and-cy49r1-physical-processes-documentation/14713)
**Author:** [@Fabian\_Debal](https://forum.ecmwf.int/u/Fabian_Debal)\ **Replies:** 1\ **Last updated:** [27 July 2026 11:16 UTC](https://forum.ecmwf.int/t/snow-depth-and-density-threshold-for-100-snow-coverage-inconsistency-between-documentation-on-ecmwf-charts-and-cy49r1-physical-processes-documentation/14713 "2026-07-27T11:16:24Z")
Hello. I noticed a potential inconsistency regarding the snow depth product documentation on:: The documentation states that: “Green shades relate directly to model assumptions regarding proportion of the ground ass… --- ## [Question for hybrid linear ozone scheme in IFS](https://forum.ecmwf.int/t/question-for-hybrid-linear-ozone-scheme-in-ifs/15052)
**Author:** [@Dong-Chan\_Hong](https://forum.ecmwf.int/u/Dong-Chan_Hong)\ **Replies:** 1\ **Last updated:** [13 June 2026 11:10 UTC](https://forum.ecmwf.int/t/question-for-hybrid-linear-ozone-scheme-in-ifs/15052 "2026-06-13T11:10:43Z")
Hello, all. I am a Ph. D. course student. The hybrid linear ozone (HLO) scheme is briefly explained In the ECMWF IFS description. I have a question that the coefficients for HLO scheme is open to share and could be dow… --- ## [Issue with running tests and locating results in the new IFStest version](https://forum.ecmwf.int/t/issue-with-running-tests-and-locating-results-in-the-new-ifstest-version/14177)
**Author:** [@Ramiro\_Checa\_Garcia](https://forum.ecmwf.int/u/Ramiro_Checa_Garcia)\ **Replies:** 1\ **Last updated:** [29 September 2025 12:37 UTC](https://forum.ecmwf.int/t/issue-with-running-tests-and-locating-results-in-the-new-ifstest-version/14177 "2025-09-29T12:37:00Z")
Hello everyone, I’m working with IFStest and I’ve noticed that some functionalities have changed in the new version compared to what used to be very convenient (I guess) In previous versions, I could: Go to a specif… --- ## [IFS and ENS control and deterministic cy49r1](https://forum.ecmwf.int/t/ifs-and-ens-control-and-deterministic-cy49r1/10173)
**Author:** [@Alessio\_Golzio](https://forum.ecmwf.int/u/Alessio_Golzio)\ **Replies:** 0\ **Last updated:** [10 December 2024 12:06 UTC](https://forum.ecmwf.int/t/ifs-and-ens-control-and-deterministic-cy49r1/10173 "2024-12-10T12:06:42Z")
Dear all, Since the upgrade of Cycle 49r1, I understood that the ENS control member and IFS deterministic run (HRES) were identical or the same run. However, in today’s clustering product for the second forecast group, … --- ## [On Mean Zonal wind graphs](https://forum.ecmwf.int/t/on-mean-zonal-wind-graphs/12366)
**Author:** [@VASILIS\_PAPPAS](https://forum.ecmwf.int/u/VASILIS_PAPPAS)\ **Replies:** 3\ **Last updated:** [1 November 2022 15:42 UTC](https://forum.ecmwf.int/t/on-mean-zonal-wind-graphs/12366 "2022-11-01T15:42:34Z")
Hello, just one small remark here which I think is easy to correct. On the Mean Zonal wind graphs, the units on the y-axis are degrees Celsius, when I believe it should be m/s? --- ## [Clustering in ensemble product](https://forum.ecmwf.int/t/clustering-in-ensemble-product/12358)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 4\ **Last updated:** [22 March 2022 10:25 UTC](https://forum.ecmwf.int/t/clustering-in-ensemble-product/12358 "2022-03-22T10:25:13Z")
Hello, I am reaching out in order to get some more information/guidance on the process of clustering in the ECMWF medium-range product. As someone can read in this documentation (https://www.ecmwf.int/en/forecasts/docume… --- ## [Reason for EC46 big volatility in weather patterns?](https://forum.ecmwf.int/t/reason-for-ec46-big-volatility-in-weather-patterns/12357)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 5\ **Last updated:** [19 November 2021 11:02 UTC](https://forum.ecmwf.int/t/reason-for-ec46-big-volatility-in-weather-patterns/12357 "2021-11-19T11:02:02Z")
On Monday 13.09, the EC46 (or EC42 as it is named in Open Charts) came up with the weather regime classification below, suggesting a really strong blocking episode, similar to the one we had seen beginning and end of Jul… --- ## [Weather regimes: another challenging forecast for EC42](https://forum.ecmwf.int/t/weather-regimes-another-challenging-forecast-for-ec42/12352)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 0\ **Last updated:** [5 October 2021 09:40 UTC](https://forum.ecmwf.int/t/weather-regimes-another-challenging-forecast-for-ec42/12352 "2021-10-05T09:40:00Z")
It appears that the extended forecast is still struggling considerably with the blocking pattern in NW Europe. Shown below are the last 4 runs. In each one of them, I have circled the week commencing 04.10.2021. In the r… --- ## [A significant forecast 'bust' by the ECMWF model](https://forum.ecmwf.int/t/a-significant-forecast-bust-by-the-ecmwf-model/12364)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 1\ **Last updated:** [3 September 2021 11:12 UTC](https://forum.ecmwf.int/t/a-significant-forecast-bust-by-the-ecmwf-model/12364 "2021-09-03T11:12:39Z")
An unusually deep trough dug into the east-central U.S. the last couple of days, causing considerable rains along the Gulf Coast and SE U.S. ECWMF forecasts anticipated the enhanced rainfall over this region reasonabl… --- ## [Western North America Extreme Heat](https://forum.ecmwf.int/t/western-north-america-extreme-heat/12351)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 6\ **Last updated:** [7 July 2021 16:11 UTC](https://forum.ecmwf.int/t/western-north-america-extreme-heat/12351 "2021-07-07T16:11:24Z")
Over the days of 25 June - 29 June 2021, there was extreme heat in western North America The US states of Washington and Oregon as well as the Canadian Province of British Columbia achieved all time record maximum tem… --- ## [Heatwave maximum 2mT overestimate](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 4\ **Last updated:** [2 July 2021 10:39 UTC](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372 "2021-07-02T10:39:45Z")
Hi all ! I would like to report a kind of systematic error associated with the current heat-wave in Europe. I noticed that 2m maximum temperatures during the heat-wave peak in Northern Italy have been overpredicted. Esp… --- ## [Severe Monsoon Surge in January over Singapore](https://forum.ecmwf.int/t/severe-monsoon-surge-in-january-over-singapore/12368)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 3\ **Last updated:** [1 July 2021 13:55 UTC](https://forum.ecmwf.int/t/severe-monsoon-surge-in-january-over-singapore/12368 "2021-07-01T13:55:08Z")
Would like to share on two episodes of monsoon surges over Singapore in January this year. The first monsoon surge had a highest daily total rainfall of 238.4mm and 210.6mm on 1 and 2 January. The second monsoon surge, w… --- ## [Flooding in New Zeeland in May-June 2021](https://forum.ecmwf.int/t/flooding-in-new-zeeland-in-may-june-2021/12376)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 1\ **Last updated:** [2 June 2021 15:04 UTC](https://forum.ecmwf.int/t/flooding-in-new-zeeland-in-may-june-2021/12376 "2021-06-02T15:04:19Z")
In the end of May Canterbury in New Zeeland experienced extreme rainfall followed by floods. We have started on a severe event page here: 202105 - Rainfall - New Zeeland , but we would appreciate more information about t… --- ## [Extreme rainfall in Sweden May 2021](https://forum.ecmwf.int/t/extreme-rainfall-in-sweden-may-2021/12355)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 0\ **Last updated:** [27 May 2021 14:18 UTC](https://forum.ecmwf.int/t/extreme-rainfall-in-sweden-may-2021/12355 "2021-05-27T14:18:00Z")
On 26th May, parts of Sweden experience heavy rainfall and flash flooding with up to 60mm recorded locally and 45-50mm more widely across the region. This was associated with a frontal system approaching from the south, … --- ## [Tropical Cyclone Tauktae](https://forum.ecmwf.int/t/tropical-cyclone-tauktae/12363)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 0\ **Last updated:** [25 May 2021 18:02 UTC](https://forum.ecmwf.int/t/tropical-cyclone-tauktae/12363 "2021-05-25T18:02:10Z")
Tropical Cyclone Tauktae recently impacted India, making landfall in Gujarat on 17th May 2021 after passing along the wester coast of India. Floodlist reports that weather stations in Mumbair recorded 230mm of rain in th… --- ## [Fujiwhara Effect of Tropical Cyclones Seroja & Odette](https://forum.ecmwf.int/t/fujiwhara-effect-of-tropical-cyclones-seroja-odette/12359)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 0\ **Last updated:** [10 May 2021 17:59 UTC](https://forum.ecmwf.int/t/fujiwhara-effect-of-tropical-cyclones-seroja-odette/12359 "2021-05-10T17:59:55Z")
On 10th April, tropical cyclones Seroja and Odette merged together - a rare phenomenon called the Fujiwhara Effect, which presents a significant challenge in forecasting track and intensity of the tropical cyclones. Ty… --- ## [Precipitation forecast biases in Southeast Asia](https://forum.ecmwf.int/t/precipitation-forecast-biases-in-southeast-asia/12374)
**Author:** [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Replies:** 0\ **Last updated:** [10 May 2021 17:53 UTC](https://forum.ecmwf.int/t/precipitation-forecast-biases-in-southeast-asia/12374 "2021-05-10T17:53:57Z")
ECMWF are aware of a systematic wet bias in IFS forecasts of precipitation over Southeast Asia, with an average bias of 1.61 mm/day in the boreal summer half-year, and precipitation overestimations on forecast day 3 of u…