# Heatwave maximum 2mT overestimate **URL:** \ **Category:** IFS\ **Created:** [21 June 2021 11:11 UTC](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372 "2021-06-21T11:11:31Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Rebecca\_Emerton](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/r/e19b73/32.png) [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Post date:** [21 June 2021 11:11 UTC](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372/1 "2021-06-21T11:11:31Z")
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. Especially in the Emilia-Romagna region where, according to model output, we were expecting Tmax on Sunday largely over 35°C. On average Tmax reached 34°C, when ECMWF 2mT forecast, especially 2-3days before, was reaching maximum values of 38°C in the same places. The error, although reduced, persisted also in the very short-term forecast (+12h). This overestimate was uniform on all the flat areas of this region. I attach here two slides: the first is showing a comparison of observed 2m T at the synop (and RSD) station ground of S.Pietro Capofiume, in the countryside near Bologna (no urban influence here), against the ECMWF forecast interpolated in a point very close (the same municipality, flat terrain, same conditions). A difference of about 2°C is still visible in the interpolated forecast in the very short term forecast ( +12h). Normally you would expect, if anything, an underestimate due to spatial interpolation and temporal smoothing of the maxima. The second slide is showing a comparison, over the same position, of the radiosounding of yesterday at 12:00UTC. In this slide I'm pointing to a small (and weird) isothermal layer present in the sounding which breaks the adiabatic (decrease/increase) of temperature with altitude, not present in the corresponding forecasted vertical profile at the same point. I guess it would be interesting better understanding these differences in order to exclude some systematic misrepresentation. Is there some process missing or a "simple" difference in radiation due to clouds ? There were clouds around, especially an extended cirrus deck. But this seems to be present as well also in the predicted vertical profile. [![](https://forum.ecmwf.int/uploads/default/original/2X/2/225414d1221c7dfcf136a3868e144f51a9ddd07d.jpeg)](https://confluence.ecmwf.int/download/attachments/226507964/Heatwave_overestimate_Tmax_Bo.pdf?version=1&modificationDate=1624282989464&api=v2) Cheers, Federico Grazzini ---
**Author:** ![Rebecca\_Emerton](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/r/e19b73/32.png) [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\ **Post date:** [21 June 2021 14:16 UTC](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372/2 "2021-06-21T14:16:48Z")
Hi Federico Grazzini - thanks for your post and information! Just a quick comment to notify that your topic has been moved to the 'current and recent weather → extra-tropics' section of the forum, and we'll respond again once we have further information or insights to share. Many thanks, Rebecca ---
**Author:** ![Fernando\_Prates](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/f/b38774/32.png) [@Fernando\_Prates](https://forum.ecmwf.int/u/Fernando_Prates)\ **Post date:** [30 June 2021 15:26 UTC](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372/3 "2021-06-30T15:26:43Z")
Ciao Federico, Overall I agree with your analysis of the situation. One aspect we investigated is the dust particles interaction with the radiation. At the time a plume of dust coming from north Africa was moving eastwards across the Mediterranean Sea (Figure 1). Mark Parrington (CAMS Team) computed the 2-m temperature differences between the CAMS model (operational, prognostic particles coupled with radiation) and a CTRL model (radiation coupling switch off) for the 19th to 21st of June at 12Z (Figure 2). The differences suggest the dust has a positive impact to cool the air temperature , in particular on 20th June, for most of Italy and to north of the Alps region. The amplitude is small (less 1K) suggesting other factors may have a role in this event (likely the cloud errors -altostratus as you pointed out in the tephigram). Fernando Prates ![](https://forum.ecmwf.int/uploads/default/original/2X/e/e8cf9bf739fc501bdab9fbefa38567ca94bc6025.gif) **Figure 1** ![](https://forum.ecmwf.int/uploads/default/original/2X/d/d78ea2d15db95f80ebc2bd69f8d5a9d0aa40be6e.gif) **Figure 2** ---
**Author:** ![Federico\_Grazzini](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/f/9dc877/32.png) [@Federico\_Grazzini](https://forum.ecmwf.int/u/Federico_Grazzini)\ **Post date:** [1 July 2021 17:23 UTC](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372/4 "2021-07-01T17:23:44Z")
Thanks Fernando and Mark for your analysis. Indeed it seems that the dust has played a role. I will forward your comments to other forecasters in Italy if you agree. Cheers, Federico ---
**Author:** ![Fernando\_Prates](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/f/b38774/32.png) [@Fernando\_Prates](https://forum.ecmwf.int/u/Fernando_Prates)\ **Post date:** [2 July 2021 10:39 UTC](https://forum.ecmwf.int/t/heatwave-maximum-2mt-overestimate/12372/5 "2021-07-02T10:39:45Z")
Federico, absolutely ! F