It looks like being a wet five days ahead, particularly for higher parts of the southeast Grampians. Perversely the wettest and driest places during these 120 hours will be little more than 50 miles apart. While parts of Perthshire will see accumulations of 66mm or more, the Spey Valley, according to the ICON model will see little more than 6 mm in that time thanks of course to the rain shadow effect. The UKMO in their yellow warning are expecting flooding and much higher totals than this.
Heavy rain may lead to flooding in places and disruption to transport.UKMO Issued: 10:19 (UTC) on Wed 9 Dec 2020
Heavy rain will fall throughout Friday and into Saturday morning across parts of eastern Scotland with accumulations around 40-60 mm, but with the potential for 100 mm over high ground.