One warning is currently in place across the Scottish Borders and East Lothian, while another one has been issued for much of the north west between 00.00am on Thursday and 3pm on Friday.
The new warning covers Central, Tayside, Fife, Strathclyde, Highlands and Eilean Siar, and predicts widespread heavy rain falling from Wednesday evening through much of Thursday and into Friday.
Accumulations of 40-70mm will build up across the country with some areas in Argyll and West Highland seeing 100-150mm.
The Met Office has said there is currently some uncertainty over which areas will see the heaviest spells but the rain should gradually ease through Friday.
Warnings of floods and damage to buildings, as well dangerous driving conditions and delays have been issued by the forecaster.
Today’s yellow warning initially was issued for areas in England but it was extended to reach into Scotland on Tuesday morning as the risk level of the heavy rain forecast increased.
The Met Office has warned residents to expect to see delays to bus and train services, potential flooding of homes and other buildings and spray and flooding on the roads making for difficult driving conditions.
A statement from the Met Office said: “Rain, accompanied with strengthening winds, will continue to affect northeast England and the far southeast of Scotland today before clearing away eastwards this evening.
"A further 15-25 mm of rain is expected quite widely whilst in some places another 40-50 mm is possible.”