I'll update my list for this this thread:
BASE: 16 Female Senators (Ayotte, Gillibrand, Warren, Mikulski, Stabenow, Klobuchar, Heitkamp, Baldwin, Fischer, McCaskill, Murray, Cantwell, Feinstein, Boxer, Murkowski, Hirono)
17 - Susan Collins wins in Maine
18 - Shelley Moore Capito/Natalie Tennant wins in West Virginia
19 - Jeanne Shaheen wins in New Hampshire
20 - Kay Hagan wins in North Carolina or is somehow beaten by Heather Grant
21 - Mary Landrieu wins in Louisiana
22 - Terri Lynn Land is elected in Michigan
23 - Colleen Hanabusa wins the Democratic primary in Hawaii, then the general
24 - Karen Handel/Michelle Nunn wins in Georgia
25 - Alison Lundergan Grimes wins in Kentucky
26 - Amy Stephens wins in Colorado
27 - Joni Ernst wins in Iowa
28 - Nancy Mace wins in South Carolina
Right now I'd say 19-23 female Senators in the 114th Congress
Thanks for this awesome list.
When you put it this way, even 25 doesn't seem all that unlikely.