I don't know how far the forecast icons compare with the forecast text but the list might help you to know if your collection is going to be complete (I attached the file wich includes this list but it comes also with the installation off TodayPlus):
1,Cloudy
3,Mostly Cloudy
4,Partly Cloudy
11,Clear
13,Light Rain
14,Showers
15,Showers Early
16,Showers Late
18,Rain
19,AM Showers
20,Scattered Showers
21,Few Showers
22,Mostly Sunny
23,Mostly Clear
24,Sunny
25,Scattered Flurries
26,AM Clouds/PM Sun
27,Isolated T-Storms
28,Scattered Thunderstorms
29,PM Showers
30,PM Showers/Wind
31,Rain/Snow Showers
32,Few Snow Showers
33,Cloudy/Wind
34,Flurries/Wind
35,Mostly Cloudy/Windy
36,Rain/Thunder
37,Partly Cloudy/Windy
38,AM Rain/Snow Showers
39,Showers / Wind Late
40,Light Rain/Wind
41,Showers/Wind
42,Clouds Early / Clearing Late
43,T-Showers
44,Mostly Sunny/Wind
45,Flurries
46,Mostly Clear / Wind
47,Rain/Wind
49,Sct Flurries/Wind
50,Sct Strong Storms
51,PM T-Storms
52,T-Storms Early
53,Thunderstorms
55,Sunny/Windy
56,AM Thunderstorms
57,T-Storms Late
62,AM Rain
63,Scattered Showers/Wind
64,Iso T-Storms/Wind
65,Rain/Snow
66,Sct T-Storms/Wind
67,AM Showers/Wind
70,Sct Snow Showers
71,Snow to Ice/Wind
73,Light Snow Late
75,Light Rain / Freezing Rain
77,Snow to Rain
78,Snow Showers Early
80,AM Light Rain
81,PM Light Rain
82,PM Rain
84,Snow Showers
85,Rain to Snow
86,PM Rain/Snow
88,Few Showers/Wind
89,PM Snow/Wind
90,Snow/Wind
91,PM Rain/Snow Showers
92,PM Rain/Snow/Wind
93,Rain/Snow Showers/Wind
94,Rain/Snow/Wind
98,Light Snow
100,PM Snow
101,Few Snow Showers/Wind
103,Light Snow/Wind
104,Wintry Mix
105,AM Wintry Mix
106,Hvy Rain/Freezing Rain
107,Snow Showers Late
108,AM Light Snow
109,Snow
114,Rain/Freezing Rain
118,T-Storms/Wind
123,Sprinkles
125,AM Snow Showers
126,AM Clouds/PM Sun/Wind
127,Rain / Snow Showers Late
128,AM Rain/Snow/Wind
130,Rain to Snow/Wind
132,Snow to Wintry Mix
133,PM Snow Showers/Wind
135,Snow and Ice to Rain
137,Heavy Rain
138,AM Rain/Ice
140,Heavy T-Storms/Wind
142,Rain/Thunder/Wind
145,AM Snow Showers/Wind
146,AM Light Snow/Wind
147,Sct Snow Showers/Wind
150,PM Light Rain/Wind
152,AM Light Wintry Mix
153,PM Light Snow/Wind
154,Heavy Rain/Wind
155,PM Snow Shower
158,Snow to Rain/Wind
163,Rain/Sleet
164,PM Light Rain/Ice
167,AM Snow
171,Snow to Ice
172,Wintry Mix/Wind
173,Strong Storms
175,PM Light Snow
178,AM Drizzle
183,Snow Showers / Wind Early
189,Strong Storms/Wind
193,PM Drizzle
194,Drizzle
201,AM Light Rain/Wind
202,PM Wintry Mix
204,AM Rain/Wind
223,Wintry Mix to Snow
231,Rain
236,Ice to Rain
259,Hvy Rain/Freezing Rain
271,Snow Showers/Windy
988,Partly Cloudy/Windy
989,Light Rain Shower
990,Light Rain with Thunder
991,Light Drizzle
992,Mist
993,Smoke
994,Haze
995,Light Snow Shower
996,Light Snow Shower/ Windy
997,Clear
998,A Few Clouds
999,Fair
Regards Ingmar