Here is an example of BE + adjective + that clause that contains notions of modality related to certainty:
Well, when you pick a Valentine,
you have to be sure that you choose the right person.
There is a wide range of adjectives that are common in this structure that are not related to modality but are still preceded by more complex modality, negation and adverbs. For example:
They come from the part of our mind
that we might not even be aware that we have.
Note that, adjectives such as ‘aware‘ and ‘sure‘ are not usually found before a noun in the attributive position.
Someone searched for ‘she is happy that’ so I thought I would do a iWeb corpus search for:
_VB _JJ that * *
1 BE SURE THAT YOU ARE 3510
2 BE AWARE THAT IF YOU 2566
3 BE SURE THAT YOU HAVE 2487
4 BE AWARE THAT THERE ARE 2443
5 BE AWARE THAT THERE IS 1678
6 IS LIKELY THAT YOU WILL 1675
7 IS IMPORTANT THAT YOU DO 1484
8 BE AWARE THAT IT IS 1351
9 IS IMPORTANT THAT YOU ARE 1302
10 BE SURE THAT IT IS 1284
11 BE AWARE THAT THIS IS 1267
12 IS IMPORTANT THAT YOU HAVE 1228
13 IS IMPORTANT THAT YOU UNDERSTAND 1143
14 BE SURE THAT THEY ARE 1117
15 BE CAREFUL THAT YOU DO 1112
16 IS UNLIKELY THAT YOU WILL 1094
17 BE AWARE THAT YOU WILL 1039
18 BE AWARE THAT YOU MAY 1002
19 IS CLEAR THAT THERE IS 997
20 BE SURE THAT YOU WILL 989
21 BE SURE THAT YOU ‘RE 980
22 IS IMPORTANT THAT YOU KNOW 897
23 ARE CONFIDENT THAT YOU WILL 884
24 BE SURE THAT YOU DO 862
25 ‘S IMPORTANT THAT YOU DO 783
26 ARE SURE THAT YOU WILL 773
27 BE AWARE THAT YOU ARE 765
28 IS IMPORTANT THAT YOU TAKE 749
29 IS TRUE THAT THERE ARE 731
30 BE AWARE THAT NOT ALL 694
31 IS IMPORTANT THAT YOU KEEP 687
32 BE AWARE THAT WHEN YOU 662
33 AM SURE THAT THERE ARE 653
34 BE AWARE THAT YOU CAN 639
35 IS ESSENTIAL THAT YOU HAVE 636
36 AM SURE THAT YOU WILL 629
37 BE SURE THAT THERE IS 628
38 BE AWARE THAT THEY ARE 617
39 ‘S LIKELY THAT YOU ‘LL 615
40 BE SURE THAT YOU CAN 612
41 IS POSSIBLE THAT SOME OF 605
42 ‘S WELL THAT ENDS WELL 579
43 IS TRUE THAT THERE IS 560
44 BE SURE THAT IT WILL 558
45 IS POSSIBLE THAT YOU MAY 554
46 BE AWARE THAT SOME OF 548
47 ‘S IMPORTANT THAT YOU HAVE 539
48 ARE CONFIDENT THAT WE CAN 535
49 IS IMPORTANT THAT YOU READ 533
50 ‘M SURE THAT THERE ARE 525
51 IS IMPORTANT THAT YOU GET 524
52 ARE CONFIDENT THAT WE WILL 515
53 IS LIKELY THAT THEY WILL 508
54 BE AWARE THAT WE ARE 504
55 IS CLEAR THAT IT IS 502
56 IS IMPORTANT THAT THEY ARE 500
57 IS CLEAR THAT THIS IS 491
58 IS POSSIBLE THAT YOU WILL 491
59 IS CLEAR THAT THERE ARE 481
60 IS IMPORTANT THAT YOU MAKE 478
61 BE SURE THAT THEY WILL 477
62 ‘S UNLIKELY THAT YOU ‘LL 465
63 ‘S IMPORTANT THAT YOU KNOW 455
64 IS IMPORTANT THAT YOU USE 436
65 BE AWARE THAT IT MAY 435
66 IS IMPORTANT THAT YOU CHECK 434
67 ‘S IMPORTANT THAT YOU UNDERSTAND 431
68 IS IMPORTANT THAT WE HAVE 420
69 WAS CLEAR THAT HE WAS 419
70 IS LIKELY THAT THERE WILL 418
71 IS LIKELY THAT YOU HAVE 418
72 BE CONFIDENT THAT YOU ARE 416
73 BE AWARE THAT THERE MAY 414
74 IS POSSIBLE THAT YOU HAVE 409
75 AM GLAD THAT I DID 406
76 ARE GLAD THAT YOU HAVE 400
77 IS LIKELY THAT YOU ARE 398
78 ARE AWARE THAT THERE ARE 388
79 IS IMPORTANT THAT WE DO 387
80 BE SURE THAT IT ‘S 386
81 BE SURE THAT THERE ARE 386
82 BE SURE THAT YOU KNOW 386
83 BE SURE THAT ALL OF 383
84 BE AWARE THAT IT ‘S 375
85 IS LIKELY THAT WE WILL 375
86 AM CONFIDENT THAT WE WILL 374
87 IS TRUE THAT YOU CAN 373
88 BE SURE THAT WE ARE 371
89 IS POSSIBLE THAT THERE IS 368
90 BE SURE THAT YOU UNDERSTAND 366
91 IS POSSIBLE THAT YOU ARE 365
92 IS IMPORTANT THAT IT IS 357
93 ‘S GREAT THAT YOU ‘RE 356
94 ARE CONFIDENT THAT WE HAVE 352
95 IS CLEAR THAT THEY ARE 351
96 IS UNLIKELY THAT THEY WILL 350
97 AM SURE THAT I WILL 345
98 IS IMPORTANT THAT YOU CHOOSE 345
99 BE AWARE THAT IT CAN 344
100 ‘S TRUE THAT THERE ARE 343
B1: confident, essential, likely, unlikely
B2: aware