The trup on הַשַּׁבָּת הַשְּׁבִיעִת תִּסְפְּרוּ

Summary: Shadal explains what the trup would have to be to support Rashi's parse of this famous pasuk.

Post: Consider the following rather famous pasuk:

and Rashi:

16. You shall count until the day after the seventh week, [namely,] the fiftieth day, [on which] you shall bring a new meal offering to the Lord.		טז. עַד מִמָּחֳרַת הַשַּׁבָּת הַשְּׁבִיעִת תִּסְפְּרוּ חֲמִשִּׁים יוֹם וְהִקְרַבְתֶּם מִנְחָה חֲדָשָׁה לַי־הֹוָ־ה:
the day after the seventh week: הַשַּׁבָּת הַשְּׁבִיעִת, as the Targum [Onkelos] renders: שְׁבוּעֲתָא שְׁבִיעָתָא, “the seventh week.”		השבת השביעת: כתרגומו שבועתא שביעתא:
You shall count until the day after the seventh week: But not inclusive, making forty-nine days.		עד ממחרת השבת השביעת תספרו:ולא עד בכלל, והן ארבעים ותשעה יום:
the fiftieth day, [on which] you will bring a meal offering to the Lord from the new [wheat crop]: [lit., “(You shall count) fifty days and bring a meal offering to the Lord from the new (wheat crop).” But we count only forty-nine days. Therefore, the meaning is:] On the fiftieth day, you shall bring this [meal offering of the new wheat crop]. But I say that this is a Midrashic explanation of the verse [since it requires the forced attachment of the words חֲמִשִּׁים יוֹם to the continuation of the verse regarding the meal offering, whereas the cantillation signs attach them to the preceding words regarding the counting]. But its simple meaning is: “until [but not inclusive of]…the day after [the completion of] the seventh week, which is the fiftieth day, shall you count.” Accordingly, this is a transposed verse.		חמשים יום והקרבתם מנחה חדשה לה': ביום החמשים תקריבוה. ואומר אני זהו מדרשו, אבל פשוטו עד ממחרת השבת השביעית, שהוא יום חמשים, תספרו. ומקרא מסורס הוא:

It seems that Rashi is parsing this pasuk as:
עד ממחרת השבת השביעת תספרו | | חמשים יום והקרבתם מנחה חדשה לה

and this would seem to go against the trup which has an etnachta on the word yom.

However, here is Shadal's analysis:

What is the difference between this suggested trup and the actual trup of the pasuk?



The original trup has a zakef on השביעית, and a zakef stands on the same stature as the tipcha on תספרו. Therefore, the earlier trup in the pasuk takes hold first, followed by the later trup, of the same stature. Therefore, we have:
עד ממחרת השבת השביעת || תספרו חמשים יום

and then, tisperu chamishim yom is further subdivided at the tipcha as

תספרו | חמשים יום

Or, in total,
עד ממחרת השבת השביעת || תספרו | חמשים יום

However, if we were to change the zakef on השביעית to a tevir, then a tevir is of a lower stature than a tipcha in the trup system. Therefore, the first trup symbol to function would be the  tipcha on תספרו, and the tevir on השביעית would subdivide that.

We would then have:
עד ממחרת השבת השביעת | תספרו || חמשים יום

which means that we could up to the seventh week, 50 days.

Now, what about that etnachta? It is kind-of parenthetical. 50 days -- at which point, etcetera, etcetera. So, it still goes against our trup, though not in the same overt manner.

Related, see my analysis of a suggestion that the mere presence of the tipcha on the word תספרו should stand as sufficient cause for the derasha.

At the end of the day, yes, the derasha might well rely on a parse which is at odds with the trup. This is OK, and might be resolved in a number of ways. (For instance, that derash involves parsing the pasuk in ways against the simple reading, and the midrashist knows it.)