Losses unlike any suffered by a main opposition party between elections for three decades. But - of course - that may all turn out to be a naively rosy expectation when the results are finally in.
The votes have yet to be counted, after all, and it's possible the Labour Party may end up wishing the outcome was merely painful and no worse.
It could just conceivably turn out to be catastrophic.
If this all sounds a little apocalyptic, forgive me.
Hair-rending and teeth gnashing
Doom-laden adjectives are the stock in trade of political punditry at election time, especially when the occasion lends itself to a little hair-rending and teeth-gnashing.
And there is already a not-especially-orderly queue of Jeremy Corbyn's critics in the Labour Party, waiting to blame poor results for their party on his leadership, and clearing their throats to strike up the chorus of voices wanting him to go.
In so far as an objective analysis exists, what would a bad night for Labour look like?
No main opposition party has suffered net losses of council seats for 30 years.
The English local council seats up for grabs were won at the height of Labour's popularity under Ed Miliband - though that's not saying a great deal. Now, losses look inevitable, and a pantheon of psephologists predict 150, 190, more?
Mr Corbyn's Labour enemies have set the bar for respectability impossibly high.
Four hundred gains are the minimum to show progress, according to the likes of defeated leadership contender Liz Kendall, and given the fact Labour's trailing the Conservatives in the national polls, she might as well have demanded 400,000.
If Labour comes third in Scotland - though that's not thought very likely - or loses in London - something almost no-one expects to happen, the hair-rending and teeth-gnashing will be so frenzied as to leave the entire Labour Party, Corbynistas and anti-Corbynistas alike, bald and toothless.
As it is, we can expect a cacophonous set of rival choruses. Those loyal to the leader blaming the disloyalty of dissident MPs for vote-sapping disunity. And those who want the leader gone blaming him; demanding a change of direction and some a change of leader.
There's no plan among the mutineers in waiting to move against Mr Corbyn this side of the European referendum. That would smack too much of treachery with a defining struggle for Britain still to be won and lost.
Will they strike afterwards?
Will any MP risk the certain wrath of Mr Corbyn's army of loyal supporters subsequently?
From all I hear, at least two and possibly more Labour MPs of vintage and deep anti-Corbyn conviction, have told friends and colleagues that they will.
As of now - tonight - a challenge looks to me more than a plausible possibility. But let's see.
Remember Michael Foot? Remember Gordon Brown at the nadir of his fortunes? Yes, Labour dumped Tony Blair, but he had a truly dedicated and ruthlessly ambitious replacement in Mr Brown (and the compromises he forced on the party grated horribly with the faithful well before Iraq). Put bluntly, Labour has always been rubbish at regicide.
This time, as far as I can detect, the mood is different.
Something damaging and conceivably dangerous for the Labour leader is about to happen. Will it end with the Labour leader's position damaged or even strengthened, at least internally?
With the Labour faithful, the ordinary members new and old, who elected Jeremy Corbyn in the first place in no mood to dump him, the chances of a challenge succeeding look remote. That doesn't mean the mutineers won't try.
As for the Conservatives, David Cameron's enjoying an easier ride than any leader of a governing party as divided as the Conservatives has any right to expect.
Split and bitterly fractious over Europe, some feeling rebellious over bossy and, it's argued, "un-Conservative" plans to force through academisation of schools and push hard for more elected mayors, the Tories really ought to be struggling, oughtn't they?
And what about the continuing austerity of the chancellor's two-steps-forward-and-one-step back drive towards deficit reduction?
The prime minister must be offering a prayer a day in thanks for Labour's troubles. If he doesn't, he needs to start.
The Liberal Democrats? They're used to fighting with their backs against the wall and, for Tim Farron, that's just as well. At least they can scarcely do worse than they did in May 2015 at the general election, and they won't.
UKIP may have passed their high water mark. But they'll hope for something to cheer about, in Wales at the very least. Then, after the referendum, Nigel Farage will get on with his dream of redesigning and rebranding his party.
It's up the voters in the end, isn't it. The ones who bother to vote, anyway. Wonder what they've made of it all?
A bad night, and a worse morning ahead for the Labour Party.