The only disappointment for player-coach Forster was that Newcastle scored their only try in the last minute of the game.
Until then, the home defence had been determined and effective despite several spells of strong Thunder pressure.
That hadn’t been the case in the first half when Newcastle hadn’t threatened the home line in the opening quarter.
Whitehaven, looking keen to make amends for the home defeat by Barrow, were dominant in the difficult, rain-soaked conditions.
They took the lead on ten minutes and twice went close to adding to that in a quick-fire start.
Newcastle had to concede a drop-out with some scrambling cover to deal with a Paul Crook grubber and Jordan Burns was just unable to ground the ball over the line.
The breakthrough came from Dion Aiye, who was to go on and prove to be a hat-trick hero for the Cumbrians.
He had too much strength for the covering defenders as he finished off from close range after Whitehaven had mounted concerted pressure. Crook converted.
There was a brief spell of Newcastle pressure but the nearest they came to scoring came when a kick through from Ben Hardcastle was knocked behind by Elliott Miller.
It was a rather special try on 31 minutes which helped double the Whitehaven lead.
Aiye, who had another outstanding game, made the initial break from deep inside his own half.
He fed Jessie Joe Parker on halfway and the centre made ground, cutting inside to avoid two tackles.
With the line in sight, he off-loaded to the supporting Miller who touched down. Crook converted.
Five minutes later Haven scored again. Forster drove in strongly towards he posts and was stopped six yards out. As three defenders halted his progress, he seemed to be going to ground but somehow kept his balance and slipped the ball to Aiye.
In turn he whipped-out a long pass for Parker to take in stride and dive over, with Cook adding his most difficult conversion.
It was a handy cushion going into the second half but Newcastle showed plenty of fight after the resumption.
Crook decided to add a drop goal on 48 minutes and it wasn’t until the last 10 minutes that Haven were able to add to that tally.
Before then, they had to withstand some persistent Newcastle attacks. At one time they forced four successive sets but the home defence held firm.
The siege was eventually lifted and, on 70 minutesm Aiye broke through on the left and shrugged off a desperate tackle to make the line.
He completed his hat-trick on 74 minutes. Crook broke down the middle, got support from Steve Roper and a nice little pass sent Aiye ploughing through for his third try.
The intensity shown by Whitehaven in defence showed how desperate they were to complete a shut out, so it was a massive disappointment when Newcastle scored in the 79th minute.
Evan Simons, from a play-the-ball, wriggled and dived through to score by the posts with Hardcastle adding the extras.
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