Here is the sequence of METARS showing the crosswinds at London-Heathrow this morning, followed by the latest 9-hour TAF.
Remember that, due to protocols, no gust below 10 knots is reported on METARS.
Visibility on Rwy 27R
is currently (1150z)
affected by blowing spray in light rain-shower.
EGLL 100320Z 17020G31KT 9999 -RA SCT018 BKN025 07/04 Q0982
EGLL 100350Z 17020KT 9999 -RA SCT020 BKN025 06/04 Q0980 TEMPO 17025G35KT RA
EGLL 100420Z 17020KT 9999 -RA SCT018 BKN021 07/04 Q0978 TEMPO 17025G35KT RA
EGLL 100450Z 17023KT 9999 -RA BKN014 07/05 Q0976 TEMPO 17025G35KT 4500 RA
EGLL 100520Z 17020G31KT 9000 RA SCT016 BKN020 07/05 Q0974 TEMPO 17025G42KT 4500 RA BKN014
EGLL 100550Z 17023G34KT 8000 RA BKN016 07/05 Q0973 TEMPO 18026G44KT 4500 RA BKN014
EGLL 100620Z 17025G35KT 6000 RA BKN015 BKN023 07/05 Q0971 TEMPO 17030G45KT 4500 BKN012
EGLL 100650Z 17023G33KT 6000 RA FEW016 BKN022 07/05 Q0971 TEMPO 17026G43KT 4500 RA BKN014
EGLL 100720Z 17023KT 5000 RA BKN015 BKN022 07/05 Q0970 TEMPO 17027G43KT 4500 RA BKN012
EGLL 100750Z 17024G34KT 6000 RA BKN016 BKN022 07/05 Q0968 TEMPO 4000 BKN014
EGLL 100820Z 18025G39KT 6000 RA SCT016 BKN022 08/06 Q0967 TEMPO 4000 BKN014
EGLL 100850Z 22018KT 9999 -RA FEW016 SCT022 BKN046 08/05 Q0968 RERA TEMPO SHRA
EGLL 100920Z 24021G31KT 9999 -RA FEW015 SCT023 06/04 Q0969 TEMPO SHRA SCT020CB
EGLL 101020Z
19017KT 9999 FEW023 08/04 Q0968 TEMPO SHRA sct020cb
EGLL 101050Z
20018KT 9999 FEW028 09/04 Q0968 TEMPO SHRA SCT020CB
EGLL 101150Z
19021KT 7000 R27R/1400 -SHRA FEW018 SCT025 08/05 Q0967 RESHRA TEMPO SHRA SCT020CB
The wind has now veered and/or abated for the time being. In the absence of much information, I wonder how many diversions there have been so far...
The decision to close Heathrow Rwy 23, to enable expansion of parking stands at T4, was no doubt caused by the planning delays to T5. 
But it looks questionable on days like this morning. There have been no north-south runways in the South of England since Thorney Island closed many years ago. But at least we had the south-westerly ones at Heathrow and Stansted. Now we only have the Stansted one.
[EGHI (Eastleigh) operators must forgive me, but I can't see a jumbo diverting your way.]
Gatwick Rwy 26 can be a nightmare in strong south-to-SW wind, because of the turbulence/windsheer in the lee of the south-side hangars. I should know - having once performed a go-around from 50ft in a DC10-30 after a flight across the pond. We went to Stansted that day, which caused chaos. [The W/V there was 230/50, but nice and steady.]
So, would Rwy 23 at LHR actually have helped this morning, with a reported W/V of 180/25-39 (at 0815z)?
On the face of it, 50 degrees off makes the 39-knot gust into a crosswind-component of about 30 knots. This is sporting, but easier than 39 knots on Rwy 27L/R.
The 170/25-35 reported at 0615z equates to a gust-component of 30 knots on Rwy 23; 35 knots on Rwy27L/R.
Not much difference, perhaps? Ah, you have forgotten that the wind usually veers at least 10 - 20 degrees in a big gust (Northern Hemisphere). As PKPF68-77 has pointed out on another thread (?), Met observers seem to be omitting these direction-changes from the METARS, except when the change is about 30 degrees (?). But even 10 degrees makes a big difference in a 40-knot gust.
The forecast suggests that the problems in the South-East may not yet be over...
You Schiphol-based pilots always had a better chance of getting home - on days like this - than the rest of us.
TAF EGLL100902Z
10 1019 20015G25KT 9999 BKN020
TEMPO 1119 20025G35KT 6000 SHRA BKN020CB
PROB30% TEMPO 1219 18028G45KT 3000 +SHRA TSRA BKN014CB
BECMG 1618 26025G35KT
Safe homecomings to everyone, and... ENJOY ! 