Unfortunately the TAFs - even allowing for Met Office CMA-factor - are looking pretty grim:
YEOVILTON: 171026Z 1712/1721 29012KT 9999 BKN015 TEMPO 1712/1714 6000 -RA FEW006 BKN012 BECMG 1714/1721 7000 -SHRA SCT020
FAIRFORD: 171030Z 1712/1721 31015KT 9999 BKN030 BECMG 1712/1713 31018G30KT TEMPO 1712/1716 4000 SHRA BKN015 PROB30 TEMPO 1712/1715 3000 +TSRA BKN012CB
BRIZE NORTON: 171037Z 1712/1812 32018G30KT 9999 BKN025 TEMPO 1712/1720 6000 SHRA BKN015 PROB40 TEMPO 1712/1718 3000 +TSRA BKN010CB BECMG 1719/1721 29013KT
However, provided that the TEMPOs really are TEMPO and the 18G30 wind is more 18 than 30, a lowish level transit
might still be possible later this afternoon. Although I wouldn't put any money on it.....