Thursday's meeting at Fontwell is in serious doubt with several areas of the track waterlogged and more rain forecast.
Officials at the West Sussex track have called an 8am inspection on Wednesday and fear the worst.
"We have still got three or four areas that are waterlogged. We have seen some improvement in other areas of the course, but those areas have got worse if anything and it's been dry since Monday lunchtime," said clerk of the course Edward Arkell.
"If we are not going to be fit to race tomorrow there is more rain forecast from Wednesday afternoon onwards, so it is better we let everybody know and they can make alternative running plans. It's going to be a struggle."
Meanwhile officials at Musselburgh have called a precautionary inspection for 8am on Wednesday ahead of the meeting that afternoon. Ground conditions are described as good, but with a "tricky forecast".
Clerk of the course Harriet Graham tweeted: "Precautionary Inspection 8am due to forecast snow starting between 7-9am changing to sleet/rain later +3 Tricky forecast."
An 8am precautionary inspection has also been called for Wednesday's meeting at Thurles due to the uncertainty of the weather forecast.
A provisional all-chase card has been programmed by the British Horseracing Authority for Sandown on Friday in an attempt to safeguard the fixture. This will consist of the three chases originally scheduled plus three additional chase opportunities.
All additional races will be free to enter and a final decision on whether the existing hurdle races will be abandoned and the provisional chases activated will be made at 8am on Thursday.
Clerk of the course Andrew Cooper said: "Parts of the hurdle course are saturated. We are expecting further rain on Thursday, with some forecasts suggesting as much as 10mm. To give ourselves the best chance of staging a day's racing we have asked BHA to provisionally schedule an all-chase card ."
29 July 2016Minding shoots for sixth Group One prize in Nassau date
Dancing aiming to Star in Stewards' Cup date at Goodwood
Bryan Cooper expected to be absent for up to a month after Galway fall
Always Smile bids to back-up Falmouth Stakes third at Goodwood
Berkshire 'back where he was' for Glorious Goodwood date
Emotionless pleasing ahead of Goodwood return
Bryan Cooper suffers partially collapsed lung in Galway incident
Rhododendron blooms in Goodwood heat
California shines in Lillie Langtry Stakes
Clondaw Warrior clings on to give Ruby Walsh glory in the Galway Hurdle
Big Orange pips them again in Goodwood Cup
Richmond glory for Mehmas and Frankie Dettori
Minding the star name in Nassau Stakes at Goodwood
28 July 2016Clondaw Warrior clings on to give Ruby Walsh glory in the Galway Hurdle
Bryan Cooper taken to hospital following Galway spill
Your're Hired makes dreams come true at Goodwood
Henry Candy not ruling out supplementing 'exceptional' Limato for Nunthorpe
Goodwood-bound Orion's Bow takes aim at Stewards' Cup from stall 12
Galway Blazers made to measure for Aranhill Chief
Newly-created inner track to be used for Champion Stakes at Ascot
Marsha out to swamp rivals in Goodwood sprint
Charlie Appleby to go the distance with Charming Thought
Sir Mark Prescott considers Sandown test for Red Box
Sisters dominate finish in Goodwood handicap
Lord Scoundrel a Galway Plate smasher for Gordon Elliott and Donagh Meyler
Brian Ellison strikes at Galway
Yalta impresses in Molecomb blitz at Goodwood
Fast-learner The Gurkha has myriad of options after Sussex thriller
Ulysses back in business with Gordon Stakes win
Pamona primed for Goodwood strike
Exciting Blue Point 'stepping into the big league' at Goodwood
Michael Bell anticipating Big performance from Orange
27 July 2016Adam Kirby hoping for swift return after missing Kodi Bear ride
Star Rider enters Cesarewitch equation at Goodwood
Connor King facing lay-off after Galway all
Pyromaniac bids to continue Tony Martin run after Galway Hurdle reprieve
Chasing switch still on Cole Harden agenda
Gimcrack a likely goal for Newbury victor Mokarris
Triumphant team consider drop in class after Ascot disappointment
Super Mac signs off with winning Connection at Goodwood
Elidor the horse for the big occasion
War Decree lays down the law with Vintage performance
Fire Fighting too hot for Goodwood king Mark Johnston
Ulysses primed to bounce back in Gordon Stakes
No grounds for concern with The Last Lion team
Meade seeking Galway Plate Riches with Road again
Hugo Palmer keen to savour winning feeling once more with Galileo Gold
Enda Bolger leads tributes to former amateur star JT McNamara
26 July 2016All-the-way Creggs Pipes powers to Galway glory
Connections to appeal Ascot demotion of Namhroodah
Dutch delight for Charlie Hills and James McDonald
Former star amateur JT McNamara dies aged 41
Competition watchdog orders sale of 350-400 shops before Ladbrokes/Coral merger
Swamp Fox takes control in Galway feature
Wolverhampton shock as Dandy Flame wins at 200-1
Willie Mullins embarks upon chasing career with Galway-bound Briar Hill
Pyromaniac given green light to run in Galway Hurdle
No Goodwood going concerns for Stewards' Cup favourite Orion's Bow
Brian Ellison bemoans Baraweez draw in Galway showpiece
Charlie Appleby anticipating Vintage display from Boynton
Minding tops 10 contenders for Nassau glory at Goodwood
Hugo Palmer hoping Lennox pair can make their mark at Goodwood