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 ."
27 October 2016Dartmouth given Hong Kong option by Sir Michael Stoute
Henry Candy relishing American dream and Tepin clash with Limato
David O'Meara favouring Breeders' Cup Turf for Mondialiste
Classic named as first preference for Found at Breeders' Cup
Treve's sister beaten but full of promise at Saint-Cloud
Colin Tizzard - Cheltenham next and all options open for Thistlecrack
More Of That heads market for BetVictor Gold Cup at Cheltenham
Willie Mullins ponders Hennessy prep for big Newbury fancy Avant Tout
Faydhan 'ready to run' on belated return at Lingfield
Muffri'Ha blossoming for Fleur De Lys at Lingfield
26 October 2016Banditry grabs Chelmsford feature
Freddy Tylicki sees no Eden hazard for Lingfield-bound Tango
Willie Mullins set to unleash Bachasson over fences
Un De Sceaux could make French connection for Willie Mullins
Thistlecrack hardens as Gold Cup favourite following thrilling Chepstow return
Value At Risk comes good over fences at Bangor
All roads lead back to Aintree for Vics Canvas
Saphir Du Rheu set to take hurdles option at Wetherby
Dual Group One winner Twilight Son retired to Cheveley Park Stud
Silviniaco Conti enjoys Chepstow gallop ahead of Down Royal return
Seeyouatmidnight all set for Carlisle comeback
Simon Crisford has Breeders' Cup ambitions for Rodaini
Mark Johnston could seek Far East enlightment with Lumiere
25 October 2016Thistlecrack oozes class on chasing debut at Chepstow
Charlie Longsdon derailed by injuries to big names
Ben Pauling has Grand National designs for Becher-bound Silvergrove
Sylvester Kirk backs Salouen to go the distance next season
James Nash plots Aintree return with 'amazing' Your Busy
Aidan O'Brien expects Minding to stay in training
Silviniaco Conti booked for Chepstow workout before racing
Tea For Two in mix for Sodexo Gold Cup
Double Shuffle in BetVictor frame for Tom George
Churchill form boost pleases Aidan O'Brien
Weather frustration set to continue for Ben Pauling and Barters Hill
Neil Mulholland to consider Haldon Gold Cup option for Fox Norton
Coneygree given Charlie Hall Wetherby entry 'just in case'
Colin Tizzard has Thistlecrack sharp and ready for Chepstow chasing bow
Time called on career of dual Derby hero Harzand
24 October 2016Tawdeea to take aim at Doncaster after Leicester strike
Coologue considered for Hennessy Gold Cup by Charlie Longsdon
Forgotten Rules team cool on hurdling career
Henry Candy has sole focus on Breeders' Cup Mile with Limato
Meydan a 'potential' destination for Gordon Elliott and Commissioned
Noel Meade rules Apache Stronghold out for the season
Ben Pauling to duck Bangor mission with Barters Hill
Third Intention books Hennessy ticket with Old Roan victory
Found set to be given Breeders' Cup Classic entry
Vazirabad repeats Prix Royal-Oak success
Titus rules in Leopardstown clash
Making Light betters colts in Killavullan Stakes
Flying Fairies floors Zawraq at Leopardstown
No Charlie Hall run for Gold Cup hero Coneygree
Native River in frame for Wetherby reappearance
William Haggas keeps Rivet's Guineas options open