By: Stephen McCoy
The 2019 IMSA season kicks off later this week with the Roar Before the Rolex 24 at Daytona International Speedway. Conditions look to start with some clouds and rain, but will end with lots of sunshine and temperatures in the mid to upper 60's.
An upper level shortwave trough is expected to develop over the southwestern US Tuesday into Wednesday as it closes off and splits from an upper level longwave trough. On Thursday, a surface low pressure system will form over the Gulf of Mexico, ahead of the trough and track northeastward through the rest of the week. A cold front will extend from the system as it approaches the Midwest Thursday night.
On Friday, winds in the low levels will be from the southwest, bringing moisture from the Gulf of Mexico over the area, resulting in partly to mostly cloudy conditions through the day. Surface winds will also be mainly from the southwest, with the strongest winds occurring before the frontal passage; winds gusts could exceed 20 mph. There is a chance for precipitation towards that late afternoon or evening on Friday as the front approaches, though the models are split on timing of the approach; the ECMWF shows the front passing in the afternoon, the GFS shows it passing in the evening. Regardless, the precipitation has the possibility of occurring during the later on-track sessions on Friday.
After the front passes through on Friday, conditions will begin to clear as winds in the low levels bring drier air into the region from the west and northwest, though upper level winds from the southwest could cause some light cloud cover in the upper levels. An area of high pressure will build in behind the front and move towards the east on Saturday and Sunday, resulting in surface winds starting from the north to northwest then shifting to the northeast. With winds from the same direction in the low levels and at the surface on Saturday, wind speeds should be slightly higher than Sunday with gusts over 15 mph possible. Surface winds will also bring in cooler air to the region, with high temperatures on Saturday and Sunday reaching the mid to upper 60's.
An upper level shortwave trough is expected to develop over the southwestern US Tuesday into Wednesday as it closes off and splits from an upper level longwave trough. On Thursday, a surface low pressure system will form over the Gulf of Mexico, ahead of the trough and track northeastward through the rest of the week. A cold front will extend from the system as it approaches the Midwest Thursday night.
On Friday, winds in the low levels will be from the southwest, bringing moisture from the Gulf of Mexico over the area, resulting in partly to mostly cloudy conditions through the day. Surface winds will also be mainly from the southwest, with the strongest winds occurring before the frontal passage; winds gusts could exceed 20 mph. There is a chance for precipitation towards that late afternoon or evening on Friday as the front approaches, though the models are split on timing of the approach; the ECMWF shows the front passing in the afternoon, the GFS shows it passing in the evening. Regardless, the precipitation has the possibility of occurring during the later on-track sessions on Friday.
After the front passes through on Friday, conditions will begin to clear as winds in the low levels bring drier air into the region from the west and northwest, though upper level winds from the southwest could cause some light cloud cover in the upper levels. An area of high pressure will build in behind the front and move towards the east on Saturday and Sunday, resulting in surface winds starting from the north to northwest then shifting to the northeast. With winds from the same direction in the low levels and at the surface on Saturday, wind speeds should be slightly higher than Sunday with gusts over 15 mph possible. Surface winds will also bring in cooler air to the region, with high temperatures on Saturday and Sunday reaching the mid to upper 60's.
