By Doug Schneider

There are no major changes to the forecast for Portland this weekend, as it still looks like the weather will be nice for racing each day. There is a small chance of seeing some light sprinkles in the area on Sunday, but it should not have an impact. 

The main weather feature to affect Portland will be a low pressure system moving slowly across the Pacific toward the Northwest coastline. This will push a front through the Portland area on Saturday night. Most of the rain with this front will stay offshore or just near the coast, and rain will decrease as it moves inland. Still, there may be some sprinkles that reach Portland on Saturday night and Sunday. I don't think there would be enough rain to even measure a hundredth of an inch, if it happens at all. The front will also cause a wind shift from south of Friday and Saturday to west on Sunday. 

By: Stephen McCoy

Some minor changes in this update for Blancpain GT World Challenge America at Watkins Glen, though the general setup remains similar to the initial forecast.

A cold front from a surface low pressure system over Hudson Bay is expected to pass through the region on Friday, bringing a slight chance for isolated showers and/or light rain. West to southwesterly winds ahead of the front will cause near-average temperatures for the day. After the frontal passage, northwesterly winds will cool temperatures to the low-to-mid 50's overnight. With dew point temperatures similar to the air temperatures, there is a possibility of fog in the area Saturday morning; temperatures will rebound to the mid-to-upper 60's. High relative humidity values in the upper and lower levels will result in partly to mostly cloudy conditions through the day.

A surface high pressure system will build into the region on Saturday behind the front, then move off-shore on Sunday. As it leaves the area, a stationary front is expected to setup to the north of the track, causing surface winds to shift to the south to southeast. Westerly winds in the rest of the atmosphere will bring moisture over the region, with much of the air aloft fully saturated. As a result, precipitation chances are higher than in the initial forecast; model guidance suggests the highest chance for showers near or after mid-day.

By: Stephen McCoy

Cool temperatures welcome the Blancpain GT World Challenge America paddock at Watkins Glen this weekend after a cold front moves through the region on Friday. The front will bring a slight chance for isolated showers, while a slim increase in chances is present on Sunday.

A surface low pressure system currently centered over western Ontario is expected to track northward through the remainder of the week. A cold front from the system will move through the mid-Atlantic region Wednesday into Thursday, resulting in a chance for rain and bringing cooler temperatures to the region. As the low moves over Hudson Bay, it is anticipated to stall, with a second cold front forming to the southwest of the center. Approaching Friday, the latter cold front will move through the northeast US, with a slight chance for isolated showers occurring along the frontal boundary. However, precipitation amounts are unlikely to be as much as the initial front due to the former utilizing most of the available moisture in the region. Southwesterly winds ahead of the front will allow temperatures to rebound into the mid-70's during the day before falling near 50 °F overnight behind the front.

On Saturday, winds will shift to the northwest behind the front, causing high temperatures for the day in the mid to upper 60's. Moisture in the low levels will cause some partly to mostly cloudy conditions during the day, however high pressure and dry air at the surface will ensure no precipitation will occur. On Sunday, the high pressure system will move off the Atlantic coast, causing winds from the south to southeast. Moisture from the ocean will move in throughout the atmosphere, bringing a slight chance for showers during the day.

By Doug Schneider

Nice weather is expected in Portland throughout the IndyCar Grand Prix weekend. 

Hot temperatures can be expected in Portland today and Wednesday, then a cold front will move across the area on Thursday, bringing a chance of showers and thunderstorms. 

Cooler temperatures will follow the front on Friday, and continue through the weekend. There will be a low pressure system moving across the Pacific and approaching Portland late Saturday and Sunday, but with limited moisture for this system to work with, only an increase in clouds is expected on Sunday. Each day is expected to have high temperatures in the lower to mid 80s, with a southwest wind at 5 to 10 mph. It should be a great weekend to be at the track.

By Doug Schneider

Good morning from VIR! I awoke to this view from my room at the Lodge - 

There are some isolated showers around this morning, but they likely won't have an impact. Most of the day will be partly to mostly cloudy, with temperatures reaching the mid to upper 80s.

A cold front will be moving across the area from north to south today. Showers and thunderstorms are expected to develop this afternoon, affecting the track starting around 4 pm (+/- 1 hour). The time period with the highest chance of storms is between 4 and 8 pm. Lightning and gusty winds will be the main threats from these storms, and rainfall may be heavy. Rain amounts are likely to be between a quarter and a half inch.

For Saturday, with the front located across central North Carolina and continuing to push south, there will be just a 20% chance of light showers in the morning. It will be mostly cloudy and cool through the day, with a high in the lower 70s. Winds will be from the northeast at 5-10 mph.

Mostly cloudy and cool conditions will continue on Sunday as high pressure to the north extends over the area.  Highs will be in the upper 70s, with a northeast wind at 5-10 mph.

By Doug Schneider

The good news with today's forecast update is that the models are starting to agree on the timing and position of a cold front south of St. Louis, which gives me more confidence in this forecast. 

A cold front is expected to cross through St. Louis on Thursday night. It will be close enough to the track and with enough uncertainty about its speed that I will keep a small chance of rain in the forecast for Friday morning. But since on-track activity does not start until the afternoon, no impact is expected. Behind the front, drier air will be building in from the north through the day, and with mostly cloudy skies, high temperatures will be quite comfortable in the lower 80s. 

As the front is expected to stall across southern Missouri on Saturday and high pressure over the Great Lakes region will extend across Illinois, Sunday will stay dry. Previous model runs had shown a weak disturbance approaching Saturday, but that no longer appears to be the case. With more sunshine expected, highs on Saturday will reach the mid 80s, but humidity will be comfortably low. Temperatures during the race will be in the 75 to 80 range. 

I will be traveling to VIR tomorrow for the IMSA race this weekend, and Friday may be a busy day of providing weather support to the track, so I may not get to update this forecast until Friday night. 

By Doug Schneider

The models are coming into better agreement on their projections for rain chances at VIR this weekend, which increases my confidence in this forecast compared to Monday. Unfortunately, they are not moving in the direction I had hoped for, as the chances of rain appear higher for Friday and Saturday morning. 

A cold front will be moving from north to south across Virginia on Friday. Showers and thunderstorms will be numerous along this front as it approaches VIR late in the day. With good instability present and plenty of moisture to work with, I have raised the chance of rain on Friday to 80%. Thunderstorms will be a concern, and some of them could be strong, producing gusty winds,frequent lightning, and heavy rainfall. Rainfall amounts are expected to be between a quarter and a half inch. While there will be a chance of rain at any time of the day, the afternoon sessions are most likely to be impacted, including the Michelin Pilot Challenge qualifying. 

Rain showers are likely to persist through Friday night as the front moves through the area. If you're camping at the track Friday night, be prepared for wet conditions. Although the front will be south of VIR Saturday morning, there could still be some scattered showers around in the morning. These showers will have less impact on activities than Friday's storms. There is a much lower chance of lightning and heavy rain. If rain occurs on Saturday, I expect it to be fairly light, less than a tenth of an inch, which would not have much impact. Behind the front, a north wind will bring cooler air, and with mostly cloudy skies, highs are expected to be in the upper 70s to near 80. 

The front is expected be located across central North Carolina on Sunday, and the rain associated with it should remain far enough south of VIR to keep any chance of rain out of the forecast. Weather for the main event on Sunday should be quite nice, with partly sunny skies and high temperatures around 80. 

I plan on posting the next update on Friday. However, I will be at the track providing weather support, and with the active weather expected, I may not have time to put a forecast together until the evening, or possibly Saturday morning.

By Doug Schneider

A programming note - Scott was originally scheduled to make this forecast, but due to a busy week at his real job, I'll be pulling double duty with IMSA at VIR and IndyCar at Gateway. Normally we would also have the forecast for the IGTC race at Suzuka, but Stephen is traveling out of the country this weekend, so that race forecast has been dropped.

A cold front is expected to move north to south across the St. Louis area on Thursday night. The front ix expected to be positioned south of the area by the time on-track activities start on Friday afternoon. However, it won't be very far away, and an upper level disturbance is expected to draw moisture northward over the front on Friday afternoon. As a result, scattered showers and possibly a thunderstorm will be possible in the St. Louis area. It appears that the afternoon hours will have the best chance of rain, which could impact the qualifying sessions for IndyCar, Indy Lights, and Pro 2000. With scattered coverage, they could be hit-and-miss, but I'd put the chance of rain at the track at 40% right now. 

The front to the south is not expected to move much through Sunday, but a little drier and more stable air may be able to build into the St. Louis area on Saturday as high pressure tracks east across the Great Lakes. With the front still being nearby, I don't feel confident enough to keep Saturday entirely dry, but the chance of rain is low, just 20%. If there is an isolated shower Saturday, it would probably be in the afternoon during the Pro 2000 and Indy Lights races. I expect that the IndyCar race in the evening will remain dry. 

One piece of good news in this forecast is that temperatures will be very pleasant through the event. Afternoon high temperatures will be in the lower to middle 80s, and temperatures during Saturday night's race will be in the 75 to 80 range. 

​I expect that there will be some changes to this forecast as we get closer to the weekend and the details come into better focus, so stay tuned.