Twin Cities with a chance for natural fireworks this coming Independence Day, strong to severe storms possible
TWIN CITIES - The Storm Prediction Center has back-to-back days for severe weather possible across the Twin Cities for Monday, July 3rd, and Tuesday, July 4th as a front slowly works across the region on Monday and Tuesday.
Marginal Risk(1 out of 5) Severe Weather Threat - Monday
Ahead of the approaching cold front that is forecast to work across the region on Tuesday, southerly winds will usher warm, moisture air northward across the Twin Cities allowing for dewpoints to surge into the mid to upper 60s, with low to middle 70 dewpoints just to the west of the Metro. The combination of muggy conditions and air temperatures in the middle 90s on Monday will allow for ample instability to develop during the afternoon and into the evening hours to support the development of isolated showers and storms. Some of which could be strong to severe in nature. The biggest threat from these, if they were to develop, would be large hail, damaging winds, and locally heavy rain that could result in flooding.
A limiting factor for storm development on Monday will be forcing, which is needed to force the warm, moist air upward in order to trigger/initiate storm development. The better forcing is forecast to be to the west-northwest of the Twin Cities, which is where storms are likely to develop before tracking east-southeast across the Metro. That will be something that will need to be monitored throughout the day on Monday. Any lingering showers and storms from Monday night into Tuesday morning could also impact the severe weather threat for Tuesday, which will be covered more below.
The greatest threat time for showers or storms across the Twin Cities Metro on Monday looks to be around or after 9 PM, with those chances increasing into the late evening hours.
Slight Risk (2 out of 5) Severe Weather Threat - Tuesday
The 4th of July looks to be a repeat of Monday in regard to muggy and hot, with dewpoints once again forecast to reach the middle to upper 60s across the Twin Cities, with a few models even showing the low 70s could be possible just ahead of the passing of the cold front. Temperatures are forecast to also get back into the low to mid-90s across the Metro. The biggest difference between Monday and Tuesday is the forcing mechanism. Unlike Monday, for Tuesday a weak cold front will be slowly working across the region which will add a little additional lift to help initiate storm development along and ahead of the front. Once again, the greatest threat will likely be large hail and damaging winds, with localized heavy, flooding rain possible.
Some limiting factors for Tuesday's severe weather threat will be the strength of the cold front and the slow forward progression of the front. A weaker, slower-moving front won't have as much upward forcing which could limit overall severity. While there could be enough forcing to promote the development of isolated to scattered showers, it might not be enough forcing for stronger storms. Additionally, any lingering showers from the night before that stick around through the late morning will impact how much daytime heating occurs from the cloud cover. This will have a direct impact on how much instability can build up and limit possible storm development.
While there could be some lingering showers early Tuesday morning, the greatest impacts for showers and storms will come during the late afternoon into the evening hours, likely around 7 PM or later. I do expect some fluctuations in this time frame over the next day or so though.
Don't cancel your 4th of July plans just yet!
While there are chances for showers and storms, including the potential for even some strong to severe storms for the Twin Cities Metro, I wouldn't cancel your Independence Day plans just yet. There still remain a few details the models need to iron out over the next day or so, but I would recommend making some backup plans just in case. More updates are likely to come over the next few days.
