Tuesday Night Outlook
Text From The RACES Tuesday Night Net:
Skies through Thursday will be partly cloudy. High temperatures tomorrow should be in the upper 80’s, and in the lower 80’s on Thursday. A cold front will cross the area Thursday evening, bringing with it a drop in temperatures and likely thunderstorms. Friday will be mostly sunny with highs around 70. High temperatures for the weekend should remain right around 70, with a chance of thunderstorms Saturday and Saturday night.
Detailed Forecast Discussion:
The main forecast concern right now is the approaching Plains cold front, it’s timing through the forecast area later this week, and the accompanying chances for thunderstorms. The other thing I’m looking at right now is the temperatures ahead of and behind the front.
A weak impulse is moving up the Mississippi Valley, causing some cloud enhancement on the visible satellite imagery and a few weak echoes on the radar. However, the air is dry enough that pretty much nothing is reaching the ground east of the Mississippi River. There is another weak disturbance that will head north along the Mississippi Valley out of eastern Kansas after the current one passes, and again, the dry air should suck any precipitation out of the skies before it hits the ground.
Model solutions are slowing the progress of the cold front, which is currently located across the Dakotas and central High Plains. An upper low over Yellowstone will lift northeastward to the southern Saskatchewan/Manitoba border by 7:00 PM Wednesday evening, while an upper level disturbance curves into the southwest around the Four Corners region. The result of this is that the cold front will make very little eastward progress until the upper level disturbance moves across the central Plains overnight Wednesday, reaching the upper Mississippi Valley by Thursday afternoon.
The models are in agreement that the cold front will only make it to far southwestern Wisconsin and northwestern Illinois by 7:00 PM Thursday evening. Very little forcing, a lack of moisture, and warm air in the mid-levels of the atmosphere ahead of the cold front will preclude any chances of significant precipitation until the front passes later Thursday evening into Thursday night.
Another upper level disturbance will drop out of the Canadian Rockies into Montana on Friday, then track across the Dakotas on Saturday with an associated surface low moving across southern Minnesota. As this system continues east across the upper Midwest Saturday and Sunday, the frontal boundary will move back north on Saturday. This will cause another chance of showers and thunderstorms Saturday, with the boundary moving south again in the form of another cold front Saturday night. This will cause more rain and thunderstorms overnight Saturday into Sunday morning.
Temperatures have been running at least a few degrees above model guidance, and the thermal profile for tomorrow is looking a little warmer than today. So, highs will probably be between 85 and 90. Things will cool off a bit Thursday due to the approaching cold front, with temperatures returning to seasonal norms after the cold front passes for Friday. Saturday will warm up just a touch, but with more clouds alongside the expected rain and thunderstorms, it probably won’t heat up much.
I’ll post an update in a few days for the Memorial Day forecast.
