Happy Mother's Day,
It was a cold start to Mother's Day as wind chill values dropped to the 20s and 30s. The afternoon will be better, but still 10-15 degrees below average temperatures. This week warmer and more humid air will return, but that opens the door for severe weather.
The reason for this prolonged period of unseasonably cold air is a blocked pattern. Below is the upper level flow for Sunday afternoon. There are upper level highs over northwest Canada and near Greenland. These highs block the pattern and have forced a piece of the Polar Vortex south to southeast Canada. This turns the upper level flow from the North Pole to Midwest. Hence, the unseasonably cold air airmass.
Here is the upper level flow for Friday afternoon. Look at the change. The block is more relaxed allowing the Polar Vortex piece to rotate north. The flow across the USA is now west-southwest from the Pacific Ocean. This will deliver warmer air. The humidity will increase as the Gulf of Mexico opens up. May and June, on average, are the wettest months of the year for our region. May is also e peak month for severe weather. The cold air has pretty much eliminated severe weather chances, except last Monday. And, rainfall amounts have been lower as well. The pattern displayed below increases the chance of thunderstorms, but there are no big storms. So, yes, severe weather will be a threat, but nothing stands out at us for a big severe weather event at this time. Let's go day by day.
MOTHER'S DAY: It will be mostly sunny, breezy and cool with highs in the 50s. A few showers may occur in northeast Missouri.
MONDAY MORNING: Frost is possible as lows drop to the mid 30s. The record is 34 set in 1981, we will come close. Now, clouds will be approaching from the west. If they arrive sooner our lows may be in the low 40s. Either way, it is cold. At least the wind will be light.
MONDAY AFTERNOON AND EVENING: A disturbance will be tracking across the Plains producing a large area of cold May rain. Our region is on the north edge of the rain. So after 2-3 PM we have a chance of rain that lasts into the evening. The best chances will be south. But, as usual, we are on the edge and a shift north or south by 20-50 miles will make a huge difference in the forecast. If you get into the rain, temperatures will drop to the 40s, possibly upper 30s! If you miss the rain, temperatures will be 50-55.
TUESDAY: The rain will exit, but some drizzle and a few showers will be possible. Clouds will hang tough, so highs will be 50-55. This is a map for noon. The sun will try to come out across northern Missouri. In sun areas temperatures will rise to 55-60.
WEDNESDAY: A warm front appears and its headed this way. We will be 60-65 with a chance of showers and thunderstorms while it is around 90 in western Oklahoma. We won't get that hot, but highs will get into the 70s.
THURSDAY-SATURDAY: The warmer and more humid air returns with fronts in and out of the region. There will be a series of disturbances tracking from southwest to northeast in the southwest flow we showed above. Each day will have it's own unique set up, so going into the details at this point is futile. The bottom line is that these days will be warmer and more humid (highs in the 70s with lows in the 60s) with chances for periods of showers and thunderstorms. Some, severe weather is possible, but there is not a classic set up.
Have a great week and stay healthy.