FLIRTING WITH SUMMER...

Over the past 24 hours high pressure which brought a dry week to the region has pushed further east into Canada. On its backside, the door has opened for southerly winds and a more active brand of weather. One that will actually bring a summery feel to our temperatures by Sunday afternoon. The surface map early Saturday shows the southerly gradient that is tapping warm moist air and sending it northward from the Gulf of Mexico.

Below you can see water vapor (in blue) has surged into the Mississippi River Valley as far north as Minnesota and Wisconsin.

While the moisture has arrived, the true warmth lags well to the south. By Saturday evening the leading edge of it is just approaching the southern Iowa border in the form of a warm front. Behind it temperatures are well into the 80s.

Overnight Friday, far in advance of the boundary warm air advection combined with the low level jet has generated showers and a few thunderstorms in my area, the first of what should be several rain chances going into Monday. A few of these showers may linger into daybreak Saturday morning ahead of a capping inversion associated with the warm front.

The northern edge of this capping boundary (EML) could be the focus for renewed strong elevated storms mid to late morning Saturday that may kick up some hail, high winds, and downpours, mainly south of HWY 34. As the cap spreads north during the day precipitation will wane from south to north. However, cloud cover will likely be significant limiting highs in the north to the mid to upper 60s with mid to perhaps upper 70s south of I-80.

CONSIDER A STAY AT ONE OF THE MOST UNIQUE ACCOMMODATIONS IN THE MIDWEST...

STORM THREATs SATURDAY AND SUNDAY NIGHTS.

Saturday night the warm front hovers near or just south of I-80. As the low level jet kicks in after dark, the potential exists for robust development of storms mainly north of I-80. These would be elevated in nature meaning hail and heavy rain would be the primary concerns. If training takes place with repeated cells some rainfall amounts of 1-2 inches are possible in a narrow band 40-45 miles wide.

This potential scenario will dictate Sunday and Sunday nights thunderstorm potential. Temperatures could also be impacted, especially in the north where clouds closer to the warm front could hinder heating. For several days models had been indicating highs areawide in the 80s Sunday but recent trends are holding the warm front closer to HWY 30. The HRRR now depicts highs that look like this, much cooler in the north while the south sizzles in mid 80s.

The EURO is the one model that remains staunch on 80s areawide. Here's what is shows for highs Sunday. I do suspect the EURO is too warm too far north. However, it has been consistent so confidence is low just how warm Sunday will be. I like a middle ground solution of the 3k NAM and EURO. That would imply highs in the upper 70s far north to the mid 80s south. A few spots south of HWY 34 could reach the upper 80s which is pushing records.

Dew points north of the warm front are pooling in the mid to upper 60s late Sunday afternoon.

Significant instability is shown on the HRRR with CAPE exceeding 3,000 J/kg in spots.

The HRRR keeps a lid on convection through the afternoon with the cap in place. However, if it breaks and it likely will in the evening, rapid development of storms is likely. Near the warm front between HWY 30 and I-80, the flow will be backed which indicates all modes of severe will be possible, which could include a tornado or two. The 3k NAM significant tornado index looks rather healthy Sunday evening.

Interestingly, SPC has taken all of eastern Iowa out of Sunday's slight risk area which was in place Friday.

The experimental Colorado State machine learning probability model still shows respectable odds of all severe weather types Sunday. This shows the variability and uncertainty in model solutions 48 hours in advance of the system. I would not be surprised to see at least parts of my area back in a higher risk at some point this weekend.

Assuming storms do blossom Sunday evening, they will progress E/SE along the warm front Sunday night.

The thing I want to emphasize is that the placement and intensity of storms Saturday night and Sunday night is highly

contingent on mesoscale details which won't be known until those specific individual days. Outflow boundaries from earlier convection is hard for models to ascertain and can have a major impact on how and where storms develop. We'll have to play it one day at a time.

With that, keep and eye to the sky as we flirt with summery conditions, especially Sunday. Roll weather...TS