Thunder threat, severe warnings increasing in 2016

Scattered. Hit or miss. Occasional. Garden variety to severe.

Meteorologists trot out a bevy of terms to describe coverage of summer thunderstorms in the Midwest. There are sound scientific reasons for the scattershot nature of qualifiers to describe storm timing and coverage in summer. Summer storms are 'convective' by nature. That means they cover relatively little area compared to larger winter 'stratiform' type rain zones. But when the tall convective type storms towering up to 10 miles high come raining down upon you, you know it.

In Arizona I watched remarkably well defined rain shafts drench our neighbors side of the street, while our driveway stayed totally dry. Try and find wording to describe that forecast.

All or nothing.

[image]

Severe risk into Tuesday

NOAA's Storm Prediction Center paints the risk zones into Tuesday morning. I wouldn't call this a high severe potential situation, but a few storms may approach or breach the severe threshold overnight into early Tuesday. Primary threats are hail greater than 1" in diameter and high winds to 60 mph.

Hit or miss

Again, don't take the timing and coverage of NOAA's NAM 4 km model below literally. But there is enough instability to spark localized storms around Minnesota anytime into Tuesday.

Warm front-cold front combo

We get a 2-for-1 weather combo deal. First the warm front triggers storms as it moves north this evening. Then the cool front rides in with a potential second storm wave from the Dakotas overnight into Tuesday morning. A bubble of high pressure promises hotter, but drier skies Wednesday. The next storm front pushes into Minnesota by Thursday.

Spotty rainfall coverage

Precisely how much rain will end up in my backyard rain gauge this week? Throw a dart on the map. Advances in weather modeling have done a remarkable job in capturing the essence of localized convective rainfall trends, but not in pinpointing heavy downpour zones to the neighborhood level.

Free AC arrives Friday

Friday's cool front scours out the sticky 70 degree dew points. A fresh northwest breeze brings a pleasant start to the weekend. Signs of heat return by mid-August. NOAA's upper air maps suggests the persistent heat dome to the south bumps north again.

We've been fortunate to get frequent Canadian air mass incursions to break up the heat this summer. Our next free Canadian vacation arrives Friday.

Severe summer of 2016

It's not your imagination. Your NOAA weather radio has gone off more this summer than last year.

I asked Todd Krause from the Twin Cities NWS office about the numbers of warnings issued so far this summer. Todd sends along the following numbers on warnings for the Twin Cities NWS area.

2016 warnings through July 31st

• 187 severe thunderstorm warnings

• 42 tornado warnings

2015 warnings through July 31st

• 115 severe thunderstorm warnings

• 27 tornado warnings

Keep the weather radio handy. My spidey weather senses tell me we'll add to those numbers this week.