Possible damaging wind event early Monday

Hello from Rock The Garden at the Walker Art Center.

We lucked out with a beautiful Father's Day and summer solstice Sunday across Minnesota. You can't ask for better weather for this year's RTG. It's been a weekend full of great music, great people and almost ideal weather. There's even been a few surprise guests. I had the pleasure of chatting with the very gracious actor Woody Harrelson Saturday as he made the rounds at RTG.

Our weekend weather timing has been excellent. Now all weather eyes in Minnesota turn toward Monday morning, and the potential for severe weather.

It's that time of the year.

We hit our climatological peak for severe storms in Minnesota in the weeks surrounding the summer solstice. Mid to late June is prime time for severe storms. Severe weather warnings peak between Memorial Day and the 4th of July.

Derecho Watch: Possible damaging wind event Monday morning

The weather maps for Monday morning favor another developing Mesoscale Convective System (MCS) racing across Minnesota. Saturday morning's MCS left a trail of damaging winds (and one fatality) across South Dakota, with gusts clocked as high as 93 mph. The Twin Cities lucked out as storms faded before arrival Saturday morning.

We may not be so lucky Monday morning.

Storms blow up again over the Dakotas again through tonight, then race east into Minnesota at speed of up to 60 mph. Southern Minnesota is in a corridor of favorable instability to maintain storm intensity through the overnight hours right into Monday morning.

The most likely window for storms in the metro appears to be between 4 and 9 am. Monday morning rush hour could be impacted by downpours, wind gusts at or above 70 mph, dangerous lightning and large hail. Significant tree damage is possible if winds reach 70 mph or higher. Hopefully we're not looking at a "blowdown" type event overnight into Monday morning, but the potential is there.

Surface weather maps show the next low pressure wave riding east into Minnesota Monday with associated storm clusters.

NOAA's Storm Prediction Center paints an enhanced risk for severe storms over the Dakota's, with a slight risk extending east to the Twin Cities.

NOAA's SPC convective outlook wording highlights the risk for anther bow echo with damaging winds racing across Minnesota Monday morning.

PRONOUNCED MASS AND MOISTURE FLUXES ARE INDICATED IN LATEST GUIDANCE ACROSS THE NORTHERN PLAINS THROUGH LATE TONIGHT AS STRONGER HEIGHT FALLS EMERGE ACROSS THE REGION AND AID DEEP-LAYER ASCENT AND FURTHER INTENSIFICATION OF SURFACE LOW. CONSOLIDATION OF LATE DAY/EVENING STORMS INTO ONE OR MULTIPLE MCSS WILL LIKELY OCCUR AS THIS ACTIVITY ACCELERATES EASTWARD TOWARD THE UPPER MS VALLEY THROUGH EARLY MONDAY ON THE NOSE OF THE STRENGTHENING MID-LEVEL JET STREAK. VERY STEEP LAPSE RATES ALOFT...MUCAPE OF 2000-4000+ J/KG AND INTENSE VERTICAL SHEAR WILL SUPPORT ELEVATED SUPERCELLS CAPABLE OF LARGE HAIL AND POSSIBLE UPSCALE EVOLUTION INTO SEVERE BOW ECHO FORMATION WITH ATTENDANT RISK FOR SIGNIFICANT WIND DAMAGE.

The Twin Cities NWS agrees and calls Monday morning's severe threat the highest so far this year. Looking back at analogs, this storm event potentially resembles a major derecho event in 1998.

THE NUMBER 1 CIPS ANALOG ACCORDING TO THE 21.00 NAM IS MAY31 1998...WHICH WAS A HIGH END DERECHO ACROSS THE GREAT LAKES REGION. GIVEN THAT INFORMATION...A THOROUGH INVESTIGATION OF THE MONDAY 12-24Z TIME PERIOD IS WARRANTED. AT THE START OF THE PERIOD...12Z MONDAY...AN MCS SHOULD ALREADY BE ONGOING ACROSS THE FORECAST AREA. A FEW THINGS STAND OUT IN THE FORECAST MODELS. FIRST IS THE FAVORABLE SHEAR PROFILE. THE DIRECTIONAL AND SPEED COMPONENT YIELD 60 TO 80KTS OF DEEP LAYER SHEAR. MEANWHILE...THE 0-3KM SHEAR IS ON THE ORDER OF 35 TO 45KTS AND IS ORIENTED EAST/WEST...WHICH WOULD BE NORMAL TO A BOW ECHO AND PROMOTES THE UPDRAFT PLACEMENT ABOVE THE COLD POOL WHICH IS FAVORABLE FOR A LONG LIFE CYCLE OF THE BOW.

THIS IS MERELY ANECDOTAL EVIDENCE THAT THE ATMOSPHERIC INGREDIENTS ARE IN PLACE FOR A SIGNIFICANT WIND EVENT...AND NOT A PREDICTION OF A REPEAT OF THE 1998 EVENT OR AN ATTEMPT TO INTRODUCE FEAR.

As we head into this potential Monday morning severe event, it's good make sure your NOAA Weather Radio is plugged in and on alert mode tonight before bed. I spoke with Jess Mador from Minnesota Monthly recently about how to prep for severe weather days like Monday morning. Keep in mind. most wind damage across Minnesota comes form straight line winds like we may see early Monday.

5 Ways to Stay Safe in Tornado Season

This year marks the 50th anniversary of “The Longest Night,” when in May of 1965 six funnel clouds touched down in the Twin Cities, killing 13 people and injuring more than 680. Minnesota Public Radio meteorologist Paul Huttner, who was 4 at the time, remembers hiding in the basement as the sky above turned “swirling and green.” Since then we’ve learned a good deal about tornado response and forecasting, and what to keep in mind during peak tornado season.

1. Broadcast meteorology saves lives. 1965 was the first time Twin Cities news stations broadcast continuous live coverage of severe weather. “It demonstrated that effective severe weather coverage saves lives and property, and that effective communication is every bit as important as effective forecasting,” says Huttner. 

2. Warning sirens do, too. 1965 was also the first time Minnesota’s civil defense sirens were activated for weather. Today, though, it’s a patchwork—policies for when they’re activated lack statewide uniformity. To get on the same page, emergency experts are pushing a new policy they hope will cut confusion and “siren fatigue” when sirens are activated too often.

3. Radar is getting even better. “We can now see rotation within storms,” Huttner says. “The software and the resolution of the radar allow us to pinpoint mesocyclones—wall clouds that are more likely to produce tornadoes.”

4. Beware the Joplin Effect. A devastating 2011 tornado in Joplin, MO, illustrates the need to better educate people about weather warnings. “People saw the warnings on TV, they heard it on the radio, somebody called them, they had a cellphone app, a siren went off—and sometimes they ignored three, four, five, even six warning signals before they took action.”  

5. It can happen again. “We may be overdue for another major tornado outbreak in the Twin Cities,” says Huttner, who recommends staying current on severe weather warnings by adding cellphone apps and a National Oceanic and Atmospheric Administration weather radio to the media mix

Be ready for watches and warnings and the potential for large hail, downpours, and damaging winds over 70 mph early Monday morning.