Marginal Risk for Storms – Severe Weather Criteria

posted in: Michigan Weather Forecast | 25

This is the day one outlook from the SPC, it is linked back the the SPC site so it should update if it changes.

It shows we are in the marginal risk for storm activity.  Marginal, Slight, Enhanced, Moderate, and High risks represent progressively larger threats for organized severe storm episodes. These risks, along with their numerical, abbreviated labels, and colors (1-MRGL-dark green, 2-SLGT-yellow, 3-ENH-orange, 4-MDT-red, 5-HIGH-magenta), are based directly on the numerical probabilities of severe weather that are provided with every outlook.

For Day 1, the percentage lines provide the chance that the given type of severe weather (tornado, hail, or damaging thunderstorm wind) will happen within about 25 miles of a point. For Day 2 and Day 3, (not shown) the probabilities cover all severe storm hazards together.

Though severe storms tend to receive a large amount of media coverage, severe weather is uncommon at any one location. Your chance of getting a tornado on any random day are very small, climatologically speaking. Put in that context, even a 10% chance of a tornado within 25 miles of a point means a much bigger threat than usual, and should be taken seriously. Think of how often tornadoes normally happen close to you on any given day, and those small-looking probabilities start to seem large by comparison!

A severe thunderstorm refers to a thunderstorm producing hail that is at least 1 inch in diameter or larger, and/or wind gusts of 58 mph or greater, and/or a tornado. Although lightning can be deadly, the NWS doesn’t use it to define a severe thunderstorm. If it did, every thunderstorm would be severe, by definition. Also, excessive rainfall may lead to deadly flash flooding, but heavy rain is not a severe criterion either. The flood threat is handled through a separate set of watches and warnings from your local NWS office.

A significant severe thunderstorm refers to a thunderstorm producing hail that is at least 2 inches in diameter or larger, and/or wind gusts of 75 mph or greater, and/or a tornado that produces EF2 or greater damage.

We refer to organized severe storms as those which persist for several hours, are capable of multiple and/or significant severe weather events, and which we are able to forecast consistently. Organized severe storms tend to form in areas where the vertical wind shear is relatively strong and has particular characteristics, while non-organized severe storms are most common when vertical wind shear is weak. The most long-lived, intense tornadoes and largest hail are usually produced by supercell thunderstorms, while the most serious convective wind storms are produced by bow echoes.


We will see hot and humid conditions today through Tuesday with chances of several round of storms – the main threat should be north of I96.  The best chances for severe weather for SW Michigan will be Tuesday as a cold front begins to push into the area.  Temps through the period will be in the mid 80s to 90 degrees with dew points in the 60s to near 70.  So, after a couple days with the windows open it will be time for the air conditioners to power back up.


 

446 total views, 1 views today

newest oldest
ROCKY (Rockford)
ROCKY (Rockford)

It may hit 90 degrees today in GR! I would say the high will either be 89 or 90 degrees?

Mr. Negative
Mr. Negative

ADA- Well…standard joke. Hoping we receive at least a half inch of “severe” raindrops.

INDY
INDY

Only made it to 86* out at thee YARDofBRICKS I’m thinking our 90′ degree days are numbered with Fall coming fast .. INDYDOG14;!

ROCKY (Rockford)
ROCKY (Rockford)

Bring on the rain. Milwaukee is getting pounded!

ROCKY (Rockford)
ROCKY (Rockford)

Like I predicted GR did not hit 90 degrees today! The official high was 88 degrees! Another BINGO!

Barry in Zeeland
Barry in Zeeland

And the actual temp if felt like was 94 with the heat index, so no 90 was even needed for you to enjoy the pleasant sweltering and oppressive heat. As for your bingo, congrats! You finally managed to get 1 out of about 20 right.

Jeff(Portland)
Jeff(Portland)

Another 90 for the day. Keep the tally going.

Mr. Negative
Mr. Negative

Storm Proof…

Jack Edwards
Jack Edwards

#StormStarvedatTheeYardofcues

Mark (East Lansing)
Mark (East Lansing)

👍

INDY
INDY

Ready for truck loads of snow .. Yeaaaa!! INDYDOG14!!

ROCKY (Rockford)
ROCKY (Rockford)

I am always ready for TONS of SNOW! Bring it!

ROCKY (Rockford)
ROCKY (Rockford)

Get ready for below normal temps starting on Wednesday! Bring it!

Mr. Negative
Mr. Negative

It’s “Summer”…

ROCKY (Rockford)
ROCKY (Rockford)

Exactly!

ROCKY (Rockford)
ROCKY (Rockford)

It wasn’t that bad out on the golf course today! Mid 80’s and filtered sunshine! It was a tad bit humid however the breeze felt good!

INDY
INDY

86* out at thee YARDofBRICKS will we hit 90* today ….. INDYDOG14!!

ROCKY (Rockford)
ROCKY (Rockford)

Not a chance!

Mookie
Mookie

What a HOT and HUMID day today!

Barry in Zeeland
Barry in Zeeland

Heat index of 93 with a dew point of 72, it is just sweltering out there today! The car thermometer hit 91 on the way home from Holland. Yet another 90 degree day for the total.

Mark (East Lansing)
Mark (East Lansing)

Man, hot and muggy on the other side of the lake. It was already 90° when we left for home this morning. The heat index was 95° well after dark last night. Tropical air. It was extremely uncomfortable.

INDY
INDY

82* out at thee YARDofBRICKS 90* maybe tough to hit we will see.. For as warm this summer has been I can’t believe we are not in the top 5 years for 90* degrees .. INDY!!

ROCKY (Rockford)
ROCKY (Rockford)

Just a typical summer with few above normal temp days!!

Barry in Zeeland
Barry in Zeeland

Weather turned out terrific yesterday for our sons wedding and the big party last night. It did get crazy humid out again, but that has been the story all Summer. We only received 2 tenths of an inch of rain in the morning, then the rest of the day was perfect. 2 kids down, 2 to go!

Mark (East Lansing)
Mark (East Lansing)

Congrats Barry. We have a high schooler and a middle schooler, so I won’t have to deal with that for a while – I hope.