Update: Severe Storms Risk Peaks Tonight

Good afternoon and don’t be deceived if you have any lingering clouds or showers at this time.  As expected… an impressive warm front is lifting into Central Indiana to lay down the tracks for storms much later this evening and overnight.

HEADLINES

All of the viewing area has the potential of seeing severe storms.  But the areas at greatest risk remain along and especially north of I-70.  Showers and clouds diminish the next few hours.

SPC

At the same time instability and wind shear increase as the front moves northward.  New storms are expected to initiate along the warm front around or after 8pm.

HRRR 8PM

We’ll be looking at northern Illinois/northwestern Indiana as the most likely initiation point… though development farther south can’t be ruled or ignored.

The cells at initiation have the highest tornado potential and a few significant tornadoes are possible around Chicagoland/northwest Indiana.  While the highest probability of tornadoes exist over that region… please note that tornadoes are possible area wide this evening and tonight.  It’s important not to just focus on one area of one weather element.  We all need to be weather aware until further notice.

TOR PROBS

Eventually these discrete supercells should congeal into a linear storm complex which results in a widespread damaging wind threat risk.  The longer it takes for the cell merger to occur, the longer the risk of tornadoes will be.

WIND PROBS

Ultimately the expected complex will produce a swath of 70+mph wind, numerous power outages and flash flooding where it tracks… which at this time seems most likely from Indy toward the Michiana border.

THREATS

We’ll update as needed this evening.

Update On Severe Weather Potential Wednesday

Before you read further please know there will be plenty of changes between now and this time Wednesday.  Please check back for the latest as the greatest risk area and scope of severity may shift either north or south

HEADLINES

All of Central Indiana is under a heightened risk for severe weather between Wednesday 7am and Thursday 7am.  During that time we’re anticipating multiple rounds of storms…beginning as early as the morning commute Wednesday.

SPC

One of the contributing factors to the severe weather set up is what will be a sharp temperature gradient across the state.  From the 70s & 80s Central/Northeast to near 100 degrees in southwestern Indiana.

HIGHS WEDNESDAY

The warm front that delineates the differing air masses also serves as a “track” for storm clusters which will most likely be in a northwest to southeast fashion.

WED 5AM WED 9AM

With little movement in the “track” or front early in the day this allows “training storms” to drop very high rainfall over a specific region.  This is why flash flooding is a big concern I have tomorrow.

Precipitable Water Values (PWATs) will already by 1-1.5″ early tomorrow and peak Wednesday evening over 2″.

PWAT MORNING

Precipitable Water Values (PWATs) will already by 1.5″+ early tomorrow and peak Wednesday evening over 2″.

PWAT EVENING

So any storms in this highly tropical environment would easily be able to achieve Flash Flood Guidance in Central Indiana… which is around 1-2″ for one hour and 1.5-2″ for three hours in areas that got walloped last night.

FLASH FLOOD GUIDANCE 3 HOUR FLASH FLOOD GUIDANCE

Storms Wednesday morning will be primarily be heavy rain-makers and prolific lightning producers but could also drop severe hail in the strongest cells.  These storms may either linger into midday or new clusters develop along a warm front that will be draped across the viewing area… both of which impede the ability of the atmosphere to destabilize quickly.

WED 12PM

It should be noted that if the modeled morning storms do not materialize then the local atmosphere will destabilize quicker and severe storms will be likely area wide from the afternoon into predawn Thursday morning.

We’ll have to wait and watch for new storm initiation during late afternoon and early evening.  It’s unknown at this time exactly where the warm front will be late in the day and how morning convection will influence it.  The “modeled” atmosphere suggests Central/Northern Illinois will be the initiation point closer to the center of low pressure.

WED 3PM

But supercelluar development in Central/Northern Indiana is also a possibility and this discrete storms that develop during peak heating have the best chance to produce tornadoes before eventually congeal into a larger complex.

WED 8PM

Another wildcard in late day development is location of the atmospheric “cap”… or where it’s too warm in the mid-levels to support vertical storm development.

THU 12AM

The “cap” or lid as it’s also called can limit storm development under it, but also aid in explosive storm development on its edge in a similar fashion to steam around a saucepan lid on a stove.

If the cap establishes over the I-70 corridor then the Indy metro area may miss the secondary storm show.  We just don’t know for sure at this juncture.

THU 7AM DAY 2 PROBS

For now the higher probabilities of severe wind and flash flooding remain along and north of I-70… with a possible bullseye along a line from Chicago to Fort Wayne.

The expected evening storm complex most likely yields a widespread swath of damaging wind in excess of 70mph and flash flooding rain of 3″+.

SPC 3 THREATS

Please don’t just focus on tornado headlines.  Flash flooding and lightning are dangerous, formidable (and likely) weather headlines with this set up… and deserves your attention.

THREAT DEFINITIONS

Please be weather aware tomorrow and have a way to get watches and warnings.  You can download the free Skytrak13 Weather app (http://www.wthr.com/category/225686/wthr-skytrak-weather-app) for local watches and warnings, forecast updates and live streaming of newscast.  The severe threat should be east of the state by 7am Thursday  Stay tuned for updates – Sean Ash

Some Severe Storms Possible Later Today

The Muggy Meter reaches oppressive humidity levels today as tropical moisture blankets Central Indiana.  This results in heat indices between 95 to 100 degrees combined with afternoon highs in the lower to mid 90s… good for Indy’s hottest day of the year if temperatures eclipse 92 degrees.

PLANNER HEAT INDEX FORECAST MUGGY METER

Though much of today is rain-free and hot, widely scattered storms develop this evening and some may reach severe limits before midnight.  Damaging wind and locally heavy rainfall are the main threats overnight.

SPC TODAY THREATS TONIGHT 7PM TODAY 10PM TODAY 11pm tonight 7AM TUESDAY

We’ll be north side of a cool front Tuesday which results in less humid air and a mainly sunny sky with seasonably warm highs in the mid-80s.  Based on lower humidity and abundant sunshine… tomorrow is our pick of the week to be outside.

TUESDAY JET STREAM

Modeled ingredients for mid-week advertise a heightened risk of severe weather and flash flooding Wednesday into Thursday.  Though uncertainty on track, intensity, and coverage remains… data sets suggest a swath 3″+ rainfall, widespread high wind (greater than 70mph) and some tornadoes could impact Central and Northern Indiana.

MID WEEK SPC

This could certainly change and as noted there’s a great deal on specifics at this time.  Please check back frequently for updated forecasts on what could be a high impact weather event – Sean Ash

7DAY

 

Stormy Mid-Week Set Up

Happy Father’s Day! Seasonably hot conditions to wrap up the weekend with highs near 90 degrees and heat indices in the low to mid 90s.  Very isolated showers developed late this afternoon but they’ll quickly fade around sunset.

MONDAY

Monday has the potential to be our hottest day of the year thus far with highs in the lower to mid-90s.  We’re going to mention a slight chance of thunderstorms late in the day, but not many cities will see much.

The bigger tomorrow will be the increasing Muggy Meter with oppressive levels of humidity.  A mid-week moisture surge brings a risk of flash flooding and severe storms.

MUGGY METER SPC

Though isolated… a few strong or severe are in play Monday evening into predawn hours of Tuesday.  At this point much of Tuesday should be dry.

MONDAY 8PM MIDNIGHT

The weather pattern gets more interesting and complicated the middle of the week.  The upper level high pressure that kept us quiet this weekend is now beginning to move toward the southwestern U.S.

JET STREAM JET STREAM 2 JET STREAM 3

Eventually we’ll begin to see storms developing on the edge of its hot dome and get pushed southeastward into the Ohio Valley.  Riding the northwest flow aloft these storm clusters are known as “ridge riders” and the belt of storms around the upper ridge is sometimes referred to as “ring of fire.”

WED 1AM WED 7AM WED 2PM

At this point exact timing and location remain uncertain, but storms do appear likely both Wednesday and Thursday.  You’ll need to be weather aware with the potential for multiple rounds of heavy storms, flash flooding and severe weather.  Check back frequently for updates – Sean Ash

RAIN CHANCES 7DAY

 

Hot Weekend Ahead

TGIF!  There are no significant changes to our Father’s Day weekend forecast.  We’ve had hot and sunny going all week… and that’s playing out.  Humidity is much more tolerable today and the warm temperatures in the 80s subside nicely after sunset this evening.

TEMPS TONIGHT

A refreshing north-northeasterly breeze makes for a pleasant finish to our day and lows tonight eventually drop back down into the 50s and 60s.  Expect a quick warm up tomorrow with temperatures in the 80s by noon and nearing 90 degrees for highs.

SATURDAY HIGHS SATURDAY AIR QUALITY

Unfortunately the weather pattern causing temperatures to go up will cause air quality to go down.  The combination of hot, stagnant air allows unhealthy levels of ground ozone to emerge this weekend.  As a result Knozone Action Days have been for the Indianapolis metro area for Saturday, Sunday and Monday.  Avoid drive-thru’s and mowing your lawns until after 6pm if possible.

AQI 2 AQI 3

Father’s Day will be sunny and hot as temperatures climb into the 90s.  The hottest air of the year thus far hits Monday when highs jump into the mid-90s.

SUNDAY HIGHS SUNDAY HIGHS MONDAY

A good portion of the U.S. will be under the influence of a large area of upper level high pressure… also known as a ridge in the jet stream.  Sinking air under the high produces a hot dome that keeps the sky mainly cloud-free and forces rain/storms to its periphery similar to steam around the lid of a pressure cooker.

JET 1 JET 2 JET 3

This feature keeps us dry until it breaks down and sinks southwestward Monday night into Tuesday of next week.  Scattered storms Tuesday will be followed by another shot of refreshing Canadian air mid to late next week.

7DAY

Have a great weekend and Happy Father’s Day to all of the dads celebrating Sunday – Sean Ash

Comfortable Night Precedes Weekend Warm Up

The wind of change is slowly but surely delivering refreshing air into the viewing area, but patience required with some areas still dealing with high heat and humidity.

OHV TEMPS

There’s an very impressive 40 degree temperature spread from north to south across Indiana… where the breeze off of Lake Michigan delivering 50s in South Bend while Evansville remains in the upper 90s!  Eventually comfortable air reaches area wide and sets the stage for a fantastic start to the weekend.

VIS MUGGY METER TONIGHT

Clouds this evening clear overnight to allow temperatures to drop into the 50s and lower 60s.  Cool enough to shut-off the A/C, open the windows and air-out the house.  Expect a bright sky tomorrow with warm highs in the mid-80s.

LOWS TONIGHT FRIDAY HIGHS TOMORROW

No changes at all to our Father’s Day weekend forecast of sunshine, upper 80s Saturday and lower 90s on Sunday.  The hottest day in the 7 day forecast is Monday when highs hit the mid-90s… likely the hottest of the year thus far.

HIGHS SATURDAY HIGHS SUNDAY HIGHS MONDAY

7DAY

We’re still expecting a period of storminess to return to the Great Lakes and Ohio Valley Monday night into Tuesday.  This brings the potential of more heavy rain and possibly severe storms.  Stay tuned and have a great evening – Sean Ash

Heavy Storms For Some This Afternoon

Storms are firing up around Central Indiana and will deliver torrential rain along their path.  Flash flooding rain rates of 1-2″ per hour and lightning remain the most likely threats with storms today, but extreme instability keeps all of the viewing area in a Level 2 (on a scale of 1-5) risk today.  Severe wind gusts and/or hail are possible before 8pm so please have a way to get watches and warnings.

SPC THREATS

You’ll also notice oppressively humid conditions today and that remains a part of the evening forecast.  Heat indices are near 100 degrees in easily the most uncomfortable day this year thus far.  Oppressively humid today but the Muggy Meter gets comfortable Friday morning and stays there for a couple of days.

HEAT INDEX MUGGY METER TONIGHT 5PM TODAY 8PM TODAY

The threat of severe weather, and storms in general, quickly diminishes after sunset and quieter times are ahead.  Areas of fog are possible overnight and early Thursday morning.  It won’t be as muggy tomorrow but still humid and warm in Central Indiana with highs in the mid to upper 80s.

THU 7AM THU PM

Noticeably cooler highs in the 70s are likely in North Central Indiana where are refreshing northerly wind takes shape and less sunshine.

THURSDAY PLANNER 7DAY

Friday looks fantastic with comfortably warm highs in the low to mid 80s with sunshine.  Father’s Day weekend features sunshine and highs near 90 both days.  Stay weather aware this evening friends – Sean Ash

Wet At Times Wednesday

Finally getting some dry time after the wettest day overall in Central Indiana since May 1st.  Much of the Indy metro area had over an inch of rain and there were a few reports of three to four inches locally.

RAIN REPORT MORNING

Areas of dense fog may be develop overnight as a result and we’ll likely see more showers and storms arriving by sunrise from Illinois.

Activity in the morning likely produces downpours and lightning.  The exit time of morning activity plays a key role in severe chances Wednesday afternoon.

4AM 7AM

Tropical moisture makes for uncomfortable conditions Wednesday as the Muggy Meter hits oppressive levels of humidity.  If temperatures can achieve the upper 80s/lower 90s this moisture helps increase instability for severe storms too.

MUGGY METER SPC THREATS

At the time of this posting we’re only expecting isolated storms in the afternoon and early evening… but they will still pose a damaging wind and/or hail threat.

5PM AFTERNOON

The risk of severe weather quickly ends before 10pm tomorrow and we’ll begin Thursday rain-free.  An impressive upper disturbance pivoting across the Ohio Valley late Thursday afternoon keeps isolated showers and storms in play.

7DAY

We continue to advertise a sunny Father’s Day weekend.  Highs Saturday will be in the mid-80s and then climb back into the 90s for Father’s Day.  Long range indicators suggest another stormy pattern setting up over the Great Lakes/Ohio Valley this time next week.  Check back for radar updates – Sean Ash

Recap Of Soggy, Stormy Day

Central Indiana continues to battle areas of heavy rain and locally strong storms.  Many rain gauges around the Indy metro area picked up nearly 2″ totals and a whopping 3.14″ reported near Monument Circle.

RAIN TOTALS RAIN TOTALS 2 STORM REPORT

Areal Flood Advisories are up for portions of southern Indiana that received 2″ to 3″ of rainfall in three hours.

FLOOD ADVISORY DEWPOINTS

Between now and Wednesday afternoon there will be a few more waves of heavy storms to deal with it.  If temperatures can warm to near 90 degrees tomorrow some of the storms may become severe during peak heating… with damaging wind the main threat.

MUGGY METER TONIGHT TOMORROW

But any storms, or showers for that matter, likely deliver heavy rain rates due to high levels of moisture in the atmosphere.  Severe weather tomorrow hinges on how much coverage of storms, cloud cover and fog we begin.  Less of those means a better chance of realizing the Level 2 risk.

WED MORNING WED AFTERNOON SPC THREATS 7DAY

A drier pattern emerges late week though isolated showers are possible late Thursday afternoon.  We continue to advertise a sunny Father’s Day weekend.  Highs Saturday will be in the mid-80s and then climb back into the 90s for Father’s Day.

Check back for radar updates – Sean Ash

Storm Chances Return Tuesday

Not as humid today but equally as bright with hot highs near 90 degrees.  The only complaint is the poor air quality due to high levels of ozone.  An Air Quality Alert remains in effect for the Indy metro area plus surrounding counties as well as Bloomington and Seymour.

AIR QUALITY TEMPS DMA TEMPS OHV

Expect a pleasant evening but we’ll be monitoring central Illinois for potential storm development that could arrive here toward midnight.

PLANNER TONIGHT PLANNER TUESDAY

Otherwise the next chance of showers and storms begins around sunrise in Central Indiana.  Though coverage won’t be widespread tomorrow, any storms that develop likely deliver heavy rain, lightning and possibly severe wind.

TUESDAY MORNING TUESDAY 5M SPC DAY 2

Increasing tropical moisture leads to oppressively humid conditions Wednesday and this feeds heavy storms too.  Greater instability ups the ante for strong or severe storms Wednesday with damaging wind being the primary threat at this point.

MUGGY METER WED 11AM WED PM SPC DAY 3

After Wednesday rain chances go down and the pattern late week into the weekend looks dry.  In fact we’ll have another shot of comfortable arriving Thursday night into Friday morning and this paves the way for sunshine and highs in the lower 80s to begin the weekend.

7DAY

Heat builds late weekend with highs nearing 90 degrees Sunday and likely going back into the 90s a week from now.  Have a great evening – Sean Ash