Severe Wx / Flooding Rain Event Combo: April 2-6, 2025

[tron777]

This will be the storm thread for the severe wx event on Wed and Thurs... followed by the flooding rains that continue on thru the weekend via a stalled out frontal boundary.

[tpweather]

Great ideal to have a separate area for the upcoming event/events for the Wednesday-Sunday period.

[tron777]

Thanks Tim! Let's get some maps posted. First, severe wx probs from the SPC for Wed and Thurs, Days 3 / 4:

day3otlk_0730.gif

day48prob.gif

WPC Excessive rainfall outlooks Day 3, 4, and 5:

WPC Day3.gif

WPC Day 4.gif

WPC Day 5.gif

WPC Day 7 Total QPF - 7" for Cincinnati if I am reading the color scale right.

WPC Total QPF.gif

[tron777]

Flood Watch now up from the boys for the entire AV Forum coverage area:

...FLOOD WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH SUNDAY
MORNING...

* WHAT...Flooding caused by excessive rainfall is possible.

* WHERE...The following counties, in Indiana, Dearborn, Fayette,
Franklin, Ohio, Ripley, Switzerland, Union and Wayne, the
following counties, in Kentucky, Boone, Bracken, Campbell,
Carroll, Gallatin, Grant, Kenton, Lewis, Mason, Owen, Pendleton
and Robertson, and the following counties, in Ohio, Adams,
Auglaize, Brown, Butler, Champaign, Clark, Clermont, Clinton,
Darke, Delaware, Fairfield, Fayette, Franklin, Greene, Hamilton,
Hardin, Highland, Hocking, Licking, Logan, Madison, Mercer, Miami,
Montgomery, Pickaway, Pike, Preble, Ross, Scioto, Shelby, Union
and Warren.

* WHEN...From Wednesday evening through Sunday morning.

* IMPACTS...Soils remain moist and excessive runoff may result in
flooding of rivers, creeks, streams, and other low-lying and
flood-prone locations.

* ADDITIONAL DETAILS...
- A boundary will cross the region on Wednesday night, creating
significant rainfall with a round of thunderstorms developing
along it. On Thursday, this boundary will lay out along the
Ohio River and linger through Saturday. Waves of energy will
interact with a deep layer of moisture along the stalled
surface front. The front begins to show a movement to the
southeast Saturday night, marking the end of any significant
rainfall. The heaviest rainfall will notably occur during the
overnight hours through the end of the week.

[Trentonwx06]

Don’t remember ILN talking like this couple days before a severe weather event.

[tpweather]

I agree 100p/c with the NWS on the severe chances. The pattern is one that really looks like a decent severe outbreak and one that no doubt could cause some problems in the Ohio Valley. Again this far away things can change and yes the evolution of the system will be key but many items at this point are lining up.

[tpweather]

Of course April 3rd 1974 is my number one weather event of all time and it had to be special if it knocked out some winter events including a blizzard. During the day it got so hot so quick and it just felt like mid-summer in early April Maybe part of that was we just came out of winter and the body had not adjusted but I was outside sweating just watching the numerous Funnel clouds drop out of the sky. It was sad day with all the destruction and deaths involved.

[tron777]

No doubt... that is some serious talk from ILN! So is this:

When all is said and done, 4 to as much as 7 inches of rainfall will
have fallen for the bulk of the CWA by daybreak Sunday, with the
highest amounts expected to be found south and west of metro
Cincinnati. Unfortunately, this is a higher-end average which will
certainly not accurately depict the maximum amount of rain any one
particular location receives. Some lucky few of us may find
themselves located directly underneath the line of nighttime
moderate rainfall for three nights running and make the averaged
rainfall look like a spring shower in comparison.

[tpweather]

My guess we will have several discussions on this topic and I will add to that with this post. Trends and yes we always talk about trends in weather forecasting. Do they always give us the perfect forecast and no but a trend that continues to develop is something we must always look at when trying to forecast. One example would be today's 12 z run and 18 z run of the gfs. The trend has been a slight northwest movement of the heavier rains. Not a huge deal but something to watch over the next day or two. A place say in eastern Kentucky may see the first system come through late Wednesday and early Thursday but the the next wave may push the front further north and they miss out completely Thursday and maybe Friday night. Again these are just possible outcomes and yes going to be a big temp difference across the Ohio Valley. Well to the northwest may see 50's and 60's starting Thursday but southeast Kentucky could very well be in the low to mid 80's Of course this set up is another reason for the heavy rain event that could last 72-84 hours totals though at times the rains will be lighter if not stopped completely but will once again ramp up with the next wave.

[tron777]

18Z GFS was overall slower too. The system exit is not until Monday the 7th as some mixed light rain and snow.

[tpweather]

18Z GFS was overall slower too. The system exit is not until Monday the 7th as some mixed light rain and snow.

The euro has been steady so far Les and yes higher than the gfs locally. This will be interesting to say the least and hopefully folks will pay attention and yes most folks will not have any problems but flooding and especially flash flooding can catch folks off guard plus first we have the possible severe threat Wednesday. Still like 4-6 locally and even once the event kicks off which could be early Wednesday with the warm front we may be updating totals every 12 hours or so.

[tron777]

18Z GFS was overall slower too. The system exit is not until Monday the 7th as some mixed light rain and snow.

The euro has been steady so far Les and yes higher than the gfs locally. This will be interesting to say the least and hopefully folks will pay attention and yes most folks will not have any problems but flooding and especially flash flooding can catch folks off guard plus first we have the possible severe threat Wednesday. Still like 4-6 locally and even once the event kicks off which could be early Wednesday with the warm front we may be updating totals every 12 hours or so.

It will probably be a nowcast for sure. Everyone is probably getting 4". Who is going to get more, we just don't yet know.

[Bgoney]

IMG_3372.png

[tpweather]

Yesterday with the severe storms and yes 3 tornado's confirmed locally temps and dewpoints did not rise much. Different story on Wednesday and would not be surprised if we a few 80's locally. When I see a big jump in temps and dews this always concerns me for severe weather. Many other factors but that one is always a good place to start.

[Bgoney]

I don’t know if I’ve seen these kind of widespread amounts for our region from models . 4-“7” looks likely(7 days), with some localized amounts in the OV in the 7”-10” range.

[MVWxObserver]

From AR to the OV!

My nephew / his wife in Columbia, TN and his wife's folks in Nashville, TN are in the Flood Watch zone also.

[tpweather]

Good Morning and this morning not much change concerning the severe chances or heavy rains over the next 5-6 days. Saw where the Louisville NWS talking about possibly being in the top 5 of rain events and those ended up with big time flooding on the Ohio River. Like Les mentioned the other day the most likely area for the heaviest rain is near the river and with such a wide area of heavy rains I agree some major problems even along the Ohio could occur. Again they are talking about the worse case here but even if they receive half its going to cause problems.

Stay tune but so far all systems go and if we get some of the higher totals my guess even here locally this event may work its way into the top 10.

[Bgoney]

Very similar setup meteorologically to March 1997, that was a two day event, this will be at least 4 days.

[tpweather]

Very similar setup meteorologically to March 1997, that was a two day event, this will be at least 4 days.

Yes and how long are the breaks in the rain each day will also determine flooding issues. Louisville NWS mentioned March of 1997 but also March of 1964 and January of 1937. I do remember seeing plenty of pictures of the 1937 event here locally but do not recall much about the 1964 flooding. The one say good item is no snow to melt which only enhances flooding issues.

[Bgoney]

Latest totals from the O6z GFS are depressing and probability of these amounts are quite high, although exact location will fluctuate

IMG_3376.jpeg

[tpweather]

Great post Bgoney and if we get near these amounts not only will we see flooding that we see quite often in the spring but many other areas that seldom see flooding. Basements across the area will take a beating and sump pumps working overtime. I remember one year where Falmouth,Ky got hammered on a Saturday with very heavy rains but that was isolated and just a one day event. These amounts of rain are something you can see with tropical systems heading in the southern states but not so much in this part of the world.

[tron777]

I am still going with 4-6" of rain at this point in time. I think that's a really good guess right now. We'll see what happens tomorrow with the warm front. If it comes thru somewhat dry and cloudless, then we are in trouble for Wed evening. We shall see!

[cloudy72]

Good morning AV family! I agree with the forecasts on here. It doesn't look good and quite frankly I can't recall the last time I saw this much QPF printed out for such a large area that included us (echoing Bgoney's thoughts). Let's just hope the HRRR doesn't verify because it looks downright scary for Wednesday afternoon/evening. Picked up over an inch of rain with the Sunday night-Monday morning event so ground is already primed.

[tron777]

[Bgoney]

Just the synoptic winds tomorrow will be gusting in the 40-50 mph range per models