March 2024 Weather Discussion

[tron777]

[tron777]

60 with a dew of 51 at CVG as of 10am.

[Angelika]

Severe Thunderstorm Watch just issued until 4 p.m.

[tpweather]

Good Morning and listened to Brian this morning and once again a great job. Dew points even in the current storms are below 60 so I believe this will help somewhat so storms don't become to strong later today. Timing for the first batch is this afternoon and just looking at the current radar that seems to get in here around 2 or 3pm. Should be a rather fast line so of course some straight line winds are possible. I am still not sold on a big tornado threat and of course any storm can produce one but I believe much further south and west with the overnight event a better shot. This low north of us is mainly moving west to east so we may not get that big push of warmth and sun that could really make the atmosphere unstable. The one overnight models also are tending to move it west to east. Getting the systems that move southwest to northeast is usually better in getting the atmosphere really unstable and because that usually brings up a quick shot of warm and moist air.

Would be nice to get rain from both and if that happens then .5-1.0 is possible but if you get missed by one or the other then totals can be closer to .25. Should be fun to watch this afternoon

[tron777]

The watch is from the I-75 corridor and points West. Here is the Watch text and SPC discussion:

https://www.spc.noaa.gov/products/watch/ww0041.html

[tron777]

Update from the boys:

.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Forecast is on track. Plenty to look at and be concerned about
in terms of severe weather impacts over the next 12-15 hours
with the ILN CWA potentially seeing several rounds of strong to
severe storms.

First concern is the organizing linear MCS over eastern Illinois
and northwest Indiana. This entire convective system is slowly
getting organized and has an open warm sector /albeit with
marginal thermodynamics/ in front of it with several hours of
sunshine to promote warming temperatures into the 70s.

Per a very stable / consistent signal in the past 4-6 HRRR runs,
expect this convective line to continue to move east-northeast
and into the ILN forecast area early this afternoon (1-2PM) and
then steadily east and out of the area by 5 PM. A concern here
is the ambient boundary layer in front of these storms is not
moist, with dewpoints in the 40s, which will slowly increase
into the mid 50s ahead of the line. This may temper storm
intensity somewhat, but on the flip side the inverted-v type
soundings seen in the HRRR/NAM in front of this line will
augment mixing of stronger convective winds to the surface. Low
level shear is adequate, but lacks curvature in the 0-1km layer,
and is more impressive on 0-3km layer where SRH is in excess of
250m2/s2. So there will be a potential for line-embedded
mesovortices for optimally oriented segments of the line to the
low level shear vector, but it is noted that the vector is
somewhat line-parallel, which may keep mesovortex formation much
more isolated.

Something also showing up in numerous CAMS is the potential for
a southern tail supercell with strong updraft helicity swath
somewhere in vicinity of the Ohio River or just north mid-late
afternoon. This seems plausible, and needs to be watched for
a larger hail threat or more localized brief tornado threat. The
signal has been in most HRRR runs, and many of the other 14.00Z
runs.

There will be time for airmass recovery in western Ohio/eastern
Indiana later this afternoon and evening, with model consensus
of lower 60s dewpoints advecting in along and south. A pretty
concerning supercell environment is depicted with a mid level
jet streak providing ample deep layer shear, low level curvature
in the hodographs, and deep instability. Supercell mode is
possible if not likely, thus threats in terms of impact seem to
maximize in the 5P-11P timeframe in southeast Indiana, western
Ohio possibly as far east as central Ohio with large hail and a
a tornado or two.

[tron777]

CAPE is finally starting to build a bit to our SW. We have a little more sunshine to go before we cloud up. Dews are in the low 50s with the closest 60 degree dewpoint located in Evansville, IN.

[cincy bud]

Sun is gone in N. Butler Co. Very windy but I feel no humidity in the air yet

[tron777]

70 now at CVG with a dew of 57. Dews have come up nicely, which was one of my initial concerns. 500 J/KG of CAPE for Cincy and 1000 down by LOU. DCAPE is at 800 just to our SW. Plenty of bulk shear 50 knots. Helicity is much better well to our NW though at this point in time. Lapse rates are good at this time so that's a plus. Line of storms now approaching IND. So far, things are looking better for these cells to maintain themselves until they get into our eastern counties. The HRRR thus far does look like it may score one. There are a few warnings out from IND Metro on north for strong winds and hail. We will continue to monitor....

Here is a mesoscale update from NWS IND:

.MESOSCALE UPDATE...
Issued at 1112 AM EDT Thu Mar 14 2024

Line of convection extending from Tippecanoe County south/southwest
through East Central Illinois and is showing forward speed around 45-
55 kts. Within the line segment there has been a few weak
circulations that show-up within 1 to 2 WSR-88D scans. Satellite
imagery is showing further vertical growth to the cloud tops,
indicative of stronger updrafts being present within the QLCS. The
surface environment ahead of this line has moisture advection
bringing dewpoints up into the upper 50s, and that has been some
locations where winds have backed marginally. This supports a slight
nudge upwards within low-lvl helicity, which will maintain a concern
that as the QLCS progresses east there could be a few couplets that
begin to rotate given the environmental setup.

The other concern is damaging winds with increased momentum transfer
aloft to the surface showing up, and cloud cover is sharply eroding
along back edge of QLCS in southcentral Illinois. Lapse rates will
continue to steepen in the mid-lvls, which coupled with the
ascending parcels could produce hail in excess of 1 inch.

[tron777]

No changes from the updated SPC Day 1 Outlook. Latest discussion from those guys:

...Missouri eastward into Kentucky/Indiana/Ohio...
A complex scenario is unfolding for today, given rather subtle
large-scale ascent across much of the area, but with a very
favorable background thermodynamic environment coupled with strong
deep-layer shear.

A line of strong/locally severe storms is ongoing this morning
across Indiana, which will continue eastward this afternoon into
Ohio. Locally damaging wind gusts will be the primary risk with
these storms, continuing across western Ohio before some weakening
eventually occurs given weakening instability with eastward extent
into the upper Ohio Valley.

In the wake of these storms, but ahead of a sagging cold front,
airmass recovery is underway. Clouds have cleared across Illinois
and for the most part Missouri as well, ahead of the front and in
the wake of earlier storms. Ongoing heating, beneath steep lapse
rates aloft, will result in a moderately unstable warm sector this
afternoon. CAMs continue to suggest redevelopment of more cellular
-- eventually clustered -- convection across this region this
afternoon, and eventually (presuming ample airmass recovery can
occur) into Indiana and possibly/eventually western Ohio. Though
low-level flow behind the initial band of Indiana storms will likely
remain somewhat veered, which may limit more substantial tornado
risk, very large hail is expected, along with damaging winds and a
couple of tornadoes. Storms could eventually grow upscale this
evening, spreading across the Tennessee Valley region accompanied by
continued severe risk.

[tron777]

Mesoscale update from NWS LOU:

.MESOSCALE...
Issued at 1138 AM EDT Thu Mar 14 2024

SPC, in coordination with surrounding WFOs, has issued Severe
Thunderstorm Watch 41. This Severe Thunderstorm Watch includes our
northern most Indiana counties. A convective line of strong to
severe storms was located from north central IN stretching south-
southeast towards Terre Haute, IN and just west of Vincennes, IN
moving east-northeast around 60 to 65 mph. Main threats will be
large hail and damaging winds but a couple of brief spin-up tornadoes
are possible.

Instability looks to increase across central KY into southern IN
through the rest of the morning into the afternoon. SBCAPE is
forecast to increase to around 2000-2500 J/kg with modest shear.
Our overall severe threat remains condition on potential outflow
boundaries that could push further southward into our CWA to produce
additional convection. Model soundings along with current ACAR
soundings show a capping inversion this morning into the afternoon
but if we can get activity to fire all severe threat are on the
table this afternoon. The best combination of thermodynamic and
kinematic parameter remain to our north closest to the stationary
boundary located across northern IN but as the QLCS quickly
progresses across central IN, the southern portion of the line will
need to be monitored for more development southward.

Another wave of storms associated with an approaching cold front is
expected later tonight close to 03-04z through the overnight before
exiting the area in the pre-dawn areas. SPC has our area in a slight
risk for severe weather across all of southern IN and northern KY
then along and west of I-65. Main threat will be gusty winds and
some hail with a brief spin-up tornado.

[tpweather]

Good Afternoon and quite windy as I took my daily walk. Line is moving fast so the amount of time for any strong storms will be short-lived. The system well to the southwest is getting its act together a tornado watch and yes more energy,higher dewpoints and a much better environment imo to have severe storms. How far northeast will they go overnight is key for us and again a very close call if we get storms from that system.

With the speed of the line of storms rainfall amounts will be less but it also allows the area to get a little more unstable later today. Very tricky forecast as you have two pieces of energy and will the leftovers from the first leave any energy behind in western Kentucky and western Tn.

Just one of the forecasts you tell folks we may have a storm or two but not a big outbreak and still not sure we even have a storm reach severe levels locally

[tron777]

Good Afternoon and quite windy as I took my daily walk. Line is moving fast so the amount of time for any strong storms will be short-lived. The system well to the southwest is getting its act together a tornado watch and yes more energy,higher dewpoints and a much better environment imo to have severe storms. How far northeast will they go overnight is key for us and again a very close call if we get storms from that system.

With the speed of the line of storms rainfall amounts will be less but it also allows the area to get a little more unstable later today. Very tricky forecast as you have two pieces of energy and will the leftovers from the first leave any energy behind in western Kentucky and western Tn.

Just one of the forecasts you tell folks we may have a storm or two but not a big outbreak and still not sure we even have a storm reach severe levels locally

Tim... today's action was always conditional and I have preferred the overnight period of having the best chance for us in the southern forecast area. This afternoon's action should have the best chance for our northern forecast area. We'll see... it's worth keeping an eye on. Western counties also have the better chance versus eastern counties. Best dews, lapse rates, CAPE, etc is in our West versus East. In short, I think we're pretty much on the same page lol

[tpweather]

Good Afternoon and quite windy as I took my daily walk. Line is moving fast so the amount of time for any strong storms will be short-lived. The system well to the southwest is getting its act together a tornado watch and yes more energy,higher dewpoints and a much better environment imo to have severe storms. How far northeast will they go overnight is key for us and again a very close call if we get storms from that system.

With the speed of the line of storms rainfall amounts will be less but it also allows the area to get a little more unstable later today. Very tricky forecast as you have two pieces of energy and will the leftovers from the first leave any energy behind in western Kentucky and western Tn.

Just one of the forecasts you tell folks we may have a storm or two but not a big outbreak and still not sure we even have a storm reach severe levels locally

Tim... today's action was always conditional and I have preferred the overnight period of having the best chance for us in the southern forecast area. This afternoon's action should have the best chance for our northern forecast area. We'll see... it's worth keeping an eye on. Western counties also have the better chance versus eastern counties. Best dews, lapse rates, CAPE, etc is in our West versus East. In short, I think we're pretty much on the same page lol

I agree Les we are on the same page. I do believe the southern system will produce some tornado's but just a better environment. Locally good have some thunder overnight but I agree with south and west much better shot. I am really just hoping to get 1/2 inch rain out of both systems

[tron777]

Good Afternoon and quite windy as I took my daily walk. Line is moving fast so the amount of time for any strong storms will be short-lived. The system well to the southwest is getting its act together a tornado watch and yes more energy,higher dewpoints and a much better environment imo to have severe storms. How far northeast will they go overnight is key for us and again a very close call if we get storms from that system.

With the speed of the line of storms rainfall amounts will be less but it also allows the area to get a little more unstable later today. Very tricky forecast as you have two pieces of energy and will the leftovers from the first leave any energy behind in western Kentucky and western Tn.

Just one of the forecasts you tell folks we may have a storm or two but not a big outbreak and still not sure we even have a storm reach severe levels locally

Tim... today's action was always conditional and I have preferred the overnight period of having the best chance for us in the southern forecast area. This afternoon's action should have the best chance for our northern forecast area. We'll see... it's worth keeping an eye on. Western counties also have the better chance versus eastern counties. Best dews, lapse rates, CAPE, etc is in our West versus East. In short, I think we're pretty much on the same page lol

I agree Les we are on the same page. I do believe the southern system will produce some tornado's but just a better environment. Locally good have some thunder overnight but I agree with south and west much better shot. I am really just hoping to get 1/2 inch rain out of both systems

For sure! I'd love to get a half inch by the time Fri morning rolls around. That would help out my new grass seed. Anything heavier would probably just wash it away!

[tron777]

So far.... no warnings minus over N IN and those cells will bypass our local area. All of the warnings in the IND area have expired as of this post. We'll have to see if these cells ramp back up, maintain, or begin to weaken as they approach us here soon.

[tron777]

In my personal opinion, the last couple of radar scans, it looks to me that the line is beginning to weaken esp on the southern end which would be the portion that would impact us in Cincinnati / NKY / SE IN areas. I like my thoughts from the last couple of days of the best chance north for this afternoon and our best chance down here is overnight. I don't really see any reason right now to change that line of thinking.

[tron777]

ILN issuing SPS's over our NW counties for the incoming line. Definitely sub severe as of this post:

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF WESTERN FRANKLIN
...WAYNE...UNION AND FAYETTE COUNTIES IN EAST CENTRAL INDIANA
THROUGH 130 PM EDT...

At 104 PM EDT, strong thunderstorms were located along a line
extending from 8 miles northwest of Hagerstown to Rushville, moving
east at 40 mph.

HAZARD...Wind gusts up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.

Locations impacted include...
Richmond, Connersville, Centerville, Cambridge City, Liberty,
Hagerstown, Fountain City, Dublin, Oldenburg, Glenwood, Lake Santee,
Franklin, Salem, Waterloo, Blooming Grove, Columbia, Metamora, Bunker
Hill, Abington, and Brownsville.

[tron777]

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF NORTHWESTERN AUGLAIZE
AND MERCER COUNTIES THROUGH 130 PM EDT...

At 1256 PM EDT, strong thunderstorms were located along a line
extending from Decatur to Portland, moving east at 45 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.

Locations impacted include...
Celina, St. Marys, Coldwater, New Bremen, St. Henry, Fort Recovery,
Rockford, Wabash, Mendon, Chickasaw, Montezuma, Chattanooga, Kossuth,
Tama, Egypt, Maria Stein, Neptune, Carthagena, and Bulkhead.

[extremeweather]

Cell south of Seymour, IN looks like it has some strength and heavy rain. .

[cincy bud]

Thunder heard here near Somerville

[tpweather]

I see one loan stronger cell near Seymour,Indiana and those are the kind you must watch. Looks like the line itself has weaken but that cell is stronger. Will watch that over the next 30 minutes.

[tpweather]

Cell south of Seymour, IN looks like it has some strength and heavy rain. .

Sorry did not see your post but exactly and we are on the same page here

[cloudy72]

I see one loan stronger cell near Seymour,Indiana and those are the kind you must watch. Looks like the line itself has weaken but that cell is stronger. Will watch that over the next 30 minutes.

Agree with you both - need to watch this cell esp NKY folk!

EDIT - just TS warned

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Louisville KY
135 PM EDT Thu Mar 14 2024

The National Weather Service in Louisville has issued a

* Severe Thunderstorm Warning for...
Jefferson County in south central Indiana...
Northern Scott County in south central Indiana...
Northwestern Trimble County in central Kentucky...

* Until 215 PM EDT.

* At 135 PM EDT, a severe thunderstorm was located near Scottsburg,
moving east at 50 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage
to roofs, siding, and trees.

* Locations impacted include...
Madison, Scottsburg, Austin, Hanover, Smyrna, Milton, Kent, Dupont,
Brooksburg, and Wakefield.

[tpweather]

Those lonely cells are always ones to watch. They are usually at the southern end of a complex.