March 2021 Weather Discussion

[Bgoney]

Wow sun is shining bright here, wasn't expecting anything like we are seeing on satellite. Things just bumped up a notch in our area

[Bgoney]

Damaging tornado south of Birmingham. Classic on radar

[tron777]

Wow sun is shining bright here, wasn't expecting anything like we are seeing on satellite. Things just bumped up a notch in our area

I didn't think we'd see any sun either. I've had a few peaks of it though here which is more then I expected. Actually seeing some weak CAPE get into our SW CWA now. This is earlier then I expected by a couple of hours. Low is starting to deepen now along the MS river West of Memphis at 1004 MB. 60 degree dews are just S of the LOU area now. Lapse rates are also starting to increase over Southern KY. Bulk shear and helicity are good to go.

[tpweather]

62 here with a dew of 57. Total rainfall: 0.37"

Wow Tim! Glad that one will miss you.

Tornado's to the north of me and Tornado's to the south of me. Sounds like a Jimmy Buffet song

[tpweather]

Wow sun is shining bright here, wasn't expecting anything like we are seeing on satellite. Things just bumped up a notch in our area

That stronger late March sun can make a difference but looking at the satellite I would not expect full sun at all.

[tron777]

62 here with a dew of 57. Total rainfall: 0.37"

Wow Tim! Glad that one will miss you.

Tornado's to the north of me and Tornado's to the south of me. Sounds like a Jimmy Buffet song

[tron777]

Bulk shear values are ridiculous. 60 knots here with 90 knots right out ahead of the surface low down in TN. Wow! Helicity values are also very impressive in the 200-400 range. We just need that fuel to get things going later on. How much we get will determine the severity of the storms. Post frontal... still expecting 50-60 mph gusts for a good 8-12 hours period IMO.

[tron777]

AFD from the boys - a good read:

.NEAR TERM /THROUGH TONIGHT/...
As expected, a fairly cohesive, but quick-moving, band of rain
with embedded thunder continues to push northeast through the
ILN FA, with generally around a half of an inch of rain
occurring in most spots, give or take a tenth or two on either
side. This initial round of widespread pcpn is occurring on the
nose of an impinging/strengthening H8 LLJ and in response to
S/W energy pivoting northeast through the strengthening SW flow
aloft. This is yielding a good deal of mass convergence/lift
across the local area, supporting the persistence of widespread
rain to move through the region through late afternoon, at which
point activity will become much more isolated/scattered in
nature "behind" and to the southwest of this initial rain. This
will occur as the warm front pivots north through the area,
with southeasterly sfc flow becoming established region-wide
this evening.

By this evening, will see a neutrally-tilted H5 trof close off
across the mid Mississippi River Valley with sfc
cyclogenesis/deepening occurring along the spine of the lower
Mississippi River. The trof will gradually become more
negatively tilted later the evening, supporting rapid deepening
of the sfc low as it tracks northeast into the western OH Vly.
This will yield a rapid strengthening of the LL wind fields
during the evening region-wide. While the guidance has honed-in
on a favored track, the most recent data suggests perhaps a
slightly weaker/less deep solution, even with the general
consensus to be a sfc low track from Paducah to north of Indy to
Toledo, putting the ILN FA squarely in the open warm sector of
the strengthening system. From the afternoon into the late
evening, many solutions still point toward a fairly rapid
deepening of the sfc cyclone from ~1000mb to ~992mb from 18z to
03z, which will result in a corresponding uptick/strengthening
of the LL wind fields in a rather dramatic fashion.

With the strengthening LL wind fields and the arrival of better
lift and forcing via increased mid/upper level diffluence, will
see a second batch of showers, with more widespread storm
activity, track northeast into the ILN FA around/past 01z. This
will occur from SSW to NNE, with the main question at this
juncture being the degree of BL destabilization that is able to
occur, especially in the wake of widespread rain occurring this
afternoon. Model soundings show a fairly saturated LL profile
through early evening, with rather unimpressive lapse rates and
very marginal instability -- especially any that is SB in
nature. The wind fields -- both in magnitude and expanse --
continue to be concerning. The LL directional and speed shear is
notable, yielding hodographs that are long and somewhat curved.
The main limiting factor for severe potential locally will be
the overwhelming lack of instability rooted near the surface,
which may be rather limited in areal extent except /just/
along/immediately ahead of and east of the actual sfc low track
and front itself. This would support an environment where the
greatest severe threat will exist immediately near/east of the
sfc low track near the triple point, which current model
consensus would place the most favorable severe potential mainly
near/west of the I-75 corridor and into the Tri-State area.
This, of course, is /entirely/ dependent on the degree to which
we can attain SB destabilization in the wake of ongoing
activity. The profile will be very saturated, but very
energetic. If even a little bit of SB-instby is realized or
becomes rooted close to the surface, it will not take much at
all for stronger cores to translate down some /very/ strong wind
to the sfc. The positioning of the local area WRT the sfc low,
which would elicit sfc winds that are largely backed in nature,
could support some tornadic activity if the instby becomes more
than just elevated in nature, especially near the triple point.
Again, feel that this will be favored immediately near/east of
the sfc low in the 01z-06z time frame, which at this time
appears it would set up in a narrow corridor from south-central
IN/SE IN /Tri-State through west-central Ohio. Hi- res data
continues to show that perhaps the best ribbon of SB instability
could lag /just/ behind the convection (immediately behind the
front and thus slightly out of phase), suggesting that most of
the storm activity could be elevated in nature. And without a
narrow N-S ribbon of SB instby coinciding with the best LL
convergence along the front, even with the H8 LLJ of 70+kts, it
would be a bit more difficult, although not impossible, to
translate stronger winds to the sfc until we get into a post-
frontal environment. Any activity east of the I-71 corridor may
be even more elevated in nature and therefore be a bit less
concerning than activity that develops immediately along the
front itself for spots near/west of the I-75 corridor.

And with all of this being said -- once we get into a post-
frontal environment, on the backside of the sfc low after the
storms move away, the setup for strong synoptic-based winds
becomes much more favorable -- especially in a corridor
immediately to the south/west of the sfc low track. This will
occur with a steepening of the LL lapse rates coincident with
the wraparound of a robust 55kt 925mb LLJ, which will slowly
translate east through the late nighttime period. Current
momentum transfer techniques suggest widespread potential for
40+kt gusts in a several hour time window (esp. 05z-11z), with
some potential for 50+ kt gusts in a small WSW to ENE corridor
immediately trailing the sfc low as the pressure rise/fall
couplet tightens rather dramatically. The isallobaric response
will be tremendous, no matter how deep the sfc low becomes. At
this juncture, there continues to be good support for 40+ kt
gusts just about everywhere, with the greatest potential for 50+
kts existing near/north of the I-71 corridor and near/north of
the Ohio River into the Tri-State area. The latest guidance has
trended just a bit weaker with the sfc low pretty much across
the board, which lends itself to some uncertainty in just how
far south the 50+kt gusts will extend. However, there was enough
data to suggest the potential for a one or two hour period of
gusts approaching 50kts from Ripley Co IN to Hocking Co OH, so
decided to extend/upgrade the High Warning for these areas. This
is in spite of the trend toward a slightly weaker solution,
which would not be insignificant from an impact standpoint. This
was especially evident in some of the global guidance, which
have the central minimum pressure generally ~5mb higher than
was being suggested/shown within the past day or two. The good
news is that this is likely to limit somewhat the more
significant gust potential (i.e. less likelihood of 65+ MPH),
but there is still a strong signal for gusts approaching 60 MPH
for mainly spots near/north of the I-70/I-71 corridors. It was
mentioned yesterday that there will be a big difference in the
damage potential between a 985mb low (which was advertised
yesterday) and a 995mb low (still not fcst to be /this/ weak).
But nonetheless, current ensemble mean probabilities have come
down a bit, although still suggest near/greater than a 50%
probability of 50+kt gusts for much of the current warning areas
(especially in west-central to central Ohio).

Drier conditions evolve late tonight in the post- frontal
environment with temperatures falling from the lower 60s to
mid/upper 40s by daybreak.

[Bgoney]

A little after 2 pm, James Spann reported on-air (ABC 33/40, Birmingham) that there had been "major damage" at his house. His wife was in shelter and was not injured.

[kywthrluvr]

Looks like a Tornado Watch is coming to our SW.

[Trevor]

A little after 2 pm, James Spann reported on-air (ABC 33/40, Birmingham) that there had been "major damage" at his house. His wife was in shelter and was not injured.

That’s terrible news!

[Bgoney]

Here's what Louisville had to say. They dont sound as impressed for our area as ILN does.


Short Term...(This evening through Friday)
Issued at 320 PM EDT Thu Mar 25 2021

Little has changed. Wind shear is still very strong, but recent
model soundings still show a low level inversion. This makes it hard
for thunderstorm development. Even though it`s borderline, some
models show the inversion dissipating in areas of south central
Kentucky. Sunshine throughout the region will help to warm the
ground, helping steepen low level lapse rates and increasing
instability. Areas farther to the north are less likely to see the
inversion dissipate, but with so much shear, it won`t take much.

The risk for severe weather is from 6 PM to 11 PM EDT across
southern Indiana and central Kentucky. This risk is expected to
advance from the southwest into southern Kentucky, north towards
southern Indiana, and slowly fade as the system moves to the east.
The remaining precipitation is expected to develop as clusters ahead
of a broken line attached to the cold front.

[tron777]

If you read ILN's AFD, we need to watch the triple point and that could occur over the Tri-state area and points just to the West of I-75. The Tornado Watch that is likely to be issued is in that triple point area as the low moves NE. That zone could be over us this evening. Again... damaging winds and a brief spin up are what we're talking about for us this evening as I've been mentioning. CAPE is still weak over the region but we have several more hours of peak heating to go. The sun doesn't set now until 8pm. 64...65 degrees basically right now with a dew of 56..57 is what I am seeing along with CVG. Lapse rates are increasing finally in our area. Still steeper over Central KY at this time. 0-6KM bulk shear continues to increase as the low continues to deepen and move NNE. 0-3KM Helicity values of 400-500 exist now and that's an increase from earlier. Slight risk is certainly warranted in our area. I'd like to see a little more CAPE. That's really the only limiting factor that I am seeing. However, with these impressive dynamics in place, isolated severe can still occur. If we get a little more CAPE though, watch out!

[tron777]

18Z NAM and HRRR both agree with my above thinking and the sounding show severe x possible with a line of storms coming in between 9-11pm. Strong winds and an isolated tornado possible. One of those brief spin up kind of deals. QCLS tornado as they are called since we're not expecting discrete super cells in our area.

nam_2021032518_006_38.98--84.69.png

hrrr_2021032518_007_39.0--84.73.png

[tron777]

Surface low is now down to 1002 MB over S ILL. Weak CAPE here mainly S of the river with the better CAPE over the Western half of KY. The best chance of super cells should be over that area. Still expecting a line of storms here between that 9-11pm window with damaging winds and a brief tornado possible. The bigger story will be the wind post frontal sustained at 25-35 mph gusting 50-60 mph after midnight thru tomorrow morning before things calm down tomorrow afternoon.

[Bgoney]

Alabama taking another beating today.

[tron777]

Brent, AL may have sustained incredible damage per radar anyway. At one point the debris signature on radar was over 2 miles! The tornado itself was likely a mile wide. Damage pics starting to come in on the internet. I've heard of 5 people dead so far. Prayers for those people impacted for sure. Watching storms in TN and SKY as well this evening.

[tron777]

Storms are firing in West KY / TN Those are rapidly moving NE and those are the ones we need to watch for us later this evening. Some cells have already moved up into Central KY. Storm motion is very quickly... probably 50-60 mph.

[MVWxObserver]

Currently 55 here in G'ville.

ILN has 60 to 65 mph progged for my area late tonight and then 50 to 55 mph Fri morning before diminishing in the afternoon.

No recyclables tub out this week, just the cart, probably between 7:30 and 8 o'clock in the morning.

[MVWxObserver]

SVR t-storm warning for Evansville, IN.

[theextremeone]

I can see lightning starting here

Screenshot_20210325-204122_RadarScope.jpg

[Trevor]

Les: any hail? That core went right over Burlington.

[Wxulikeitornot]

Hey all old user. New account. Could not find my old. Formerly subzero. New forum is looking amazing!!!

[Trevor]

Hey all old user. New account. Could not find my old. Formerly subzero. New forum is looking amazing!!!

Welcome back!

[Angelika]

When is the wind coming?