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ClicheVortex2014

March 14, 2019 | Pi Day Severe Outbreak

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Appears to be at least some potential for severe weather before the Gulf of Mexico gets shut down until the last week of March. Unidirectional winds but extremely strong speed shear just ahead of the front. Furthermore, looks like there'll be an inverted V profile with seasonably warm temps and seasonably modest dew points... this'll enhance downdrafts and therefore the damaging wind threat.

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Sounding in SW OH

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Lower Great Lakes

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ILN

Quote

Longer-range synoptic-based models remain in fairly good agreement
showing a potent vertically-stacked system across the central plains
by late Wednesday evening, with stronger vorticity advection and
moisture transport still just west of the area. However, by
Wednesday night, the system will migrate far enough east that
widespread rain showers will be maintained in the forecast for
Wednesday night into early Thursday morning.

The window for rain appears to be fairly narrow -- perhaps a 12-hr
period or so -- as substantial dry air wrapping around the southern
flank of the system will quickly intrude by Thursday afternoon. Not
only will this shunt the best chance for pcpn a bit further
south/east of the ILN FA, but it will also result in an increasingly
well-mixed BL amidst strong/deep southwesterly flow. This may very
well yield another windy day on Thursday, with the potential need
for wind headlines not out of the question. Although it is perhaps a
bit premature to speculate, it does appear that gusts in excess of
45-50 MPH may be possible Thursday afternoon into the evening period
before winds subside somewhat as mixing becomes a bit more muted.

The way things stand now -- it appears that the wind may end up
being the bigger story for midweek (Thursday afternoon) than the
rain (early Thursday morning), especially if current model trends
continue. The other story will be the very warm temperatures poised
to filter into the region on Thursday, with the potential for highs
approaching or exceeding 70 degrees in some spots -- a feat that was
last accomplished at the Big 3 climate sites on October 11. While
these kinds of temperatures will not last for more than an
afternoon, the latter part of Thursday is shaping up to be a warm
and windy period.

 

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IND discussion from this morning regarding the wind gusts. GFS maps posted below seem to agree with them from a high level.

Quote

Intense occluding surface low over the central Plains Thursday
morning will lift northeast and open up through Thursday night.
The convection expected ahead of the system Wednesday night should
be largely east of the region Thursday morning with only a lower
chance for showers and storms warranted over eastern counties
focused mainly during the first half of the day. The much bigger
impact for Thursday will be the potential for strong winds as a
dry slot advects into the region between the prefrontal convection
and the occluded front to the west. Model soundings already have
an ominous look to them for Thursday with the potential for a well
mixed airmass that could extend as high as 7-8kft. Lapse rates
could exceed 8-9 deg C/km as high as 700mb which would enable easy
access to the 60-70kt jet present near the upper part of the
boundary layer. Headlines will be needed at some point should
these trends continue as confidence growing in 50-60mph peak gusts
Thursday afternoon. Will highlight in the HWO at this time.

USA_GUSTM_sfc_084.thumb.gif.8776112a5a7b3de4c140694915e427ed.gif

USA_GUSTM_sfc_087.thumb.gif.5da25510fb00d5b240b550c340174656.gif

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36 minutes ago, ak9971 said:

IND discussion from this morning regarding the wind gusts. GFS maps posted below seem to agree with them from a high level.

USA_GUSTM_sfc_084.thumb.gif.8776112a5a7b3de4c140694915e427ed.gif

USA_GUSTM_sfc_087.thumb.gif.5da25510fb00d5b240b550c340174656.gif

I went ahead and created a thread for the wind event to keep this one on track for severe weather.

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ILN is liking some severe potential in the eastern counties

Quote

Pressure gradient will tighten Wednesday night as low pressure lifts
northeast into the upper Mississippi Valley, making its closest
approach to the forecast area. This will result in increasing winds
Wednesday night and mild temperatures, with readings only dropping 5
to 8 degrees from Wednesday highs. A strong low level jet will push
across the area Wednesday night and then move off to the east
Thursday morning. This will bring a surge of moisture along with
lift to result in showers. These showers will translate east with
the low level jet. So after this occurs, there will likely be a
lull in precipitation late morning into early afternoon.

In this lull period, winds will become gusty with some potential for
very deep mixing, especially northwest of I-71. If clouds persist,
this would limit mixing potential somewhat, but at this point in
time, there is the possibility of advisory level winds. It will be
very warm. How warm will again dependent on cloud cover. Expect at
least the Tri-State to get into the lower 70s. Additional showers
will form later Thursday afternoon and continue into the evening as
they move east ahead of a cold front. There is some potential for
thunder, and if enough instability can be realized in a very high
shear environment, then some severe storms will be possible in
eastern counties.

Latest GFS has a little more of a tornado threat in SW OH. Got rid of the dry low-levels and allows for a little more directional shear. 

DtQ8rqC.png

 

NAM being the NAM. Interestingly has semi-discrete storm mode.

WmowPM1.png

qge0AEo.png

UVqkZE0.png

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5 minutes ago, ClicheVortex2014 said:

ILN is liking some severe potential in the eastern counties

Latest GFS has a little more of a tornado threat in SW OH. Got rid of the dry low-levels and allows for a little more directional shear. 

DtQ8rqC.png

 

NAM being the NAM. Interestingly has semi-discrete storm mode.

WmowPM1.png

qge0AEo.png

UVqkZE0.png

The Euro doesn't have a simulated radar, that I know of anyway, but it almost appears to be showing semi-discrete cells as well based on the 6-hourly QPF:

1110147113_9-kmECMWFUSASurfaceIndianaIllinois6-hPrecip850hPaTemperature84.thumb.png.aa126aaa4d33a88d466d9ae9b7dca639.png

It also shows some impressive transfer of winds to near surface level:

842115124_9-kmECMWFUSACitiesIndianaIllinois10-mWindGust84.thumb.png.788b6cb8d63d2bf14b395b21df203e66.png

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Latest ILN AFD still liking at least some severe potential, with NAM being the higher severe threat.

Quote

In developing southwesterly flow, an area of isentropic lift
will shift north across northern portions of our area Wednesday
morning. This will lead to a chance of showers early in the long
term period before possibly drying out through Wednesday
afternoon. Ahead of the low, a strengthening 50-60 knot 925-850
mb jet will pivot up into our area later Wednesday night and
through the day on Thursday. This will allow for fairly
widespread showers to spread in from the west later Wednesday
night and then shift east across the area through Thursday
morning. There are some differences between the NAM and GFS as
to how much drying will work into our area behind this and ahead
of the approaching frontal boundary Thursday afternoon. This
will affect how well we are able to mix through Thursday
afternoon and therefore how windy we will be able to get. With
the deeper mixing off of the GFS, we may approach advisory
criteria across the northwest through the day on Thursday and
will continue with a mention of winds in the HWO. Meanwhile, the
more moist NAM is considerably more unstable, especially across
the west Thursday afternoon into Thursday evening. Will
continue with a chance of thunder during this time frame, and
given the strong wind fields, there will be at least a lower end
severe threat Thursday afternoon/evening. In the southerly flow
pattern, temperatures will be well above normal with highs on
Thursday in the upper 60s to around 70 degrees. Pcpn will taper
off from the west through Thursday night as a dry slot moves
into the region behind the front. However, some wrap around
moisture will lead to a chance of a few showers Friday into
Friday evening. Highs on Friday will range from the mid 40s in
the northwest to the lower 50s in the southeast.

 

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I do wonder if the drier solutions show back up(though not going full on inverted V) if we could potentially see some LP Supercells with a bit more turning. 

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Lol the 18z NAM could possibly support a LP supercell in southwest Ohio.

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The hell, NAM?

Po09bLI.png

CKLo0FH.png

 

0aA0CtU.png

22 minutes ago, Ingyball said:

I do wonder if the drier solutions show back up(though not going full on inverted V) if we could potentially see some LP Supercells with a bit more turning. 

12km NAM is definitely showing some supercells. This setup really doesn't scream outbreak... strange

QxdbO31.png

0QfDpED.png

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1 hour ago, ClicheVortex2014 said:

The hell, NAM?

Po09bLI.png

CKLo0FH.png

 

0aA0CtU.png

12km NAM is definitely showing some supercells. This setup really doesn't scream outbreak... strange

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0QfDpED.png

It's been a strange year thus far, I would expect nothing less out of this system! Lol

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SREF has a mean MUCAPE of 500-600 j/kg for central Indiana and SW OH. For SW OH, a few members have 800+ j/kg... and about 5 members in central IN, 3 of which are >1000. So 18z NAM is at the high end. But SREF also has the southerly surface winds that NAM has, suggesting good directional shear.

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The battle between the dry air and the wet air is pretty unusual for March. My dewpoints are near 50 now, extraordinary for the SW in March. Expecting to go from heavy rain, with 50-60 mph winds, and maybe some hail, to brief periods of heavy brick-like wet snow as the cold front comes in. The dew points in SE NM may top 60 or more, which is probably part of why the NAM has such a big line of thunderstorms developing in Eastern NM.

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5 minutes ago, Central Illinois said:

Screen Shot 2019-03-11 at 9.20.15 PM.png

Yeah I don't know what's up with this. I guess it only looks at 500mb setup or something because everything about this is off.

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Slightly more realistic but still probably on the higher end

z7oyZ0w.png

1jrAUXY.png

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GFS took a step toward NAM... has some more southerly flow and higher instability in some places.

eFmtcYw.png

 

SW MI

KsWwKv7.png

 

West of Louisville

iBrOLab.png

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3 hours ago, raindancewx said:

Season of Cliche continues.

Will look amazing on satellite 

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ILX talking severe potential here, but not seeing their talk line up with SWODY3 for the western half of their CWA

 

 

Quote

Thursday`s forecast seems a bit more muddled than it looked
yesterday. The models have trended to push the main 500mb low
slightly east which translates the axis of the dry slot further
east into our southeast counties. This area will likely still see
breaks and given the nearly dry adiabitic lapse rate, high
momentum air should work down to the surface before the front
pushes across the area in the afternoon. GEFS output from 18z
suggests that 850 mb winds may be greater than 60 mph with jet.
Looks like area east of I-57 in particular should be in for quite
a windy day.

However, with the translation east, both 00z GFS and ECMWF suggest
fairly substantial destabiliation Thursday morning in the western
half of the area as 500mb temps fall below -20C. Low-level
moisture may be somewhat limited, but with strong dynamics and
CAPE values progged by the 00z NAM over 700 J/kg at ILX with 0-3km
SRH over 400 m/s2 at 18z, strong storms may develop over the area
by late morning. New SPC Day 3 reflects this potential of strong
convective development along the boundary and then pushes it
quickly east.

 

day3otlk_0730.gif.7e940974916bba14d8863c29bd282b17.gif

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Posted (edited)

I would have to think if we keep seeing NAM like solutions on other models the area would get more than a marginal risk. With this and the high winds it should be an interesting day to follow.

Edited by ak9971

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19 minutes ago, WeatherMonger said:

ILX talking severe potential here, but not seeing their talk line up with SWODY3 for the western half of their CWA

 

 

 

day3otlk_0730.gif.7e940974916bba14d8863c29bd282b17.gif

Their Facebook post clears it up, must have been a typo, quite a few in their AFD

 

FB_IMG_1552392299417.jpg.5a9f012dfad7a853a2f3edb7e1753efd.jpg

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Posted (edited)

ILN not really mentioning any severe threat in their discussion other than the wind threat.

Quote

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A strong system will begin to approach the region Wednesday night.
Temperatures will rise into the 60s to around 70 on Thursday.
Multiple rounds of precipitation will move through the area from
Wednesday night through Thursday night. This will lead to a
localized flooding threat. There is also some instability and
therefore have a chance thunder mention in the forecast as well.
There is at least an isolated damaging wind potential with storms
Thursday afternoon into Thursday night due to strong low level flow.
Model soundings are showing winds in excess of 45 mph across
portions of the region with the strongest gusts Thursday afternoon
into Thursday night.  Will continue to mention this threat in the
HWO.

 

Edited by ak9971
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IND has a good right up this morning and talk about a lot of different things. One of them being the chance for strong to severe storms.

Quote

.SHORT TERM /Tonight through Thursday Night/...
Issued at 345 AM EDT Tue Mar 12 2019

Forecast challenges focus on impacts to the forecast area from yet
another powerhouse storm system set to track front he central Plains
into the western Great Lakes Wednesday and Thursday. The potential
for scattered strong to severe storms exists Thursday along with a
growing confidence in a period of high winds focused on Thursday
afternoon.

The upper low over the Four Corners region will emerge over the High
Plains on Wednesday at a much deeper strength as polar energy dives
into the trough and amplifies the feature. The system will have a
negative tilt to it as it lifts out into the Central Plains late
Wednesday before tracking northeast and weakening over the Great
Lakes by Thursday night. At the surface...intense cyclogenesis will
commence over the central Rockies with a sub-975mb low emerging onto
the High Plains by Wednesday afternoon...an exceptionally strong
surface wave for this part of the country. The system will begin to
occlude as it shifts E/NE across the central Plains then into the
western Great Lakes by late Thursday. Even as the system weakens on
approach to the region...associated dynamics aloft remain impressive
and are likely to create a number of impacts for central Indiana on
Thursday.

Clouds will continue to increase this evening as dry air and
subsidence lingering in the boundary layer slowly erodes. A warm
front will lift north into the area overnight tonight in response to
the developing low back to the west...with rain becoming likely over
the northern half of the forecast area after midnight as low level
convergence and lift increase. Expect these showers to linger into
Wednesday morning before shifting north with the warm front quickly
during the afternoon. Dry and mild conditions are expected for late
day as much warmer air advects into the Ohio Valley south of the
warm front.

Convection will surge well ahead of the occluding low late day
Wednesday into Wednesday night along a prefrontal trough. Moisture
will increase noticeably Wednesday evening aided by a 70kt 850mb jet
extending into the region from the lower Mississippi Valley. Precip
water values will climb to 1.00-1.25 inches within a narrow corridor.
With an abundance of instability and strong forcing aloft with mid
and upper level diffluence present as well...expect widespread rain
with embedded thunderstorms impacting the region Wednesday night.
The strong winds within the upper parts of the boundary layer should
be kept from reaching the surface by a developing inversion that
will hold into Thursday morning. Categorical pops are warranted late
Wednesday night and early Thursday.

The most active part of the forecast with respect to impacts will
come Thursday as the forecast sits wedged between the moisture plume
being drawn into the system and focused just east of the region...
and the approaching occluded front with another 850mb jet curling
around the base of the upper level low and pointed towards the area.
Model trends over the last day have slowed the progression of the
moisture plume and now focus it over the eastern half of the
forecast area east into the upper Ohio Valley on Thursday. The
presence of deeper moisture further west as stronger dynamics arrive
from the west suggest a bit better threat for rain and storms to
linger on Thursday and as the secondary low level jet arrives an
argument can be made for a few strong to severe storms that can
pull some of the higher winds aloft to the surface. BL shear and
helicity values remain impressive over the western part of the
forecast area while the deeper moisture is focused east. In
addition...instability levels remain weaker than desired for more
robust convection. All of the above produces a lower confidence on
convective coverage and strength for Thursday. That being
said...have bumped up pops substantially with highest categorical
pops over eastern counties. Model runs later today and tonight
will hopefully a bit more clarity with regards to convective
potential Thursday.

Still feel the primary impact on Thursday will be the high winds
with the presence of 60-70kt flow at 850mb and higher...but even
here the confidence in this occurring has lowered a bit from
previous model runs with uncertainty in cloud coverage and mixing
depth. Due to the slower departure eastward to the deeper moisture
plume...and clearing within the dry slot may be focused more over
the western half of the forecast area during the afternoon spreading
east prior to sunset. Model soundings remain impressive with a
potential for a few hours during the afternoon and early evening
where mixing levels may surge to 6-8kft and are supportive of peak
wind gusts to 50 mph and greater. Wind headlines of some sort will
eventually be needed but considering above thoughts...we are still
at a premature stage on introducing these headlines. Will continue
to highlight the threat via the HWO and social media platforms at
this time.

 

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3K NAM definitely looks interesting for Indiana and western Ohio. 

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