Severe WX Severe Weather Event 3/28/17-3/31/17

[ChaninCullman]

If this doesn't do anything, I think a lot of people will start paying less attention to severe weather outlooks more than 24 hours out from the event. In my area, we've had several consecutive events forecast 2 days out to be fairly significant and turn out to be pretty much nothing. When that happens too many times in a row, people get real cynical.

There's people who are not going to pay attention period, with everything that's happened in the past with destructive storms in Alabama, if people don't take into consideration the possibility we could have more storms, there's nothing that will change their minds.

 

[TWBot]

MD 0377 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR COASTAL MS AND AL

​

Mesoscale Discussion 0377
NWS Storm Prediction Center Norman OK
1110 AM CDT Thu Mar 30 2017

Areas affected...coastal MS and AL

Concerning...Severe potential...Watch unlikely

Valid 301610Z - 301715Z

Probability of Watch Issuance...20 percent

SUMMARY...While wind damage is perhaps possible on a localized and
intermittent basis, the expected coverage and magnitude of this
possible risk will likely preclude a severe thunderstorm watch.

DISCUSSION...Visible satellite imagery shows a cumulus field over
the coastal counties of MS east into the FL Panhandle and surface
observations show temperatures have warmed into the upper 70s with
dewpoints near 70 degrees F. 500-mb upper air analysis this morning
shows the leading edge of more appreciable height falls (30-60 m per
12 hours) have overspread the coastal plain of MS/AL. Background
upward vertical motion associated with mid- to upper-level forcing
for ascent and 50+ kt flow at 500-mb are aiding in the maintenance
of the squall line over coastal MS southward to the Mouth of the MS
River. A 25-kt gust was measured at KASD at 1451z in association
with the squall line.

Analysis of the KMOB VAD data shows speed shear in the lowest 5-km
but the unidirectional southerly flow will probably prove
unfavorable for isolated 50-60 mph gusts and resultant widespread
wind damage given the north-south orientation of the convective
line. Nonetheless, the mature trailing stratiform convective line
will likely continue to move east across coastal MS/AL during the
next several hours. Localized/intermittent wind damage is possible,
but the weakness in mid-level lapse rates and aforementioned
concerns on the flow geometry imply the need for a severe
thunderstorm watch is low.

..Smith/Guyer.. 03/30/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MOB...LIX...

LAT...LON 30168918 30678923 30838764 30358745 30168918


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[Bama Ravens]

Now most of MS is out of the slight risk:

 

[TWBot]

MD 0378 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR CENTRAL AND SOUTHERN IL...SOUTHEAST MO...WESTERN KY

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Mesoscale Discussion 0378
NWS Storm Prediction Center Norman OK
1156 AM CDT Thu Mar 30 2017

Areas affected...central and southern IL...southeast MO...western KY

Concerning...Severe potential...Watch likely

Valid 301656Z - 301800Z

Probability of Watch Issuance...80 percent

SUMMARY...Storms will likely continue to develop and intensify near
the cold front. A wind-damage risk will likely develop this
afternoon. Hail is possible once stronger updrafts become sustained
and a tornado threat may focus near the warm front as storms
interact with the low-level vorticity rich environment.

DISCUSSION...Radar mosaic at 1645z shows a broken band of
thunderstorms across eastern and southeastern MO. Subjective
surface mesoanalysis places a warm front 30 miles north of STL
eastward to Indianapolis with a destabilizing warm sector across the
lower OH and middle MS Valleys with temperatures warming into the
upper 60s and dewpoints near 60 degrees F---yielding around 1000
J/kg SBCAPE per modified RAP soundings which is slightly greater
than objective analysis fields. Deep southerly flow strengthening
with height is resulting in 35-40 kt effective shear. Along the
warm frontal zone where the winds are relatively backed, an enlarged
hodograph yields around 150 m2/s2 0-1km SRH.

A mixed mode of both linear structures and cells are expected to
evolve within the convective band and move into IL/KY during the
next few hours. Hail may accompany the stronger cells. Wind damage
and isolated strong/severe gusts are possible with the cells and
linear segments as greater storm organization occurs this afternoon.
The conditional tornado risk may tend to focus near the warm front
and likely be predicated/dependent on a strong updraft interacting
favorably with the low-level vorticity rich environment.

..Smith/Guyer.. 03/30/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...PAH...ILX...MEG...LSX...

LAT...LON 39159074 39628990 40158841 39888795 38688794 37538824
36678881 36368962 36399010 39159074


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[ARCC]

From past experience I would say the biggest threat will be along the track of the MCS and Mesolow along the coast. Don't be surprised to see some powerful supercells come ashore in that area of uninhibited cape and localized high helicity.

 

[gangstonc]

Sun is out nicely in Huntsville.

I think the meteorologists did a great job with this forecast and relaying it to the public. They really took the time on social media to explain all the potential scenarios and their likelihood.

 

[TWBot]

MD 0379 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR CENTRAL/SOUTHERN IN...FAR NORTHERN KY...WESTERN OH

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Mesoscale Discussion 0379
NWS Storm Prediction Center Norman OK
1255 PM CDT Thu Mar 30 2017

Areas affected...Central/Southern IN...far northern KY...western OH

Concerning...Severe potential...Watch likely

Valid 301755Z - 302000Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorm coverage will increase over the next hour or
so, with an attendant increase in the severe threat as well.
Damaging wind gusts and few tornadoes are possible and a watch will
likely be needed across portions of the area to cover the potential
threat.

DISCUSSION...Visible satellite imagery shows that cumulus clouds
have increased in the area of clearing across western IN over the
past half hour, suggesting both an increase in the forcing for
ascent as well as some destabilization. Wave structure to the new
clouds suggests the area remains stable but continued moisture
advection into the region should result in further destabilization
and an overall environment more supportive of surface-based storms.

Strong kinematic fields across the region have been sampled well by
area VAD profiles. Recent data from IND and ILX reported 0-6 km bulk
shear around 50 kt, which is more than sufficient for organized
updrafts. The somewhat limited instability and poor mid-level lapse
rates should limit hail production within these organized updrafts
but damaging wind gusts and a few tornadoes are still possible. The
tornado threat will be locally higher in those areas where the
surface winds remain backed, especially near the warm front. Given
this potential threat, a watch will likely be needed across portions
of the region this afternoon and evening.

..Mosier/Guyer.. 03/30/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...ILN...LMK...IWX...IND...PAH...ILX...

LAT...LON 39008758 40078760 40548648 40228344 39288335 38428430
37848800 39008758


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[Bama Ravens]

This is from the latest AFD from BMX, pretty interesting.

Now the north. Kept this threat roughly intact from 4 pm through 1
am. This would largely be associated with the large scale lift
from the upper trough and northern stream jet and the surface
front. Currently, a very odd occurrence has made this area rather
stable. A less than impressive fine line from previous convection
moved through the northern counties this morning. This fine line
was associated with a wake low/gravity wave. Gusty winds and very
stable low level has overspread the north behind this feature. The
question will be can this area recover enough for additional
storms. A few peaks of sun are evident near the Mississippi River
with some cumulus developing. Model output...Hi-Res and
global...do not match and no consensus exist. I think there still
is a chance that enough instability will be possible for a few
severe storms north. There is better shear located north and will
keep things as is at this time.

 

[HazardousWx]

I know we had some on and off sunshine up here in Huntsville and temps are 76-77 range with 61F dewpoint and strong southerly winds.

 

[TWBot]

MD 0380 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHERN AL...WESTERN FL PANHANDLE

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Mesoscale Discussion 0380
NWS Storm Prediction Center Norman OK
0144 PM CDT Thu Mar 30 2017

Areas affected...Southern AL...western FL Panhandle

Concerning...Severe potential...Watch possible

Valid 301844Z - 301945Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated wind damage and hail is possible across southern
AL for the next few hours. Isolated damaging wind gust/tornado
threat is also possible ahead of the line across the western FL
panhandle.

DISCUSSION...Thunderstorm coverage has increased over the past hour
across southern AL, with several of these storms exhibiting
supercellular characteristics, particularly the storm which
developed over Escambia county (now in Butler county). This increase
in activity appears to be associated with the arrival of better low
to mid-level moisture and possibly an increase in large-scale
forcing for ascent as the upper level jet streak approaches the
region. The airmass across the region is currently moderately
unstable and the shear is expected to gradually increase over the
next few hours and mid-level flow increases. The close proximity of
much of this development suggests a mixed storm mode with
clusters/small bowing segments likely dominating. As a result, the
primary severe threat will likely result from storm mergers, at
least over the next few hours. Some hail and damaging wind gusts are
possible.

Farther south, the ongoing line of storms currently moving through
southern AL will continue eastward into the western FL panhandle
during the next hour so. Surface winds ahead of the line aren't
particularly strong but the more southeasterly character of these
winds coupled with a moist low-level airmass will support an
isolated damaging wind gust/tornado threat.

..Mosier/Guyer.. 03/30/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...TAE...BMX...MOB...

LAT...LON 30448720 31118796 31828802 32508731 32728593 32338513
30888556 30448720


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[gangstonc]

I know we had some on and off sunshine up here in Huntsville and temps are 76-77 range with 61F dewpoint and strong southerly winds.

Yes, you can feel that the atmosphere has destabilized somewhat up here.

 

[Richardjacks]

There may be just enough instability to fire a few storms in north Alabama this afternoon and evening. If so, they will need to be watched closely with just enough speed shear available and maybe some enhanced low level shear due to leftover boundaries.

 

[Bama Ravens]

Interestingly, my DP here north of Birmingham has actually gone down to 58. The wind sort of has a cool feel to it.

Clouds have also hung tough.

 

[CheeselandSkies]

Meanwhile in Indiana, that tornado-warned storm actually appears to be becoming more supercellular (was the center part of a bowing line segment when the initial warning went out) and looks like it wants to turn right and hug the warm front. Smaller cell that just developed near Pittsboro may race NNE and smash into it, though.

 

[Taylor Campbell]

Nice supercell structures in southeast Alabama.

 

[Lori]

From past experience I would say the biggest threat will be along the track of the MCS and Mesolow along the coast. Don't be surprised to see some powerful supercells come ashore in that area of uninhibited cape and localized high helicity.

That happened various times during the winter severe wx.

 

[Hailey]

New day 1


Sent from my iPhone using TalkWeather mobile app

 

[Bama Ravens]

New day 1


Sent from my iPhone using TalkWeather mobile app

Clearly they don't have much confidence in the line along the cold front.

 

[TWBot]

MD 0381 CONCERNING SEVERE THUNDERSTORM WATCH 103...104... FOR WESTERN KY...SOUTHERN AND EAST-CENTRAL IL...SOUTHWEST INTO CENTRAL IN...WEST-CENTRAL OH

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Mesoscale Discussion 0381
NWS Storm Prediction Center Norman OK
0327 PM CDT Thu Mar 30 2017

Areas affected...western KY...southern and east-central
IL...southwest into central IN...west-central OH

Concerning...Severe Thunderstorm Watch 103...104...

Valid 302027Z - 302100Z

The severe weather threat for Severe Thunderstorm Watch 103, 104
continues.

SUMMARY...Isolated marginally severe hail and strong to locally
severe gusts are possible this afternoon with the stronger storms.
A low risk for a tornado will likely focus over central and
east-central Indiana within tornado watch 104.

DISCUSSION...Radar mosaic shows a broken band of line segments and
cells from north to south from central IL into western TN. Cellular
storms continue to develop ahead of the band in the free warm sector
across the lower Wabash Valley and into central Indiana and
west-central OH. A warm front is slowly advancing northward across
central Indiana and west-central OH and is evident by temperatures
warming into the middle 60s from the upper 50s along the I-69
corridor northeast of Indianapolis. Easterly low-level flow is
being maintained immediately north of I-70 in central Indiana and OH
and is resulting in enlarged hodographs which may bolster a narrow
north-south corridor for weak supercell tornado potential.
Elsewhere away from the warm front, tornado potential appears
significantly limited as both low-level shear and surface
temperature-dewpoint spreads become less favorable for low-level
mesocyclones. However, warmer temperatures over the lower Wabash
Valley and eastward across south-central Indiana have resulted in
steepened 0-3 km lapse rates. Isolated damaging winds via
strong/locally severe gusts and marginally severe hail with the more
intense updrafts will likely be the main hazards with this activity
as it moves eastward across the lower Wabash Valley and into
south-central Indiana over the next 2-3 hours.

..Smith.. 03/30/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...ILN...LMK...IWX...IND...PAH...ILX...LSX...

LAT...LON 39938879 40278800 40368745 40548637 40568464 40288425
39858425 39528472 39028671 37668762 36858822 37058874
39938879


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For additional SPC information click here

 

[Chris3024]

Wind is roaring out of the south here in Cullman county