SPC MD 1483

MD 1483 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR PORTIONS OF WESTERN IOWA…EASTERN NEBRASKA…NORTH-CENTRAL AND NORTHEASTERN KANSAS…AND FAR NORTHWESTERN MISSOURI.

MD 1483 Image


Mesoscale Discussion 1483
NWS Storm Prediction Center Norman OK
0231 PM CDT Thu Sep 20 2018

Areas affected...Portions of western Iowa...eastern Nebraska...
north-central and northeastern Kansas...and far northwestern
Missouri.

Concerning...Severe potential...Watch likely 

Valid 201931Z - 202130Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorms capable of severe wind gusts will slowly
increase along the front and move east throughout the
afternoon/early evening. A Severe Thunderstorm Watch may be needed
for at least portions of the area.

DISCUSSION...A cold front trailing into southeastern Colorado from a
deepening surface low near SUX will serve as the primary forcing
mechanism for thunderstorm development this afternoon over this
area. The strong frontal forcing, rather weak shear in the
cloud-bearing layer, and veered low-level winds will support a
rather quick evolution to a squall line mode, especially along the
sharper portion of the front in Nebraska and far northern Kansas, as
depicted in multiple convection-allowing model guidance through the
morning.  The consolidating cold front/narrow cold pool is expected
to undercut the squall line, which will limit the overall severe
threat.  However, a deeply-mixed boundary layer with mixed-layer
LCLs of 1600-2200 m and moderate mid-level lapse rates could support
damaging wind gusts with the stronger embedded downdrafts that can
remain close to the front.  

Farther west, thunderstorms have developed along and slightly behind
the front in eastern Colorado and far western Kansas aided by the
southern fringe of an elongated mid-level vorticity maximum.  These
storms may evolve more as cluster compared to the squall line to the
northeast, but rather weak low-to-mid-level shear magnitudes should
prevent any long-lived organization with these storms. However,
severe wind gusts are possible given the moderate lapse rates and
evaporation potential in the deeply-mixed boundary layer as they
push east into west-central Kansas through the mid-late afternoon.

Overall, a Severe Thunderstorm Watch may be needed for at least
portions of the MCD area to cover the severe wind threat.

..Coniglio/Hart.. 09/20/2018

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

ATTN...WFO...DMX...EAX...FSD...OAX...TOP...ICT...GID...

LAT...LON   42339709 42659676 42979613 42949493 42869434 42589379
            41889388 40449476 39749536 39199627 38509775 38479883
            39559904 40329881 40609866 41089836 42339709 

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SPC MD 1474

MD 1474 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR SOUTH-CENTRAL…SOUTHEAST AND EAST-CENTRAL SD

MD 1474 Image


Mesoscale Discussion 1474
NWS Storm Prediction Center Norman OK
0248 AM CDT Tue Sep 18 2018

Areas affected...South-central...southeast and east-central SD

Concerning...Severe potential...Watch unlikely 

Valid 180748Z - 181015Z

Probability of Watch Issuance...20 percent

SUMMARY...An ongoing cluster of elevated storms moving to the east
across south-central South Dakota is expected to have a greater
potential to produce a periodic threat for large hail, as it tracks
into southeast and east-central South Dakota during the next few
hours.  If these storms are able to maintain their intensity, then
portions of far southwest Minnesota and adjacent northwest Iowa
could be affected, as well, toward 7 AM CDT.

DISCUSSION...IR imagery indicated cooling cloud tops again with the
ongoing eastward-moving SD cluster of storms, located in the
south-central part of this state at 0736Z.  A progressive midlevel
impulse shifting east from western SD/NE combined with warm
advection at the apex of the western branch of the central Plains
southerly low-level jet has been supporting this somewhat
disorganized cluster, as it moved through weaker instability. 
Although weak forcing aloft will be maintained as the impulse moves
east early this morning, this cluster will be advancing into the
eastern branch of the Great Plains low-level jet as it veers to
westerly by 12Z.  This latter evolution in the low-level wind field
will eventually limit convergence into this cluster of storms,
suggesting a diminishing trend in coverage of stronger storms and
potential decrease in activity.  Until this trend occurs, this
cluster of storms will begin to encounter stronger elevated
instability that is present across southeast SD into southwest MN
and northwest IA that should promote stronger updrafts in the short
term and larger hail at times.

..Peters/Edwards.. 09/18/2018

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

ATTN...WFO...MPX...FSD...ABR...UNR...

LAT...LON   43209889 43279946 43779986 44109981 44599938 44719857
            44829745 44749614 44319569 43399571 43139599 42989676
            43109825 43209889 

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SPC MD 1414

MD 1414 CONCERNING SEVERE THUNDERSTORM WATCH 365… FOR KANSAS

MD 1414 Image


Mesoscale Discussion 1414
NWS Storm Prediction Center Norman OK
0701 PM CDT Sun Sep 02 2018

Areas affected...Kansas

Concerning...Severe Thunderstorm Watch 365...

Valid 030001Z - 030200Z

The severe weather threat for Severe Thunderstorm Watch 365
continues.

SUMMARY...An isolated severe threat will be possible over the next
couple of hours across parts of central and northeastern Kansas.
Wind damage will be the primary severe weather hazard.

DISCUSSION...The latest radar imagery shows a large area of
thunderstorms extending from near the Kansas-Oklahoma state line
northward into far southern Nebraska. Numerous multicells are
ongoing in this cluster. This activity has overturned the airmass
across much of central Kansas. A pocket of moderate instability
likely exists a bit further east from near I-35 northeastward to
near Topeka. The RAP is estimating MLCAPE along this corridor in the
2000 to 2500 J/kg range which combined with 0-6 km of 30 kt on the
Topeka WSR-88D VWP should be sufficient for an isolated severe
threat. The instability combined with the moist airmass may result
in a few wet downbursts near severe limits over the next couple of
hours.

..Broyles/Thompson.. 09/03/2018

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

ATTN...WFO...TOP...ICT...GID...DDC...

LAT...LON   38579584 37969712 37419831 37339887 37549916 38059932
            38959896 39649831 39919778 39909724 39749560 38579584 

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SPC MD 1412

MD 1412 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR PORTIONS OF WEST-CENTRAL KANSAS…NORTH-CENTRAL KANSAS…PORTIONS OF NORTHEAST KANSAS…FAR SOUTHERN NEBRASKA

MD 1412 Image


Mesoscale Discussion 1412
NWS Storm Prediction Center Norman OK
0320 PM CDT Sun Sep 02 2018

Areas affected...Portions of west-central Kansas...north-central
Kansas...portions of northeast Kansas...far southern Nebraska

Concerning...Severe potential...Watch possible 

Valid 022020Z - 022215Z

Probability of Watch Issuance...40 percent

SUMMARY...A cluster of storms developing near Hays, KS is expected
to eventually congeal into a linear segment. Initial development
that can remain discrete will pose a threat for severe hail and
perhaps a tornado. With time, as storm coverage increases and cold
pools congeal, the primary threat will become severe wind gusts.
Convective trends will be monitored for possible WW.

DISCUSSION...A storm or two has recently initiated out of a cluster
of agitated cumulus on visible satellite imagery near Hays, KS.
Given the upstream ascent, evidenced by cirrus moving in from the
southwest on visible satellite, this activity should continue to
increase over the next few hours. Modest lapse rates near 6-6.5 C/km
and effective deep-layer shear of 35-45 kts will support storm
organization with isolated severe hail possible. A subtle
differential heating boundary/wind shift draped across northern
Kansas has enhanced the low-level hodograph curvature to a degree,
if a storm can remain discrete and interact with this boundary, a
tornado cannot be ruled out. However, as storm coverage increases,
as depicted in much of the CAM guidance, storm interactions and
upscale growth should limit tornado and hail potential. With time,
an east/northeastward propagating linear segment will pose primarily
a severe wind gust threat. Trends in convective mode/intensity will
be monitored for possible WW issuance.

..Wendt/Guyer.. 09/02/2018

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

ATTN...WFO...OAX...TOP...ICT...GID...DDC...GLD...

LAT...LON   39089980 39599887 40159695 40039579 39379571 38569743
            38279856 38109955 38300011 38770019 39089980 

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SPC MD 1409

MD 1409 CONCERNING SEVERE THUNDERSTORM WATCH 364… FOR PORTIONS OF IOWA…FAR NORTHERN MISSOURI…AND FAR NORTHWESTERN ILLINOIS

MD 1409 Image


Mesoscale Discussion 1409
NWS Storm Prediction Center Norman OK
1027 PM CDT Sat Sep 01 2018

Areas affected...Portions of Iowa...far northern Missouri...and far
northwestern Illinois

Concerning...Severe Thunderstorm Watch 364...

Valid 020327Z - 020430Z

The severe weather threat for Severe Thunderstorm Watch 364
continues.

SUMMARY...The severe threat continues across WW 364.

DISCUSSION...Widespread strong to marginally severe convection
continues across the WW at this time, although the combination of
widespread convective overturning and low-level
cooling/stabilization has tempered the severe threat somewhat. 
Nevertheless, newer updrafts in areas that have not been
convectively overturned will have access to steep mid-level lapse
rates and moderate to strong instability, supporting an isolated
hail and damaging wind threat for the next couple of hours or so. 
Additionally, forward-propagating linear segments entering
southwestern Iowa and vicinity will pose a threat for wind gusts
approaching severe thresholds.  Areas west of these linear segments
will have a decreased severe threat, and cancellations for portions
of WW 364 may be needed behind this line.

..Cook.. 09/02/2018

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

ATTN...WFO...LOT...ILX...DVN...DMX...EAX...OAX...TOP...

LAT...LON   41619539 42079493 42339269 42299109 42239015 42048972
            41718956 41238988 40939067 40569217 40289384 39989499
            40019585 40559598 41039591 41619539 

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SPC MD 1408

MD 1408 CONCERNING SEVERE THUNDERSTORM WATCH 363… FOR SOUTHEAST NE

MD 1408 Image


Mesoscale Discussion 1408
NWS Storm Prediction Center Norman OK
0939 PM CDT Sat Sep 01 2018

Areas affected...Southeast NE

Concerning...Severe Thunderstorm Watch 363...

Valid 020239Z - 020415Z

The severe weather threat for Severe Thunderstorm Watch 363
continues.

SUMMARY...Damaging winds and large hail remain a severe weather
threat across the southeast Nebraska portion of WW 363.  The storms
located generally west and southwest of Saline and Jefferson
Counties, NE should continue to diminish in intensity, as the
stronger storms advance toward southwest Iowa.  The western half or
western two thirds of WW 363 will likely be canceled early.

DISCUSSION...Long-lived cluster of storms, with a history of
producing severe wind gusts, is now moving into the far eastern
portion of WW 363 in southeast NE where storms have already occurred
or are ongoing, though the environment remains very unstable. 
Effective bulk shear vectors oriented parallel to the surface
boundary extending through southeast NE and then east across
southern IA continue to favor bowing line segments.  The favorable
CAPE/shear parameter space will support damaging winds and large
hail across the eastern third of WW 363.  The recent tracks of the
Lancaster, Otoe, Johnson to Saline cluster of storms indicated these
storms should exit WW 363 into WW 364 between 03-0330Z, allowing the
former watch to expire as scheduled or a little early.

..Peters.. 09/02/2018

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

ATTN...WFO...EAX...OAX...TOP...ICT...GID...DDC...

LAT...LON   38759974 40299861 41359665 41369592 40039544 39989618
            39649630 39569731 39309735 39309786 38879794 38849844
            38739850 38709932 38759974 

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SPC MD 1407

MD 1407 CONCERNING SEVERE THUNDERSTORM WATCH 363… FOR NORTHERN KS AND SOUTHEASTERN NE

MD 1407 Image


Mesoscale Discussion 1407
NWS Storm Prediction Center Norman OK
0638 PM CDT Sat Sep 01 2018

Areas affected...Northern KS and southeastern NE

Concerning...Severe Thunderstorm Watch 363...

Valid 012338Z - 020145Z

The severe weather threat for Severe Thunderstorm Watch 363
continues.

SUMMARY...Large hail and strong, damaging wind gusts remain severe
threats as storms continue to increase in coverage and intensity
across north-central Kansas, and develop/track to the northeast into
southeast Nebraska this evening.

DISCUSSION...Trends in mosaic radar imagery since 2130Z showed a
cluster of intense storms is tracking to the northeast across
north-central KS, with this cluster centered on Osborne/western
Mitchell Counties at 2325Z.  Meanwhile, additional strong/intense
cells have developed immediately downstream into Jewell County near
the surface boundary which extends from the ongoing cluster into
southeast NE.  Further strengthening of a southerly low-level jet
with increasing warm advection this evening into northern KS and
eventually southeast NE will allow for continued thunderstorm
development.  This combined with the ongoing larger storm cluster
tracking into stronger instability with east-northeast extent
suggests similar storm intensities can be expected with large hail
and damaging winds the primary threats.  If a cold pool becomes
established with the north-central KS cluster, then damaging winds
will become the primary threat, as the low-level jet veers to
southwesterly into southeast NE.

Additional strong to severe storms have also formed along the
southwest flank/outflow boundary of the initial cluster of storms,
mainly in vicinity of Ellis County where the environment remained
unstable and sufficiently sheared.  Until these latter storms
weaken, the southwest portion of WW 363 should not be canceled.

..Peters.. 09/01/2018

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

ATTN...WFO...EAX...OAX...TOP...ICT...GID...DDC...

LAT...LON   38599961 38999933 39229906 39699896 40119861 40549810
            41099683 41399674 41389599 40299553 40019606 39599626
            39279736 39169780 38879794 38659856 38599961 

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SPC MD 1402

MD 1402 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR WESTERN/CENTRAL KS…SOUTH-CENTRAL NE

MD 1402 Image


Mesoscale Discussion 1402
NWS Storm Prediction Center Norman OK
0245 PM CDT Sat Sep 01 2018

Areas affected...Western/Central KS...South-Central NE

Concerning...Severe potential...Watch possible 

Valid 011945Z - 012145Z

Probability of Watch Issuance...40 percent

SUMMARY...Gradually increasing thunderstorm coverage is anticipated
with a resulting threat for a few instances of strong wind gusts
and/or large hail. Trends are being monitored for a possible watch.

DISCUSSION...Visible satellite imagery has shown increased vertical
development within the cluster of predominately mid-level cloudiness
moving northeastward through western KS. This cloudiness is most
likely tied to lift attendant to the shortwave trough moving into
the same area. This lift, coupled with convergence along a surface
trough and continued airmass destabilization (supported by diurnal
heating and moisture advection), is expected to result in increased
thunderstorm coverage over the next hour or two. The development
early in this time frame will likely be elevated but eventual
surface-based development is anticipated. 

Vertical shear is strong enough to support storm organization and
robust updrafts. High-based character to these thunderstorms will
favor the development of potentially strong downdrafts, which
appears to be the primary severe threat. Some large hail is also
possible within the more organized updrafts. Uncertainties regarding
severe coverage preclude high watch probabilities but convective
trends will be monitored closely.

..Mosier/Grams.. 09/01/2018

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

ATTN...WFO...OAX...TOP...ICT...GID...DDC...GLD...

LAT...LON   39150088 40190033 40679887 40229730 39059752 38499862
            37920052 39150088 

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SPC MD 1399

MD 1399 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR SOUTHEAST NEBRASKA INTO CENTRAL IOWA AND NORTHERN MISSOURI

MD 1399 Image


Mesoscale Discussion 1399
NWS Storm Prediction Center Norman OK
0847 PM CDT Fri Aug 31 2018

Areas affected...southeast Nebraska into central Iowa and northern
Missouri

Concerning...Severe potential...Watch possible 

Valid 010147Z - 010345Z

Probability of Watch Issuance...60 percent

SUMMARY...Scattered storms capable of large hail are expected to
develop this evening.

DISCUSSION...An very unstable air mass currently resides along and
west of a warm front roughly along the MO River. The 00Z OAX and TOP
soundings both show MLCAPE in excess of 3000 J/kg, with MUCAPE of
4000-5000 J/kg. In addition, low level shear near the warm front is
strong, owing to large looping hodographs in a warm advection
regime.

Although the air mass is largely capped, a southwesterly low-level
jet increasing to around 50 kt will maintain lift, while the
presence of steep lapse rates aloft support strong updrafts capable
of hail. Overall, convection may remain disorganized, but the amount
of available instability will likely support large to damaging hail
in some of the cells. Therefore, a watch cannot be ruled out this
evening if storm trends suggest more than an isolated severe threat.

..Jewell/Thompson.. 09/01/2018

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

ATTN...WFO...DMX...EAX...FSD...OAX...GID...

LAT...LON   39649467 40019525 40159633 40419735 40859759 41389725
            41969637 42229572 42229461 41999385 41589315 40959266
            40359249 39849267 39589301 39479367 39649467 

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SPC MD 1396

MD 1396 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR SOUTHEAST NE…NORTHEAST KS…NORTHWEST MO…WESTERN/CENTRAL IA

MD 1396 Image


Mesoscale Discussion 1396
NWS Storm Prediction Center Norman OK
0110 AM CDT Fri Aug 31 2018

Areas affected...Southeast NE...Northeast KS...Northwest
MO...Western/Central IA

Concerning...Severe potential...Watch unlikely 

Valid 310610Z - 310845Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated severe hail is possible with elevated convection
overnight.

DISCUSSION...ACCAS field over southeast NE/northeast KS has recently
blossomed into deep convection. Steep midlevel lapse rates noted on
area 00Z soundings are supporting moderate elevated instability
across the region, with MUCAPE of 1000-2000 J/kg noted per recent
mesoanalyses. Most CAM guidance suggests elevated convection will
increase in coverage across western/central IA later tonight (around
08-09Z). While the timing is somewhat uncertain, an increase in
convection with time appears plausible as a relatively strong
low-level jet remains focused into the area and the plume of steep
midlevel lapse rates is maintained from the west. 

Midlevel flow is sufficient for effective shear of 30-40 kt for
convection rooted around 800 mb, which will support at least
transient updraft organization with a potential for severe hail.
Most CAM guidance suggests a dominant cluster mode, which would be
somewhat unfavorable for a more organized hail threat, and watch
issuance is currently considered unlikely. However, if a trend
toward more long-lived discrete modes is observed overnight, then
the watch potential will be reconsidered.

..Dean/Edwards.. 08/31/2018

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

ATTN...WFO...DMX...EAX...FSD...OAX...TOP...

LAT...LON   39299587 40219646 42129597 43469502 43419401 43099341
            42379306 41409315 40489358 39589416 39139478 39079532
            39299587 

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