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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SPC MD 1393

MD 1393 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR EASTERN KANSAS…ADJACENT WESTERN MISSOURI

MD 1393 Image


Mesoscale Discussion 1393
NWS Storm Prediction Center Norman OK
0344 AM CDT Thu Aug 30 2018

Areas affected...Eastern Kansas...adjacent western Missouri

Concerning...Severe potential...Watch unlikely 

Valid 300844Z - 301045Z

Probability of Watch Issuance...5 percent

SUMMARY...An upscale growing cluster of thunderstorms is possible
through daybreak, with a mostly marginal severe hail risk possibly
transitioning to at least some potential for a few strong surface
gusts.  The need for a watch is not currently anticipated, but
trends will continue to be monitored.

DISCUSSION...An ongoing increase in thunderstorm development,
generally near/north of Wichita, appears largely in response to
forcing associated with low-level warm advection.  This is on the
nose of one branch of a modest 850 mb jet (around 30 kt), which
output from the Rapid Refresh suggests may develop northeastward
near/just west of the I-35 corridor through daybreak, before
weakening.  

In the presence of sizable CAPE (2000-3000+ J/kg) for moist parcels
based above a relatively stable near surface layer, but rather
modest to weak shear, convection appears likely to increase in
coverage.  This probably will remain focused to the east of the
warmer and more strongly capping elevated mixed-layer air (reflected
by the thermal gradient at 700 mb across central/eastern Kansas). 
The evolution of an upscale growing cluster of storms is possible. 
As this occurs, a mostly isolated/marginal severe hail threat
probably will diminish, but there could still become a period with
some increase in potential for strong wind gusts associated with a
developing eastward advancing (in the presence of 20 kt westerly
deep layer mean flow) cold pool, before activity weakens.

..Kerr/Edwards.. 08/30/2018

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

ATTN...WFO...SGF...EAX...TOP...ICT...

LAT...LON   39459566 39229476 37999406 37399489 37289639 37849792
            38599761 39459566 

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SPC MD 1368

MD 1368 CONCERNING SEVERE THUNDERSTORM WATCH 352… FOR NORTHERN MN

MD 1368 Image


Mesoscale Discussion 1368
NWS Storm Prediction Center Norman OK
0204 AM CDT Mon Aug 27 2018

Areas affected...Northern MN

Concerning...Severe Thunderstorm Watch 352...

Valid 270704Z - 270930Z

The severe weather threat for Severe Thunderstorm Watch 352
continues.

SUMMARY...Damaging wind threat spreading across northern Minnesota
with potential for WW 352 to be expanded east into part of the
Minnesota Arrowhead region.

DISCUSSION...At 0650Z, mosaic radar imagery showed a line of fast
moving (45-50 kt) storms extending from Ontario and across the
international border into northern MN (near KINL) and then southwest
to southern Beltrami and Hubbard Counties.  Although objective
analyses had indicated an increase in inhibition during Sunday
evening across northern MN, rising surface temperatures and dew
points per observations across northeast MN ahead of the line are
aiding in late night destabilization, and some steepening of
low-level lapse rates.  This is being aided further by steep
midlevel lapse rates spreading east across this region ahead of a
progressive shortwave trough. IR satellite imagery indicated cooling
cloud tops with the southern extent of the line, suggesting
intensifying storms.  Given these factors combined with strong
effective bulk shear, the threat for damaging winds persists
eastward overnight.

..Peters.. 08/27/2018

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

ATTN...WFO...DLH...FGF...

LAT...LON   46999468 47239526 47779483 48149375 48309356 48589345
            48639315 48439248 48219177 48169102 47789101 47309177
            47069310 46979385 46999468 

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SPC MD 1304

MD 1304 CONCERNING SEVERE THUNDERSTORM WATCH 338… FOR PARTS OF CENTRAL KANSAS

MD 1304 Image


Mesoscale Discussion 1304
NWS Storm Prediction Center Norman OK
0954 PM CDT Thu Aug 16 2018

Areas affected...Parts of central Kansas

Concerning...Severe Thunderstorm Watch 338...

Valid 170254Z - 170430Z

The severe weather threat for Severe Thunderstorm Watch 338
continues.

SUMMARY...Lingering thunderstorm activity and associated risk for
mainly severe hail is expected to gradually diminish late this
evening.  An additional severe weather watch is not anticipated.

DISCUSSION...A low-level baroclinic zone remains a focus for strong
to severe thunderstorm development near and east/southeast of
Salina.  This appears to be supported by a corridor of residual
moderate boundary layer instability (CAPE in excess of 2000 J/kg),
in the presence of  moderate to strong deep layer shear beneath
30-40 kt northwesterly 500 mb flow.  With the continuing progression
of the mid-level closed low into the middle Mississippi Valley and,
perhaps more importantly, continuing boundary layer cooling and
gradual stabilization, the lingering risk for severe hail and
locally strong surface gusts is expected to diminish through the
04-05Z time frame.

..Kerr.. 08/17/2018

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

ATTN...WFO...EAX...TOP...ICT...

LAT...LON   39019803 38969609 38649496 37639558 37629672 38259796
            39019803 

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SPC MD 1303

MD 1303 CONCERNING SEVERE THUNDERSTORM WATCH 338… FOR PARTS OF EASTERN KANSAS/WESTERN MISSOURI/NORTHEASTERN OKLAHOMA/NORTHWEST ARKANSAS

MD 1303 Image


Mesoscale Discussion 1303
NWS Storm Prediction Center Norman OK
0552 PM CDT Thu Aug 16 2018

Areas affected...Parts of eastern Kansas/western
Missouri/northeastern Oklahoma/northwest Arkansas

Concerning...Severe Thunderstorm Watch 338...

Valid 162252Z - 170015Z

The severe weather threat for Severe Thunderstorm Watch 338
continues.

SUMMARY...Thunderstorm activity will continue to develop across the
watch area and pose some risk for severe hail and wind into the 7-8
PM time frame.  Thereafter, continuing severe weather potential
remains unclear, but it is possible that another watch could become
necessary to the east, across parts of southern Missouri and
adjacent northern Arkansas.

DISCUSSION...Thunderstorm activity continues to increase to the
southeast of the Interstate 35 corridor of eastern Kansas.  This
activity appears focused along a weak baroclinic zone near the
southern periphery of a mid-level closed low now digging across the
middle Missouri Valley, where 30-40+ kt westerly 500 mb flow is
contributing to moderately strong deep layer shear.

Into the the early evening hours, it does appear that a gradual
merger/consolidation of this activity with vigorous thunderstorms
now developing along northeastward advancing convective outflow
(emanating from north central Oklahoma) will continue east of
Wichita, across the Chanute area into the southern Kansas/Missouri
border vicinity.  Subsequent evolution and the potential for an
appreciable continuing risk for severe hail and wind remain unclear
thereafter, due to generally weak low-level forcing for maintaining
convective development.  However, it appears at least possible that
one prominent surface cold pool could eventually emerge and maintain
vigorous convective development on its leading/eastern edge, tending
to propagate southeastward across the Interstate 44 corridor of
southwest Missouri, in the presence of 20-30 kt westerly deep layer
mean flow.

..Kerr.. 08/16/2018

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

ATTN...WFO...LSX...LZK...SGF...EAX...TSA...TOP...ICT...

LAT...LON   38739272 38299187 37199141 36349172 36139302 36339431
            36439490 36839606 37799724 38579564 38879336 38739272 

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SPC MD 1302

MD 1302 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR NORTHEAST KANSAS…NORTHWEST MISSOURI

MD 1302 Image


Mesoscale Discussion 1302
NWS Storm Prediction Center Norman OK
0312 PM CDT Thu Aug 16 2018

Areas affected...Northeast Kansas...northwest Missouri

Concerning...Severe potential...Watch likely 

Valid 162012Z - 162115Z

Probability of Watch Issuance...95 percent

SUMMARY...Scattered strong storms, some producing severe hail and
gusty winds, are expected within the next few hours. Issuance of a
Severe Thunderstorm Watch is likely soon.

DISCUSSION...Convective initiation has recently occurred just to the
west of TOP, south of a cold front, with additional storms expected
(as indicated by recent CAM guidance) over the next few hours.
Though directional low-level shear is present, 925-850 mb flow is
rather weak, with unidirectional shear present mainly above 850 mb.
Still, steep mid-level lapse rates on the order of 7.0+ C/km,
resulting in 1500+ J/kg MLCAPE, and 40 knots of effective bulk shear
suggest that organized updrafts are possible, with large hail a
concern. A few damaging wind gusts also cannot be ruled out,
especially given deep moisture throughout the troposphere (PWAT
values over 1.8 inches in many locales), which may promote wet
downbursts.

Given the relatively strong forcing for ascent associated with the
cold front and the propensity for multiple storms to develop in a
relatively favorable sheared/unstable environment, a Severe
Thunderstorm Watch will likely be issued for both the highlighted
area, and the region discussed in MCD 1301.

..Squitieri/Hart.. 08/16/2018

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

ATTN...WFO...EAX...TOP...

LAT...LON   38779537 38929598 39309627 39829620 39929608 39909557
            39969514 40219428 39929361 39449331 38859366 38779537 

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SPC MD 1301

MD 1301 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR CENTRAL/EASTERN OKLAHOMA…SOUTHEAST KANSAS

MD 1301 Image


Mesoscale Discussion 1301
NWS Storm Prediction Center Norman OK
0218 PM CDT Thu Aug 16 2018

Areas affected...Central/eastern Oklahoma...Southeast Kansas

Concerning...Severe potential...Watch possible 

Valid 161918Z - 162145Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated severe thunderstorms are possible during the
mid-late afternoon hours. Large hail and damaging gusty winds are
the primary threats. Convective trends are being monitored for the
potential issuance of a Severe Thunderstorm Watch.

DISCUSSION...A well-defined MCV, currently centered over northwest
Oklahoma, is propagating eastward, with scattered thunderstorms
ongoing across Alfalfa to Kingfisher Counties. Additional cells are
initiating along a surface boundary, where a pooling of higher
dewpoints (mid 70s F) were observed, roughly located from north of
END to GCM. 

The MCV is progressing eastward into an increasingly unstable
airmass, characterized by 1500-2000+ J/kg MLCAPE, mainly driven by
deep low-level moisture (72-75 F dewpoints) and noticeably steep low
and mid-level lapse rates of 6.5-7.5 C/km. Effective bulk shear
values are stronger in the northern regions of the discussion area
(i.e 30 knots), with weaker values (20 knots) farther south. 

Current thinking is that the greatest concentration of storms will
occur ahead of the MCV, along the aforementioned surface boundary,
where congealment into a multicellular complex is likely. Damaging
wind gusts associated with downbursts from water-loaded downdrafts
are more likely with the most intense storms. In addition, the
relatively steep 700-500 mb level lapse rates (evident via the 18Z
TOP special sounding) may also promote the generation of severe
hail, especially with some of storms associated with the stronger
deep-layer shear to the north. 

Confidence regarding the coverage of severe wind and hail are a bit
uncertain at this time, and convective trends are being monitored
for the potential issuance of a Severe Thunderstorm Watch as details
of severe coverage become more clear.

..Squitieri/Hart.. 08/16/2018

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

ATTN...WFO...SGF...TSA...TOP...ICT...OUN...

LAT...LON   35959797 36219805 36529807 37239787 38749752 38979662
            38609548 38109518 37429508 36849481 36389475 35759482
            35659592 35669672 35729736 35779788 35959797 

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SPC MD 1273

MD 1273 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF THE SOUTHERN PLAINS AND MID MISSOURI/MISSISSIPPI VALLEYS

MD 1273 Image


Mesoscale Discussion 1273
NWS Storm Prediction Center Norman OK
0456 PM CDT Fri Aug 10 2018

Areas affected...Portions of the Southern Plains and Mid
Missouri/Mississippi Valleys

Concerning...Severe potential...Watch unlikely 

Valid 102156Z - 110030Z

Probability of Watch Issuance...5 percent

SUMMARY...Thunderstorms continue to develop along/near a surface
boundary and an upper-level trough axis. Strong wind gusts are
possible.

DISCUSSION...Scattered pulse thunderstorms continue to develop
across this region in the vicinity of a surface boundary and
upper-level trough axis. Storms are forming in a moderately buoyant
environment (1500-2500 J/kg), but without strong shear and flow
aloft, a pulse storm mode should continue as outflow from
dissipating storms will help generate new storms. Strong daytime
heating has destabilized lower-levels and DCAPE of 1000+ J/kg
indicate the potential for strong wind gusts. Some severe wind
reports have already occurred in Oklahoma and the wind threat should
continue until around sunset when activity is likely to decrease.
The convection should remain unorganized and the overall severe wind
threat is limited/isolated, therefore, a watch is unlikely.

..Nauslar/Grams.. 08/10/2018

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

ATTN...WFO...LSX...LZK...SGF...EAX...TSA...TOP...ICT...OUN...
DDC...AMA...

LAT...LON   36450011 35540060 34960030 34479958 34569880 34909741
            34949541 35459465 35989411 36589312 36989247 37299193
            37699116 38199035 38669002 39039027 39159154 38859334
            37989600 37369830 37279852 36999968 36450011 

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SPC MD 1252

MD 1252 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR SOUTHEAST NEBRASKA…SOUTHERN IOWA…NORTHERN MISSOURI…FAR NORTHEAST KANSAS

MD 1252 Image


Mesoscale Discussion 1252
NWS Storm Prediction Center Norman OK
0638 PM CDT Mon Aug 06 2018

Areas affected...Southeast Nebraska...southern Iowa...northern
Missouri...far northeast Kansas

Concerning...Severe potential...Watch unlikely 

Valid 062338Z - 070145Z

Probability of Watch Issuance...20 percent

SUMMARY...Storms along a cold front will be capable of mainly severe
wind gusts with perhaps an isolated instance of severe hail. A WW is
not anticipated though trends in storm organization are being
monitored.

DISCUSSION...Storms have initiated along a cold front from Nemaha
County, KS northeastward to areas along the Iowa/Missouri border in
response to a mid-level wave approaching from the northwest. Local
subsidence in the wake of a weak disturbance now located in western
Illinois appears to be limiting storm coverage currently; however,
increasing influence of the upstream trough should increase coverage
with time. Effective bulk shear values of 30-45 kts -- increasing
modestly with time -- will support storm organization. Modest
mid-level lapse rates should limit the hail threat. Strong surface
heating has contributed to MLCAPE values of 2000-2500 J/kg and, with
low-level lapse rates of 8-9 C/km, a threat for severe wind gusts
will be greatest threat. Concerns regarding the overall coverage of
the threat make a WW unlikely. However, should a more organized
linear system evolve, a WW would be possible.

..Wendt/Hart.. 08/06/2018

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

ATTN...WFO...LSX...DVN...DMX...EAX...OAX...TOP...

LAT...LON   40689647 41209523 41269386 41009200 40619146 40179219
            39999350 39849463 39709564 39729637 40219669 40689647 

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