SPC - No watches are valid as of Sun May 16 18:30:02 UTC 2021

No watches are valid as of Sun May 16 18:30:02 UTC 2021.

SPC MD 635

MD 0635 Image

Mesoscale Discussion 0635
NWS Storm Prediction Center Norman OK
0127 PM CDT Sun May 16 2021

Areas affected...eastern Kansas western Missouri

Concerning...Severe potential...Watch unlikely 

Valid 161827Z - 162000Z

Probability of Watch Issuance...20 percent

SUMMARY...A few strong/severe thunderstorms may develop this
afternoon along and south of an outflow boundary across the Kansas
Missouri border. Damaging wind gusts and hail will be possible.

DISCUSSION...1800 UTC RADAR observation showed a poorly organized
cluster of thunderstorm across portions of eastern Kansas and
western Missouri ahead of an MCV across central Oklahoma. To the
south of the ongoing complex, a well defined outflow boundary was
observed in the vicinity of the Kansas City Metro. A few
thunderstorms have developed along and south of this boundary within
the last half hour. Visible satellite and surface data show clearing
and warming are ongoing to the south and east of these storms across
southern Missouri and northwest Arkansas. Airmass recovery from
earlier cloud cover appears to be underway with surface temperatures
and dewpoints in the low 70s and low 60s F respectively contributing
to 1000-1500 J/kg of MLCAPE from SPC mesoanalysis. 

Primary uncertainty revolves around the limited potential for
convective organization given weak mid and upper-level flow. Some
increase in the weak bulk-shear profile (currently < 25 kts) is
possible as the MCV across Oklahoma spreads northeastward over the
next couple of hours. The main severe threat with storms through
this afternoon will be damaging winds, but some potential for
near-severe hail will remain possible given mid-level lapse rates
around 7 C/km. Convective trends will be monitored, but uncertainty
on storm organization suggests a weather watch is unlikely.

..Lyons/Guyer.. 05/16/2021

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


LAT...LON   38759510 39249390 39299282 39259219 38829173 38029161
            37639202 37149312 37209553 37369599 38069621 38759510 

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SPC MD 634

MD 0634 Image

Mesoscale Discussion 0634
NWS Storm Prediction Center Norman OK
1215 PM CDT Sun May 16 2021

Areas affected...Central/East TX

Concerning...Severe potential...Watch unlikely 

Valid 161715Z - 161915Z

Probability of Watch Issuance...20 percent

SUMMARY...A few strong to severe storms possible this afternoon
across portions of central and east TX. Isolated damaging wind gusts
are the primary threat.

DISCUSSION...Regional satellite and radar imagery reveals a pair of
MCVs across the southern Plains, one over central OK and the other
along the middle TX Coast. Modest southerly low-level flow exists
between these two features, roughly along and east of I-35. The
thermodynamic environment is expected to remain only marginally
buoyant, with overall buoyancy tempered by the limited diurnal
heating. Even so, thunderstorms are expected to persist while
gradually drifting eastward throughout the day. 

Surface winds have been backing a bit more southeasterly just ahead
of the storms, which, when coupled with the modest low-level
southerly flow and westerly flow aloft, result in a kinematic
profile that could support a supercell or two. Damaging wind gusts
would be the primary threat with any stronger updrafts/supercells,
with some low-probability potential for a brief tornado as well.
Marginal and isolated nature of the severe threat is expected to
preclude the need for a watch.

..Mosier/Guyer.. 05/16/2021

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


LAT...LON   31549740 32299689 32619581 32419494 31799459 30429490
            29919706 30389770 31549740 

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SPC May 16, 2021 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1142 AM CDT Sun May 16 2021

Valid 161630Z - 171200Z


Scattered strong/severe thunderstorms are once again expected across
portions of the central and southern Plains late this afternoon and
evening. Large hail and severe wind gusts are the most likely risks.

...Central/Southern Plains...
To the east of an east/southeastward-spreading upper low over the
Desert Southwest, the leading edge of weak height falls will extend
into the central/southern High Plains later today. In vicinity of a
surface low, a front will continue southeastward across the
south-central High Plains through tonight while a
north/south-oriented dryline extends southward into the Trans-pecos
region of west/southwest Texas.

Similar to yesterday, the greatest threat of initial strong/severe
development is expected late this afternoon/early evening from
east-central/southeast Colorado to along the New Mexico/Texas border
vicinity including western portions of the Texas/Oklahoma
Panhandles. It is also plausible that ample moisture/heating and
convergence in vicinity of the dryline leads to at least isolated
deep convective development late this afternoon across
west/southwest Texas, where deep-layer shear/ample instability could
support a few supercells capable of large hail. The most probable
zone of severe thunderstorm development and organization into this
evening will likely be across the Texas Panhandle and nearby south
Plains/Low Rolling Plains. Initial multicells/supercells capable of
large hail are expected. Over time, storm mergers should lead to a
tendency for storm clustering/MCS development this evening with
damaging wind potential also increasing.

Farther east, a few transient supercells could occur this
afternoon/early evening across central/northern parts of Texas into
Oklahoma in association with an MCV and/or warm conveyor.

...Nevada into northeast Colorado...
As the upper trough moves into the southwest states today, a
consensus of model solutions indicate an arcing band of showers and
thunderstorms will develop from northeast NV into parts of
UT/ID/WY/CO. Very steep low/mid level lapse rates and sufficient
CAPE suggest a risk of isolated hail and gusty winds for a few hours
this afternoon and early evening.

..Guyer/Lyons.. 05/16/2021

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SPC May 16, 2021 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook
Day 2 Outlook Image
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1228 PM CDT Sun May 16 2021

Valid 171200Z - 181200Z


Severe thunderstorms capable of very large hail, damaging wind, and
a couple of tornadoes will be possible Monday afternoon into Monday
night from portions of the central and southern High Plains into
southwest Texas.

The large-scale pattern will become more favorable for organized
convection within parts of the central and southern High Plains as
an upper-level trough moves into the Four Corners. Another dryline
will set up across this region and become the focus for the
development of severe convection during the afternoon/evening. Shear
profiles and mid-level lapse rates will favor large/very-large hail
with initial supercell storm modes. Strong boundary-layer
instability will then favor an increasing threat for damaging/severe
winds as storms grow upscale into the evening. A couple of tornadoes
will be possible early in the convective cycle. Farther east into
the broader central/southern Plains. MCVs from convection on Sunday
night will provide focus for convective development as the airmass
destabilizes during the afternoon.

...Texas Panhandle/South Plains...
Strong instability is expected to develop ahead of the dryline on
Monday. MLCAPE values of 3000-3500 J/kg are forecast in the warm
sector. Compared to previous days, southwesterly flow aloft will be
increasing during the day as the upper-trough moves into the Four
Corners. 40-50 kts of effective shear orthogonal to the dryline will
favor supercells initially. The initial storms will be capable of
very large hail and a couple of tornadoes. Tornado potential will
likely be maximized near where outflow from Sunday night's
convection intersects with the dryline. Low-level hodographs will
enlarge toward late afternoon and early evening with a modest
increase in the low-level jet. With time, storms are expected to
grow upscale into an MCS and propagate eastward. Damaging/severe
winds are probable along with this activity as the airmass will
remain unstable into the evening. There is some uncertainty
regarding the northern extent of the greatest severe risk given the
potential impact of overnight MCS on Sunday. However, guidance is in
general agreement that airmass recovery will occur during the day.

...Western/Central Oklahoma...
Forecast soundings indicate that the airmass will remain unstable
into the evening. Given the expected development of an MCS to the
west, damaging wind gusts appear probable as these storms move into
western/central Oklahoma later in the period. Given the storm mode,
large hail will likely be more isolated.

...Edwards Plateau/Hill Country Vicinity...
Storm coverage is expected to be more a bit more sparse within the
region on account greater capping. However, similarly strong
instability and effective shear will bring potential for a isolated
supercells to develop with an attendant very large hail and damaging
wind gusts threat. Should any clusters form in this region, it is
possible that a more organized wind threat could evolve during the

..Wendt/Jewell.. 05/16/2021

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SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook Image
Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1054 AM CDT Sun May 16 2021

Valid 161700Z - 171200Z

No changes. Previous discussion follows.

..Bentley.. 05/16/2021

.PREV DISCUSSION... /ISSUED 0123 AM CDT Sun May 16 2021/

A closed upper-level low embedded in a mid-level trough over
portions of California/Nevada will slowly shift east throughout the
day, sliding into portions of the lower Great Basin by the end of
the period. As this occurs, a broad region of marginally enhanced
southwesterly mid-level flow will overspread much of the Southwest
into the southern High Plains throughout the day. At the surface,
warm/dry conditions are expected to persist.

...Southwest into West Texas...
Diurnal heating/mixing processes will allow some of the marginally
enhanced mid-level flow to mix toward the surface, resulting in
sustained southwesterly winds of 10-15 mph. Meanwhile, RH values
should fall into the teens and single digits. Fuels across the
region remain at least marginally receptive to large-fire spread.
Thus elevated fire-weather conditions can be expected, with perhaps
some localized critical fire-weather conditions possible where winds
manage to be a bit stronger.

...Northern ND into northwest MN...
A surface low will track through south central portions of Canada
throughout the day, with southwesterly post-frontal surface flow
extending into northern portions of North Dakota into far northwest
Minnesota. RH values should fall into the teens to lower 20s, with
sustained winds of 10-15 mph. Locally elevated conditions can be
expected across this region, but such conditions appear too
localized to warrant any highlights at this time.

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

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