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Storm Prediction Center

06/23/2018 02:55 PM
SPC Severe Thunderstorm Watch 207 Status Reports
WW 0207 Status Updates
WW 0207 Status Image

STATUS FOR WATCH 0207 HAS NOT BEEN ISSUED YET
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06/23/2018 02:55 PM
SPC Severe Thunderstorm Watch 207
WW 207 SEVERE TSTM OK TX 232055Z - 240300Z
WW 0207 Image

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 207
NWS Storm Prediction Center Norman OK
355 PM CDT Sat Jun 23 2018

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Parts of central and western Oklahoma
  Extreme northwest Texas

* Effective this Saturday afternoon and evening from 355 PM until
  1000 PM CDT.

* Primary threats include...
  Scattered large hail and isolated very large hail events to 2.5
    inches in diameter possible
  Scattered damaging wind gusts to 70 mph possible
  A tornado or two possible

SUMMARY...Thunderstorm development is expected in the next couple of
hours along a stalled boundary near I-40, from the southern Oklahoma
City metro area westward.  The storm environment favors supercells
capable of producing very large hail and damaging winds.  A modest
increase in low-level shear this evening could also support the
threat for an isolated tornado, though this threat is secondary to
the hail and wind.  Some clustering of storms and southward
movement/development will be possible later this evening across the
southern portions of the watch area.

The severe thunderstorm watch area is approximately along and 50
statute miles north and south of a line from 30 miles west southwest
of Clinton OK to 50 miles north northeast of Ardmore OK. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 205...WW 206...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
30015.

...Thompson

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06/23/2018 02:20 PM
SPC Severe Thunderstorm Watch 206 Status Reports
WW 0206 Status Updates
WW 0206 Status Image

STATUS FOR WATCH 0206 HAS NOT BEEN ISSUED YET
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06/23/2018 02:20 PM
SPC Severe Thunderstorm Watch 206
WW 206 SEVERE TSTM CO KS NM OK 232020Z - 240300Z
WW 0206 Image

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 206
NWS Storm Prediction Center Norman OK
220 PM MDT Sat Jun 23 2018

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  East central and southeast Colorado
  Western Kansas
  Extreme northeast New Mexico
  The extreme western Oklahoma Panhandle

* Effective this Saturday afternoon and evening from 220 PM until
  900 PM MDT.

* Primary threats include...
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  Scattered damaging wind gusts to 70 mph possible

SUMMARY...Ongoing thunderstorms from Limon to Goodland should expand
some in coverage and intensify the remainder of the afternoon, with
some potential for storms to coalesce into a cluster and move
southeastward this evening.  The initial threat will be large hail
with splitting supercells, while the threat for damaging winds
should increase this evening as a cluster forms.  Farther south,
more isolated storms could form east of the high terrain.  Any
sustained storms will likely be supercells capable of producing
large hail for a few hours this afternoon/evening.

The severe thunderstorm watch area is approximately along and 75
statute miles east and west of a line from 25 miles west northwest
of Burlington CO to 30 miles south of Springfield CO. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU6).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 205...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
29025.

...Thompson

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06/23/2018 01:57 PM
SPC Jun 23, 2018 2000 UTC Day 1 Convective Outlook
SPC 2000Z Day 1 Outlook
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0253 PM CDT Sat Jun 23 2018

Valid 232000Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
PLAINS TO THE TN VALLEY...ACROSS THE MID ATLANTIC AND THE CENTRAL
HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms are expected this afternoon and
evening from the southern Plains to the lower Mississippi Valley and
a portion of the Southeast States. Other severe storms are expected
over the Middle Atlantic region and central High Plains.

Overall minor changes have been made to the Day 1 Outlook this
update. Some trimming was done on the southern end of the Slight
risk from TX to AL based on latest surface observation and hi-res
guidance trends. The sig hail area was expanded north and east
across central OK to account for the current position of the outflow
boundary and expected storm initiation over the next couple of
hours. See MCD 838 for more details on this threat. 

Additional adjustments include expanding the eastern CO Slight risk
eastward into portions of far western KS as guidance has been
consistent in maintaining storm cluster across this area this
evening. Damaging winds and hail will be the main threats with this
activity. See MCD 839 for more details. 

Finally, operational HRRR guidance suggests this cluster may persist
overnight into parts of southwest KS and northwest OK and a marginal
wind and hail threat could accompany this activity. The Marginal
risk area was expanded to account for this potential. Otherwise, no
other changes were made.

..Leitman.. 06/23/2018

.PREV DISCUSSION... /ISSUED 1147 AM CDT Sat Jun 23 2018/

...TN and lower MS Valley region today...
The remnants of an overnight MCS, now moving into northwest AL and
southern middle TN, will be accompanied by some threat for damaging
winds about as far east as southeast TN and northwest GA through
early afternoon, given a belt of 40+ kt flow near 700 mb (enhanced
some by the MCV with the convection).  However, the widespread
clouds/convection ongoing farther to the south in AL casts doubt of
the degree of destabilization possible in advance of these storms. 
Otherwise, additional strong/isolated severe storms could evolve
from the ongoing central AL storms into GA, or develop this
afternoon along the residual outflow from southeast AR into MS and
eventually spread into central AL (along the southern fringe of the
current storms).  Damaging outflow gusts will be the main threat.

...Northwest TX into southern OK this afternoon into early
tonight...
The outflow boundary from overnight and ongoing convection has
consolidated immediately north of I-20 across north central and
northeast TX, and the boundary may begin to retreat a little to the
north across northwest TX this afternoon.  An influx of low-mid 70s
boundary-layer dewpoints into the boundary, along with daytime
heating and midlevel lapse rates near 9 C/km, will boost MLCAPE into
the 3000-4000 J/kg range this afternoon.  This corridor will lie
along the southern fringe of the stronger midlevel flow (near or
above 30 kt), with some enhancement to low-level shear along the
boundary.  The net result will be profiles sufficient for supercells
where deep mixing reduces convective inhibition across northwest TX,
and in the warm advection zone to the north into southern OK this
afternoon/evening.  The strongest storms could produce isolated very
large hail and damaging gusts.

...Chesapeake region this afternoon/evening...
A midlevel trough over the upper OH Valley will progress
east-northeastward to southern New England tonight.  Embedded speed
maxima will continue to rotate around the southeast periphery of the
trough and interact with a diffuse lee trough across VA.  The richer
low-level moisture/buoyancy should remain near Chesapeake Bay
through the afternoon, while mid-upper flow/shear will be sufficient
for organized storms.  A few supercells will be possible, with a
primary threat for a few damaging gusts.

...Central High Plains this afternoon through early tonight...
Another midlevel trough is beginning to amplify and will move from
the northern Rockies to WY/CO tonight.  Low-level moisture is
returning northward across southeast CO in the wake of overnight
convection, and profiles will become sufficient for supercells by
this afternoon.  A few storms should form along the Palmer Divide,
and potentially the Raton Mesa, and then spread east-southeastward
over the Plains this evening.  There are still some concerns
regarding storm coverage, but any supercells that form will be
capable of producing large hail and damaging winds, and storms could
grow into a small cluster and persist into early tonight.

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06/23/2018 01:37 PM
SPC MD 839
MD 0839 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF THE SOUTHERN/CENTRAL HIGH PLAINS
MD 0839 Image

Mesoscale Discussion 0839
NWS Storm Prediction Center Norman OK
0236 PM CDT Sat Jun 23 2018

Areas affected...Portions of the southern/central High Plains

Concerning...Severe potential...Watch possible 

Valid 231936Z - 232130Z

Probability of Watch Issuance...60 percent

SUMMARY...Isolated thunderstorms could pose a risk for large hail
and damaging winds into this evening. Watch issuance could be
needed.

DISCUSSION...A few strong/severe storms have developed near the
Palmer Divide eastward into northwest Kansas this afternoon, amidst
an environment characterized by favorable effective shear, but
modest boundary-layer moisture (e.g., upper 40s/lower 50s dew
points). Still, sufficient mixed-layer buoyancy exists for isolated
multicells/splitting supercells, capable of large hail and damaging
winds. If a few cells continue to organize and evolve southeastward
into improved storm-relative flow and higher dew points, an
increasing severe threat would likely evolve, perhaps in the form of
a small convective complex. As such, convective trends are being
monitored for possible watch issuance.

..Picca/Thompson.. 06/23/2018

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

ATTN...WFO...DDC...GLD...AMA...PUB...BOU...ABQ...

LAT...LON   37380089 36610234 36490345 36810384 37220401 37960403
            38610412 39390414 39510396 39630343 39660210 39520114
            39030067 38040046 37380089 

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06/23/2018 01:19 PM
SPC MD 838
MD 0838 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF OKLAHOMA AND NORTH TEXAS
MD 0838 Image

Mesoscale Discussion 0838
NWS Storm Prediction Center Norman OK
0217 PM CDT Sat Jun 23 2018

Areas affected...Portions of Oklahoma and north Texas

Concerning...Severe potential...Watch likely 

Valid 231917Z - 232115Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorms are expected to develop over western/central
Oklahoma by late afternoon. Several will likely become severe,
accompanied by a threat of large hail (some potentially 2+" in
diameter), damaging winds, and perhaps a tornado. Watch issuance is
likely.

DISCUSSION...Visible satellite imagery shows developing cumulus
along a boundary extending from western Oklahoma east/southeastward
to near Norman. A 19Z OUN sounding sampled a subsidence inversion
near 850-800 mb, although it has lifted considerably since 12Z.
Subtle mid-level ascent is currently overspreading the region, and
modest cooling aloft should combine with further surface heating to
remove remaining inhibition over the next couple of hours. Steep
mid-level lapse rates and a warm/moist boundary layer should
contribute to around 2500-3500 J/kg of MLCAPE as well. In turn, once
profiles near 850-700mb moisten sufficiently, rather robust
convection is forecast to develop near the boundary.

Ample veering of winds with height will likely support one or more
high-precipitation supercells, capable of very large hail (2+" in
diameter possible) and damaging winds. Although storm-relative
helicity is not particularly strong, backed near-surface flow and
any southeasterly propagation component may locally enhance the
potential for a tornado. Over time, intense precipitation
cores/outflow will likely force upscale growth into a complex that 
accelerates south/southeast towards the Red River. Considering the
threat, watch issuance will likely be needed within the next few
hours.

..Picca/Thompson.. 06/23/2018

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

ATTN...WFO...FWD...OUN...

LAT...LON   33339846 33409869 33859926 34769975 35249980 35689982
            35789966 35729861 35649794 35589733 35009673 34069635
            33479628 33329697 33329770 33339846 

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06/23/2018 01:00 PM
SPC Day 2 Fire Weather Outlook
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook Image
Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0159 PM CDT Sat Jun 23 2018

Valid 241200Z - 251200Z

Elevated fire weather conditions are expected to develop across
portions of the Southwest and southern High Plains on Sunday.
Locally critical fire weather conditions (sustained winds of 15-20
mph; RH values of 5-15%) are also possible over northern New Mexico
and far southwest Colorado. The elevated was expanded farther north
in Utah/Colorado as post-frontal dry/breezy conditions are forecast
to continue across the area. The eastward extent of the elevated is
limited by below average ERCs due to recent rainfall, and a cold
front that is forecast to move south across the High Plains during
afternoon/evening.

..Nauslar.. 06/23/2018

.PREV DISCUSSION... /ISSUED 0147 AM CDT Sat Jun 23 2018/

...Synopsis...
An upper-level trough will progress across the Great Basin into the
central Rockies on D2/Sunday. At the surface, a lee trough will
develop and deepen over the Texas Panhandle.

...New Mexico...northwest Arizona...far southern Utah and
Colorado...
Strong surface heating will lead to mid-level flow mixing to the
surface across the Four Corners region. In response to this
upper-level system, a lee trough will deepen over the Texas
Panhandle and lead to enhanced surface flow over much of New Mexico.
These areas will experience elevated to locally critical fire
weather conditions. RH will generally range from 5-15%. Confidence
is low in placing any critical areas due to the sporadic nature of
20+ mph surface winds across the region. Winds of 15-20 mph will be
common, however.

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

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06/23/2018 01:00 PM
SPC Severe Thunderstorm Watch 204 Status Reports
WW 0204 Status Updates
WW 0204 Status Image

STATUS REPORT ON WW 204

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 NE CHA TO
20 SW CSV.

WW 204 WILL BE ALLOWED TO EXPIRE AT 232000Z.

..SMITH..06/23/18

ATTN...WFO...HUN...FFC...OHX...MRX...


STATUS REPORT FOR WS 204 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

TNC007-107-121-139-143-232000-

TN 
.    TENNESSEE COUNTIES INCLUDED ARE

BLEDSOE              MCMINN              MEIGS               
POLK                 RHEA                


THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY.  PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.

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06/23/2018 12:00 PM
SPC Severe Thunderstorm Watch 205 Status Reports
WW 0205 Status Updates
WW 0205 Status Image

STATUS FOR WATCH 0205 HAS NOT BEEN ISSUED YET
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06/23/2018 12:00 PM
SPC Severe Thunderstorm Watch 205
WW 205 SEVERE TSTM NC VA CW 231800Z - 240000Z
WW 0205 Image

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 205
NWS Storm Prediction Center Norman OK
200 PM EDT Sat Jun 23 2018

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Northeast North Carolina
  Southeast Virginia
  Coastal Waters

* Effective this Saturday afternoon and evening from 200 PM until
  800 PM EDT.

* Primary threats include...
  Scattered damaging wind gusts to 70 mph possible
  Isolated large hail events to 1 inch in diameter possible

SUMMARY...Scattered thunderstorms are developing from North Carolina
into southeast Virginia early this afternoon, and the storms will
likely increase in coverage and intensity for the next few hours. 
The storm environment supports a threat for damaging winds with
organized storms/supercells, and the threat should persist through
the afternoon into this evening.

The severe thunderstorm watch area is approximately along and 50
statute miles east and west of a line from 65 miles east northeast
of Richmond VA to 35 miles southeast of Roanoke Rapids NC. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU5).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 204...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
24035.

...Thompson

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06/23/2018 11:47 AM
SPC Jun 23, 2018 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
1244 PM CDT Sat Jun 23 2018

Valid 241200Z - 251200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF SOUTHERN KANSAS INTO NORTHWEST OKLAHOMA...

...SUMMARY...
Significant severe storms capable of destructive winds, very large
hail and a few tornadoes are possible on Sunday across much of
Kansas, northern Oklahoma and into the eastern Texas Panhandle. A
few severe storms are also possible from Missouri toward Tennessee
and Kentucky.

...Central/Southern Plains to Mid-Missouri Valley...

A shortwave trough will migrate across the Plains, bringing a band
of 40-50 kt southwesterly midlevel flow across the region. At the
surface, rich low level moisture (dewpoints upper 60s to low 70s)
will be in place ahead of a southeastward advancing cold front.
Additionally, a dryline will extend southward from a surface low
over the TX Panhandle. Convection will likely be ongoing across
parts of NE at the beginning of the period. Further south, some
cloud debris is possible from overnight convection in the Day 1
period, but the airmass across KS into OK should experience strong
heating. As such, an extremely unstable airmass will evolve by
afternoon. 

There is some uncertainty regarding convective evolution, with the
NAM forecast continuing to be an outlier compared to other
deterministic and hi-res guidance. Expect that one or more clusters
will develop across NE along the front and track east/southeast
through the morning. Additional storms will then develop southward
along the front across western KS, as well as across the OK/TX
Panhandles in the vicinity of the surface low/triple point. 40+ kt
deep layer shear coupled with very steep lapse rates will favor
initial supercells capable of very large hail and damaging winds.
Cells likely will not stay discrete long and quick upscale growth is
expected. The strength of deep layer shear and degree of instability
will support widespread damaging winds, with many significant wind
gusts possible. Any cell that can remain discrete will pose a
tornado threat initially given high-quality low level moisture (mean
mixing rations around 17 g/kg) and favorable low level shear.
Additionally, embedded mesovortex circulations are possible once
upscale growth occurs. One or more bowing segments are expected to
track east/southeast across KS and northern OK overnight, with
strong wind potential being maintained due to increasing 40-50 kt
southwesterly low level jet. 

Additional strong to severe storm are possible in warm advection
across MO into IA. A very unstable and moist airmass will be in
place, though deep layer shear will remain more modest. Still, steep
low level lapse rates and high PW values could result in scattered
strong wind gusts.

...Portions of the mid-Mo Valley into KY/TX Vicinity...

A weak lead shortwave impulse will track eastward across the region
during the afternoon. This will provide enough deep layer shear and
forcing some organized cells capable of strong wind gusts. Lapse
rates will remain poor in spite of moderate instability, limiting
large hail potential.

...MAXIMUM RISK BY HAZARD...
Tornado:   5%     - Slight
Wind:     45% SIG - Moderate
Hail:     30% SIG - Enhanced

..Leitman/Smith.. 06/23/2018

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06/23/2018 10:57 AM
SPC Jun 23, 2018 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
1147 AM CDT Sat Jun 23 2018

Valid 231630Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
PLAINS TO THE TN VALLEY...ACROSS THE MID ATLANTIC...AND THE CENTRAL
HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms are expected especially this
afternoon and evening from the southern Plains to the lower
Mississippi Valley and a portion of the Southeast States. Other
severe storms are expected over the Middle Atlantic region and
central High Plains.

...TN and lower MS Valley region today...
The remnants of an overnight MCS, now moving into northwest AL and
southern middle TN, will be accompanied by some threat for damaging
winds about as far east as southeast TN and northwest GA through
early afternoon, given a belt of 40+ kt flow near 700 mb (enhanced
some by the MCV with the convection).  However, the widespread
clouds/convection ongoing farther to the south in AL casts doubt of
the degree of destabilization possible in advance of these storms. 
Otherwise, additional strong/isolated severe storms could evolve
from the ongoing central AL storms into GA, or develop this
afternoon along the residual outflow from southeast AR into MS and
eventually spread into central AL (along the southern fringe of the
current storms).  Damaging outflow gusts will be the main threat.

...Northwest TX into southern OK this afternoon into early
tonight...
The outflow boundary from overnight and ongoing convection has
consolidated immediately north of I-20 across north central and
northeast TX, and the boundary may begin to retreat a little to the
north across northwest TX this afternoon.  An influx of low-mid 70s
boundary-layer dewpoints into the boundary, along with daytime
heating and midlevel lapse rates near 9 C/km, will boost MLCAPE into
the 3000-4000 J/kg range this afternoon.  This corridor will lie
along the southern fringe of the stronger midlevel flow (near or
above 30 kt), with some enhancement to low-level shear along the
boundary.  The net result will be profiles sufficient for supercells
where deep mixing reduces convective inhibition across northwest TX,
and in the warm advection zone to the north into southern OK this
afternoon/evening.  The strongest storms could produce isolated very
large hail and damaging gusts.

...Chesapeake region this afternoon/evening...
A midlevel trough over the upper OH Valley will progress
east-northeastward to southern New England tonight.  Embedded speed
maxima will continue to rotate around the southeast periphery of the
trough and interact with a diffuse lee trough across VA.  The richer
low-level moisture/buoyancy should remain near Chesapeake Bay
through the afternoon, while mid-upper flow/shear will be sufficient
for organized storms.  A few supercells will be possible, with a
primary threat for a few damaging gusts.

...Central High Plains this afternoon through early tonight...
Another midlevel trough is beginning to amplify and will move from
the northern Rockies to WY/CO tonight.  Low-level moisture is
returning northward across southeast CO in the wake of overnight
convection, and profiles will become sufficient for supercells by
this afternoon.  A few storms should form along the Palmer Divide,
and potentially the Raton Mesa, and then spread east-southeastward
over the Plains this evening.  There are still some concerns
regarding storm coverage, but any supercells that form will be
capable of producing large hail and damaging winds, and storms could
grow into a small cluster and persist into early tonight.

..Thompson/Smith.. 06/23/2018

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