Jump to content
  • Member Statistics

    17,502
    Total Members
    7,904
    Most Online
    Weathernoob335
    Newest Member
    Weathernoob335
    Joined

April 13-15 Severe Weather Threat


snowlover2

Recommended Posts

New Day 2 shifted enhanced north through southern IA with mention of very large hail and a strong tornado. Day 3 has a marginal for parts of IL/IN/OH/KY.

Quote

 Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1250 PM CDT Thu Apr 12 2018

   Valid 131200Z - 141200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   SOUTHERN IA TO NORTHEAST TX AND NORTHERN LA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   ENHANCED FROM IA AND SOUTHEAST NE TO EAST TX AND THE LOWER
   MISSISSIPPI VALLEY...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT FROM FAR SOUTHERN MN TO THE NORTHWEST GULF COASTAL REGION...

   ...SUMMARY...
   Strong/severe storms are expected to develop Friday afternoon and
   continue into the overnight hours extending from Iowa and part of
   the middle Missouri Valley southward across the Arklatex region, and
   lower Mississippi Valley.  All severe hazards are possible with very
   large hail and a few tornadoes, one or two of which could be strong,
   being the primary threats.

   ...Synopsis...
   An upper trough moving through and amplifying across the western
   states into the Rockies during D1, will undergo further
   amplification Friday into Friday night across much of the central
   United States.  An embedded closed low, likely forming by the start
   of D2 across the central Rockies, is expected to deepen as it tracks
   through the central Plains toward the mid Missouri Valley. 
   Meanwhile, an upstream shortwave trough digging southeast through
   AZ/NM to far west TX and northern Mexico by later Friday night will
   aid in the expected amplification of the central Plains parent
   trough.

   Given the slow eastward shift of the large closed mid-upper level
   low, the associated surface low is forecast to move from near the
   north-central KS/NE border into southeast NE to near Omaha, where it
   should occlude Friday night.  By mid-late Friday afternoon, a warm
   front will extend east across IA (generally in vicinity of I-80),
   while a cold front trails southwest from the low into south-central
   KS to western OK and the TX Panhandle.  A dryline, mixing eastward,
   is expected to extend south from a secondary low near ICT through
   east-central OK into central TX Friday afternoon.  The cold front is
   expected to sweep east Friday night toward the middle and lower
   Mississippi Valley.

   ...Eastern NE/IA to northern and western MO/eastern KS...
   The Enhanced and Slight risk area, including the significant severe
   potential, have been expanded north across northern MO, more of IA
   and eastern NE, given run-to-run consistencies and confidence of the
   ECMWF and NAM continuing to show the warm front moving into southern
   IA before the start of D2.  

   An increasingly favorable environment for severe storms is forecast
   to evolve during the day Friday, across the northern extent of the
   warm sector, ahead of the advancing cold front.  As the deepening
   upper system shifts slowly eastward, a very strong deep-layer wind
   field will overspread the evolving warm sector.  Diurnal heating
   combined with low-level moistening beneath cooling mid-level
   temperatures will result in moderate destabilization during the
   afternoon, with MUCAPE up to 1500-2000 J/kg from eastern KS to
   southeast NE and southern IA. 

   Operational and CAM output suggest discrete storm development will
   occur by late afternoon near the southeast NE low and southward
   along the cold front and dry line.  These storms will track quickly
   to the north-northeast as strengthening deep-layer wind fields
   spread across the warm sector.  The environment will support
   strong/rotating updrafts, with very large hail and a tornado threat
   expected.  A strong tornado or two will be possible, especially
   across parts of northern MO into southern IA.  Farther north, very
   steep midlevel lapse rates associated with the EML suggest hail,
   some very large, will be possible north of the warm front, with a
   marginal risk extending into far southern MN.  

   ...Rest of MO to Arklatex, east TX and lower Mississippi Valley...
   Although stronger forcing for ascent is not expected to spread
   across the southern extent of the D2 severe risk areas until Friday
   night, a modifying warm sector becoming moderately unstable and
   strongly sheared will support strong to severe storms from Friday
   afternoon into the overnight.  Mixed-layer CAPE up to 2500 J/kg
   suggests sustained updrafts will be likely with storm rotation. 
   This will result in all severe hazards being possible.  The Enhanced
   and Slight risk areas have been expanded east to the lower
   Mississippi Valley region, as the a strong southerly low-level jet
   shifts toward western MS Friday night.  Mixed storm modes, initially
   cellular, are expected with the mode possibly becoming linear as
   stronger forcing for ascent spreads across this region Friday night.
    Given some uncertainty in the overall evolution of storms across
   this part of the severe risk areas, a moderate risk is not being
   introduced at this time.

   ..Peters.. 04/12/2018

 

day2otlk_1730.gif

Link to comment
Share on other sites

Afformentioned Day 3.

Quote

Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0227 AM CDT Thu Apr 12 2018

   Valid 141200Z - 151200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
   ALABAMA SOUTHWARD TO EASTERN LOUISIANA...SOUTHEAST MISSISSIPPI...THE
   ALABAMA COAST...AND FLORIDA PANHANDLE...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MID SOUTH
   SOUTHWARD TO THE CENTRAL GULF COAST REGION...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT AND ENHANCED RISKS...AND EXTENDING NORTH INTO THE OHIO VALLEY
   AREA...

  

   ...Midwest/Ohio Valley...
   A highly conditional severe risk may extend north across the Ohio
   Valley into parts of the Illinois/Indiana vicinity, as the occluded
   low/front shift eastward across this region.  If ample heating
   beneath steep mid-level lapse rates can occur, low-topped storms may
   evolve, within an area of ample shear.  Though this scenario is
   quite uncertain at best, potential for a very isolated, strongly
   diurnal, all-hazards risk deserves mention at this time.

 

day3otlk_0730.gif

Link to comment
Share on other sites

Also there's a small Marginal risk on the latest Day 1 for NW Iowa and SE SD--so small in fact that Ledyard, Iowa (population 130) in Kossuth County was listed on the SPC outlook as one of the top 5 "larger population centers" in the risk zone.  Little ol' Ledyard beating out big ol' Sioux Falls, Estherville, Spencer, Storm Lake, and countless others for inclusion on that list.  :huh::D

http://www.spc.noaa.gov/products/outlook/day1otlk.html

 

day1otlk_1630.gif?1523556863401

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 18,057 604,309 Sioux City, IA...Mason City, IA...Fort Dodge, IA...Ledyard, IA...Yankton, SD...
Link to comment
Share on other sites

New day 1

Quote

 Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1250 AM CDT Fri Apr 13 2018

   Valid 131200Z - 141200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE MID MO
   VALLEY TO EAST TEXAS AND THE LOWER MS VALLEY...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM IOWA TO
   SOUTHEAST TEXAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
   MIDWEST TO THE WESTERN GULF COAST...

   ...SUMMARY...
   Severe storms, capable of large hail, tornadoes, and damaging winds,
   are expected from parts of the middle Missouri Valley southward to
   east Texas this afternoon and evening. Through the overnight hours,
   storms across Louisiana and Arkansas will move eastward towards the
   lower Mississippi Valley, with a continued threat of tornadoes and
   damaging winds.

   ...Synopsis...
   An expansive mid-level trough will continue to amplify across the
   central US today, concurrent with a 90-100kt south/southwesterly
   500mb jet organizing from the Desert Southwest to the Missouri
   Valley. Following this evolution, a surface low will advance
   eastward from northern Kansas to the mid Missouri Valley through the
   day, with a warm front extending to its east and a dry line
   extending southward to Texas.

   ...Middle Missouri Valley to the Ozarks...
   Ahead of the aforementioned dry line, the warm sector will be
   strongly capped early today, owing to an impressive elevated mixed
   layer. However, as large-scale ascent notably increases through
   afternoon, cooling/moistening around 700mb, diurnal heating, and
   modest boundary-layer moisture return will foster around 1000-2000
   J/kg of MLCAPE. Isolated to widely scattered thunderstorms are
   expected to develop during the afternoon, from the surface low (near
   southeast Nebraska/southwest Iowa) southward to the
   Oklahoma/Arkansas border. Strong effective shear, characterized by
   fairly straight hodographs, will likely yield some supercellular
   structures (capable of large hail) and perhaps a few small bowing
   structures. Robust 0-3km flow will be favorable for occasional
   low-level mesocyclones, and a few tornadoes may be possible. This
   threat may be tempered somewhat by dry air aloft resulting in
   stronger/colder RFDs, though. Nonetheless, severe storms capable of
   all hazards are expected during the afternoon and early/mid evening,
   before weakening during the late evening hours.

 

day1otlk_1200.gif

Link to comment
Share on other sites

New day 2 adds a slight risk to parts of E IL/W IN.

Quote

  Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1204 AM CDT Fri Apr 13 2018

   Valid 141200Z - 151200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE MID SOUTH TO THE CENTRAL GULF COAST...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   ENH RISK INTO MIDDLE TN...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   IL/IN...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
   THE GULF COAST TO THE OH VALLEY...

   ...SUMMARY...
   Strong to severe storms are expected  from portions of the Midwest
   to the central Gulf Coast Saturday.

   ...Discussion...

   Lower CO River Valley mid-level speed max is forecast to eject
   through the base of western US trough during the day1 period before
   translating into MO by 14/18z. This feature will induce a surface
   low that should track near/along the I-70 corridor from KS into
   central IL by peak heating Saturday. An attendant warm front will
   advance into the OH Valley early in the period; however, the
   strongest diurnal heating/steep low-level lapse rate environment are
   expected to be confined to portions of IL/IN immediately ahead of
   the surface low. Strong/severe convection is expected to develop
   ahead of the cold front by early afternoon across IL then spread
   into western IN by late afternoon.

 

day2otlk_0600.gif

Link to comment
Share on other sites

Small 10% tornado area in SW IA.

Quote

 Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1120 AM CDT Fri Apr 13 2018



   ...IA/KS/MO...
   A deepening surface low over southeast NE will track into southwest
   IA today along a strong warm front.  Isolated supercell storms are
   expected to form in the vicinity of the warm front and the dryline
   extending southward into KS.  Very large hail will be possible, but
   forecast soundings also suggest sufficient vertical shear and
   low-level CAPE to pose a risk of tornadoes for the first 1-2 hours
   of the event.

   Farther south across western MO, confidence in the eventual storm
   evolution is low.  A few 12z CAMs suggest that isolated supercell
   storms will affect this region.  Forecast soundings are also quite
   favorable with ample CAPE, steep lapse rates, and favorable shear. 
   However, quite a bit of guidance casts doubt on the convective
   coverage.  Will maintain the ENH risk area due to the conditional
   risk, but confidence is decreasing.

   ..Hart/Broyles.. 04/13/2018

 

day1probotlk_1630_torn.gif

Link to comment
Share on other sites

Day 2 wording for IL/IN.  Yes we're pretty familiar with these speed demons around here, especially if some of the shear profiles pan out.  The chaser becomes the chasee(?) lol.

...Lower Ohio Valley (IL/IN)...
   Forcing for ascent within the exit region of a strong 500-mb jet
   translating into the eastern periphery of the central states large
   closed low will spread into the lower Ohio Valley by late Saturday
   afternoon to the early evening.  A surface low induced by this
   feature will track east along a warm front which will extend through
   central IL, IN, and OH.  The strongest diurnal heating/steep
   low-level lapse rate environment should be confined to portions of
   IL/IN immediately ahead of the surface low.  Low-topped
   strong/severe convection should develop ahead of the cold front by
   early afternoon across IL then spread into western IN by late
   afternoon or early evening.
Link to comment
Share on other sites

On 4/13/2018 at 2:01 PM, Jackstraw said:

SPC pulled the PDS trigger down in AR.  Is it just me or have we been seeing more and more PDS TOR watches nationwide lately?  I remember maybe 1 or 2 a year but seems like there's been a lot more the last few years.

I'd say something, but I'm sure everyone has gotten my SPC hate by now.

Link to comment
Share on other sites

New tornado watch for parts of IA/MO.

Quote

 URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 41
   NWS Storm Prediction Center Norman OK
   220 PM CDT Fri Apr 13 2018

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Southern Iowa
     Northeast Kansas
     Northwest Missouri
     Southeast Nebraska

   * Effective this Friday afternoon and evening from 220 PM until
     900 PM CDT.

   * Primary threats include...
     A few tornadoes likely
     Widespread large hail and isolated very large hail events to 2.5
       inches in diameter likely
     Scattered damaging wind gusts to 70 mph likely

   SUMMARY...Thunderstorms developing over eastern Kansas will track
   northeastward across the watch area, while other isolated cells form
   over IA/northern MO.  Supercells capable of large hail and a few
   tornadoes are expected.

   The tornado watch area is approximately along and 65 statute miles
   east and west of a line from 40 miles west northwest of Knoxville IA
   to 60 miles south southwest of Olathe KS. For a complete depiction
   of the watch see the associated watch outline update (WOUS64 KWNS
   WOU1).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A Tornado Watch means conditions are favorable for
   tornadoes and 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.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 39...WW 40...

   AVIATION...Tornadoes and 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 450. Mean
   storm motion vector 23035.

   ...Hart

 

ww0041_radar.gif

Link to comment
Share on other sites

6 hours ago, CheeselandSkies said:

So...who had WI leading the nation in severe reports at any point today? I sure didn't. We broke in to the Today Show/Megyn Kelly Today three times this morning.

Was well north of Madison, just foggy cold rain here. Geoboy645, anything by you? Looked like parts of Richland/Sauk/Columbia got rocked pretty good.

 

Had a downpour and some pea sized hail. Didn't hear any thunder though :C the streak continues.

Link to comment
Share on other sites

Unless WICS-20.1 in Springfield, IL (our local ABC affiliate) is seeing something that the SPC isn't--or if tomorrow does indeed ramp up significantly in our part of central Illinois, their newscasts tonight are really hyping up tomorrow's severe threat as if we were under at least a Moderate Risk instead.  They have labeled tomorrow a Code Red day for severe weather in their viewing area.

Even though Springfield is on the Marginal/Slight risk line.  Then again, this same station has been known to really hype up Marginal Risks in our area since the SPC expanded their severe risk categories around 2015.

Here's one of their stories about tomorrow's risk from this evening's Channel 20 news: http://newschannel20.com/news/local/roadway-precautions-in-emergency-weather 

WICS also produces the news for the local Fox station (WRSP-55.1) and their newscast at 9 has had the same theme.  Including a live report from the Cook Street overpass near mile market 99 on I-55 about 1-2 miles east of their station building on the east side of Springfield.  You can watch their recent newscasts or individual stories at this site and see for yourself.  I am certain 10PM on 20.1 will not be much different: http://newschannel20.com/watch

Unless the area is still very shaken over 12 years later from the twin F2s affecting the south and east sides of Springfield on 3/12/2006.

Link to comment
Share on other sites

23 hours ago, Chicago Storm said:

I'd say something, but I sure everyone has gotten my SPC hate by now.

Well it certainly didn't quite pan out to what would be expected of a PDS watch (I guess unless you were directly affected).  Interesting that NOAA's project vortex was flying around and reported a couple but looks like strongest may have been EF-2 as of right now.  

Tornado Reports (CSV) (Raw Tornado CSV)(?)
Time   Location County State Lat Lon Comments
1212   9 WNW STERLINGTON UNION LA 3272 9222 ROOF AND STRUCTURAL DAMAGE WITH TREES SNAPPED AND UPROOTED. (SHV)
2118   MOUNTAINBURG CRAWFORD AR 3564 9417 SPRINGDALE ASP ADVISES THAT ONE HOME DAMAGED. (TSA)
2304   8 NNE DE KALB BOWIE TX 3362 9456 TORNADO ON THE GROUND REPORTED BY BROADCAST MEDIA. (SHV)
2332   WINTHROP LITTLE RIVER AR 3384 9435 TORNADO REPORTED ON THE GROUND ON HWY 41 AND 231. (SHV)
2335   7 SSE DOWNSVILLE OUACHITA LA 3253 9236 TORNADO OBSERVED BY NOAA AIRCRAFT PROJECT VORTEX 1 MILE NORTH OF CALHOUN. (SHV)
2335   7 SSE DOWNSVILLE OUACHITA LA 3254 9237 REISSUANCE OF ORIGINAL LSR - TORNADO OBSERVED BY NOAA AIRCRAFT PROJECT VORTEX 1 MILE NORTH OF CALHOUN. (SHV)
0008   8 NW STERLINGTON UNION LA 3278 9216 NOAA P3 AIRCRAFT SIGHTS TORNADO 8 NW STERLINGTON AND POWER FLASHES.(SHV)
0012   9 WNW STERLINGTON UNION LA 3272 9222 CORRECTS FOR TIME TO PREVIOUS TORNADO REPORT FROM 9 WNW STERLINGTON. ROOF AND STRUCTURAL DAMAGE WITH TREES SNAPPED AND UPROOTED. (SHV)
0013   MACOMB WRIGHT MO 3710 9249 AN EF-2 TORNADO 100 YARDS WIDE WITH ESTIMATED MAXIMUM WIND SPEEDS OF 130 MPH TRACKED FROM NEAR MACOMB NORTHEASTWARD FOR 9 MILES BEFORE LIFTING 5 MILES NORTH NORTHEAST O (SGF)
0020   12 NNW DIERKS HOWARD AR 3429 9406 HIGHWAY 278 WEST OF UMPIRE TREES DAMAGE. (SHV)
0021   7 SSE DOWNSVILLE OUACHITA LA 3253 9236 HIGHWAY 151 IMPASSABLE DUE TO TREES ... POWER POLES DEBRIS DOWN NORTH OF CALHOUN. (SHV)
0035   1 W DAWSON WRIGHT MO 3726 9233 AN EF-1 TORNADO WITH MAXIMUM WIDTH OF 75 YARDS AND MAXIMUM WINDS OF 100 MPH MOVED NORTHEAST FROM DOVE CREEK ROAD TO BATY ROAD. TREES AND OUTBUILDINGS WERE DAMAGED. (SGF)
0050   3 W PENCIL BLUFF MONTGOMERY AR 3463 9379 BRIEF TORNADO TOUCHDOWN REPORTED(LZK)
0415   9 SSE ORE CITY HARRISON TX 3267 9468 NUMEROUS UP ROOTED TREES AND DOWN POWER LINES IN DIANA ... TEXAS ON DUNN BOTTOM RD. OFF HWY 154. (SHV)
Link to comment
Share on other sites

1 hour ago, OHweather said:

Here’s video of what flipped those cars.  Still awaiting word from CLE but this was a tornado in Coventry south of Akron.  Was also some interesting damage near Twinsburg with what was the strongest radar signature. 

 

http://fox8.com/2018/04/16/video-shows-what-appears-to-be-tornado-flipping-car-in-coventry-township/

For surveillance video that is halfway decent. I like the little blast of inflow before that little vortex blows through in the opposite direction.

Link to comment
Share on other sites

Yeah, it’s also amusing to watch people sprinting in who see it off camera.  Luckily it wasn’t too damaging.

CLE initially ruled it a “downburst”...and then half an hour later changed it to an EF-1 with a 0.1 mile long path length after someone posted that video in NWS chat.  They also ruled the damage in Twinsburg (the strongest radar signature) a downburst.  It wasn’t a downburst environment and there was little outflow wind elsewhere with the lines.  I know embedded circulations can localy enhance outflow as well, so it is possible that Twinsburg wasn’t a tornado.  There was damage reported both upwind and downwind of the damage in Twinsburg which should have given a path length of at least half a mile, but the path length on that was also listed as 0.1 miles and the other damage wasn’t mentioned in their PNS.  Almost wonder if they just went by what the EMs said. 

Link to comment
Share on other sites

2 hours ago, OHweather said:

Yeah, it’s also amusing to watch people sprinting in who see it off camera.  Luckily it wasn’t too damaging.

CLE initially ruled it a “downburst”...and then half an hour later changed it to an EF-1 with a 0.1 mile long path length after someone posted that video in NWS chat.  They also ruled the damage in Twinsburg (the strongest radar signature) a downburst.  It wasn’t a downburst environment and there was little outflow wind elsewhere with the lines.  I know embedded circulations can localy enhance outflow as well, so it is possible that Twinsburg wasn’t a tornado.  There was damage reported both upwind and downwind of the damage in Twinsburg which should have given a path length of at least half a mile, but the path length on that was also listed as 0.1 miles and the other damage wasn’t mentioned in their PNS.  Almost wonder if they just went by what the EMs said. 

I know the embedded QLCS tornadoes can be more difficult to identify in survey as the debris sometimes gets blown mostly in one direction, especially in a very fast moving line.  But looking back at the warning text from yesterday, the storm speed wasn't all that fast.

Link to comment
Share on other sites

2 hours ago, Hoosier said:

I know the embedded QLCS tornadoes can be more difficult to identify in survey as the debris sometimes gets blown mostly in one direction, especially in a very fast moving line.  But looking back at the warning text from yesterday, the storm speed wasn't all that fast.

The one on video spent a lot of its life in parking lots, so I sort of understand that one (though radar and context suggested a tornado was definitely possible...especially the flipped cars).  The other one may have tracked through some wooded area, and there were reports of siding/shingle type damage upwind of the roof damage they referenced in the PNS.  But again, they didn’t mention the other damage, so I’m not sure if they weren’t aware or just didn’t find it interesting.  The radar near Twinsburg was very suggestive as well.  Usually their surveys are more detailed so I was a little surprised/disappointed. 

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...