7-19 Severe outbreak MN into upper MI

[janetjanet998]

AY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
0736 AM CDT FRI JUL 19 2019  
  
VALID 191300Z - 201200Z  
  
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS EAST-CENTRAL MN  
AND NORTHERN WI...  
   
..SUMMARY  
  
A REGIONAL OUTBREAK OF SEVERE THUNDERSTORMS WITH STRONG TORNADOES  
AND POTENTIALLY WIDESPREAD SIGNIFICANT WIND DAMAGE MAY OCCUR FROM  
CENTRAL MINNESOTA ACROSS NORTHERN WISCONSIN DURING THE MID-AFTERNOON  
TO EVENING.  
   
..UPPER MIDWEST/GREAT LAKES  
  
UPGRADING TO MODERATE RISK THIS OUTLOOK FOR THE POTENTIAL THREATS OF  
MULTIPLE STRONG TORNADOES AND A DERECHO LATER THIS AFTERNOON AND  
EVENING. CAPE/SHEAR/SRH PARAMETER SPACE IN THIS REGION IS FORECAST  
TO BE EXCEPTIONALLY RARE FOR MID JULY AMID A PREDOMINATELY ZONAL  
FLOW REGIME ACROSS THE NORTHERN STATES.  
  
A CONVECTIVE CLUSTER IS ONGOING ACROSS NORTH-CENTRAL SD AIDED BY  
WARM/MOIST ADVECTION AROUND 700 MB ALONG A PRONOUNCED BAROCLINIC  
ZONE. 00Z CAM GUIDANCE HAD A DECENT HANDLE ON THIS ACTIVITY EARLIER  
THIS MORNING AND ARE CONSISTENT WITH A DECAYING TREND THROUGH LATE  
MORNING AS ADVECTION SHIFTS EAST AMID PRONOUNCED MLCIN AS SAMPLED BY  
THE 12Z ABERDEEN SOUNDING. THERE IS A LOW CONFIDENCE SCENARIO THAT A  
STRONG ENOUGH COLD POOL IS BECOMING ESTABLISHED WITH THIS EARLY-DAY  
CLUSTER SUCH THAT TOTAL DECAY DOES NOT OCCUR. IF THIS OCCURS, ROBUST  
BOUNDARY-LAYER HEATING DOWNSTREAM MAY BE SUFFICIENT FOR AN  
INCREASING THREAT DURING THE AFTERNOON OF STRONG TO SEVERE WIND  
GUSTS. THIS COULD STILL YIELD A SCATTERED TO WIDESPREAD DAMAGING  
WIND SCENARIO, ALBEIT IN AN EARLIER TIME FRAME THAN PROGGED BY  
GUIDANCE.  
  
THE MORE PROBABLE SCENARIO IS FOR AN EXTREMELY UNSTABLE AIR MASS  
(MLCAPE > 4000 J/KG) TO BECOME ESTABLISHED TO FROM SOUTHEAST SD  
THROUGH CENTRAL/SOUTHERN WI AS THE ELEVATED MIXED-LAYER OVERSPREADS  
SURFACE DEW POINTS RISING INTO THE MID TO UPPER 70S. A SURFACE  
CYCLONE OVER CENTRAL SD SHOULD TRACK TOWARDS THE TWIN CITIES THROUGH  
EARLY EVENING. STRONG LOW-LEVEL CONVERGENCE NEAR/NORTHEAST OF THIS  
CYCLONE ALONG THE WARM FRONT SHOULD SUSTAIN SURFACE-BASED STORM  
DEVELOPMENT ACROSS CENTRAL INTO EAST-CENTRAL MN. ONCE INITIATION  
OCCURS, INTENSE SUPERCELLS WILL DEVELOP RAPIDLY, WITH AN ATTENDANT  
THREAT FOR ALL SEVERE HAZARDS INCLUDING STRONG TORNADOES AMID 50-60  
KT EFFECTIVE SHEAR AND 0-3 KM SRH > 300 M2/S2. THE VERY WARM/MOIST  
THERMODYNAMIC PROFILES WILL ALSO SUPPORT GENERATION OF STRONG COLD  
POOLS WHICH SHOULD EVENTUALLY YIELD A BOWING, FORWARD-PROPAGATING  
MCS ACROSS NORTHERN WI INTO PARTS OF NORTHERN LOWER AND UPPER MI.  
STRENGTH OF THE VERTICAL SHEAR SUGGESTS THE POTENTIAL FOR INTENSE  
BOWING SEGMENTS CAPABLE OF YIELDING A DERECHO WITH SIGNIFICANT  
SEVERE WIND GUSTS.  
   
..LOWER GREAT LAKES  
  
AN MCV PROGRESSING EAST OVER THE LOWER GREAT LAKES THIS AFTERNOON  
SHOULD PROVIDE ENOUGH LIFT FOR SCATTERED THUNDERSTORMS DEVELOPMENT.  
AIR MASS OVER THE REGION WILL BE MODERATELY TO STRONGLY UNSTABLE BUT  
MODESTLY SHEARED. EXPECTATION IS FOR PREDOMINANTLY MULTICELLULAR,  
OUTFLOW-DOMINANT STORMS CAPABLE OF ISOLATED DAMAGING WIND GUSTS.  

 

[Indystorm]

Thanks for starting this thread for today's episode.  Soundings for later today are quite ominous in the affected area.

[Jackstraw]

Ya mean like this?  Yikes

[Indystorm]

I know the outlook depends more on extent of geographical coverage of storms than intensity of soundings, but I do have to wonder looking at some of these soundings for later today if we might even see an upgrade to high risk based on derecho probs let alone tornadic activity.

[yoda]

2 minutes ago, Indystorm said:

I know the outlook depends more on extent of geographical coverage of storms than intensity of soundings, but I do have to wonder looking at some of these soundings for later today if we might even see an upgrade to high risk based on derecho probs let alone tornadic activity.

In order to get a high risk for wind it has to be 60 percent hatched... 30 percent hatched or anything higher gets you the high risk for tornadoes

[janetjanet998]

That T-storm cluster is still going pretty good and a new storm on the western flank...I wonder if it will retard the WF and place it more south into the northern MSP metro for Tornadoes

on another note:  If we had a Tropical System making landfall..even a mid strength CAT 1 hurricane..this set up as the potential to do just as much damage (perhaps more if  the tornado potential happens) , there would be non-stop reporting from the media..  l often roll my eyes with all the hype of a tropical storm and point people towards derechos

It's is not very populated in the MOD risk area, but there are people on vacations in trailers and cabins around the lakes

15z HRRR still favors the area Between MSP and Duluth it seems

[janetjanet998]

MESOSCALE DISCUSSION 1523  
NWS STORM PREDICTION CENTER NORMAN OK  
1106 AM CDT FRI JUL 19 2019  
  
AREAS AFFECTED...WEST-CENTRAL MINNESOTA  
  
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE   
  
VALID 191606Z - 191800Z  
  
PROBABILITY OF WATCH ISSUANCE...40 PERCENT  
  
SUMMARY...TRENDS AROUND A DYING MCS ARE BEING MONITORED FOR EVENTUAL  
SUPERCELL DEVELOPMENT LATER TODAY.  
  
DISCUSSION...A SMALL BUT IMPRESSIVE MCS HAS FINALLY DIED OVER  
NORTHEAST SD INTO WEST-CENTRAL MN, AND IS NOW PRODUCING NORTHERLY  
OUTFLOW WINDS. SOUNDINGS INDICATE THIS COMPLEX WAS BEING SUSTAINED  
BY ELEVATED PARCELS AS THE BOUNDARY LAYER REMAINS CAPPED THIS  
MORNING.  
  
GIVEN DECREASING NEAR-TERM TRENDS, THE LARGE CIRRUS CANOPY IS  
EXPECTED TO THIN ON THE SOUTHERN FRINGE WHICH WILL AID INSOLATION.  
IN ADDITION, THE OUTFLOW SHOULD MODIFY AS WELL. THIS RESIDUAL  
OUTFLOW MAY SERVE AS THE STORM INITIATION ZONE LATER THIS AFTERNOON  
AS THE AIR MASS BECOMES VERY UNSTABLE UPSTREAM, AND SOUTHWEST WINDS  
CREATE LIFT. A LONE CELL CURRENTLY EXITS ALONG THE SD/MN BORDER IN  
THE WAKE OF THE MCS. THIS GENERAL ZONE, AND EXTENDING EAST ALONG A  
MODIFYING OUTFLOW BOUNDARY, WILL BE THE PRIMARY AREA OF CONCERN  
THROUGH EARLY AFTERNOON.   
  
IN THE NEAR TERM, THE OUTFLOW BOUNDARY WILL BE MONITORED AS THE AIR  
MASS CONTINUES TO HEAT AND DESTABILIZE. ANY SIGNS OF SURFACE-BASED  
DEVELOPMENT WOULD LIKELY REQUIRE A WATCH FOR A TORNADO AND WIND  
THREAT.  
  
..JEWELL/GUYER.. 07/19/2019  

 

[Santa Clause]

Amateur question but doesn't derechos lower the chance of strong tors and leads more to spin ups in nature?

[janetjanet998]

3 minutes ago, Wmsptwx said:

Amateur question but doesn't derechos lower the chance of strong tors and leads more to spin ups in nature?

this is a two part threat:

1) Tornadic supercells at first

2) Then storms merging into that derercho..with isolated weaker spin ups still possible

 

[janetjanet998]

The clouds/precip moving into the MOD risk area, have got to have at least some affect on the parameters and/or location

[yoda]

No 1630 SPC OTLK yet

[janetjanet998]

DAY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
1147 AM CDT FRI JUL 19 2019  
  
VALID 191630Z - 201200Z  
  
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS  
EAST-CENTRAL MINNESOTA AND NORTHERN WISCONSIN...  
   
..SUMMARY  
  
A REGIONAL OUTBREAK OF SEVERE THUNDERSTORMS WITH THE POSSIBILITY OF  
STRONG TORNADOES AND WIDESPREAD SIGNIFICANT WIND DAMAGE IS EXPECTED  
FROM CENTRAL MINNESOTA ACROSS NORTHERN WISCONSIN DURING THE MID/LATE  
AFTERNOON INTO TONIGHT.  
   
..UPPER MIDWEST/GREAT LAKES  
  
A REGIONAL OUTBREAK OF SEVERE THUNDERSTORMS IS EXPECTED LATER THIS  
AFTERNOON INTO TONIGHT. THAT SAID, SOME SPECIFIC UNCERTAINTIES  
REMAIN WITH THE TIMING DETAILS/EXACT SUB-REGIONAL CORRIDOR OF PEAK  
SEVERE-WEATHER RISK GIVEN CAPPING/WARM TEMPERATURES ALOFT AND  
UNCERTAINTY WITH THE DECAY OF THE CLOUD SHIELD FROM THE EARLIER MCS  
ACROSS SOUTH DAKOTA.  
  
A VERY STRONG SUMMERTIME BELT OF WESTERLIES EXISTS ACROSS THE  
NORTHERN TIER OF THE CONUS, WITH 50-100 KT WESTERLIES NOTED BETWEEN  
500/250 MB IN 12Z UPPER-AIR DATA SPANNING MONTANA TO THE  
DAKOTAS/MINNESOTA. WHERE STORMS DEVELOP/INCREASE LATER TODAY, THIS  
VERY STRONG BELT OF WINDS ALOFT WILL BE INFLUENTIAL IN STORM  
ORGANIZATION INCLUDING SUPERCELLS AND POTENTIAL EVOLUTION OF A  
FAST-MOVING MCS (POSSIBLE IF NOT LIKELY DERECHO) LATER  
TODAY/TONIGHT.  
  
CONSULT MESOSCALE DISCUSSION 1523 REGARDING MIDDAY DETAILS ACROSS  
WESTERN MINNESOTA. ADDITIONAL SURFACE-BASED THUNDERSTORM DEVELOPMENT  
MAY EMANATE FROM THE ASCENT/DIFFERENTIAL HEATING RELATED TO THE MCS  
REMNANTS, FOCUSING DOWNSTREAM SURFACE-BASED SEVERE POTENTIAL ACROSS  
CENTRAL MINNESOTA. AN EXTREMELY UNSTABLE AIR MASS (MLCAPE >4000  
J/KG) WILL CONTINUE TO BECOME ESTABLISHED FROM SOUTHEAST SOUTHEAST  
SOUTH DAKOTA THROUGH CENTRAL/SOUTHERN WISCONSIN AS THE ELEVATED  
MIXED-LAYER OVERSPREADS SURFACE DEW POINTS RISING INTO THE MID TO  
UPPER 70S. A SURFACE CYCLONE OVER CENTRAL SOUTH DAKOTAS SHOULD TRACK  
TOWARDS THE TWIN CITIES THROUGH EARLY EVENING. STRONG LOW-LEVEL  
CONVERGENCE NEAR/NORTHEAST OF THIS CYCLONE ALONG THE WARM FRONT  
SHOULD SUSTAIN SURFACE-BASED STORM DEVELOPMENT ACROSS CENTRAL INTO  
EAST-CENTRAL MINNESOTA.   
  
INTENSE SUPERCELLS ARE LIKELY TO DEVELOP RAPIDLY, WITH AN ATTENDANT  
THREAT FOR ALL SEVERE HAZARDS INCLUDING THE POSSIBILITY OF A STRONG  
TORNADO OR TWO AMID 50-60 KT EFFECTIVE SHEAR AND 0-3 KM SRH >300  
M2/S2. THE VERY WARM/MOIST THERMODYNAMIC PROFILES WILL ALSO SUPPORT  
GENERATION OF STRONG COLD POOLS WHICH SHOULD EVENTUALLY YIELD A  
BOWING, FORWARD-PROPAGATING MCS ACROSS NORTHERN WISCONSIN INTO PARTS  
OF NORTHERN LOWER AND UPPER MICHIGAN. STRENGTH OF THE VERTICAL SHEAR  
SUGGESTS THE POTENTIAL FOR INTENSE BOWING SEGMENTS CAPABLE OF  
YIELDING A DERECHO WITH SIGNIFICANT/WIDESPREAD SEVERE WIND GUSTS.  
   
..LOWER GREAT LAKES/NORTHEAST STATES  
  
HAVE UPGRADED PARTS OF THE REGION FOR THUNDERSTORM-WIND RELATED  
POTENTIAL THIS AFTERNOON INTO EVENING. THIS WILL BE RELATED TO THE  
POSSIBLE EAST-SOUTHEASTWARD PERSISTENCE OF A COMPLEX OF STORMS  
ACROSS ONTARIO AND ADDITIONAL SCATTERED DEVELOPMENT THAT IS EXPECTED  
IN THE LEE OF THE LOWER GREAT LAKES. THE AMBIENT AIR MASS WILL BE  
MODERATELY TO STRONGLY UNSTABLE BUT THE REGION WILL GENERALLY BE  
SOUTH OF THE STRONGER WESTERLIES ALOFT. THE OVERALL EXPECTATION IS  
FOR PREDOMINANTLY MULTICELLULAR, OUTFLOW-DOMINANT STORMS CAPABLE OF  
ISOLATED DAMAGING WIND GUSTS THIS AFTERNOON AND EVENING.  
   

[Indystorm]

Effective sig tor value up to 9 already in western MN....derecho composite up to 16

[janetjanet998]

winds have turned due east or even NE in the MSP metro...that outflow is pretty  far south now..but should move/mix more north again

 

[Chinook]

The latest HRRR has significant storms in MN as soon as 21z, with, as you might expect, high values of SCP and STP nearby.

[MNstorms]

Quote

Mesoscale Discussion 1526
   NWS Storm Prediction Center Norman OK
   0153 PM CDT Fri Jul 19 2019

   Areas affected...much of central Minnesota

   Concerning...Severe potential...Tornado Watch likely 

   Valid 191853Z - 192130Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Storms are expected to form over west-central Minnesota
   around 20-21Z, with supercells possible initially. Tornadoes and
   large hail are likely. A damaging wind threat is expected later
   today as storms merge into an MCS.

   DISCUSSION...The combination of satellite imagery and surface
   observations show an east-west oriented outflow boundary across
   southern MN, with low pressure over east-central SD into southwest
   MN. A very warm, moist, and unstable air mass exists along and south
   of the boundary where temperatures continue to rise above 90 F.
   While temperatures north of the boundary are relatively cooler,
   rapid recovery will occur due to southwest flow just above the
   surface combined with mixing. Substantial pressure falls are
   occurring over the cooler air, mainly due to warm advection just off
   the surface.

   Deep, moist convergence is currently centered over west-central MN,
   and this is where several models suggest initiation will occur. This
   seems reasonable, especially once warmer temperatures > 90 F arrive.

   Backed surface winds are contributing to 0-1 SRH values in excess of
   300 m2/s2, with relatively low LCLs near the boundary, and extreme
   instability. This will certainly support supercells and tornadoes,
   assuming discrete cells. As such, a tornado watch will be needed
   soon. Eventually, storms will merge into an MCS with a damaging wind
   threat.

 

[Jackstraw]

Don't know much about it but this is one of the higher VTP's I've seen on SPC Meso, right over Minneapolis....

[DanLarsen34]

Parameters like STP aren’t as valuable this time of the year, but these are still eye-popping. 14 STP on the effective layer map on the SPC Mesoanalysis. Over 20 EHI. I’m not sure I’ve ever seen EHI numbers this high before across a severe risk area.

[janetjanet998]

storms developing but pretty far north along the northern "front"..may be slightly elevated over warm layer for now

southern outflow seen right in the middle of MSP radar site

[MNstorms]

[janetjanet998]

URGENT - IMMEDIATE BROADCAST REQUESTED  
TORNADO WATCH NUMBER 524  
NWS STORM PREDICTION CENTER NORMAN OK  
240 PM CDT FRI JUL 19 2019  
  
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
  
* TORNADO WATCH FOR PORTIONS OF   
  CENTRAL MINNESOTA  
  NORTHWEST WISCONSIN  
  
* EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 240 PM UNTIL  
  1000 PM CDT.  
  
* PRIMARY THREATS INCLUDE...  
  A FEW TORNADOES AND A COUPLE INTENSE TORNADOES POSSIBLE  
  WIDESPREAD DAMAGING WINDS LIKELY WITH ISOLATED SIGNIFICANT GUSTS  
    TO 80 MPH POSSIBLE  
  SCATTERED LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL EVENTS  
    TO 3 INCHES IN DIAMETER POSSIBLE  
  
SUMMARY...SCATTERED SUPERCELLS ARE LIKELY TO DEVELOP AND BECOME  
INCREASINGLY SURFACE BASED, INITIALLY ACROSS MUCH OF CENTRAL  
MINNESOTA, THROUGH LATE AFTERNOON/EARLY EVENING AS A WARM FRONT  
GRADUALLY SPREADS NORTHWARD. LARGE HAIL AND A TORNADO RISK WILL  
EXIST, INCLUDING THE POTENTIAL FOR A COUPLE OF STRONG TORNADOES.  
STORMS WILL EVENTUALLY MERGE INTO AN EASTWARD-ACCELERATING STORM  
COMPLEX BY THIS EVENING, WITH WIDESPREAD/SIGNIFICANT WIND GUSTS  
BECOMING AN INCREASING CONCERN INTO WISCONSIN.  

[Amped]

7500 sbcape in Iowa. That's insane.

[DanLarsen34]

I’m a little surprised that the watch values were 50-50 given that there’s a moderate risk over that area for tornadoes. Watch probabilities don’t really mesh with the SPC outlook IMO (not that it matters that much).

[Indystorm]

Expected storm tops to 65,000 feet, 3 inch hail, and winds up to 80 mph will sure mean business as well as the possibility of strong tornadoes.

[hlcater]

Those supercells are well elevated at this time. I'd watch for more development on the front down by Benson where there is currently a patch of agitated cumulus. I do think storms up by Little Falls do eventually become surface based, but probably not within the next hour.

[DanLarsen34]

First tornado warning just went up. 

[hlcater]

No idea why, those storms are almost certainly at least somewhat elevated.

[Indystorm]

11 minutes ago, hlcater said:

No idea why, those storms are almost certainly at least somewhat elevated.

Trained spotters reported a funnel cloud nw of Little Falls

[yoda]

12 minutes ago, hlcater said:

No idea why, those storms are almost certainly at least somewhat elevated.

Because trained spotters reported a funnel cloud 

[hlcater]

Funnel cloud on a storm with no 0-3km CAPE, no surface based parcels and that's outflow dominant? I understand covering your bases and being safe but I'd probably call BS on a funnel report, even from a trained spotter, in the environment that storm is in unless I had a picture.