Severe Weather 4-4-23

[cheese007]

Decided to make a second thread in here since Arkansas makes up the bulk of the highest threat area atm. 30% D6

 

[BuffaloWeather]

Will this extend into Indiana and Ohio on Wednesday? Was thinking of taking a PTO day and heading out chasing if it does. 

[bkviking]

4/4/23: Gensini is usually cautious..

[Quincy]

Strong synoptic signal, but not sure I’d be calling for a high risk this far out. 

[WxSynopsisDavid]

46 minutes ago, Quincy said:

Strong synoptic signal, but not sure I’d be calling for a high risk this far out. 

Agreed. Between mixing, LCL's, morning convection, capping inversion issues this is something we wont know until the morning of, in terms of SPC issuance. But this is the strongest synoptic signal we have had for a severe weather outbreak since 2011 over such a large area/expanse of the US. It's shaping up to be a conus-wide outbreak.

[stormdragonwx]

SPC Outlooks that seem to be straight out of the movie "Groundhog Day". Lovely

 

[Powerball]

Given there's a marginal risk in place for tomorrow, I'd argue this thread should be combined with the other for 4/2 (and include 4/3) as this is appears it may be a multi-day event for the subforum.

That's just MHO.

[Quincy]

Three main areas of concern:

1. Warm sector/near the warm front from Missouri toward the Iowa/Illinois border area. Pretty good model agreement that either a cluster or perhaps just a renegade storm or two initiates. A significant severe threat would likely accompany any storms, with large CAPE, supercell wind profiles and low level hodograph enlargement.

2. Dryline from eastern Kansas into Oklahoma. With slower trough ejection modeled, convective initiation seems unlikely. Should a storm manage to form, it would very likely be severe. I think this is the least likely of the three scenarios, especially if the model trend continues.

3. A more widespread severe threat may materialize after dark as the trough ejects and the low level jet ramps up. We could see a broken line of storms move across eastern Kansas, along with cellular warm sector activity possible across the Ozarks. The only thing perhaps limiting this threat is that the main line of storms may grow upscale due to nearly boundary-parallel shear and pre-frontal activity is a bit more uncertain.

 

[Chinook]

While we are waiting for this to get on the Day-2 type time frame, I'll post the CIPS analogs, with Apr. 2, 12z data, for two different sectors. The way the data goes into the sector of the analog system must make a significant difference as to which analogs are picked. And get this: None of these analogs are what Ryan Hall mentioned as the best analogs, 4/26/94 and 2/29/2012.

 

Midwest sector

 

Southern Plains sector.

 

[Chinook]

The newest rage in town: CAPE with embedded hodographs

 

[weatherextreme]

Day 2 Mod out with split 15/10% Tor. Almost a repeat of the previous outbreak

 

 

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1203 AM CDT Mon Apr 03 2023

   Valid 041200Z - 051200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS LATE TUESDAY
   AFTERNOON AND EVENING ACROSS PARTS OF NORTHEASTERN MISSOURI INTO
   SOUTHEASTERN IOWA...NORTHWESTERN AND WEST CENTRAL ILLINOIS...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   MODERATE RISK ACROSS MUCH OF NORTHERN MISSOURI....CENTRAL AND
   EASTERN IOWA...NORTHWESTERN AND CENTRAL ILLINOIS...AS WELL AS PARTS
   OF NORTHEASTERN TEXAS...SOUTHEASTERN OKLAHOMA...MUCH OF
   ARKANSAS...INTO SOUTHERN MISSOURI...

   ...SUMMARY...
   Severe thunderstorms appear likely to develop late Tuesday afternoon
   into Tuesday night across the lower Missouri Valley into southern
   portions of the Upper Midwest, and across parts of the southeastern
   Great Plains into portions of the Mid South.  These could pose a
   risk for a few strong tornadoes, large hail and damaging wind gusts.

   ...Synopsis...
   As initially amplified mid-level ridging over the mid-latitude
   eastern Pacific gradually becomes suppressed, models indicate that
   downstream troughing will broaden from the Great Basin into the
   Mississippi Valley.  This will be lead by a vigorous short wave
   trough, which is forecast to be accompanied by continuing strong
   surface cyclogenesis from the central Great Plains into the Upper
   Midwest, and building downstream mid-level ridging across the Upper
   Ohio Valley into Ontario, as well as across the northeastern Gulf of
   Mexico into Southeast.

   An intensifying southwesterly mid/upper jet streak (including speeds
   in excess of 100 kt at 500 mb) nosing across the central Great
   Plains through Upper Midwest will contribute to strong deep-layer
   shear within the warm sector of the cyclone.  At the same time,
   intensification of southerly lower-level flow (to 50-70+ kt around
   850 mb) likely will contribute to large clockwise-curved low-level
   hodographs.  This could potentially contribute to an environment
   conducive to supercells and organizing lines or clusters capable of
   producing strong tornadoes and damaging winds, where large-scale
   forcing for ascent and thermodynamic profiles can become favorable.

   However, among a number of substantive lingering uncertainties, the
   quality of the boundary-layer moisture return from the Gulf of
   Mexico remains in question.  Due to (at least initially) relatively
   shallow boundary-layer depth, downward mixing of drier air might
   impact sizable pockets of the potentially broad warm sector through
   the day, based on model output.  Also, ahead of the mid/upper
   troughing, destabilization associated with large-scale ascent and an
   influx of high-level moisture from the subtropical Pacific may
   contribute to convective development which tends to saturate and
   stabilize lapse rates down into the mid-levels, across much of the
   Ozark Plateau into middle Mississippi Valley.  While it appears that
   this will not completely erode the capping elevated mixed-layer air,
   thickening cloud cover aloft may inhibit surface heating and
   suppress potential thunderstorm development in the absence of lift
   to overcome the inhibition.

   ...Great Plains into the Mississippi Valley...
   Both the latest NAM and Rapid Refresh appear increasingly suggestive
   that the dryline could surge east-northeastward across southwestern
   Iowa and northwestern/west central Missouri, at least above the
   surface, by mid to late afternoon, in response to the progression of
   at least one speed maximum within the mid-level flow.  Model output
   generally indicates that largest CAPE will become focused ahead of
   this feature, and south of the warm front advancing northward across
   central Iowa/northern Illinois during the late afternoon.  And the
   dryline might provide a focus for sustained discrete supercell
   development with the potential to produce strong tornadoes while 
   propagating northeastward across northeastern Missouri and
   southeastern Iowa into northwestern and west central Illinois
   through early evening.

   In the wake of this activity, as the cold front begins to overtake
   the dryline and advance southeastward, various model output
   continues to suggest that the evolution of an organizing line or
   cluster of storms is possible.  This may pose a risk for large hail,
   damaging wind gusts, and perhaps a few tornadoes while propagating
   east-southeastward across the lower Missouri/middle Mississippi
   Valley vicinity into Tuesday night.

   Farther south, developments initially along the dryline and then
   ahead of the southeastward advancing cold front remain a bit more
   unclear.  However, there has been a persistent signal within the
   model output that a narrow corridor of more substantive
   boundary-layer moistening could provide a focus for enhanced severe
   weather potential by Tuesday evening.  It is possible that
   associated destabilization may become aligned with the strong
   deep-layer mean flow, possibly allowing for the evolution of one or
   two long track supercells, ahead of a developing squall line.

[Roger Smith]

I'm seeing a parallel to the Apr 3-4 1974 situation shifted a bit to the northwest, so therefore it could be extreme on two consecutive days because in 1974 the second day's outcome was somewhat diminished by having much of the severe zone over the Appalachians to mid-Atlantic states by mid-afternoon (there still was a minor resurgence), in this case the explosive development zone would be further west on Tuesday 4th (similar to Apr 3 1974 but shifted northwest) and as with 1974 it would be very active all night then become prone to redevelopment but more so because the cold front would still be west of the mountains in the Ohio valley by 18z-21z. A two-day outbreak with an overnight component and extreme potential in a heavily populated region, has super-outbreak potential. 

I fully expect to see high risk and PDS situations over all states from e KS to OH and e TX to GA, let's hope this either misfires or contains its worst cells to farmland because there could be quite a few long-track F3-5 cells involved in this. 

[WxSynopsisDavid]

22 minutes ago, Roger Smith said:

I'm seeing a parallel to the Apr 3-4 1974 situation shifted a bit to the northwest, so therefore it could be extreme on two consecutive days because in 1974 the second day's outcome was somewhat diminished by having much of the severe zone over the Appalachians to mid-Atlantic states by mid-afternoon (there still was a minor resurgence), in this case the explosive development zone would be further west on Tuesday 4th (similar to Apr 3 1974 but shifted northwest) and as with 1974 it would be very active all night then become prone to redevelopment but more so because the cold front would still be west of the mountains in the Ohio valley by 18z-21z. A two-day outbreak with an overnight component and extreme potential in a heavily populated region, has super-outbreak potential. 

I fully expect to see high risk and PDS situations over all states from e KS to OH and e TX to GA, let's hope this either misfires or contains its worst cells to farmland because there could be quite a few long-track F3-5 cells involved in this. 

Synoptically, this setup is different and not similar. This past outbreak actually had similarities and the analog was shown in the soundings. Just not seeing the similarities this time around.

[Chinook]

Maybe this is just a case where the 12z CAM models see a cap of some strength. Then, none of the CAM models have much convection at 00z-04z tomorrow night. The SPC is essentially saying they're just really wrong.

 

[weatherextreme]

Is it me or is the new day 2 update coming in very late  : Edit.  Day 2 updated

 

 

[stormdragonwx]

Ominous new D2. The familiar trend continues.

 

[weatherextreme]

15 hours ago, Quincy said:

Three main areas of concern:

1. Warm sector/near the warm front from Missouri toward the Iowa/Illinois border area. Pretty good model agreement that either a cluster or perhaps just a renegade storm or two initiates. A significant severe threat would likely accompany any storms, with large CAPE, supercell wind profiles and low level hodograph enlargement.

2. Dryline from eastern Kansas into Oklahoma. With slower trough ejection modeled, convective initiation seems unlikely. Should a storm manage to form, it would very likely be severe. I think this is the least likely of the three scenarios, especially if the model trend continues.

3. A more widespread severe threat may materialize after dark as the trough ejects and the low level jet ramps up. We could see a broken line of storms move across eastern Kansas, along with cellular warm sector activity possible across the Ozarks. The only thing perhaps limiting this threat is that the main line of storms may grow upscale due to nearly boundary-parallel shear and pre-frontal activity is a bit more uncertain.

 

 

 

Looks like # 3 so far

 

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 PM CDT MON APR 03 2023

VALID 041200Z - 051200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM EASTERN
IOWA INTO NORTHWEST ILLINOIS...AND FROM SOUTHERN MISSOURI
SOUTHWESTWARD TOWARD THE ARKLATEX....

..SUMMARY

A LARGE AREA OF SEVERE POTENTIAL WILL EXIST FROM TUESDAY AFTERNOON
INTO WEDNESDAY MORNING, FROM EASTERN PORTIONS OF THE PLAINS INTO THE
MISSOURI AND MID/UPPER MISSISSIPPI VALLEYS. STRONG TORNADOES AND
PARTICULARLY DAMAGING WINDS ARE EXPECTED. BOTH AFTERNOON AND
OVERNIGHT POTENTIAL WILL EXIST ACROSS VARIOUS REGIONS, INCLUDING THE
RISK OF DANGEROUS NIGHTTIME TORNADOES.

..SYNOPSIS

A LARGE UPPER TROUGH WILL MOVE FROM THE ROCKIES INTO THE PLAINS ON
TUESDAY, WITH AN UPPER LOW TRACKING FROM WY TO NORTHERN MN BY
WEDNESDAY MORNING, DEEPENING AFTER 00Z. MEANWHILE, UPPER RIDGING
WILL OCCUR OVER THE EASTERN STATES. A STRONG 100 KT MIDLEVEL JET MAX
WILL BE POSITIONED FROM NM INTO WESTERN KS DURING THE DAY, WITH AN
INTENSIFYING JET CORE TUESDAY NIGHT FROM KS INTO IA. JUST AHEAD OF
THE PRIMARY UPPER TROUGH/JET, A LEADING SPEED MAX WILL STRENGTHEN
FROM OK INTO KS AND MO DURING THE DAY, PERHAPS WITH A SUBTLE LOBE OF
COOLING ALOFT.

AT THE SURFACE, LOW PRESSURE WILL EXIST OVER EASTERN CO TUESDAY
MORNING, AND WILL SHIFT EASTWARD ACROSS KS DURING THE DAY,
TRANSLATING EAST/NORTHEAST ALONG A COLD FRONT. THIS LOW WILL SHIFT
INTO IA BY EVENING, AND INTO WI BY 12Z WEDNESDAY. AHEAD OF THE LOW,
A PROMINENT WARM FRONT WILL MOVE RAPIDLY NORTH, BEGINNING THE DAY
FROM NORTHEAST KS INTO CENTRAL IL, AND REACHING NEAR I-80 FROM IA
INTO NORTHERN IL BY 00Z. THIS BOUNDARY WILL CONTINUE NORTH INTO
SOUTHERN WI AND WESTERN LOWER MI OVERNIGHT, AHEAD OF THE SURFACE
LOW. BEHIND THE LOW, A COLD FRONT WILL MAKE AN EASTWARD PUSH DURING
THE LATE EVENING AND OVERNIGHT ACROSS IA, NORTHWEST MO AND EASTERN
KS.

SOUTH OF THE LOW, A DRYLINE WILL STRETCH FROM EASTERN KS INTO
CENTRAL OK AND NORTH TX AT 00Z, AND MAY BECOME STATIONARY OR EVEN
BACK WESTWARD OVER THE SOUTHERN PLAINS DURING THE LATE EVENING AND
PRIOR TO THE COLD FRONT ARRIVING FROM THE NORTH.

GIVEN RELATIVELY HIGH HEIGHTS OVER THE EASTERN CONUS PRECEDING THE
UPPER TROUGH, A VERY WIDE WARM SECTOR WILL DEVELOP FROM THE SURFACE
LOW AND DRYLINE EASTWARD WELL EAST OF THE MS RIVER, WITH UPPER 60S F
DEWPOINTS COMMON FROM EASTERN OK AND AR SOUTHWARD. THE COMBINATION
OF AN EXPANSIVE WARM SECTOR AND STRONG SHEAR, FOR LONG DURATION AND
IN VARIOUS FORCING REGIMES, SUGGESTS THAT SIGNIFICANT SEVERE WEATHER
IS LIKELY. HOWEVER, SUBTLETIES REGARDING TIMING WITH REGARD TO THE
DIURNAL CYCLE, CAPPING, AND CONFLICTING MODEL OUTPUT WILL MAKE THIS
PREDICTION CHALLENGING, ESPECIALLY WHEN WEIGHING POTENTIAL IMPACTS
TO LIFE AND PROPERTY.

..IA...NORTHERN MO...IL...SOUTHERN WI - DAYTIME

THE AREA NEAR THE WARM FRONT AND LATER IN LATE INTO THE OVERNIGHT
HOURS AHEAD OF THE SURFACE LOW WILL BE A FAVORED AREA FOR SUPERCELLS
AND TORNADOES. STORMS ARE EXPECTED TO FORM FROM NORTHERN MO INTO IA
DURING THE LATE AFTERNOON, SHIFTING NORTHEASTWARD WITH THE WARM.
LOW-LEVEL SHEAR WILL BE EXTREMELY FAVORABLE FOR TORNADOES, AS WITH
OVER 300 M2/S2 SRH AND MUCAPE PERHAPS UP TO 3000 J/KG. THE STEEP
LAPSE RATES ALOFT WILL MAXIMIZE UPDRAFT STRENGTH AS WELL, RESULTING
IN STRONG TORNADOES. THIS THREAT MAY PERSIST FARTHER NORTHEAST INTO
SOUTHERN WI AND NORTHERN IL INTO THE NIGHT AS THE WARM AND UNSTABLE
AIR WITH THE WARM FRONT CONTINUES TO MOVE NORTH WITH THIS STRONG
SYSTEM.

..NORTHEAST TX INTO AR AND INTO MO - OVERNIGHT

CONFIDENCE IS INCREASING IN THE POTENTIAL FOR RARE AND DANGEROUS
OVERNIGHT TORNADOES AND DAMAGING WINDS, AND A MODERATE RISK HAS BEEN
INTRODUCED FOR THIS REGION. THE AIR MASS WILL REMAIN CAPPED DURING
THE DAY, AS BOUNDARY-LAYER MOISTURE BUILDS. STEEP LAPSE RATES WILL
EXIST ABOVE THE CAPPING LAYER, WHICH WILL NOT BE PARTICULARLY STRONG
OVERNIGHT DUE TO ROBUST MOISTURE. AS THE COLD FRONT APPROACHES FROM
THE WEST, THE LOW-LEVEL JET WILL REMAIN STRONG PROVIDING THETA-E
ADVECTION THROUGH THE NIGHT. NOCTURNAL STORMS ARE FORECAST TO ERUPT
AFTER 06Z, AND PERHAPS CLOSER TO 08Z FROM SOUTHWEST MO INTO WESTERN
AR AND INTO NORTHEAST TX. HODOGRAPHS WILL STRONGLY FAVOR TORNADIC
SUPERCELLS WITH EFFECTIVE SRH NEAR 400 M2/S2. FURTHER, STEEP LAPSE
RATES ALOFT AND AMPLE INSTABILITY WILL FAVOR STRONG TORNADOES, AND A
LONG TRACKED TORNADO CANNOT BE RULED OUT. THIS APPEARS TO BE A RARE
CASE WHERE THE FRONT MAY ACT MORE LIKE A DRYLINE DURING THE
OVERNIGHT HOURS, WITH VEERING AT 850 MB BEING MORE GRADUAL. CAPPING
IS MOST LIKELY TO LIMIT THE EASTWARD EXTENT OF THE THREAT FOR
SOUTHERN AREAS NEAR LA.

..JEWELL.. 04/03/2023

[weatherextreme]

 

[weatherextreme]

Looks like FWD is still looking at dryline storms and westward/southward extent of the threat for tomorrow.   (Imagine isn't copying)  This can be seen from the FWD NWS site.

 

 

[weatherextreme]

 

[stormdragonwx]

Can't help but feel my area is gonna get nailed tomorrow. Also the same model (RRFS A) that nailed the Little Rock tornadic supercell is showing a storm tracking right over my area after 05z tomorrow night. Also the HREF is already lighting up the STP probs.

 

[Quincy]

Looking rather ominous between about 11 PM and maybe 5-6 AM. Just a terrible time for this sort of tornado threat. 

[Witness Protection Program]

 

[Ed, snow and hurricane fan]

NAMs have impressive instability and shear in the Southern moderate area, but a paltry with storms forming that can take advantage of the conditions.  Bit of a loaded gun but the trigger may not be pulled.

[Quincy]

Quick overview including 15z surface analysis. Can’t overlook the wildfire threat across the plains, but evening and overnight tornadoes will arguably be the most dangerous hazard. 

 

[stormdragonwx]

Thought I'd note too 2500-3500 MLCAPE and 300-500 j/kg SRH was more than what was encountered in central/eastern AR Friday. Yikes. I will be interested to see how the storm motions evolve too. So far it looks similar to Friday as well. 50-70 mph NE movement. Being at night will be especially dangerous if there's a violent wedge on the ground.

[cstrunk]

Central Iowa looks to have a rough go of it late this afternoon/early evening...

[JMT417]

Enhanced risk and 10% tor probabilities pushed west to Joplin with 11:30 SPC update 

[Quincy]

 

[olafminesaw]

This one in Missouri looks legit.