Severe WX Severe Weather Threat - February 15-16, 2023

[Timbo64]

FFS, can we PLEASE give it a rest?
This is the kind of back and forth crap that really turns people off if they are first time visitors here!

EDIT: Sorry if I'm a little angry this morning, but I've been in a foul mood ever since that Black Hawk helicopter crashed outside of Huntsville yesterday afternoon. I hate it when soldiers get killed in training accidents!
I never saw any combat action when I was a Marine back in the early 80s, but I did see several really bad training accidents and those images tend to stay with you.

 

[Former Member 1430]

Just a few days ago we were seeing comments such as these:





People were talking about a possible High Risk and/or a repeat of 2 Mar 2012 in terms of aerial scope, based solely on modelling. Obviously not even close...

This will still be locally significant, but certainly the ceiling is far lower than it was depicted several days ago. An isolated EF2+ or two ≠ a widespread outbreak.

How is this not a large area? I don’t believe I was out of bounds there bud

 

[Timhsv]

To me...this is concerning with this morning with that type of EML in place


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
255 AM CST THU FEB 16 2023

...NEW SHORT TERM, LONG TERM...



THE 6Z SPECIAL SOUNDING FROM JACKSON MS IN SUPPORT OF PERILS
INDICATES AN IMPRESSIVE ELEVATED MIXED LAYER WITH A 700-500MB LAPSE
RATE OF 8 C/KM AS WELL AS A STRONG CAP. THIS CAP SHOULD HOLD
OVERNIGHT SOUTH OF NORTHERN MISSISSIPPI AND WILL REMOVE THE
OVERNIGHT MARGINAL RISK FOR OUR NORTHWEST COUNTIES. DESPITE THE LACK
OF GREATER SYNOPTIC FORCING, MODELS INCLUDING CAMS ARE CONSISTENT IN
A WEAK IMPULSE IN SOUTHWEST FLOW ALOFT BREAKING THE CAP AND
INITIATING SUPERCELLS ACROSS CENTRAL AND SOUTHERN MISSISSIPPI LATE
THIS MORNING, THEN MOVING NORTHEASTWARD INTO OUR SOUTHWEST COUNTIES
EARLY THIS AFTERNOON. THESE DISCRETE TO SEMI-DISCRETE SUPERCELLS
WILL THEN CONTINUE NORTHEASTWARD ACROSS THE FORECAST AREA THROUGH
THE AFTERNOON HOURS WITH ADDITIONAL DEVELOPMENT OCCURRING ALONG THE
COLD FRONT OVER MISSISSIPPI AND IN BETWEEN. YOU DON'T OFTEN SEE THE
NUMBER OF IDENTIFIABLE SUPERCELLS APPARENT IN CAM OUTPUT IN THIS
AREA THAT RECENT RUNS HAVE SHOWN. A MOIST (PWATS AROUND 1.75") AND
VOLATILE AIR MASS WILL BE IN PLACE ESPECIALLY ALONG AND WEST OF I-65
WITH SBCAPE VALUES OF 1000 TO 2000 J/KG, STEEP MID-LEVEL LAPSE
RATES, AND 0-6 KM BULK SHEAR VALUES AROUND 60 KTS.

 

[UncleJuJu98]

Just a few days ago we were seeing comments such as these:





People were talking about a possible High Risk and/or a repeat of 2 Mar 2012 in terms of aerial scope, based solely on modelling. Obviously not even close...

This will still be locally significant, but certainly the ceiling is far lower than it was depicted several days ago. An isolated EF2+ or two ≠ a widespread outbreak.

You took my comment out of context. I clearly said not the same magnitude of that event. Whatever ... Are you here to just bring strife?

 

[Tanner]

At this point I am still skeptical that a MDT Risk will verify tornado-wise, much less “4/27 lite.” I think there will be an isolated supercell that produces an intense tornado or two, but multiple long-lived, intense tornado families seem rather unlikely at this time. The major threat appears to be localised and based on the mesoscale rather than synoptic scale. The aerial coverage of discrete activity also looks to be rather limited. People should definitely be prepared, but I still think that this event will not reach its “ceiling,” especially compared to projections* that were issued several days ago.

*Modelled, not SPC

Lord have mercy


Sent from my iPhone using Tapatalk

 

[Brice]

You took my comment out of context. I clearly said not the same magnitude of that event. Whatever ... Are you here to just bring strife?

Back on topic please before things could get out of hand. I think our best case scenario for a bust here is if the capping is underdone, think about it, if may 20 was forecasted to be a top 5 outbreak of the decade, not even thinking about the capping stabilizing storms. Then why can’t this do the same thing? This certainly has many different factors than that day, but just a thought

 

[cincywx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0700 AM CST THU FEB 16 2023

VALID 161300Z - 171200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
MISSISSIPPI TO CENTRAL KENTUCKY...

..SUMMARY

WIDELY SCATTERED SEVERE THUNDERSTORMS ARE LIKELY FROM THE CENTRAL
GULF COAST STATES NORTHWARD INTO THE OHIO VALLEY. STRONG TORNADOES
ARE MOST LIKELY OVER MISSISSIPPI, ALABAMA AND MIDDLE TENNESSEE.

..SYNOPSIS

IN MID/UPPER LEVELS, THE MOST IMPORTANT FEATURE FOR THIS CONVECTIVE
CYCLE WILL BE A POSITIVELY TILTED SYNOPTIC TROUGH, INITIALLY
APPARENT IN MOISTURE-CHANNEL IMAGERY FROM NEAR OMA SOUTHWESTWARD
THROUGH A SMALL CLOSED CYCLONE OVER NORTHWESTERN KS/SOUTH-CENTRAL
NE, TO THE NORTHERN TX PANHANDLE, SOUTH-CENTRAL NM AND SOUTHERN AZ.
AN INITIALLY SEPARATE, NORTHERN-STREAM PERTURBATION OVER MB AND THE
DAKOTAS WILL MOVE SOUTHEASTWARD AND AMPLIFY THROUGH THE DAY,
GRADUALLY PHASING WITH THE SOUTHERN TROUGH. BY 00Z, THE RESULT
SHOULD BE A LENGTHY TROUGH FROM LAKE SUPERIOR SOUTHWESTWARD TO THE
SOUTHERN HIGH PLAINS AND OVER THE ELP/DMN CORRIDOR. BY 12Z, THE
TROUGH SHOULD EXTEND FROM LOWER MI ACROSS THE OZARKS TO CENTRAL TX.

AT THE SURFACE, 11Z ANALYSIS SHOWED A SURFACE LOW OVER THE EAST-
CENTRAL OZARKS NEAR THE AR/MO BORDER, WITH COLD FRONT SOUTHWESTWARD
ACROSS THE ARKLATEX TO THE MIDDLE TX COASTAL PLAIN AND DEEP SOUTH
TX. THROUGH THE DAY, AS THE SURFACE LOW MOVES TOWARD SOUTHERN IN,
THE COLD FRONT SHOULD SWEEP SOUTHEASTWARD ACROSS THE LOWER/MID
MISSISSIPPI VALLEY, AND THE REMAINDER OF SOUTH/SOUTHEAST TX INTO THE
GULF AND NORTHEASTERN MX. BY 00Z, THE LOW SHOULD BE NEAR THE IN/OH
BORDER, WITH COLD FRONT ACROSS CENTRAL KY, MIDDLE TN, SOUTHERN MS,
AND SOUTHEASTERN LA. BY 12Z, THE LOW SHOULD BE OVER EASTERN/CENTRAL
NY NEAR UCA, WITH COLD FRONT FROM THERE ACROSS CENTRAL PA, WESTERN
PARTS OF VA/NC, CENTRAL/SOUTHWESTERN GA, THE CENTRAL/WESTERN FL
PANHANDLE, AND THE CENTRAL/SOUTHWESTERN GULF.

..CENTRAL GULF STATES TO OHIO VALLEY

ONGOING STRONG/ISOLATED SEVERE THUNDERSTORMS ARE NOTED IN TWO MAIN
CORRIDORS -- ONE OVER WESTERN PARTS OF TN/KY, ANOTHER NEAR THE COLD
FRONT OVER AR. SEE SPC TORNADO WATCH 37 AND RELATED MESOSCALE
DISCUSSIONS FOR NEAR-TERM CONCERNS.

AN ADDITIONAL ROUND OF CONVECTION IS EXPECTED TO DEVELOP AHEAD OF
THE SURFACE COLD FRONT AS DIURNAL HEATING DESTABILIZES A FAVORABLY
MOIST WARM SECTOR, AMIDST WEAKENING MLCINH. THE MOST PROBABLE AREA
AND TIMING FOR THIS DEVELOPMENT APPEARS TO BE LATE MORNING INTO
EARLY AFTERNOON ACROSS SOUTHEASTERN LA AND SOUTHERN MS, MOVING/
BUILDING NORTHEASTWARD INTO MORE OF MS/AL INTO THE AFTERNOON.
SURFACE DEWPOINTS IN THE MID 60S TO NEAR 70 F, AT THE BOTTOM OF A
DEEP BOUNDARY LAYER WITH UP TO ABOUT 1.5-INCH PW, WILL CONTRIBUTE TO
MLCAPE COMMONLY AROUND 1500 J/KG, LOCALLY NEAR 2000 J/KG.

KINEMATICALLY, A PERIOD OF STRENGTHENING SHEAR IS EXPECTED INTO THE
AFTERNOON, FOLLOWED BY LEVELING OFF AND PERHAPS SOME LESSENING OF
SHEAR DUE TO VEERING SURFACE WINDS. THIS WILL LEAD TO VARYING BUT
GENERALLY LARGE HODOGRAPH SIZES AND SHAPES, BUT WITH EFFECTIVE SRH
GENERALLY REMAINING IN THE 250-400 J/KG RANGE OVER MUCH OF THE AREA.
THE WIND PROFILES THROUGHOUT THAT CYCLE WILL BE FAVORABLE FOR
SUPERCELLS, WITH EFFECTIVE-SHEAR MAGNITUDES IN THE 45-55-KT RANGE
OVER SOUTHERN AREAS, TO 50-60 KT ACROSS THE TENNESSEE VALLEY REGION.
A NORTHWARD EXTENSION OF SIGNIFICANT-TORNADO PROBABILITIES IS BEING
MADE ACCORDINGLY, AND SOME PARTS OF THIS REGION MAY NEED A FURTHER,
TACTICALLY FOCUSED, TORNADO-DRIVEN UPGRADE TODAY, AS MESOSCALE
TRENDS AND LATER OBJECTIVE GUIDANCE WARRANT.

THE STRONGEST UNCONDITIONAL PARAMETER SPACE FOR SIGNIFICANT-TORNADO
POTENTIAL THIS AFTERNOON AND EVENING STILL APPEARS TO BE IN THE
CORRIDOR FROM SOUTHERN MS TO MIDDLE TN AND WESTERN/CENTRAL/NORTHERN
AL, BUT THAT DOESN'T PRECLUDE ONE FARTHER NORTH INTO A MUCH MORE
CONDITIONAL REGIME AS WELL. DEEP SHEAR AND SRH WILL REMAIN
FAVORABLE NORTHWARD INTO THE OHIO VALLEY, BUT INSTABILITY AT ALL
DEPTHS SHOULD DIMINISH DUE TO A COMBINATION OF ANTECEDENT PRECIP AND
LESS-MATURE, LOWER-THETA-E RETURN FLOW. AS FRONTAL/PREFRONTAL
CONVECTION MOVES OVER THE REGION, A BLEND OF LINEAR AND PRECURSORY
SUPERCELL MODES IS POSSIBLE, WITH DAMAGING TO SEVERE WIND BEING THE
MOST COMMON EVENT, AND A FEW TORNADOES ALSO POSSIBLE. SEVERE
POTENTIAL ALSO SHOULD DIMINISH IN THE OHIO VALLEY CORRIDOR SOONER
THAN THE GULF COAST STATES, AS THE FRONTAL/PREFRONTAL CONVECTION
OUTRUNS A NARROWER WARM SECTOR.

latest disco. lot to unpack but worth the read.

 

[Clancy]

If y'all were wondering if it was muggy this morning.

 

[UncleJuJu98]

Didn't realize but they increased the hatched 10% area I think last night

 

[UncleJuJu98]

Back on topic please before things could get out of hand. I think our best case scenario for a bust here is if the capping is underdone, think about it, if may 20 was forecasted to be a top 5 outbreak of the decade, not even thinking about the capping stabilizing storms. Then why can’t this do the same thing? This certainly has many different factors than that day, but just a thought

Good post! Yeah there's always bust factors but I'm considering what could go wrong this event. It could end up being a memorable event but we will see hrrr sure looks nasty for central alabama

 

[Clancy]

From latest SPC disco.

Kinematically, a period of strengthening shear is expected into the
afternoon, followed by leveling off and perhaps some lessening of
shear due to veering surface winds. This will lead to varying but
generally large hodograph sizes and shapes, but with effective SRH
generally remaining in the 250-400 J/kg range over much of the area.
The wind profiles throughout that cycle will be favorable for
supercells, with effective-shear magnitudes in the 45-55-kt range
over southern areas, to 50-60 kt across the Tennessee Valley region.
A northward extension of significant-tornado probabilities is being
made accordingly, and some parts of this region may need a further,
tactically focused, tornado-driven upgrade today, as mesoscale
trends and later objective guidance warrant

 

[tennessee storm chaser]

Just a few days ago we were seeing comments such as these:





People were talking about a possible High Risk and/or a repeat of 2 Mar 2012 in terms of aerial scope, based solely on modelling. Obviously not even close...

This will still be locally significant, but certainly the ceiling is far lower than it was depicted several days ago. An isolated EF2+ or two ≠ a widespread outbreak.

In all honesty. This setup was just plain sicking 4 days ago. Just 4 days ago. You know that If you can read models lol… not knocking on you. But come on… just matter time we see a high risk day it be this spring or next or even next one ..

 

[Mike S]

Let's stop with the back and forth and focus on nowcasting please

 

[tennessee storm chaser]

Let's stop with the back and forth and focus on nowcasting please

Absolutely agree

 

[GTWXAlum]

10% hatched tornado probs expanded northward to include Nashville with this SPC update

 

[kcyalater]

that’s a massive 10%H. geez

 

[Timhsv]

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0700 AM CST Thu Feb 16 2023

Valid 161300Z - 171200Z
...........................
Edited:
Kinematically, a period of strengthening shear is expected into the
afternoon, followed by leveling off and perhaps some lessening of
shear due to veering surface winds. This will lead to varying but
generally large hodograph sizes and shapes, but with effective SRH
generally remaining in the 250-400 J/kg range over much of the area.
The wind profiles throughout that cycle will be favorable for
supercells, with effective-shear magnitudes in the 45-55-kt range
over southern areas, to 50-60 kt across the Tennessee Valley region.
A northward extension of significant-tornado probabilities is being
made accordingly, and some parts of this region may need a further,
tactically focused, tornado-driven upgrade today, as mesoscale
trends and later objective guidance warrant.

 

[xJownage]

The cap is going to get advected out at just the wrong time. Very subtle forcing is making a discrete mode very likely.

One thing to note...latest HRRR runs are decreasing the LLJ strength, which would help to slightly dampen the situation, however 300 0-3 SRH will still come with a large area of significant tornado threat.

Yesterday towards the front the LLJ largely overperformed by about 10 kts, however, which is something to note with a system like this.

 

[Brice]

that’s a massive 10%H. geez

Seems like a hint, if they’re issuing a big 10%, then is the SPC confident that they’ll issue a tornado-generated MDT risk for the next update?

 

[Justin Hindman]

Leaving work out of Birmingham at 11 and headed to chase.