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Svr Wx threat April 1-April 2 2024

Edith said:
Huh seems Trey mentioned a more linear event to preclude more of a tornado risk.
Click to expand...

a linear storm mode tends to be the saving grace for the ohio valley, so although it looks probable, it is just too early to confidently predict at this point. we'll have a better idea of storm mode once we see how today and tonight evolve across the plains & midwest.

the increasing cause for concern stems from the fact that models have showed a decreasing number of flies in the ointment, setting the stage for a really ugly day tomorrow across much of the ohio valley. i can probably count on one hand how many times the cincinnati area has seen, this early in a calendar year over the past 15 years, a synoptic environment like the one expected tomorrow. storm mode is absolutely the biggest question mark, but it's getting gradually more apparent that it is one of the few that remain.
 
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT MON APR 01 2024

VALID 011630Z - 021200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM EXTREME
NORTH TX INTO CENTRAL/EASTERN OK...

..SUMMARY

SEVERE THUNDERSTORMS WITH VERY LARGE HAIL (2-3 INCH DIAMETER OR
GREATER), DAMAGING GUSTS (60-80 MPH) AND A FEW TORNADOES
(POTENTIALLY UP TO EF2) ARE EXPECTED THIS AFTERNOON INTO TONIGHT
FROM NORTH TEXAS AND OKLAHOMA INTO THE LOWER OHIO RIVER VALLEY.

..SYNOPSIS

EMBEDDED SPEED MAXIMA (90-100+ KT 500 MB) FROM SOUTHERN NM/FAR WEST
TX TO NORTHWEST MEXICO WILL EJECT NORTHEASTWARD TO OK THIS EVENING
AND MO OVERNIGHT. AN ASSOCIATED LEE CYCLONE WILL DEEPEN THIS
AFTERNOON ACROSS THE TX SOUTH PLAINS AND THEN PROGRESS INTO
NORTHWEST OK THIS EVENING AND THE MID MS VALLEY BY THE END OF THE
PERIOD. A BROAD/MOIST WARM SECTOR IS IN PLACE FROM THE SOUTHERN
PLAINS TO THE MID MS/LOWER OH VALLEYS, BENEATH A WARM ELEVATED MIXED
LAYER WITH 8-9 C/KM MIDLEVEL LAPSE RATES. THE CAP WILL WEAKEN
THROUGH THE AFTERNOON FROM THE WEST, WITH THUNDERSTORM INITIATION
BECOMING LIKELY BY MID AFTERNOON ALONG A SURFACE FRONT FROM KS INTO
MO/IL, AND MID-LATE AFTERNOON ALONG THE DRYLINE FROM WESTERN/CENTRAL
OK INTO NORTHWEST TX.

..KS/MO/IL/IN THROUGH TONIGHT

SCATTERED THUNDERSTORM DEVELOPMENT IS LIKELY STARTING MID AFTERNOON
ALONG THE BAROCLINIC ZONE FROM KS INTO MO, AND STORMS WILL
SUBSEQUENTLY SPREAD EASTWARD ALONG THE WARM FRONT FROM MO INTO
IL/IN. THE ENVIRONMENT WILL FAVOR SUPERCELLS CAPABLE OF PRODUCING
VERY LARGE HAIL (2-3 INCHES IN DIAMETER) AND A FEW TORNADOES, WITH
AN ISOLATED STRONG TORNADO POSSIBLE. STORM MODE WILL BECOME MESSIER
INTO THE OVERNIGHT HOURS WITH UPSCALE GROWTH INTO CLUSTERS/LINE
SEGMENTS, WITH AN INCREASE IN THE THREAT FOR DAMAGING WINDS (60-80
MPH), AND A CONTINUED THREAT FOR TORNADOES (POSSIBLY UP TO EF2) WITH
EMBEDDED/QLCS CIRCULATIONS.

..OK/TX THIS AFTERNOON INTO EARLY TONIGHT

THE ELEVATED MIXED LAYER AND ASSOCIATED CAP, ALONG WITH WIDESPREAD
CLOUDS, WILL TEND TO DELAY SURFACE-BASED STORM DEVELOPMENT UNTIL
MID-LATE AFTERNOON, WHEN FORCING FOR ASCENT INCREASES FROM THE
SOUTHWEST WITH THE APPROACH OF THE MID-UPPER JET STREAK. BY ABOUT
21Z, SCATTERED THUNDERSTORM DEVELOPMENT IS EXPECTED ALONG THE
DRYLINE FROM NORTHWEST TX INTO WESTERN OK, AND STORMS WILL SPREAD
QUICKLY NORTHEASTWARD INTO CENTRAL/EASTERN OK THROUGH THIS
EVENING/EARLY TONIGHT. STEEP MIDLEVEL LAPSE RATES AND
BOUNDARY-LAYER DEWPOINTS IN THE MID-UPPER 60S WILL CONTRIBUTE TO
MLCAPE OF 2000-3000 J/KG, IN AN ENVIRONMENT WITH VERY STRONG
DEEP-LAYER SHEAR/LONG HODOGRAPHS FAVORABLE FOR MULTIPLE SUPERCELLS
WITH VERY LARGE HAIL (3 INCHES IN DIAMETER OR GREATER). THE
MAGNITUDE OF THE TORNADO THREAT IS A BIT LESS CERTAIN, GIVEN A
WEAKNESS IN THE LOW-LEVEL SHEAR UNTIL A MORE CONSOLIDATED LOW-LEVEL
JET RESPONSE BEGINS BY LATE EVENING, WHEN STORM MERGERS AND UPSCALE
GROWTH BECOME MORE PROBABLE INTO EASTERN OK/NORTHWEST AR/SOUTHWEST
MO EARLY TONIGHT. HOWEVER, GIVEN THE VERY STRONG FLOW AND
SEASONABLY RICH LOW-LEVEL MOISTURE, THERE WILL BE THE POTENTIAL FOR
A COUPLE OF STRONG (ROUGHLY EF2) TORNADOES LATE THIS AFTERNOON INTO
TONIGHT.
Click to expand...
 
An important note: models have trended trough ejection less and less positive each run, and this is likely a significant contributor to increasingly favorable forecasted wind fields on Tuesday.
trend-nam-2024040112-f042.500wh.conus.gif
 
IIRC I haven't seen discussion regarding this, but something I've found interesting is that the GFS has consistently developed a new low further west around 09z-12z tomorrow, which then proceeds to rapidly deepen which I believe would enhance the northern threat area. Here are some screenshots at 9z, 15z, and 21z tomorrow from the 12z run today (new to posting screenshots, so hopefully these show up)

I believe if this solution played out it would help locally back the winds in the northern target and the induced mass response would ensure ample moisture is still available after the initial MCS moves through. This combined with the previously discussed trend towards a less positive tilt, is making this seem more concerning to me. However, I'm not a met and I haven't seen any other models hop on board with this solution, so I'm curious as to what others think about this.

Screenshot 2024-04-01 125229.pngScreenshot 2024-04-01 125256.pngScreenshot 2024-04-01 125322.png
 
They were a little late but….

1711994738695.png

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 PM CDT MON APR 01 2024

VALID 021200Z - 031200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS A LARGE PORTION OF OHIO...AND INCLUDING ADJACENT PARTS OF SOUTHEASTERN INDIANA...NORTHERN KENTUCKY...AND WESTERN WEST VIRGINIA...

..SUMMARY
A POTENTIALLY SUBSTANTIAL SEVERE WEATHER OUTBREAK -- POSSIBLY
INCLUDING A FEW SIGNIFICANT/LONG-TRACK TORNADOES -- IS EVIDENT FOR
TUESDAY AFTERNOON AND EVENING, WITH HIGHEST PROBABILITY CENTERED
OVER THE OHIO VICINITY, AND EXTENDING SOUTHWARD ACROSS THE TENNESSEE
VALLEY. SOME SEVERE RISK EXISTS AS FAR SOUTH AS THE GULF COAST, AND
AS FAR EAST AS WESTERN PORTIONS OF VIRGINIA AND THE CAROLINAS.

..SYNOPSIS
WHILE A POSITIVELY TILTED UPPER TROUGH MOVES ACROSS THE CENTRAL THIRD OF THE COUNTRY TUESDAY, A MORE COMPACT/ENERGETIC SHORT-WAVE
FEATURE IS EXPECTED TO DIG AGGRESSIVELY/QUICKLY SOUTHEASTWARD ACROSS THE UPPER MIDWEST, GRADUALLY EVOLVING INTO A CLOSED LOW AS IT DOES.
BY WEDNESDAY MORNING, THE DEEPENING LOW IS PROGGED TO RESIDE OVER
THE ILLINOIS VICINITY.

AT THE SURFACE, A LOW INITIALLY OVER THE MISSOURI VICINITY IS PROGGED TO DEEPEN AS THE UPPER SYSTEM DIGS SOUTHEASTWARD, SHIFTING
NORTHEASTWARD ACROSS THE MIDWEST THROUGH THE DAY, AND THEN OCCLUDING
NORTHWARD INTO LOWER MICHIGAN OVERNIGHT. A COLD FRONT ASSOCIATED WITH THE LOW WILL SWEEP ACROSS THE MID MISSISSIPPI AND LOWER OHIO VALLEY THROUGH THE DAY, AND THE LOWER MISSISSIPPI/TENNESSEE/UPPER OHIO VALLEYS OVERNIGHT, CROSSING CENTRAL/SOUTHERN APPALACHIAN CREST LATE. MEANWHILE, A WARM SECTOR SHOULD EXPAND AS FAR NORTH AND EAST
AS CENTRAL AND NORTHEAST INDIANA/NORTHERN OHIO/WESTERN PENNSYLVANIA, THOUGH LIMITED IN NORTHWARD PROGRESS TO WEST VIRGINIA/NORTHERN VIRGINIA/MARYLAND BY PERSISTENT/SLOW-TO-RETREAT COLD-AIR DAMMING OVER THE NORTHEAST.

..OHIO AND TENNESSEE VALLEYS
WIDESPREAD THUNDERSTORMS -- INCLUDING SOME DEGREE OF ALL-HAZARDS
SEVERE RISK -- WILL LIKELY BE SPREADING RAPIDLY EASTWARD ACROSS THE
OHIO VALLEY AREA AT THE START OF THE PERIOD. THIS CONVECTION SHOULD
REACH THE CENTRAL APPALACHIANS BY LATE MORNING/MIDDAY, BUT -- THOUGH
POTENTIALLY HAVING SOME IMPACT ON DESTABILIZATION POTENTIAL ACROSS
THE MDT AND ENH RISK AREAS -- SHOULD LARGELY SHIFT FAR ENOUGH EAST
TO ALLOW WARM-SECTOR DESTABILIZATION TO COMMENCE.

AS THE SURFACE LOW DEEPENS AND CROSSES ILLINOIS AND EVENTUALLY MOVES
INTO INDIANA, AND THE COLD FRONT ADVANCES ACROSS THE MID MISSISSIPPI
AND LOWER OHIO VALLEYS, STORM REDEVELOPMENT IS EXPECTED TO OCCUR
DURING THE AFTERNOON. WHILE EVOLUTION/STORM MODE REMAINS SOMEWHAT DIFFICULT TO DISCERN -- IN PART DUE TO EARLIER STORMS -- SOME MIX OF CELLULAR AND CLUSTER/LINEAR MODE IS EXPECTED TO EVOLVE. GIVEN THE
AMPLE DESTABILIZATION EXPECTED IN COMBINATION WITH VERY STRONG/VEERING DEEP-LAYER FLOW, ALL-HAZARDS SEVERE POTENTIAL IS EVIDENT, INCLUDING VERY LARGE HAIL, STRONG/DAMAGING WINDS, AND SEVERAL SIGNIFICANT TORNADOES.

THE GREATEST RISK, WHICH WILL INCLUDE POTENTIAL FOR A COUPLE OF
INTENSE/LONG-TRACK TORNADOES, SHOULD BEGIN ACROSS INDIANA, AND THE
SPREAD ACROSS OHIO THROUGH THE AFTERNOON AND EVENING, POTENTIALLY
REACHING AS FAR EAST AS WESTERN PORTIONS OF WEST VIRGINIA AND FAR
WESTERN PENNSYLVANIA INTO THE EVENING. EASTWARD ADVANCE OF THE RISK
INTO CENTRAL PENNSYLVANIA WILL LIKELY REMAIN LIMITED, BUT OTHERWISE THREAT MAY SPREAD INTO WESTERN PORTIONS OF VIRGINIA AND THECAROLINAS LATE.

...FLORIDA/GEORGIA/SOUTHEASTERN ALABAMA AND PERHAPS INTO THE WESTERN
CAROLINAS... THUNDERSTORM DEVELOPMENT IS EXPECTED TO INCREASE LATE IN THE PERIOD FROM THE FLORIDA PANHANDLE NORTHEASTWARD, AHEAD OF THE ADVANCING COLD FRONT. WITH INDICATIONS OF POTENTIALLY CELLULAR MODE WITH THIS CONVECTION, CONCERNS FOR A VERY LATE-PERIOD INCREASE IN TORNADO POTENTIAL EXIST, GIVEN BACKGROUND SHEAR PROFILES SUPPORTIVE OF UPDRAFT ROTATION. WHILE SOMEWHAT UNCERTAIN AT THIS POINT, HAVE
EXPANDED 5% TORNADO PROBABILITY SUBSTANTIALLY EASTWARD/SOUTHEASTWARD TO INCLUDE THIS POTENTIAL.
 
Probably the biggest wording escalation I have ever seen in one update within a day of the event. Broyles was calling for a linear event this morning with a few QLCS tornadoes possible. Now it's discrete supercells and long-track tornadoes. Gotta love it. A HUGE 10% hatched, too. I wouldnt me shocked to see that moderate go a little Southwest in the morning into More central KY and possibly another small moderate around Northeast MS/NW Alabama.
 
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