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Severe WX Severe Weather Threat 3/14-3/16

Brice W said:
10 minutes have past since 0730z. I’m starting to get more antsy about this.
Click to expand...
0730z = 2:30am CT/3:30am ET

READY Tools - Time Conversion Table

www.ready.noaa.gov www.ready.noaa.gov

Quick conversion tip that I use… Take the Z time and:
-subtract 5 (hours) for central (0730 - 5 = 0230)
-subtract 4 (hours) for eastern (0730 - 4 = 0330)

The result you get is the time in “military time”. Convert that and you have the actual 12 hour time :)
Looo at that chart and practice a bit :)

This also works for when you are looking at the “valid at” on the model runs.
 
D3 MOD it is

1741851418380.png

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT THU MAR 13 2025

VALID 151200Z - 161200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
SOUTHEAST LOUISIANA INTO SOUTHERN AND CENTRAL MS/AL...

..SUMMARY

A SEVERE WEATHER OUTBREAK IS EXPECTED ON SATURDAY FROM THE CENTRAL GULF COAST STATES/DEEP SOUTH INTO THE OHIO VALLEY. SIGNIFICANT TORNADOES (FOCUSED ACROSS THE SOUTH), SWATHS OF DAMAGING GUSTS, AND HAIL ARE EXPECTED.

..SYNOPSIS

AN UPPER CYCLONE OVER THE UPPER MIDWEST WILL LIFT NORTHEAST INTO ONTARIO THROUGH SATURDAY EVENING. MEANWHILE, A LARGE-SCALE UPPER TROUGH OVER THE PLAINS WILL EJECT EAST TOWARD THE MS VALLEY. STRONG SOUTHWESTERLY MID/UPPER FLOW (WITH A 500 MB JET STREAK NEAR 100 KT) WILL OVERSPREAD THE LOWER MS VALLEY/MID-SOUTH VICINITY BY 00Z, AND CONTINUE EAST/NORTHEAST OVERNIGHT INTO THE OHIO VALLEY AND CENTRAL APPALACHIANS. AN INTENSE SOUTH/SOUTHWESTERLY LOW LEVEL JET GREATER THAN 60 KT IS FORECAST TO OVERSPREAD THE CENTRAL GULF COAST/DEEP SOUTH INTO THE TN/OH VALLEY DURING THE LATE AFTERNOON AND NIGHTTIME HOURS. RICH GULF MOISTURE WITH DEWPOINTS IN THE MID/UPPER 60S IS EXPECTED TO BE FOCUSED OVER LA/MS/AL AND THE FL PANHANDLE, AND POSSIBLY AS FAR NORTH AS MIDDLE TN AND FAR WESTERN GA. 50S TO LOW 60S F DEWPOINTS WILL EXTEND NORTH INTO THE OHIO VALLEY. THIS SHOULD SUPPORT A WIDESPREAD RISK FOR SEVERE STORMS ACROSS MUCH OF THE
CENTRAL INTO THE SOUTHEASTERN U.S. SATURDAY INTO EARLY SUNDAY.

..DEEP SOUTH/TN VALLEY VICINITY

FORECAST GUIDANCE HAS GENERALLY TRENDED TOWARD LESS WIDESPREAD PRECIPITATION COVERAGE SATURDAY MORNING AS STRONGER HEIGHT FALLS ARE NOT EXPECTED UNTIL LATE MORNING/EARLY AFTERNOON AS THE PLAINS TROUGH EJECTS AND A SURFACE LOW BEGINS TO DEVELOP OVER THE MID-SOUTH. PERSISTENT STRONG SOUTHERLY LOW-LEVEL FLOW WILL ALLOW FOR A MOISTURE-RICH BOUNDARY LAYER THAT SHOULD REMAIN RELATIVELY PRISTINE
ACROSS SOUTHEAST LA INTO SOUTHERN/CENTRAL MS/AL BEFORE CONVECTION DEVELOPS BY MIDDAY. FORECAST SOUNDINGS SHOW COOLING ALOFT WILL SUPPORT STEEP MIDLEVEL LAPSE RATES ATOP THIS MOIST BOUNDARY LAYER, LEADING TO MLCAPE VALUES PERHAPS APPROACHING 2000 J/KG (DECREASING WITH NORTHWARD EXTENT IN MIDDLE TN). VERTICALLY VEERING WIND PROFILES WITH STRONG ANVIL-LEVEL DIVERGENCE AMID MODERATE
INSTABILITY SHOULD SUPPORT ROBUST UPDRAFTS AND INTENSE SUPERCELLS. SIGNIFICANT TORNADOES, DAMAGING GUSTS AND LARGE HAIL WILL BE POSSIBLE THROUGH THE AFTERNOON AND SPREADING INTO AL DURING THE EVENING/NIGHTTIME HOURS.

ADDITIONAL CONVECTION IS EXPECTED TO DEVELOP ALONG AN EASTWARD-ADVANCING COLD FRONT DURING THE AFTERNOON AND INTO THE OVERNIGHT. AN ORGANIZED LINE OF STORMS WILL POSE A RISK FOR DAMAGING WIND SWATHS AND TORNADOES ACROSS NORTHERN MS/AL INTO TN, EASTWARD INTO GA AND THE WESTERN CAROLINAS OVERNIGHT.

..OHIO VALLEY

VERY STRONG DEEP-LAYER FLOW WILL BE IN PLACE ACROSS THE OHIO VALLEY ON SATURDAY WITH SOME CONVECTION POSSIBLY ONGOING FROM SOUTHEAST LOWER MI INTO WESTERN/CENTRAL KY. THE EXTENT OF SEVERE POTENTIAL IS UNCERTAIN AND DEPENDENT ON HOW MUCH PRECIPITATION OCCURS EARLY IN THE FORECAST PERIOD. TOO MUCH CONVECTION EARLY IN THE DAY COULD LARGELY LIMIT DESTABILIZATION AND TEMPER THE OVERALL RISK. HOWEVER, IF LESS CONVECTIVE CONTAMINATION OCCURS, GREATER DESTABILIZATION COULD OCCUR AHEAD OF A DEEPENING SURFACE LOW LIFTING NORTHEAST FROM THE MID-SOUTH TO OH DURING THE EVENING. GIVEN THE STRENGTH OF DEEP-LAYER FLOW AT LEAST SOME RISK OF STRONG/DAMAGING GUSTS WITHIN BANDS OF THUNDERSTORMS SHOULD OCCUR THROUGH SATURDAY NIGHT.

..LEITMAN.. 03/13/2025
 
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andyhb said:
That's not how that works. 45 percent hatched is MDT-equivalent probabilities in D2 and D3 outlooks.
Click to expand...
Maybe I just miscommunicated, because this 45% hatched risk is exactly what I was looking for. For a layman like me, it communicates the urgency (and elevated risk) of the situation in exactly the way it needed to. The probabilistic graphic will generate buzz and make the rounds on social media like it needs to as well. All I want is for everyone in Alabama and Mississippi to understand what's coming.

The messaging conveys the seriousness of the situation as well
Vertically veering wind profiles with strong anvil-level divergence amid moderate instability should support robust updrafts and intense supercells. Significant tornadoes, damaging gusts and large hail will be possible through the afternoon and spreading into AL during the evening/nighttime hours.
Click to expand...

Edit: 45% and purple is technically the same as 30% and red on probabilistic graphics for Day 2 and 3. However 45% and purple is also considered high-risk, but only if it's on the main graphic, and it can't be on Day 2 or 3. I think I got it guys. Thanks.

Edit Edit: The SPC deserves enormous credit for issuing this 45% hatched 3 days out. Couldn't have been an easy decision, but it's the type of clear messaging the public needs right now, even if some people want to get hung up on the semantics.
 
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As a member of the “old guard” that’s been tracking this stuff since the 90’s I often smile at the “I’ve never seen an outlook like this” posts that often happen here. With that said, I’m struggling to recall the last Day 3 outlook that had such direct and clear language about an upcoming event. Or it could be the time of night and I’m not thinking clearly. Either way, dangerous days ahead. Stay safe everyone!
 
Incoming NAM continues the trend of the northward expansion of the warm sector well into southern middle Tennessee, with soundings like attached below as far north as places like Hohenwald, Columbia, and Lewisburg. From just after 18z on past midnight, the 6z NAM is a face value violent supercell swarm outbreak from just south of I-40 all the way down to US. 84 across MS/AL/TN and likely eventually holding on into west GA for the late night. Expect northward expansions or bodily shifts of the Saturday Moderate Risk. Nothing Leitman had access to overnight supported it being restricted and centered so far south except the CSU-MLP.

1741855821189.png
 
I'll be honest, the last system that I remember that had this much hype was the he who shall not be named system.

I was here for the whole thing, even had to leave here and help work the aftermath of Smithville.
I doubt, hope really, that this will be near what that was, but, it's definitely bringing back flashbacks.
I just don't know what to think. I'm desperately looking for anything that may weaken this.
 
Fred Gossage said:
Expect northward expansions or bodily shifts of the Saturday Moderate Risk. Nothing Leitman had access to overnight supported it being restricted and centered so far south except the CSU-MLP.

View attachment 35284
Click to expand...
Is it possible they were just trying to seperate the extraordinary conditions in MS and AL as much as possible within the confines of the 4 teirs they're allowed to use this far out? Surely, they'll give Tennessee moderate and MS and AL high on the next outlook. At least the 30% hatched probabilistic gives you something to work with now and conveys the same message to the casual viewer as the moderate risk.
 
-16 to -17C temps at 500mb are spread overtop the warm sector in northeast MS up into McNairy and Hardin Counties of TN at 21z Saturday, with -14C at 500mb extending down to near Jackson. 300mb temps of -41 to -42C are found in point soundings in that northeast MS area, and they're in the -42 to -43C range at 300mb across north/central MS ahead of the nose of that channel jet approaching. This is a stunning warm sector environment that is being modeled. This is how we're getting 1600-1800 CAPE being modeled on the NAM deep up into southern middle TN with only 62-64 dewpoints (that may be a couple degrees too low because of the about-to-be-mentioned reason) and face value temps of 68-70 (which are likely too cool). Cold mid/upper temps like that make the low-level thermos much more efficient with less.
 
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