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rolltide_130

Severe Potential Feb 23-24

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Figured there was enough forecast confidence to start a thread. Models have been converging on the potential for severe weather Tuesday into Wednesday for much of this subforum, starting across parts of SE AL and S GA and stretching up into the Carolinas. As it looks right now, a SLP looks to deepen and cross over parts of Northern MS/AL or points north and west, with a very stout 500 mb trough rounding the base in addition to an LLJ upwards of 60 knots crashing into this area. Synoptically, this is quite a stout system that, barring mesoscale details, has the potential to create widespread severe weather problems Tuesday into Wednesday. 

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Yes!!! The weather rule that thunderstorms in winter and a week later you get snow. Sign me up. Sets up perfect for the superstorm in March. 

 

maybe the 2-3rd biggest snow I have ever seen here was Feb 24th 1989, it had to have been 12-16" and windy with strong cold air not even close on temps it was in the 20's, with the winds it was close to a true blizzard....3 days before it was in the 70's with tornadic storms in the SE, we even had a tornado warning in Pitt Co I think but no ground truth....

 

then that Dec 23rd 1989 blizzard gave us another 12"....damn 1989 was a good year lol.

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It does make sense with winter storms following severe storms in winter. You have to have a lot of energy floating around to get severe storms this time of year, and usually means we get warm and then a cold front comes through to create the severe storms. With that much energy flying around and it turning colder, it makes sense to see how it could snow soon after having severe storms.

Of course, 99% of the time we had talk about severe weather around here last year we never really got any storms at all. It is about as hard getting sever weather to actually produce here the past couple f years as it had with winter storms.

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The expanse of the threat on the 00z Euro is pretty amazing. Taken verbatim, it viably suggests severe potential from LA all the way to DC from Tuesday afternoon through Thursday morning. There is no part of this timeframe where the wind fields wouldn't be favorable for supercells as well, it's just a matter of how widespread the buoyancy is (and there certainly is a large expanse of appreciable destabilization).

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MOB certainly has their eye on this event. Here is part of last nights long term AFD.

 

THE OPERATIONAL GFS AND ECMWF GUIDANCE REMAINS IN AGREEMENT WITH
DEEPENING AN UPPER LEVEL LOW IN THE VICINITY OF NORTH AND NORTHEAST
TX DURING THE DAY TUESDAY...BEFORE LIFTING THIS SYSTEM NORTHEASTWARD
INTO NORTHERN PORTIONS OF MS BY EARLY WEDNESDAY MORNING. AN
ASSOCIATED AREA OF SURFACE LOW PRESSURE IS FORECAST TO DEEPEN OVER
NORTHERN LA/SOUTHERN AR TUESDAY AFTERNOON...LIFTING NORTHEASTWARD
TOWARD NORTHERN MS AND WESTERN TN BY EARLY WEDNESDAY MORNING. DEEP
LAYER FORCING SPREADING EASTWARD AHEAD OF THE EJECTING TROUGH WILL
BRING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ACROSS OUR REGION
TUESDAY AFTERNOON INTO TUESDAY NIGHT. A MOIST SOUTHERLY FLOW PATTERN
WILL PERSIST ACROSS OUR FORECAST AREA IN THE WARM SECTOR EAST OF THE
SURFACE LOW...WITH MUCH OF THE OPERATIONAL GUIDANCE SHOWING SURFACE
DEWPOINTS IN THE LOWER TO MID 60S ACROSS THE REGION TUESDAY AFTERNOON
INTO TUESDAY EVENING
...RESULTING IN CAPE VALUES BETWEEN 500-1000 J/KG
AND POSSIBLY LOCALLY HIGHER. A STRONG 850 MB JET ON THE ORDER OF AT
LEAST 40-50 KNOTS IS ALSO LIKELY TO SPREAD ACROSS OUR FORECAST LATE
TUESDAY AFTERNOON INTO TUESDAY EVENING/NIGHT
AS THE DEEP LOW PRESSURE
SYSTEM LIFTS NORTHEASTWARD FROM THE ARKLATEX REGION TOWARD THE
TENNESSEE VALLEY. MID LEVEL LAPSE RATES ALSO LOOK TO STEEPEN TO
AROUND 6.5 C/KM LATE TUESDAY AFTERNOON INTO TUESDAY NIGHT.
GIVEN THE
MODEL CONSISTENCY OVER THE PAST FEW RUNS OF THE INCREASED
INSTABILITY...WIND SHEAR...AND STEEPENING LAPSE RATES.
..WE THINK
THERE WILL BE POTENTIAL FOR SEVERE STORMS ACROSS MUCH OF OUR FORECAST
AREA LATE TUESDAY AFTERNOON INTO TUESDAY NIGHT
...AND WILL MENTION IN
THE HAZARDOUS WEATHER OUTLOOK AND ALSO INTRODUCE A GRAPHICAST WITH AT
LEAST A LIMITED SEVERE POTENTIAL ACROSS MUCH OF OUR REGION. ALL
SEVERE WEATHER MODES LOOK POSSIBLE INCLUDING DAMAGING WINDS...LARGE
HAIL AND ISOLATED TORNADOES.

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MHX also mentions the chance into Wed for us 

 

HAVE TRENDED TOWARD A GFS/ECMWF BLEND AND THIS TYPE OF SETUP BECOMES

SOMEWHAT CONDUCIVE FOR STRONG/SEVERE TSTMS WEDNESDAY AFTERNOON AND

EVENING AND HAVE ADDED A SLIGHT CHANCE OF THUNDERSTORMS. FORECAST SOUNDINGS SHOW

CAPE VALUES NEAR 1000 J/KG AND LI`S AROUND -5 IN THE AFTERNOON
HOURS ON THURSDAY WITH BACKED LOW-LEVEL WINDS.

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Alabama & Mississippi both look dangerous Tuesday evening with LI's projected to be between -4 & -5, 750-1000j/kg of cape in place and 0-3km EHI above 2. Should be an interesting week for severe.

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This is 12z NAM sounding for New Iberia Louisiana, at 21z Tuesday. This has some pretty seriously high parameters, including 622 m2/s2 effective SRH.  Just based on this, you would think there's a chance for several wind reports and/or several tornado reports from southern Louisiana to southern Mississippi Tuesday

 

jbv8E5L.png

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RAH disco...

STORM THREAT: AS PRECIP COVERAGE AND INTENSITY RAMP BACK UP WED INTOWED EVENING WITHIN THE INLAND-SURGING WARM SECTOR AHEAD OF THE COLDFRONT... THE POTENTIAL FOR A FEW STORMS APPEARS TO BE GROWING...WITH A FOCUS ON CENTRAL/ERN NC. LATEST MODEL RUNS ARE DEPICTING MOREINSTABILITY (500-1000 J/KG) WED AFTERNOON THROUGH EARLY EVENING THANTHEIR PREVIOUS RUNS... WITH MID LEVEL LAPSE RATES PROJECTED TO BEOVER 6.5 C/KM IN CONJUNCTION WITH VERY STRONG KINEMATICS... ANINCOMING MID LEVEL DRY PUNCH... AND INTENSE UPPER DIVERGENCE.ADDITIONALLY... THE SHERB PARAMETER USING A NAM/GFS BLEND YIELDSVALUES PEAKING NEAR 1.5... INDICATIVE OF THE POTENTIAL FOR A QLCSAND DAMAGING STRAIGHT LINE WINDS AND PERHAPS A LOW END TORNADOTHREAT. AFTER FRONTAL PASSAGE ON THU... GIVEN THE TIGHTENING MSLPGRADIENT... WE SHOULD SEE SUSTAINED WINDS NEAR 20 MPH WITH PERIODICGUSTS OF 30-35 MPH LIKELY BASED ON THE MOMENTUM TRANSPORT SUGGESTEDBY FORECAST SOUNDINGS. 

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CAE disco

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...THE MAIN CONCERN IS A THREAT OF SEVERE THUNDERSTORMS LATE TUESDAYNIGHT AND WEDNESDAY. THE GFS AND ECMWF SHOW THE WARM FRONT LIFTINGNORTHWARD AND INTO THE FORECAST AREA LATE TUESDAY NIGHT ANDWEDNESDAY AHEAD OF THE STRONG COLD FRONT. THE MODELS DEPICT HIGHSHEAR WITH A 50- TO 60-KNOT H85 JET. THE MODELS MAY BE TOO FASTERODING THE WEDGE LATE TUESDAY NIGHT. THE MAIN THREAT TIME MAY BEEARLY WEDNESDAY IN THE HIGH-SHEAR AREA ALONG THE WARM FRONT ANDAGAIN LATER WEDNESDAY JUST AHEAD OF THE COLD FRONT.

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This is 12z NAM sounding for New Iberia Louisiana, at 21z Tuesday. This has some pretty seriously high parameters, including 622 m2/s2 effective SRH.  Just based on this, you would think there's a chance for several wind reports and/or several tornado reports from southern Louisiana to southern Mississippi Tuesday

 

jbv8E5L.png

 

Looks scary, not little weak spin ups with those parameters....it seems so far this year when the parameters look severe we get the goods especially down in Dixie Alley and Florida...

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Looks scary, not little weak spin ups with those parameters....it seems so far this year when the parameters look severe we get the goods especially down in Dixie Alley and Florida...

 

Pretty classic trademark of the spring exiting an El Nino winter. Most of the biggest outbreaks along and just north of the gulf coast including Florida seem to come during the late winter in these El Nino seasons. 

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Pretty classic trademark of the spring exiting an El Nino winter. Most of the biggest outbreaks along and just north of the gulf coast including Florida seem to come during the late winter in these El Nino seasons. 

 

yeah would love to see old storm report maps for 1998 but the archives on SPC only go back till 6/99

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yeah would love to see old storm report maps for 1998 but the archives on SPC only go back till 6/99

You can view old severe weather reports with Online SeverePlot. Check the bottom of this page

 

http://www.spc.noaa.gov/climo/online/

 

Note: CIPS analogs-SE sector seems to be highlighting the same areas as the SPC 3-day Slight outlook.

 

http://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=SE&fhr=F060&rundt=2016022112&map=SVRall1

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Me and my team will be heading towards Biloxi early Tuesday morning.  This event works perfectly into my schedule.  STP looks very favorable late Tuesday on the Gulf with high cape values for Feb and good 0-1km shear.

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Someone at another board said this looks similar to the 4/16/11 setup when the tornados hit Sanford and Raleigh, and the one that hit Raleigh ended up going not too far from me.

 

Thanks for not including the caveat I mentioned.

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You can view old severe weather reports with Online SeverePlot. Check the bottom of this page

 

http://www.spc.noaa.gov/climo/online/

 

Note: CIPS analogs-SE sector seems to be highlighting the same areas as the SPC 3-day Slight outlook.

 

http://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=SE&fhr=F060&rundt=2016022112&map=SVRall1

 

Cool thanks, looks like Florida had a couple 10+ tornado days in Feb 1998 including the states deadliest ever

 

https://en.wikipedia.org/wiki/1998_Kissimmee_tornado_outbreak

 

then there was these with a couple of F5's outside of the plains, and some NE events.....really looking at it seems the activity outside the traditional tornado alley was pretty extensive.....

 

https://en.wikipedia.org/wiki/April_6%E2%80%939,_1998_tornado_outbreak

 

https://en.wikipedia.org/wiki/April_15%E2%80%9316,_1998_tornado_outbreak

 

https://en.wikipedia.org/wiki/1998_Eastern_tornado_outbreak

 

http://www.weather.gov/gsp/5May1989Review

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At least as far as Tuesday's concerned, 00z NAM took a step toward Euro which is showing 1000-1500 CAPE. Still more than enough instability given the wind field.

 

I also thought it was interesting how SPC updated day 3 in the middle of this afternoon. Don't think I've seen that in my 3 years of experience.

 

Euro's not as aggressive with the event on Wednesday. Some isolated spots reach 1000 j/kg, that's it. Doesn't look as potent as Tuesday.

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At least as far as Tuesday's concerned, 00z NAM took a step toward Euro which is showing 1000-1500 CAPE. Still more than enough instability given the wind field.

 

I also thought it was interesting how SPC updated day 3 in the middle of this afternoon. Don't think I've seen that in my 3 years of experience.

 

Euro's not as aggressive with the event on Wednesday. Some isolated spots reach 1000 j/kg, that's it. Doesn't look as potent as Tuesday.

00z NAM is certainly an outlier, but this would be pretty impressive. Also has lifted index at -7 to -8. NAM_CAPE_se_f66.png

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At least as far as Tuesday's concerned, 00z NAM took a step toward Euro which is showing 1000-1500 CAPE. Still more than enough instability given the wind field.

 

I also thought it was interesting how SPC updated day 3 in the middle of this afternoon. Don't think I've seen that in my 3 years of experience.

 

Euro's not as aggressive with the event on Wednesday. Some isolated spots reach 1000 j/kg, that's it. Doesn't look as potent as Tuesday.

 

Given the projected high temperatures and degree of moisture in the BL on Wednesday (owing to a very potent WAA regime), barring widespread antecedent convection, there is going to be more than isolated areas with 1000+ J/kg of CAPE.

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00z NAM is certainly an outlier, but this would be pretty impressive. Also has lifted index at -7 to -8. NAM_CAPE_se_f66.png

Hahaha yeah that's the NAM for ya. I think it's a bit too excited for spring to come.

 

Given the projected high temperatures and degree of moisture in the BL on Wednesday (owing to a very potent WAA regime), barring widespread antecedent convection, there is going to be more than isolated areas with 1000+ J/kg of CAPE.

Even 750 j/kg could probably get some strong tornado risk with the SRH/shear in place, assuming cells can stay supercellular. But so far this cool season, that really hasn't been an issue. We've seen some really impressive supercells and tornadoes. 

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People need to give this threat more attention.  Screw the 240 hour+ non-snow event for the majority of us.

 

Here in my area, I have not seen soundings as ominous in quite the while.  I'm going to leave comparable dates out, but the setup isn't far from at least one major date per modeling.  There were strong tornadoes then, and there is the possibility of the same here.  Andy is one of the best with this stuff, and I hope he posts more on here dealing with dates and other ideas.

 

Andy has much better posts elsewhere(TW), and Matt (BMXNWS) was the first one to start a thread elsewhere.  Threat is real, me do think.  I suggest checking them out. 

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I snagged this from another source (thanks warneagle).  This is raleigh, nc.

 
nam_2016022200_066_35_78_78_59.png

 

66 hours out on NAM showing 2300 CAPE, I wouldn't put much stock in it at this point. But as I said earlier, with SRH/shear like that, you don't need much more than 750 j/kg for a serious tornado threat.

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