April 1st-4th Severe Weather Thread

[JoMo]

So I see scattered/isolated supercells on Wed evening.... and then Thurs looks like more of a line up this way.... will be worse if the GFS is correct.... I blame you andyhb.  

[brettjrob]

Finally seeing the window of solutions beginning to narrow... but still relatively significant differences by Thursday. The ECMWF solution doesn't impress me much, with fairly unidirectional flow and a strung-out sfc low. GFS significantly more favorable for Thursday IMHO.

 

Since the ECMWF sort of caved on the trough amplitude/tilt this morning, I'm not inclined to weight its solution disproportionately; a rough compromise down the middle of the 12z runs is probably best. Said compromise would seem to involve: cap bust Tuesday, nailbiter Wednesday with current runs leaning in favor of isolated supercells by 00z, and a moderate to significant threat Thursday for E OK, E KS, MO and AR probably peaking in the mid-afternoon.

[Indystorm]

I do have concern for you, JoMo, and other Joplin residents.  But after a long season of nw flow events this winter the pattern just might shift to a stormy sw flow for spring as troughs establish themselves in the west.   No scientific reason for this...just the rubber band effect.   I have read elsewhere that the oncoming El Nino won't affect our svr wx season this spring but only the possible hurricane season.  Stay safe and alert as I know you will.

[Chinook]

I thought they would have a slight risk on Tuesday, Wednesday, and Thursday. Obviously Thursday is showing up as a 30% or better, as SPC only would highlight day 5 as 30% or better. Perhaps Tuesday (Day 3 outlook) just looks too weak right now.

[andyhb]

Since the ECMWF sort of caved on the trough amplitude/tilt this morning, I'm not inclined to weight its solution disproportionately; a rough compromise down the middle of the 12z runs is probably best. Said compromise would seem to involve: cap bust Tuesday, nailbiter Wednesday with current runs leaning in favor of isolated supercells by 00z, and a moderate to significant threat Thursday for E OK, E KS, MO and AR probably peaking in the mid-afternoon.

 

The Euro caved on trough amplitude? I'm more inclined to think the GFS caved in terms of amplitude of the trough.

 

The size/intensity of the Euro's warm sector for early April on Thursday is pretty incredible.

[Indystorm]

Regarding that size of the Euro's warm sector, ya, right on the 40th anniversary of the Superoutbreak.   Not a forecast but irony.

[andyhb]

Wednesday/Thursday increasing substantially on the latest run from the CFSv2 SCP output.

 

http://wxvu.net/spc/cfs_scp/

 

And to add on what Brett said about Wednesday, the ceiling Wednesday evening into Thursday morning is quite high if we can get discrete storm development to take place. While this is a rather big "if", the environment speaks for itself with widespread 2000-3000+ J/kg of CAPE and strongly backing surface winds to the east of the dryline, in addition to an intensifying LLJ and increasingly low LCL heights. That is a recipe for big problems with any isolated supercells that form, and the isolated nature of them would make it more likely that they are able to tap all of the favorable parameter space.

[Stebo]

The Euro caved on trough amplitude? I'm more inclined to think the GFS caved in terms of amplitude of the trough.

The size/intensity of the Euro's warm sector for early April on Thursday is pretty incredible.

Completely agree.

[David Reimer]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
350 PM CDT SUN MAR 30 2014

.DISCUSSION...
WATER VAPOR LOOP SHOWS A STRONG SHORTWAVE TROUGH MOVING THROUGH
UTAH TODAY...AND THIS FEATURE WILL EJECT OUT INTO THE PLAINS
TOMORROW. AS A RESULT...BREEZY SOUTH WINDS WILL CONTINUE TONIGHT
AND INTO TOMORROW WHICH WILL ALLOW LOW LEVEL GULF MOISTURE TO
RETURN TO THE REGION. LOWS TONIGHT WILL BE MUCH WARMER DUE TO THE
WINDS AND INCREASING CLOUD COVER AFTER MIDNIGHT. IN ADVANCE OF THE
SHORTWAVE TROUGH...A PLUME OF NEARLY DRY ADIABATIC MID-UPPER LEVEL
LAPSE RATES WILL SPREAD ACROSS THE REGION BY DAWN. WHILE THE LOW
LEVEL AIRMASS WILL BE STRONGLY CAPPED...THERE MAY BE JUST ENOUGH
MID LEVEL MOISTURE FOR SOME ELEVATED CONVECTION PARTICULARLY
ACROSS THE NORTHERN ZONES. MOST OF THE RAIN WITH THIS CONVECTION
SHOULD EVAPORATE BEFORE REACHING THE GROUND...BUT SOME VERY LIGHT
AMOUNTS WILL BE POSSIBLE AND THERE ARE LOW POPS FORECAST OVER THE
NORTHERN COUNTIES TOMORROW FOR THIS ACTIVITY. OTHERWISE
BREEZY...MOSTLY CLOUDY...AND WARM CONDITIONS ARE EXPECTED FOR THE
ENTIRE CWA TOMORROW. A WEAK COLD FRONT WILL DROP INTO THE RED
RIVER COUNTIES BY MONDAY EVENING AND MODEL SOUNDINGS SHOW THE CAP
WILL BE BREAKABLE FOR SURFACE CONVECTION ALONG THE FRONT. WILL
SHOW 20 POPS OVER THE FAR NW/N ZONES FOR MONDAY EVENING FOR ANY
ISOLATED ACTIVITY THAT MAY TRY TO DEVELOP.

THE UPPER LEVEL PATTERN WILL REMAIN IN WEST/SOUTHWEST FLOW ALOFT
WITH SEVERAL SHORTWAVE TROUGHS MOVING THROUGH THE FLOW INTO NEXT
WEEKEND. THIS WILL ENSURE MOIST SOUTHERLY FLOW WHICH WILL KEEP DEW
POINTS HIGH...OVERNIGHT LOWS WELL ABOVE NORMAL...AND MOSTLY CLOUDY
SKIES THROUGH AT LEAST THURSDAY. THE AIRMASS OVER NORTH TEXAS WILL
CONTAIN AMPLE INSTABILITY AND SHEAR WILL BE MORE THAN ADEQUATE FOR
ORGANIZED CONVECTIVE MODES. HIGHS WILL RANGE FROM THE MID 70S EAST
WHERE CLOUDS WILL BE TOUGH TO BREAK DURING THE DAY TO THE MID 80S
WEST WHERE MORE AFTERNOON SUNSHINE IS EXPECTED.

THERE IS NO DISCERNIBLE SIGNAL IN THE MODELS THAT SUGGESTS THERE
WILL BE UPPER LEVEL FORCING FOR ASCENT ON TUESDAY...AND THEREFORE
MOST OF NORTH TEXAS WILL BE STRONGLY CAPPED AND SHOULD STAY DRY.
THE EXCEPTION WILL BE OVER THE WESTERN COUNTIES WHERE THE CAP DOES
WEAKEN BY LATE AFTERNOON DUE TO STRONGER DIURNAL HEATING. A
DRYLINE WILL APPROACH THE WESTERN CWA BOUNDARY AND CIN MAY BE
WEAK ENOUGH FOR ISOLATED CONVECTION TO DEVELOP. ANY STORMS THAT
FIRE ON THE DRYLINE WOULD MOVE EAST/NORTHEAST AND HAVE THE
POTENTIAL TO MOVE INTO THE WESTERN CWA. THIS ACTIVITY WOULD TEND
TO WEAKEN AND DISSIPATE AS IT ENTERS THE STRONGER CAPPED
AIRMASS OVER OUR CWA...SO ANY SEVERE THREAT IS LIMITED TO A FAIRLY
SMALL SPATIAL AND TEMPORAL WINDOW OVER THE FAR WESTERN ZONES.

ON WEDNESDAY...ANOTHER SHORTWAVE WILL MOVE INTO THE PLAINS AND
CYCLONIC CURVATURE ALOFT OVER THE REGION WILL ASSIST IN SYNOPTIC
SCALE LIFT AND HEIGHT FALLS. THIS SHOULD HELP LIFT/WEAKEN THE
CAP...BUT MODELS STILL SUGGEST IT WILL NOT COMPLETELY ERODE FOR
SURFACE BASED CONVECTION. INSTEAD THIS DYNAMIC LIFTING WOULD MORE
LIKELY RESULT IN ELEVATED CONVECTION ABOVE THE CAP. MODEL GUIDANCE
IS A BIT SPLIT...WITH THE ECMWF/NAM SHOWING LITTLE QPF DUE TO A
DRIER MID-LEVEL MOISTURE PROFILE. THE GFS/SREF/CMC HAVE MORE MID-
LEVEL MOISTURE AND THUS ARE QUICK TO DEVELOP SCATTERED TO
WIDESPREAD CONVECTION OVER THE AREA. WILL AVERAGE THE GUIDANCE AT
THIS POINT AND KEEP POPS IN BETWEEN THE TWO EXTREMES IN THE 30-50
PERCENT RANGE...WITH THE HIGHEST POPS OVER THE NORTHEAST ZONES
WHERE FORCING IS BEST. SEVERE THREAT POSSIBLE ON WEDNESDAY...BUT
IF MOST CONVECTION STAYS ELEVATED ABOVE THE CAP IT WILL NOT HAVE
AS MUCH INSTABILITY TO WORK WITH...SO THREAT IS LOWER THAN A
CURSORY GLANCE AT THE CONVECTIVE INDICES WOULD INDICATE.

A STRONG SHORTWAVE WILL MOVE ACROSS THE SOUTHERN PLAINS THURSDAY
AND THIS WILL SEND THE DRYLINE EAST INTO THE REGION DURING THE
AFTERNOON. THE FORCING WILL LIFT THE CAPPING INVERSION AND
SCATTERED CONVECTION IS FORECAST TO DEVELOP ALONG AND AHEAD OF THE
DRYLINE. BEST POPS OF 50 PERCENT WILL BE IN THE EAST...TAPERING
DOWN TO 20 PERCENT IN THE WEST. INSTABILITY AND DEEP LAYER SHEAR
WILL BE SUFFICIENT FOR SEVERE CONVECTION...AND THE THURSDAY SYSTEM
PRESENTS THE BEST CHANCE OF SEVERE WEATHER IN OUR CWA.

A FRONT IS FORECAST TO MOVE INTO THE CWA THURSDAY EVENING WITH
CLEAR AND TRANQUIL CONDITIONS FORECAST ON FRIDAY. HOWEVER YET
ANOTHER STRONG SHORTWAVE WILL BE APPROACHING THE REGION BY THE
WEEKEND...AND THIS ONE WILL TAKE A MORE SOUTHERLY TRACK. AGAIN
THE GFS REMAINS THE OUTLIER SOLUTION WITH A GENERALLY DRY WEEKEND
FORECAST...DESPITE SHOWING THIS SHORTWAVE TROUGH LIKE THE OTHER
GUIDANCE. THE DIFFERENCE IS THAT ECMWF/CANADIAN/UKMET BRING THE
THURSDAY NIGHT FRONT NORTH AS WARM FRONT NEXT WEEKEND WITH HIGH
MOISTURE AVAILABLE AS THE TROUGH APPROACHES. THE LATTER MODEL
GROUP PAINTS A WET AND POTENTIALLY STORMY PICTURE NEXT WEEKEND.
WILL SHOW SLIGHT CHANCES OF RAIN AT THIS POINT...SINCE THE GFS IS
STILL NOT ON BOARD AND DUE TO INHERENT FORECAST UNCERTAINTY AT
THIS TIME RANGE.

[tornadotony]

The details have yet to be worked out, and of course when it comes to severe wx events the devil is in the details, but someone's getting smoked in the Thursday-Friday timeframe.  There's just no two ways about it.  Tuesday and Wednesday could be isolated severe along the dryline, and anything that forms on those days could get quite frisky.  But the size of the warm sector and the richness of the boundary layer moisture that is going to be contained within it is something you just don't see every year in early April.  Even though the main ULL is going to pass to the north, the contribution of the STJ should ensure a huge area of favorable upper-level support, and it's going to be cold aloft.  And I mean cold.  Most of the wide, moisture-rich warm sector is going to have H5 T of -16C to -14C.  That's just kind of absurd.  This looks like a multi-day higher-end severe wx potential from the southern plains through the Ozarks, mid-lower MS valley, and the OH and TN Valleys.  After that, things get even more interesting.  The Euro holds backs a piece of energy and never fully scours the Gulf with the first system.  That energy would eventually eject out for another potentially higher-end threat in the Sunday-Monday timeframe.  Welcome to Spring 2014.  If it's anything like Winter 2014, hold on tight.

[blizzardof96]

18z GFS looks really impressive for the thursday threat with a 140kt 200mb jet nosing in behind the dryline with DP's in the 60's extending up into the S IL. CAPE values are generally between 2000-3000j/kg in the warm sector with 0-6km bulk shear between 35-50kts along with significant backing at the sfc.

 

[huronicane]

KFOR posted their new severe weather outlook graphic.  They're about to REALLY confuse the public:

 

[andyhb]

The details have yet to be worked out, and of course when it comes to severe wx events the devil is in the details, but someone's getting smoked in the Thursday-Friday timeframe.  There's just no two ways about it.  Tuesday and Wednesday could be isolated severe along the dryline, and anything that forms on those days could get quite frisky.  But the size of the warm sector and the richness of the boundary layer moisture that is going to be contained within it is something you just don't see every year in early April.  Even though the main ULL is going to pass to the north, the contribution of the STJ should ensure a huge area of favorable upper-level support, and it's going to be cold aloft.  And I mean cold.  Most of the wide, moisture-rich warm sector is going to have H5 T of -16C to -14C.  That's just kind of absurd.  This looks like a multi-day higher-end severe wx potential from the southern plains through the Ozarks, mid-lower MS valley, and the OH and TN Valleys.  After that, things get even more interesting.  The Euro holds backs a piece of energy and never fully scours the Gulf with the first system.  That energy would eventually eject out for another potentially higher-end threat in the Sunday-Monday timeframe.  Welcome to Spring 2014.  If it's anything like Winter 2014, hold on tight.

 

Good to see you drop in. 

 

Agreed with everything you mention especially the unusual expanse of the warm sector and cold temperatures aloft.

[Superstorm93]

Gulf is just wide open for Thursday...

 

[David Reimer]

After a relatively quiet March in terms of weather in Texas I'm glad things are finally about to heat back up. While the professionals here have the severe weather threat detailed out I wanted to mention that we'll also likely have major fire weather problems behind the dryline. Some Texas NWS offices are already calling that a classic setup for a "Southern Plains Wildfire Outbreak." - I mention it here because the potential for widespread blowing dust (and maybe even smoke) could cause a few problems with storm visibility by the late afternoon hours. 

[SluggerWx]

I do have concern for you, JoMo, and other Joplin residents. But after a long season of nw flow events this winter the pattern just might shift to a stormy sw flow for spring as troughs establish themselves in the west. No scientific reason for this...just the rubber band effect. I have read elsewhere that the oncoming El Nino won't affect our svr wx season this spring but only the possible hurricane season. Stay safe and alert as I know you will.

JoMo, was talking to Andy on another forum about you guys potentially being at risk this week.

Question... Do you feel like the Joplin public would try to flee the area via auto if a tornado warned storm is headed towards Joplin?

I'm asking because it's interesting that's how some in the OKC metro chose to handle the threat last year (even being encouraged to do so by the local Met, I believe).

I was just wondering what your thoughts were having been through the worst case scenario before.

I hope it doesn't happen, but I couldn't believe that was an actual action plan for folks in OKC.

[andyhb]

JoMo, was talking to Andy on another forum about you guys potentially being at risk this week.

Question... Do you feel like the Joplin public would try to flee the area via auto if a tornado warned storm is headed towards Joplin?

I'm asking because it's interesting that's how some in the OKC metro chose to handle the threat last year (even being encouraged to do so by the local Met, I believe).

I was just wondering what your thoughts were having been through the worst case scenario before.

I hope it doesn't happen, but I couldn't believe that was an actual action plan for folks in OKC.

 

And I said it was too early to be discussing specific things like this, the surface low could still go south of them for all we know, although that potential is becoming less likely.

 

I'm not sure this is the best place to be opening the whole staying put vs. fleeing can of worms again.

[gusfront]

I agree Andyhb, I just hope and pray that this doesn't look like a worst case scenario setup for us here in Joplin mo ... what are thoughts from you guys here on this ..???  

[soonertrey]

I'm not sure this is the best place to be opening the whole staying put vs. fleeing can of worms again.

You're correct. This thread is not the place for that discussion. Let's keep the focus on the event.

[andyhb]

Lol, 00z GFS with yet another idea for the trough, this is getting pretty silly. It makes progress towards the other guidance through the day, only to revert back to a different solution at 00z.

 

Although, I'll say that Thursday still looks reasonable on it, it's trying to put out something along the lines of the 12z run at least (instantwxmaps made it look a lot weaker than it really was).

[SluggerWx]

My bad, didn't mean to get OT.

Sent from my RM-927_nam_vzw_100 using Tapatalk

[brettjrob]

So far, 00z GFS and RGEM both say yes to initiation Tuesday evening along the Red River, while the NAM is a nay. The environment there is nearly as potent as it is on Wednesday, depending on your solution of choice. Probably grasping at straws, as SREF probs are quite meager for this range and the ECMWF has been quiet Tuesday more runs than not.

[David Reimer]

So far, 00z GFS and RGEM both say yes to initiation Tuesday evening along the Red River, while the NAM is a nay. The environment there is nearly as potent as it is on Wednesday, depending on your solution of choice. Probably grasping at straws, as SREF probs are quite meager for this range and the ECMWF has been quiet Tuesday more runs than not.

 

The 12KM and 4KM NAM both show convection at 0Z Wednesday (7 PM Tuesday). 

 

EDIT: Looking at the 12KM NAM on TwisterData I see it doesn't initiate convection. Weird... Anyway the 4KM NAM does initiate two supercells. One near SPS and another near Graham, TX in Young County. 

[andyhb]

Pretty nasty looking sounding out of Southern MO @ 93 hrs on the 00z GFS, with rich low level moisture (check out the near 15˚C dewpoint at H85). 45-55 kts of 0-6 km shear to boot.

 

[thewxmann]

So far, 00z GFS and RGEM both say yes to initiation Tuesday evening along the Red River, while the NAM is a nay. The environment there is nearly as potent as it is on Wednesday, depending on your solution of choice. Probably grasping at straws, as SREF probs are quite meager for this range and the ECMWF has been quiet Tuesday more runs than not.

 

I thought the NAM showed (very isolated) initiation... sure looks like that on the H7 RH and QPF maps.

 

It's quite a potent environment indeed (especially in SW OK near the triple point) but I think Tues will remain capped.

[JoMo]

SluggerWx, I answered your question in a private message.

 

I'm not sure how long any surface based storms on Tues evening would be able to sustain themselves if they do develop in TX and OK. CIN looks to be on the increase. Possibly elevated storms?

[JoMo]

New Day 2 (Tues) is out. Mentioning the isolated storm threat in NW TX and SW OK.

 

 

 

PLUME OF WARM AIR AT BASE OF THE EML WILL ADVECT NEWD  
ABOVE THE MOISTENING WARM SECTOR...PROMOTED BY SWLY WINDS ALOFT AND  
WILL SERVE TO EFFECTIVELY CAP THE BOUNDARY LAYER MOST OF THE DAY.  
BEST CHANCE FOR AN ISOLATED SURFACE-BASED STORM OR TWO WILL PROBABLY  
BE NEAR THE INTERSECTION OF THE DRYLINE AND WARM FRONT ACROSS NWRN  
TX OR EXTREME SWRN OK BY LATE AFTERNOON. AN ISOLATED STORM OR TWO  
COULD ALSO INITIATE SOME DISTANCE DOWN THE DRYLINE AS MIXING GETS  
UNDERWAY. SHOULD THESE STORMS DEVELOP...STEEP LAPSE RATES AND STRONG  
VERTICAL SHEAR WILL PROMOTE SUPERCELL STRUCTURES WITH VERY LARGE  
HAIL AND PERHAPS A TORNADO POSSIBLE. HOWEVER...ACTIVITY WILL LIKELY  
DISSIPATE TOWARD SUNSET WITH THE ONSET OF NOCTURNAL COOLING AND  
INCREASING CONVECTIVE INHIBITION.  

[brettjrob]

I'm not sure how long any surface based storms on Tues evening would be able to sustain themselves if they do develop in TX and OK. CIN looks to be on the increase. Possibly elevated storms?

 

Agreed. The most likely scenario is still a cap bust, but the second most-likely by far is the initiation of one or two supercells with LP tendencies that last 2-4 hours from initial updraft to dissipation. Any substantial tornado threat has very long odds as it stands.

[andyhb]

Euro still going gung ho on Wednesday evening with supercells tapping that very favorable parameter space from I-35 eastward.

[JoMo]

Day 3 is finally out. Slight risk with a hatched area over central OK.