April 27-29 Severe Threat

[snowlover2]

Parts of Missouri are in a day 6 highlighted area with SPC mentioning strong tornadoes being possible. 

 

 

 

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0345 AM CDT TUE APR 22 2014

VALID 251200Z - 301200Z

...DISCUSSION...
...SIGNIFICANT MULTI-DAY SEVERE EVENT EXPECTED ACROSS THE SOUTH
CENTRAL U.S. SATURDAY AND SUNDAY...STRONG TORNADOES ARE POSSIBLE...

22/00Z ECMWF IS EXHIBITING REASONABLE RUN-TO-RUN CONSISTENCY OVER
THE LAST FEW DAYS WITH THE GFS NOW TRENDING TOWARD ECMWF SOLUTIONS.
THIS FORECAST IS HEAVILY WEIGHTED TOWARD THE ECMWF.

EARLIER CONCERNS REGARDING A POLAR FRONT UNDERCUTTING STRONG SWLY
FLOW ALOFT OVER THE SRN PLAINS ARE LESSENING. WHILE UPPER BLOCK
OVER CNTRL CANADA WILL ULTIMATELY FORCE A DOMINANT SFC ANTICYCLONE
INTO THE MIDDLE OF THE CONUS...IT APPEARS THE LEADING EDGE OF THIS
AIR MASS SHOULD STRUGGLE TO ADVANCE MUCH SOUTH OF I-70 OVER KS/MO
THIS WEEKEND.

STRONG MID-LEVEL SPEED MAX IS FORECAST TO DIG SEWD INTO THE LOWER CO
RIVER VALLEY SATURDAY WITH UPPER DIFLUENCE EXPECTED ACROSS THE
PLAINS AS FAR SOUTH AS WEST TX AT 27/00Z. THIS EVOLUTION WILL ALLOW
SUBSTANTIAL MOISTURE TO ADVANCE POLEWARD ACROSS THE SRN PLAINS WHERE
PW VALUES SHOULD EASILY APPROACH 1.25 INCHES AS SFC DEW POINTS CLIMB
THROUGH THE MID-UPPER 60S ACROSS A BROAD WARM SECTOR. LATEST
THINKING IS MODERATE-EXTREME INSTABILITY SHOULD DEVELOP ALONG ERN
PLUME OF STEEP LAPSE RATES FROM WCNTRL TX...NWD INTO SCNTRL KS
SATURDAY WHERE MUCAPE COULD APPROACH 4000 J/KG. IF THERMODYNAMIC
ENVIRONMENT EVOLVES AS LATEST GUIDANCE SUGGESTS THEN POTENTIALLY
SIGNIFICANT SUPERCELL DEVELOPMENT WITH VERY LARGE HAIL AND TORNADOES
CAN BE EXPECTED. CONVECTION SHOULD INITIATE ALONG DRYLINE FROM SWRN
TX...NWD INTO WRN KS SATURDAY THEN REDEVELOP AGAIN SUNDAY FROM SERN
KS...SWD INTO CNTRL TX AS MID-LEVEL SPEED MAX EJECTS INTO THE SRN
PLAINS. SEVERE TSTMS SHOULD SPREAD INTO THE MS VALLEY BY EARLY
MONDAY. ORGANIZED SEVERE MAY CONTINUE INTO THE DAY7 PERIOD BUT
SUBSTANTIAL CONVECTION DURING THE DAY5-6 TIME FRAME COULD
POTENTIALLY DISRUPT THERMODYNAMIC ENVIRONMENT...THUS CONFIDENCE IS
NOT AS HIGH.

..DARROW.. 04/22/2014

 

[A-L-E-K]

mostly outside our sub, good discussion will be in central/western

[Jonger]

Severe weather is getting more and more rare it seems.

[Chicago Storm]

Severe weather is getting more and more rare it seems.

lol

[Stebo]

mostly outside our sub, good discussion will be in central/western

If the Euro is right, parts of this subforum will be under the gun as well, the warm front gets almost to I-80 on Monday.

[TimChgo9]

My son (who lives in  Texas, near Dallas) was just texting me about the elevated threat for the coming weekend.  Gets me to wondering when it's going to get active in this subforum.  

[andyhb]

lol

 

ditto

[A-L-E-K]

Severe weather is getting more and more rare it seems.

lol your climo sux

[Stebo]

lol your climo sux

So does his memory, because his county had a severe storm just 9 days ago.

[Chargers09]

Severe weather is getting more and more rare it seems.

Lmao

[dmc76]

So does his memory, because his county had a severe storm just 9 days ago.

 

I could have sworn I seen a 1.5" of Hail, Widespread damage and power outages all across Northern Oakland just 10 days ago. LOL

[snowlover2]

Newest 4-8 Day Outlook.

 

 

 

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0351 AM CDT WED APR 23 2014

VALID 261200Z - 011200Z

...DISCUSSION...
..SIGNIFICANT MULTI-DAY SEVERE EVENT EXPECTED ACROSS PORTIONS OF THE
CENTRAL AND SOUTHERN PLAINS SATURDAY AND SUNDAY AND ACROSS THE MS
VALLEY AND MID SOUTH ON MONDAY...STRONG TORNADOES ARE POSSIBLE...

MEDIUM RANGE FORECAST CONTINUES TO BE HEAVILY WEIGHTED TOWARD THE
ECMWF DUE TO RUN-TO-RUN CONSISTENCY REGARDING THE 500MB EVOLUTION OF
WRN U.S. TROUGH. CONCERNS REGARDING POLAR FRONT UNDERCUTTING STRONG
SWLY FLOW ALOFT HAVE ABATED THIS MORNING. LATEST GUIDANCE DEEPENS
LEE CYCLONE OVER SERN CO SATURDAY AFTERNOON WITH SUBSEQUENT MOVEMENT
INTO WRN KS ON SUNDAY. INTENSE 500MB SPEED MAX APPROACHING 90KT
SHOULD ROUND THE BASE OF THE TROUGH ALONG THE AZ/MEXICAN BORDER THEN
EJECT INTO SWRN KS EARLY SUNDAY. AS A RESULT SFC LOW IS NOT
EXPECTED TO ADVANCE APPRECIABLY EWD UNTIL LATER MONDAY AS SECONDARY
MID-LEVEL SPEED MAX DEVELOPS FROM NORTH TX INTO THE LOWER OH RIVER
VALLEY.

MODERATE TO EXTREME INSTABILITY SHOULD DEVELOP EAST OF THE DRYLINE
SATURDAY AFTERNOON ALONG ERN PLUME OF STEEP LAPSE RATES. STRONGLY
DIFLUENT FLOW ALOFT SHOULD ENCOURAGE VIGOROUS SUPERCELL DEVELOPMENT
FROM PORTIONS OF WCNTRL TX...NWD INTO KS. VERY LARGE HAIL AND
TORNADOES CAN BE EXPECTED WITH THIS ACTIVITY.

IT/S NOT ENTIRELY CLEAR HOW FAR EAST THE DRYLINE WILL MIX SUNDAY AS
LOWEST PRESSURES WILL REMAIN FOCUSED ACROSS THE HIGH PLAINS OF WRN
KS. MODELS MIX DRYLINE EAST OF I-35 CORRIDOR ACROSS OK BY 18Z
SUNDAY BUT THE DAY5 FORECAST WILL ACCOUNT FOR DRYLINE NOT MIXING
ACROSS THE PLAINS AS FAST AS MODELS CURRENTLY DEPICT. AS A
RESULT...SUBSTANTIAL MID-LEVEL FLOW SHOULD OVERSPREAD THE
MOIST/BUOYANT WARM SECTOR AND ANOTHER DIURNALLY-INITIATED ROUND OF
POTENTIALLY TORNADIC SUPERCELLS COULD EVOLVE.

LATER MONDAY IT APPEARS THE SFC FRONT/DRYLINE SHOULD ADVANCE INTO
THE MS VALLEY. SCATTERED-NUMEROUS SUPERCELLS SHOULD EVOLVE AHEAD OF
THE FRONT FROM LA...NWD INTO MO AND POSSIBLY AS FAR EAST AS MIDDLE
TN. TORNADOES AND LARGE HAIL REMAIN POSSIBLE WITH WARM-SECTOR
CONVECTION.

..DARROW.. 04/23/2014

 

[Powerball]

Severe weather is getting more and more rare it seems.

 

It's April 23rd, not June 23rd...

[Thunder Road]

I'm mildly interested in Monday in IL.

 

CAPE maxes out at 1000-1500 J/kg at 18z (depending on your model of choice) but decreases closer to 0z as more rain forms.

 

What we really need is the LLJ to push north of where it's progged now, but that's probably going to be hard to do as the 850 Low fills in with time, reducing the height gradient.  But 30-35 kts isn't going to produce anything memorable.

 

Also need to see how quickly the surface Low occludes.  We may end up with the front stuck in Missouri until after daytime heating.

[RCNYILWX]

I'm mildly interested in Monday in IL.

CAPE maxes out at 1000-1500 J/kg at 18z (depending on your model of choice) but decreases closer to 0z as more rain forms.

What we really need is the LLJ to push north of where it's progged now, but that's probably going to be hard to do as the 850 Low fills in with time, reducing the height gradient. But 30-35 kts isn't going to produce anything memorable.

Also need to see how quickly the surface Low occludes. We may end up with the front stuck in Missouri until after daytime heating.

Early Monday evening looked pretty threatening in southern IL and IN on the 12z GFS. Still showing 2k j/kg of SBCAPE uncapped and supercell composite ranging from 7-10 at 00z 4/29 near EVV. Some decent low level cape and ~35-40 kt of 0-1 km shear.

[Thunder Road]

Early Monday evening looked pretty threatening in southern IL and IN on the 12z GFS. Still showing 2k j/kg of SBCAPE uncapped and supercell composite ranging from 7-10 at 00z 4/29 near EVV. Some decent low level cape and ~35-40 kt of 0-1 km shear.

 

I should clarify that I'm only "mildly" interested because I'm biased into only caring about what's within range for a day chase from Valpo.  I agree, west TN and west KY looks threatening, and that could include parts of IL and IN as well, but probably too far distance wise and in terrain that's too messy even if we could get to it.

 

But we're still four days out as well.

[IWXwx]

I should clarify that I'm only "mildly" interested because I'm biased into only caring about what's within range for a day chase from Valpo.  I agree, west TN and west KY looks threatening, and that could include parts of IL and IN as well, but probably too far distance wise and in terrain that's too messy even if we could get to it.

 

But we're still four days out as well.

 

OT, but I really like your disclaimer. The way it's going school could be out for the summer before we see any severe up this way.

[IWXwx]

I probably spoke too soon in my last post about severe....

 

"POOL OF COLD 500 MB TEMPS WILL BE APPROACHING...POSSIBLY
PUSHING -20 C DEPENDING ON MODEL OF CHOICE. IF POCKET OF LIMITED
CLEARING CAN OCCUR...VERY STEEP LAPSE RATES WOULD ENSURE WITH
POTENTIAL FOR LOW TOPPED CONVECTION."  - IWX

[Thunder Road]

I probably spoke too soon in my last post about severe....

 

"POOL OF COLD 500 MB TEMPS WILL BE APPROACHING...POSSIBLY

PUSHING -20 C DEPENDING ON MODEL OF CHOICE. IF POCKET OF LIMITED

CLEARING CAN OCCUR...VERY STEEP LAPSE RATES WOULD ENSURE WITH

POTENTIAL FOR LOW TOPPED CONVECTION."  - IWX

 

Wasn't there a prolific hail producer (by Indiana standards) near Indy with the cutoff Low in March 2012?

[IWXwx]

Wasn't there a prolific hail producer (by Indiana standards) near Indy with the cutoff Low in March 2012?

 

There was a lot of hail with the March 2, 2012 storm. Was it a cutoff?

[Thunder Road]

There was a lot of hail with the March 2, 2012 storm. Was it a cutoff?

 

Nah that was the Henryville day.  I'm thinking of something later in the month.

[Thunder Road]

If the 18z GFS verifies, I suspect we'll decide that Decatur is close enough to chase...

 

 

[cyclone77]

18z GFS looking pretty good for the southern half of IL late Monday.  Shear profiles look increasingly good as the afternoon/evening go on with the approach of the powerful mid and upper jet.  The GFS shows the warm sector relatively free of precip through early to mid afternoon, which is always nice to see.  Lets hope that holds.  Deep moisture will be firmly in place after the previous few days of flow off the gulf in the warm sector.  Could be a pretty big day for this area and points south if trends continue.

 

We'll be out in KS or NE on Sunday, but will definitely be chasing this setup for Monday. 

[RCNYILWX]

18z GFS looking pretty good for the southern half of IL late Monday. Shear profiles look increasingly good as the afternoon/evening go on with the approach of the powerful mid and upper jet. The GFS shows the warm sector relatively free of precip through early to mid afternoon, which is always nice to see. Lets hope that holds. Deep moisture will be firmly in place after the previous few days of flow off the gulf in the warm sector. Could be a pretty big day for this area and points south if trends continue.

We'll be out in KS or NE on Sunday, but will definitely be chasing this setup for Monday.

Agree with this based on everything I looked at last night. Solid low and deep layer shear (speed and directional) and moderate instability with minimal capping will be in place late afternoon into the early evening. Actually based off soundings I pulled from southern IL and southeast MO, Monday could be a better bet chase wise than KS or NE on Sunday because of better wind fields throughout the column and better orientation of the bulk shear vectors.

Still trying decide whether to pull the trigger on a daytrip out to KS/NE/western MO Sunday, downstate IL/southeast MO on Monday or both It rarely lines up that I'm off and the threat for anything significant is outside the LOT CWA, so I'd really like to get out there and chase.

[Thunder Road]

Tuesday is starting to look pretty potent in downstate IN as well.

[Thundersnow12]

Monday on the NAM in central/southern IL looks very interesting.

Sups and tors if that verifies.

[Hoosier]

Certainly expect the greater severe threat to be south of here at this point but looks like some threat locally early next week.

[cyclone77]

The Euro has hinted at a weak surface wave developing over the MO/AR border area Monday afternoon.  This helps keeps the low-levels nicely backed over southern MO and southern IL later in the day.  The GFS doesn't have the secondary surface low, but the low-levels remain nicely backed over this area.  The best area for tornadoes, (and there may be quite a few of them) will probably be a little south of our sub over AR/northern LA/MS, but southern MO and southern IL will be on the northern end of this potential outbreak.  GFS shows a nose of 2000j/kg cape reaching up into southern MO late Mon afternoon.  The GFS has consistently shown the warm sector to remain relatively precip free through at least early afternoon allowing for good destabilization. 

 

From a chasing standpoint southern MO doesn't look that great, with lots of trees and hills.  I've never chased there myself, but it looks pretty crappy in that area lol.  I'm hoping things trend a little further north to put central MO more in line with the higher tor threat.  If things stay as they are I might just play on the IL side and hope for the best.  Definitely ain't going to AR lol.

[Hoosier]

The Euro has hinted at a weak surface wave developing over the MO/AR border area Monday afternoon.  This helps keeps the low-levels nicely backed over southern MO and southern IL later in the day.  The GFS doesn't have the secondary surface low, but the low-levels remain nicely backed over this area.  The best area for tornadoes, (and there may be quite a few of them) will probably be a little south of our sub over AR/northern LA/MS, but southern MO and southern IL will be on the northern end of this potential outbreak.  GFS shows a nose of 2000j/kg cape reaching up into southern MO late Mon afternoon.  The GFS has consistently shown the warm sector to remain relatively precip free through at least early afternoon allowing for good destabilization. 

 

From a chasing standpoint southern MO doesn't look that great, with lots of trees and hills.  I've never chased there myself, but it looks pretty crappy in that area lol.  I'm hoping things trend a little further north to put central MO more in line with the higher tor threat.  If things stay as they are I might just play on the IL side and hope for the best.  Definitely ain't going to AR lol.

 

 

 

I thought I heard that the area around the bootheel is ok but don't quote me on that.

[cyclone77]

I thought I heard that the area around the bootheel is ok but don't quote me on that.

 

Yeah that area does look pretty good on closer inspection.  Looks like northeast and east-central AR aren't too bad either.