April 12th/13th and 15-16th Severe Weather Thread

[andyhb]

After last year's 500 something tornado deaths, maybe we should be rooting against high-end deadly tornadoes this year.

I think everyone is just excited for an extended period of potentially great chasing opportunities.

[Minnesota Meso]

I'm not allowed to post GFS EHI values, but trust me they are showing 2-2.5 from SW IA , through DMX and as far north as Waterloo IA to just SW of Madison WI, for Sat. night 7pm. BTW that's both 0-1km and 0-3km

[David Reimer]

0Z NAM Cap Strength at 7 PM Thursday

[needbiggerboat]

After last year's 500 something tornado deaths, maybe we should be rooting against high-end deadly tornadoes this year.

IIRC references to morality are discouraged here, since analysis and enthusiasm for weather seems to trump impact on life and limb (although much credit goes to the many posters who strive to warn and encourage others to seek safety in these events).

But I agree with your sentiment...what's humbling IMO is that , if these set ups play out as depicted, there are likely people in the path that are spending their last few days alive... I get the fascination spurred by severe weather, but the end result is sad, really.

[David Reimer]

00Z and 03Z (shown) has things a bit further west compared to global models. This graphic shows surface based instability values at 7 PM Thursday.

[Thundersnow12]

I'll guess SPC goes with 30% hatched probs on the Day 3 outlook.

[David Reimer]

I'll guess SPC goes with 30% hatched probs on the Day 3 outlook.

I think that's the minimum they'll end up going with. I honestly wouldn't be surprised to see them issue a small Day 3 45% (Moderate Risk). Yes, I know those are rare, but so is the output for Saturday.

[Thundersnow12]

Agreed. Could def see a day 2 MDT if current forecasts hold.

[Minnesota Meso]

IIRC references to morality are discouraged here, since analysis and enthusiasm for weather seems to trump impact on life and limb (although much credit goes to the many posters who strive to warn and encourage others to seek safety in these events).

But I agree with your sentiment...what's humbling IMO is that , if these set ups play out as depicted, there are likely people in the path that are spending their last few days alive... I get the fascination spurred by severe weather, but the end result is sad, really.

I agree, there are many people in danger if this set up verifies (which it likely will.) What I find fascinating in this day and age is that most people have the resources to do research when severe weather is forecast, (it's called the internet.) How many times did you here people say I had no idea it could be this bad. Even though a broadcast met told me it was only a slight chance or a moderate chance according to the Storm Prediction Center. Hello! google the Storm Prediction Center, read the text, (even though it's technical) they will always tell you what the treat is. Or just google severe weather for such and such a date and you can find what others are thinking. It's time people take their safety into their hands.

[Thundersnow12]

[Stebo]

Really hitting the warm front across Iowa hard. The dryline is still very respectable, of course at this range those are some high numbers.

[Minnesota Meso]

I agree that a 45% risk is possible with this set up for day 3, but what I think the SPC will do is to keep it 30% (possibly hatched in some area's. ) In the text I think you will see something like this.... the hatched area will be monitored for the possibility of a upgraded severe threat in further outlooks.....Just my opinion.

[andyhb]

Added the Lower MO Valley to the description to account for the warm frontal threat into MO, Eastern NE and IA on Saturday.

[SmokeEater]

Slight risk, 10% tor for later today.

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1252 AM CDT THU APR 12 2012

VALID 121200Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS THU AFTN AND EVE ACROSS MUCH OF

THE CNTRL AND SRN HIGH PLAINS...

..SYNOPSIS

A STRONG UPPER JET...CURRENTLY EXTENDING IN A BROAD CYCLONIC BELT

FROM THE MID-LATITUDE CENTRAL PACIFIC INTO THE CENTRAL/SOUTHERN

CALIFORNIA COAST...IS PROGGED TO CONTINUE GRADUALLY NOSING EASTWARD

TODAY. WHILE THE MAIN SHORT WAVE IMPULSE ASSOCIATED WITH THIS

FEATURE LIKELY WILL STILL BE DIGGING OFF THE PACIFIC COAST DURING

THE LATTER HALF OF THIS PERIOD...MODELS CONTINUE TO INDICATE THAT A

SIGNIFICANT DOWNSTREAM IMPULSE WILL LIFT OUT OF THE SOUTHERN GREAT

BASIN THROUGH THE CENTRAL ROCKIES INTO THE NORTH CENTRAL PLAINS BY

12Z FRIDAY. THIS WILL BEGIN TO BREAK DOWN AMPLIFIED UPPER RIDGING

TO THE EAST OF THE ROCKIES...AS DOWNSTREAM TROUGHING LINGERS ACROSS

THE EASTERN U.S. INTO THE WESTERN ATLANTIC.

IN RESPONSE TO THE EVOLVING UPPER PATTERN...ELONGATED SURFACE

RIDGING...NOW EXTENDING FROM THE CENTRAL CANADIAN PROVINCES INTO THE

GULF OF MEXICO...SHOULD GRADUALLY SHIFT EASTWARD...AS A PACIFIC COLD

FRONT ADVANCES EAST OF THE ROCKIES...INTO THE NORTHERN AND CENTRAL

PLAINS BY LATE TONIGHT. AHEAD OF THIS FRONT...LOW-LEVEL

MOISTENING...FROM SOUTH TO NORTH ACROSS THE PLAINS...WILL OCCUR

THROUGH THE PERIOD...BUT MOISTURE RETURN OFF THE GULF OF MEXICO

LIKELY WILL REMAIN RATHER MODEST. EVEN WITH A PLUME OF STEEP

MID-LEVEL LAPSE RATES ADVECTING EAST OF THE SOUTHERN ROCKIES...MIXED

LAYER CAPE IS EXPECTED TO REMAIN LIMITED TO AROUND 1500

J/KG...MAINLY IN A RELATIVELY NARROW PRE-FRONTAL/DRY LINE CORRIDOR

ACROSS PARTS OF THE CENTRAL AND SOUTHERN PLAINS. STILL...THIS

SHOULD BE SUFFICIENT FOR INCREASING SEVERE POTENTIAL...AS DEEP LAYER

FLOW FIELDS AND SHEAR INCREASE EAST OF THE ROCKIES.

..CENTRAL/SOUTHERN HIGH PLAINS

THE DRY LINE SHOULD BE THE PRIMARY FOCUS FOR SEVERE STORM

DEVELOPMENT LATE THIS AFTERNOON AND EVENING. IN THE WAKE OF EARLY

DAY CONVECTIVE CLOUD COVER...CLEARING IS EXPECTED TO ALLOW

CONSIDERABLE SUNSHINE ACROSS PARTS OF EASTERN COLORADO AND WESTERN

KANSAS SOUTHWARD INTO WEST TEXAS. DESTABILIZATION ON THE LEADING

EDGE OF MID-LEVEL HEIGHT FALLS MAY CONTRIBUTE TO THE INITIATION OF

STORMS ACROSS PARTS OF EASTERN COLORADO INTO SOUTHWEST NEBRASKA AND

NORTHWEST KANSAS AS EARLY AS 18-21Z. THIS SHOULD DEVELOP EAST

SOUTHEASTWARD THROUGH THE REMAINDER OF THE AFTERNOON...ACROSS

WESTERN KANSAS INTO EASTERN PORTIONS OF THE TEXAS PANHANDLE AND

WESTERN OKLAHOMA...WHERE THE MID-LEVEL JET CORE OVERSPREADING THE

DRY LINE MAY FOCUS STRONGEST STORMS...GENERALLY IN THE FORM OF

DISCRETE SUPERCELLS. SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS

NEAR A SOUTHERLY 850 MB JET AXIS...WHICH IS EXPECTED TO STRENGTHEN

IN EXCESS OF 40 KTS BY EARLY EVENING...WILL CONTRIBUTE TO THE RISK

FOR A FEW TORNADOES ...IN ADDITION TO THE POTENTIAL FOR VERY LARGE

HAIL.

ADDITIONAL...BUT MORE ISOLATED...STRONG/SEVERE STORM DEVELOPMENT IS

EXPECTED SOUTHWARD ACROSS PARTS OF NORTHWEST AND WEST CENTRAL TEXAS

INTO THE PECOS VALLEY...WHERE THE DRY LINE MAY BEGIN RETREATING

WESTWARD DURING THE EVENING HOURS.

..KERR/LEITMAN.. 04/12/2012

[Minnesota Meso]

Added the Lower MO Valley to the description to account for the warm frontal threat into MO, Eastern NE and IA on Saturday.

Good move...From the perspective of the Upper Mississippi Valley, say later in the period (like Sunday through Tuesday Morning.) This looks like a classic mid to to late March storm. Rain up here, turning colder as the surface low moves to our NE, accumulating snow is possible on grassy surface's as we get into the cold sector, while severe storms are possible along the trailing cold to our south.

So what month is this.. March or April?? Call it Marchil. LOL

[SmokeEater]

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0108 AM CDT THU APR 12 2012

VALID 131200Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE SRN AND

CENTRAL PLAINS TO SRN/CENTRAL IA...

..SYNOPSIS

MODELS ARE CONSISTENT IN MAINTAINING AN AMPLIFIED UPPER FLOW PATTERN

ACROSS THE CONTINENTAL U.S. THROUGH D2/FRI...REINFORCING AND

STRENGTHENING A SWLY FLOW REGIME ACROSS THE CENTRAL/SRN PLAINS TO

THE GREAT LAKES/OH VALLEY REGION. A LARGE PACIFIC TROUGH WILL

CONTINUE TO DIG SEWD...DEEPENING THE WRN STATES LONGWAVE

TROUGH...WHILE DOWNSTREAM HEIGHTS RISE/RIDGE BUILDS E OF THE MS

RIVER IN THE WAKE OF THE DEPARTING ERN STATES TROUGH.

AT THE SURFACE...AN AREA OF LOW PRESSURE WILL TRACK NNEWD FROM

NEB/SD ATTENDANT TO A PROGRESSIVE MIDLEVEL TROUGH LIFTING NWD INTO

SOUTH CENTRAL CANADA. A SURFACE TROUGH TRAILING SWD FROM THE NEB/SD

LOW WILL ADVANCE EWD BEFORE STALLING BY EARLY FRI AFTERNOON FROM THE

MID MO VALLEY TO ERN KS AND SWWD INTO CENTRAL/SWRN OK. MODELS

CONTINUE TO INDICATE THE KS/OK AND N TX PORTION OF THIS BOUNDARY

WILL SURGE WNWWD FROM LATE FRI AFTERNOON THROUGH THE EVENING...AS

SLY WINDS INCREASE IN RESPONSE TO PRESSURE FALLS INVOF A SECONDARY

SURFACE LOW FORMING OVER THE CENTRAL HIGH PLAINS.

..NW TX INCLUDING ERN TX PANHANDLE...OK...CENTRAL/ERN KS

SURFACE DEWPOINTS IN THE LOWER-MID 60S WILL RETREAT WNWWD WITH THE

DRY LINE LATE FRI AFTERNOON/EVENING. THE DRY LINE SHOULD EXTEND

FROM W CENTRAL/NW TX INTO WRN OK TO W OF ICT BY 14/00Z. MODELS

DIFFER IN THE DEVELOPMENT OF TSTMS ACROSS THE WARM SECTOR FRIDAY

AFTERNOON...THOUGH GIVEN MODERATE-STRONG INSTABILITY COMBINED WITH

STRENGTHENING BULK SHEAR TO 35-40 KT SUGGESTS ANY STORMS FORMING

WILL POSE A THREAT FOR SEVERE WEATHER INCLUDING VERY LARGE HAIL AND

TORNADOES. GIVEN MODEL UNCERTAINTY IN AFTERNOON DEVELOPMENT...15

PERCENT PROBABILITIES WILL BE MAINTAINED.

GREATER CERTAINTY EXISTS IN MODELS SHOWING TSTM INITIATION ALONG THE

RETREATING DRY LINE OVER PARTS OF WRN OK...POTENTIALLY INTO NW TX

AND ALSO NNEWD INTO SOUTH CENTRAL/ERN KS. SIMILAR DEGREES OF

INSTABILITY /MODERATE-STRONG/ AND A FURTHER INCREASE IN EFFECTIVE

BULK SHEAR TO 50 KT WILL SUPPORT TORNADIC SUPERCELLS AS THE LOW

LEVEL MOISTURE INCREASES GIVEN A STRENGTHENING SLY LLJ TO 50-60 KT.

VERY LARGE HAIL AND DAMAGING WINDS WILL ALSO BE LIKELY. GIVEN THE

STRENGTHENING WIND FIELDS INTO THE EVENING...SEVERE WEATHER THREATS

ARE EXPECTED TO PERSIST AFTER DARK INCLUDING A THREAT FOR TORNADOES.

UNCERTAINTIES IN TSTM DEVELOPMENT DURING THE AFTERNOON ACROSS PARTS

OF N TX THROUGH OK AND ERN KS INVOF THE DRY LINE...AND THE LACK OF

HEIGHT FALLS AND DETECTABLE MIDLEVEL IMPULSE ADVANCING ACROSS OK/KS

FRI PRECLUDES THE INTRODUCTION OF HIGHER SEVERE WEATHER

PROBABILITIES AT THIS TIME.

..SERN NEB/CENTRAL AND SRN IA/NRN MO

ELEVATED TSTMS SHOULD BE ONGOING AT THE START OF D2 ACROSS THE LOWER

AND MID MO VALLEY WITHIN A WAA REGIME...E THROUGH SE OF THE NEB/SD

SURFACE LOW. THIS ACTIVITY WILL SHIFT EWD DURING THE DAY WITH SOME

UNCERTAINTY IN NEW DIURNAL TSTM DEVELOPMENT IN ITS WAKE AS THE

ATTENDANT MIDLEVEL TROUGH MOVES NWD AWAY FROM THIS REGION. MODELS

DO SUGGEST A SECOND...THOUGH WEAKER...IMPULSE TRACKS ENEWD ACROSS

NEB REACHING ERN NEB/WRN IA BY 14/00Z. DESTABILIZATION IN THE WAKE

OF THE MORNING ACTIVITY MAY PROVE SUFFICIENT FOR LATE AFTERNOON/

EARLY EVENING TSTM DEVELOPMENT ALONG THE NEB/IA BORDER. EFFECTIVE

BULK SHEAR OF 40-50 KT COMBINED WITH A NARROW CORRIDOR OF MODERATE

INSTABILITY SUGGESTS ORGANIZED STORMS WOULD BE POSSIBLE. ADDITIONAL

STORMS ARE EXPECTED TO DEVELOP FRI NIGHT FROM NERN KS INTO NRN MO

AND SRN/CENTRAL IA IN RESPONSE TO STRONG MASS CONVERGENCE WITHIN AN

INCREASING WAA REGIME ATTENDANT TO A STRENGTHENING AND VEERING LLJ.

THIS ACTIVITY MAY TEND TO BE ELEVATED WITH PRIMARILY A HAIL THREAT

AFTER DARK...BUT AN ISOLATED TORNADO THREAT CANNOT BE RULED OUT

ALONG A NWD MOVING WARM FRONT THROUGH NRN MO AND IA FRI NIGHT AS THE

ACTIVITY SPREADS EWD.

..PETERS.. 04/12/2012

[baroclinic_instability]

IIRC references to morality are discouraged here, since analysis and enthusiasm for weather seems to trump impact on life and limb (although much credit goes to the many posters who strive to warn and encourage others to seek safety in these events).

But I agree with your sentiment...what's humbling IMO is that , if these set ups play out as depicted, there are likely people in the path that are spending their last few days alive... I get the fascination spurred by severe weather, but the end result is sad, really.

A discussion that will never end. Nobody roots for death and destruction. The reality is weather does what it wants, it really does not matter what we wish it to do. In that regard, I could care less if folks are enthusiastic about weather. The funny thing few people ever talk about in this discussion is that the enthusiasm of these weather nuts is what has spurred the incredible advances in meteorology the last 50 years. It can be easily argued that these weather nuts have saved countless numbers of lives; I can't say their enthusiasm for extreme weather has resulted in many fatalities, however.

[Stebo]

A discussion that will never end. Nobody roots for death and destruction. The reality is weather does what it wants, it really does not matter what we wish it to do. In that regard, I could care less if folks are enthusiastic about weather. The funny thing few people ever talk about in this discussion is that the enthusiasm of these weather nuts is what has spurred the incredible advances in meteorology the last 50 years. It can be easily argued that these weather nuts have saved countless numbers of lives; I can't say their enthusiasm for extreme weather has resulted in many fatalities, however.

Well put, I mean some of your most fanatic weather nuts are your storm chasers out there reporting the information back to the NWS. Without these people who knows how bad some of these outbreaks could have been...

[baroclinic_instability]

Well put, I mean some of your most fanatic weather nuts are your storm chasers out there reporting the information back to the NWS. Without these people who knows how bad some of these outbreaks could have been...

I have come to terms with most storm chasers. I used to abhor the "weekend warrior" (in certain cases some "chasers" are still sickening), but many do provide a public service with their observations and reports.

[andyhb]

I'd also argue that, while prior convection is more of a concern, Sunday's potential is increasing per the 00z suite of models.

[JoMo]

A discussion that will never end. Nobody roots for death and destruction. The reality is weather does what it wants, it really does not matter what we wish it to be. In that regard, I could care less if folks are enthusiastic about weather. The funny thing few people ever talk about in this discussion is that the enthusiasm of these weather nuts is what has spurred the incredible advances in meteorology the last 50 years. It can be easily argued that these weather nuts have saved countless numbers of lives; I can't say their enthusiasm for extreme weather has resulted in many fatalities.

Exactly. No amount of hoping and wishing for something to or not to happen is going to change the outcome of the situation. If anything, getting the word out that a situation may be particularly bad well ahead of time may save lives or get people to pay attention. Either way, ma nature is going to do what she wants.

[andyhb]

Day 3 MDT guys...

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0234 AM CDT THU APR 12 2012

VALID 141200Z - 151200Z

..THERE IS A MDT RISK OF SVR TSTMS ACROSS CENTRAL OK AND ERN KS

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA

AND EXTENDING ACROSS THE SRN/CENTRAL PLAINS INTO THE UPPER MS

VALLEY...

...POTENTIAL EXISTS FOR A SIGNIFICANT OUTBREAK OF TORNADOES AND VERY

LARGE HAIL ACROSS PARTS OF OK/KS INTO SERN NEB/NWRN MO/SWRN IA...

..SYNOPSIS

AN AMPLIFIED FLOW PATTERN WILL REMAIN ACROSS THE CONUS THROUGH

D3/SAT...WITH A LARGE TROUGH IN THE WEST AND DOWNSTREAM RIDGE ACROSS

THE ERN STATES. THIS WILL MAINTAIN A CORRIDOR OF STRONG SWLY

MIDLEVEL WIND EXTENDING FROM AZ/NM THROUGH OK/KS INTO THE UPPER MS

VALLEY TO GREAT LAKES REGION. A PACIFIC TROUGH DIGGING SEWD INTO THE

LOWER CO RIVER VALLEY DURING D2/FRI WILL MOVE THROUGH THE BASE OF

THE WRN LONGWAVE TROUGH DURING ON SAT...REACHING CO/NM BY 12Z

SUNDAY. AN ATTENDANT 100 KT MIDLEVEL JET WILL EMERGE INTO THE SRN

HIGH PLAINS TO KS SAT NIGHT...WITH 60-80 KT SWLY MIDLEVEL WINDS

EXPECTED ACROSS MUCH OF THE SLIGHT AND MODERATE RISK AREAS THROUGH

THE FORECAST PERIOD.

AT THE SURFACE...A FRONT IS EXPECTED TO ADVANCE EWD FROM THE UPPER

MIDWEST INTO THE GREAT LAKES...WHILE THE TRAILING PORTION OF THIS

BOUNDARY MOVES SLOWLY SWD ACROSS NEB. A LEE CYCLONE IS FORECAST TO

DEVELOP AND DEEPEN ACROSS ERN CO WITH A WARM FRONT EXTENDING EWD

THROUGH SRN NEB TO SRN IA. THE WARM FRONT WILL SPREAD NEWD INTO THE

UPPER MS VALLEY ON SAT. A DRY LINE WILL MOVE EWD SOME BY SAT

AFTERNOON AND SHOULD EXTEND FROM FAR ERN NEB SSWWD THROUGH CENTRAL

KS TO FAR WRN OK TO THE TX BIG BEND REGION BY LATE SAT AFTERNOON.

..SRN AND CENTRAL PLAINS

WEAK HEIGHT FALLS ARE EXPECTED ACROSS THE SRN/CENTRAL PLAINS THROUGH

SAT AFTERNOON...WITH STRONGER FALLS FORECAST FOR SAT

EVENING/OVERNIGHT AS THE PACIFIC TROUGH MOVES TOWARD THE SRN AND

CENTRAL HIGH PLAINS. STRONG SLY LOW LEVEL WINDS WILL MAINTAIN

MOISTURE ADVECTION E OF THE DRY LINE ON SAT WITH SURFACE DEWPOINTS

IN THE MID 60S EXPECTED ACROSS MUCH OF OK AND REACHING CENTRAL/ERN

KS BY SAT EVENING. THIS MOISTURE RETURN COUPLED WITH STEEP MIDLEVEL

LAPSE RATES AND STRONG SURFACE HEATING /ESPECIALLY NEAR THE DRY

LINE/ WILL RESULT IN MODERATE TO STRONG INSTABILITY /MLCAPE

2000-2500 J PER KG/ ACROSS THE MODERATE RISK AREA BY LATE AFTERNOON

AND THE SURROUNDING SLIGHT RISK. STRENGTHENING DEEP LAYER WIND

FIELDS...VEERING WITH HEIGHT...WILL RESULT IN STRONG EFFECTIVE BULK

SHEAR /EXCEEDING 50 KT/ AND ORIENTED ACROSS THE DRY LINE. THIS

COMBINED WITH INCREASING LOW LEVEL HODOGRAPH CURVATURE WILL SUPPORT

TORNADIC SUPERCELLS AND THE POTENTIAL FOR VERY LARGE HAIL AND

DAMAGING WINDS. THESE FACTORS COMBINED WITH FAST STORM MOTIONS

SUGGEST THE POTENTIAL FOR LONG-TRACKED...STRONG TORNADOES OCCURRING

FROM THE AFTERNOON THROUGH THE EVENING /INCLUDING AFTER DARK/.

..ERN NEB/IA/NRN MO/NWRN IL/SWRN-SRN WI

STRENGTHENING SWLY MIDLEVEL WINDS ACROSS THIS REGION THROUGH D3

COMBINED WITH MOISTURE/DESTABILIZATION OCCURRING AS A WARM FRONT

ADVANCES NNEWD SUGGESTS THE ENVIRONMENT WILL BECOME INCREASINGLY

FAVORABLE FOR STRONG TO SEVERE STORMS. MODELS SUGGEST SHORTWAVE

RIDGING ACROSS THIS REGION. HOWEVER..A FEW WEAK IMPULSES EMBEDDED

IN THE STRONGER FLOW ALOFT AND FORCING FOR ASCENT ALONG THE SWD

MOVING FRONT AND INVOF OF THE WARM FRONT SHOULD SUPPORT DEEP MOIST

CONVECTION/TSTMS. MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR OF

40-50 KT WILL FAVOR ORGANIZED STORMS WITH ALL FACETS OF SEVERE

WEATHER POSSIBLE. GREATEST TORNADO THREAT SHOULD BE CONFINED TO THE

WARM FRONT AND ALSO WWD NEAR THE INTERSECTION OF THE DRY LINE WARM

FRONT...WHERE LOW LEVEL SHEAR WILL BE ENHANCED.

..PETERS.. 04/12/2012

[nwburbschaser]

That is some strong wording for a Day 3 outlook.

[Hoosier]

Dang, I've rarely seen a day 3 moderate with wording as strong as that.

[Reed Stough]

Dang, I've rarely seen a day 3 moderate with wording as strong as that.

That is not good if this verifies!

[Stebo]

Dang, I've rarely seen a day 3 moderate with wording as strong as that.

I believe there has only been 11 day 3 moderate risks ever issued. So obviously it is rare territory, that being said this is very strongly worded of course rightfully so in my opinion.

[RCNYILWX]

I texted this to tornadotony a few hours ago: I'm thinking mod for the southern and central plains and slight up into eastern iowa and northern illinois possibly southwest wisconsin and far southern mn as well.

Pretty similar to what they went with. Given the good overall deterministic and ensemble agreement and consistency the past few days and that they were outlooking the moderate risk area in the day 4-8 outlooks (30% probs required) a day 3 mod, although rare, is well justified. The potential for this event is truly scary, and as others have posted the synoptic set-up of 3/13/90 and as this one has been appearing on the modelling are eerily similar. Haven't looked at the CIPS analogs based off the 00z gfs, but one of the top analogs based off the 12z run for Saturday was the day of the Parkersburg Ef5.

[andyhb]

Kind of eerie that this falls on the one year anniversary of the Tushka event last year, associated with the PV bomb over the Central Plains (and then the craziness further east across the SE and Carolinas).

[andyhb]

Sunday wants to join the fray...

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0357 AM CDT THU APR 12 2012

VALID 151200Z - 201200Z

...DISCUSSION...

GFS/ECMWF ARE IN FAIRLY GOOD AGREEMENT THROUGH D4/SUN AS THE STRONG

PACIFIC TROUGH EXPECTED TO REACH CO/NM BY 12Z SUN TRACKS NEWD

THROUGH THE PLAINS STATES REACHING THE MID MO TO UPPER MS VALLEYS BY

12Z MON. THIS EVOLUTION WILL BE THE BEGINNING OF A PATTERN CHANGE

FORECAST INTO NEXT WEEK AS THE UPPER FLOW PATTERN BECOMES LESS

AMPLIFIED AND MORE ZONAL. BEYOND D4...THESE MODELS DIFFER IN THE

TIMING FOR THE DEAMPLIFICATION OF THE PACIFIC SYSTEM AS IT TRACKS

EWD.

GREATEST POTENTIAL FOR A REGIONAL SEVERE WEATHER THREAT DURING THE

EXTENDED PERIOD IS EXPECTED TO BE ON D4/SUN FROM PARTS OF NERN TX

THROUGH ERN OK/WRN AR TO THE LOWER MO/MID MS VALLEYS. TSTMS...SOME

SEVERE...WILL LIKELY BE ONGOING ACROSS THE SRN/CENTRAL PLAINS INTO

THE GREAT LAKES REGION...WITH THE PLAINS ACTIVITY LOCATED ALONG AND

E OF A DRY LINE. A PACIFIC FRONT IS FORECAST TO OVERTAKE THE DRY

LINE ON SUN WITH THE FRONT ADVANCING EWD AS AN ATTENDANT SURFACE LOW

MOVES FROM WRN/NWRN KS TO IA. ALTHOUGH INSTABILITY IS EXPECTED TO

BE RELATIVELY WEAKER THAN FORECAST FOR D3/SAT...MODERATE INSTABILITY

AND STRONG WIND FIELDS WILL SUPPORT A SEVERE WEATHER THREAT ACROSS

THE D4 OUTLOOK AREA. MODELS SUGGEST PRIMARILY A LINEAR STORM

MODE...THOUGH LOW LEVEL DIRECTIONAL SHEAR/HODOGRAPH CURVATURE SHOULD

BE SUFFICIENT FOR A TORNADO THREAT.

ALTHOUGH THE GFS/ECMWF DIFFER WITH THE TIMING AND STRENGTH OF THE

PROGRESSIVE TROUGH THROUGH D5/MON AND D6/TUE...THERE IS AGREEMENT

SHOWING THE PRIMARY THREAT FOR TSTMS WILL SPREAD ACROSS E/SE TX AND

THE LOWER MS VALLEY ON D4 AND THROUGH THE CENTRAL GULF COAST STATES

ON D5. DESPITE THE POTENTIAL FOR SEVERE STORMS EACH OF THESE

DAYS...WEAKER INSTABILITY AND/OR DEEP LAYER SHEAR PRECLUDES THE

INCLUSION OF REGIONAL SEVERE WEATHER THREAT AREAS.

..PETERS.. 04/12/2012

[OceanStWx]

For later today, pretty much the area we were describing yesterday. My gut says there will be two areas in play, one in Kansas and another down by KFDR. There always seems to be a little dry line bulge and local backing in that area.

For Saturday, the 50% contour has shown up now. Shifting some of the higher probabilities down the warm front, but I believe the 50% is in response to the dry line/warm front intersection (which on this image is probably too far east).