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Sunday April 10th severe outbreak


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AY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1118 AM CDT SUN APR 10 2011

VALID 101630Z - 111200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER

PARTS OF SOUTHEAST MN...NORTHEAST IA...NORTHWEST IL...MUCH OF

WI...AND WESTERN UPPER MI...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES REGION

INTO CENTRAL TX...

...CONDITIONS STILL APPEAR FAVORABLE FOR A REGIONAL OUTBREAK OF

SEVERE THUNDERSTORMS INCLUDING POTENTIAL FOR STRONG TORNADOES LATER

THIS AFTERNOON AND EVENING OVER PORTIONS OF UPPER MISSISSIPPI VALLEY

AND ADJACENT WESTERN GREAT LAKES...

DEEP WRN UPPER TROUGH NOW MOVING BODILY EWD INTO PLAINS WITH A VERY

STRONG...100-130 KT...MID/UPR JET APPROACHING THE UPPER MS VALLEY

FROM THE CENTRAL PLAINS. THIS WILL PROVIDE THE LARGE SCALE ASCENT

AND SHEAR TO DRIVE A SEVERE THUNDERSTORM OUTBREAK ONCE SURFACE BASED

CONVECTION IS ABLE TO INITIATE.

WITH THE SURFACE LOW SWRN MN DEEPENING NEWD ACROSS LAKE SUPERIOR BY

TONIGHT...STRONG SLY LOW LEVEL JET WILL CONTINUE SPREADING MOISTURE

NWD ACROSS WI INTO WRN GREAT LAKES. A PRONOUNCED EML WITH STEEP

LAPSE RATES PREVAILS ABOVE THE MOIST BOUNDARY LAYER AND WILL AID IN

VERY RAPID THUNDERSTORM DEVELOPMENT VICINITY OF THE COLD FRONT WHICH

BY MID AFTERNOON WILL EXTEND SWD FROM SURFACE LOW EXPECTED TO BE

BETWEEN DLH AND MSP INTO NERN IA.

SUPERCELL THUNDERSTORMS SHOULD DEVELOP RAPIDLY AS SURFACE TEMPS RISE

INTO THE LOW 80S BY MID AFTERNOON IN SERN MN/ERN IA WHERE MLCAPES

AOA 2000 J/KG WILL BE IN PLACE. FORECAST SOUNDINGS AT THE TIME OF

EXPECTED INITIATION SHOW EFFECTIVE HELICITY VALUES OF 250-400 MS/S2

AND VERY STRONG DEEP LAYER VERTICAL SHEAR.

SUPERCELLS WILL BE THE MODE OF THE DAY ALONG WITH POTENTIAL FOR VERY

LARGE HAIL AND TORNADOES. A COUPLE LONG LIVED SUPERCELLS ARE LIKELY

LATER THIS AFTERNOON AND EVENING ACROSS WI WITH THE THREAT FOR

STRONG...LONG TRACK TORNADOES. STORMS WILL MOVE VERY FAST...IN

EXCESS OF 50KT...GIVEN THE STRENGTH OF THE WIND FIELDS ALOFT.

SUPERCELLS ALONG WITH A TORNADO THREAT COULD SPREAD AS FAR N AS

PORTIONS OF THE WRN UP OF MI PRIOR TO ENCOUNTERING COOLER/STABLE

BOUNDARY LAYER THIS EVENING.

HIGH RES MODELS SUGGEST THAT STORMS EVOLVE INTO A FORWARD

PROPAGATING MCS ACROSS THE UP OF MI LATE EVENING DRIVEN BY THE

INTENSIFYING WIND FIELDS AS SURFACE LOW CONTINUES TO DEEPEN NEWD

ACROSS LAKE SUPERIOR. THUS HAVE RAISED THE WIND DAMAGE PROBS THIS

AREA...EVEN THOUGH STORMS BY THEN COULD BE SOMEWHAT ELEVATED.

..MID MS VALLEY TO ARKLATEX

IT WILL TAKE MUCH OF THE AFTERNOON TO ERODE THE CAP ALONG THE SWD

EXTENSION OF THE COLD FRONT/DRY LINE. HOWEVER THE STRONG DEEP LAYER

SHEAR WITH THE ADVANCING UPPER TROUGH COUPLED WITH THE STEEP

EML...SUPPORT SEVERE THUNDERSTORMS ONCE SURFACE INITIATION OCCURS.

AGAIN SUPERCELLS EXPECTED TO BE THE EARLY MODE WITH LARGE

HAIL/DAMAGING WINDS AND ISOLATED TORNADOES POSSIBLE. DURING THE

LATE EVENING TRANSITION TO A MORE LINEAR MODE LIKELY WITH A

CONTINUED SEVERE THREAT.

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Thanks....I will keep posting....still have to get a laptop for home so just post while working in my "gaps" where I have time to between my duties....that and studying to pass my upper air certification test (which I did two weeks ago passed on first try which was sweet) is why I have been mostly absent. Today looks like a classic big outbreak and janetjanet is heading to the right spot. I'd probably setup shop somewhere near La Cross depending what analysis shows at 3pm. I get off work in an hour so won't be on then but wish everyone good luck. After this storm I haven't looked at data for down there but we will be having a high amplitude flow up here with a 567 500mb max over Dutch Harbor and a 515 500mb low south in the Gulf of Alaska south of anchorage. The ridge pokes northeast to almost north of Nome, Alaska, with a flow in the heart of the trough over Cold Bay straight from north of Barrow. That cold air looks to funnel due south before turning southeast off the west coast. With that type of flow pattern I would bet another storm will develop/emerge late next week down there.

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Kind of surprised the warm front hung up like it did.

Keeping a wary eye on things. With the warm front now more or less stationary, and we are in full sun with some good SSW winds and temps at 77 degrees, I wouldn't be surprised if the game changes somewhere along the line today.

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Kind of surprised the warm front hung up like it did.

Keeping a wary eye on things. With the warm front now more or less stationary, and we are in full sun with some good SSW winds and temps at 77 degrees, I wouldn't be surprised if the game changes somewhere along the line today.

Not to mention those light showers in WC and NW Wisconsin. Those will keep the sun away for an hour or two, perhaps limiting the instability I would believe. I would say from LaCrosse to Madison northeast to Sheboygan would be the area to watch.

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pushing 80+ already with sbcape nearing 1500. Widespread severe wx looking unlikely this far south, but i thing the tail end cell in far southern wisc, or northern illinois will be one to watch this evening.

EDIT: looking throug things, i'd really watch the lakeside areas in southern wisconsin (kenosha maybe), storms will be arriving there a bit later and we might see some locally enhanced helicity off the lake..

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The RUC and HRRR don't really show much backing of the surface winds over NE IA and S WI, laying credence to the NAM and GFS veering the surface flow over much of the warm sector for the past several days. The main tornado threat appears to be across central and NW WI near the surface low. It's hard to envision seeing enough directional shear to support sustained supercellular mode farther south.

As a side note, perhaps one of you modeling experts can explain to me how the RUC and HRRR still have snow cover over portions of northern WI, which causes a pretty hilarious cold pool with temps in the 30s.

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BULLETIN - EAS ACTIVATION REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE DULUTH MN

1245 PM CDT SUN APR 10 2011

THE NATIONAL WEATHER SERVICE IN DULUTH MN HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

NORTHWESTERN LAKE COUNTY IN NORTHEAST MINNESOTA...

NORTHERN ST. LOUIS COUNTY IN NORTHEAST MINNESOTA...

* UNTIL 145 PM CDT

* AT 1240 PM CDT...THE PUBLIC REPORTED A SEVERE THUNDERSTORM

PRODUCING QUARTER SIZE HAIL...AND DESTRUCTIVE WINDS IN EXCESS OF 80

MPH. THIS STORM WAS LOCATED 5 MILES NORTHEAST OF COOK...AND MOVING

EAST AT 45 MPH.

SIGNIFICANT WIND DAMAGE WAS REPORTED WITH THIS STORM WEST OF COOK.

THIS IS A DANGEROUS STORM.

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Got kind of a late start after sleeping in at Fort Dodge. About our only choice at this point is to try northeast Iowa and hope for the best. Agree with many of you guys that Wisconsin looks the best. Don't think we can make it there in time though.

Theoretically you could gun it to La Crosse and hope that storms initiate later rather than sooner...

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The RUC and HRRR don't really show much backing of the surface winds over NE IA and S WI, laying credence to the NAM and GFS veering the surface flow over much of the warm sector for the past several days. The main tornado threat appears to be across central and NW WI near the surface low. It's hard to envision seeing enough directional shear to support sustained supercellular mode farther south.

As a side note, perhaps one of you modeling experts can explain to me how the RUC and HRRR still have snow cover over portions of northern WI, which causes a pretty hilarious cold pool with temps in the 30s.

I might be missing something but with moderate instability, modest directional shear, good speed shear, and lack of linear forcing early on, why wouldn't there be supercellular structures around S WI/N IL with anything that can fire in the early evening? Unless you meant multiple tornadic cells which is more debatable.

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as i mentioned this mnorning..we can't forget about this area

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE SPRINGFIELD MO

1244 PM CDT SUN APR 10 2011

..MESOSCALE CONVECTIVE DISCUSSION

UPDATE

STRONG TO SEVERE STORMS ARE STILL POSSIBLE VERY LATE IN THE

AFTERNOON INTO THIS EVENING.

CONVECTION WILL REMAIN SUPPRESSED THROUGH MUCH OF THE AFTERNOON

HOURS AS AN ELEVATED MIXED LAYER CREATING A STRONG CAP REMAINS OVER

THE AREA. CONVECTIVE INHIBITION (MLCIN) IS LESS THAT -150J/KG

ACROSS THE AREA WHILE 700MB TEMPERATURES ARE ABOVE 10 DEGREES

CELSIUS.

A DRYLINE IS CURRENTLY SURGING EAST ACROSS KANSAS AT MIDDAY AND

SHOULD REACH THE MISSOURI KANSAS BORDER BY EARLY AFTERNOON.

MESOSCALE MODELS SHOW THE CAP ERODING THIS AFTERNOON AS THE UPPER

LEVEL TROUGH PUSHES EAST ACROSS THE PLAINS. MESOSCALE MODELS MAYBE

A TAD TOO AGGRESSIVE ON ERODING THE CAP...AS THE GOOD HEIGHT FALLS

DO NOT REACH THE AREA UNTIL THIS EVENING. ALSO WARMER MID LEVEL

TEMPERATURES MAY BE ADVECTING TO THE NORTHEAST AHEAD OF THE DRY

LINE. WILL LIKELY DO A SPECIAL SOUNDING LATE THIS AFTERNOON TO

DETERMINE THE STRENGTH OF THE CAP. THE DRYLINE IS EXPECTED SLOW IN

FORWARD PROGRESS AND REMAIN ACROSS THE FAR SOUTHWEST MISSOURI THIS

AFTERNOON.

AS THE UPPER LEVEL TROUGH PUSHES EAST...BETTER HEIGHT FALLS WILL SPREAD

INTO THE AREA WHICH SHOULD WEAKEN THE CAP. AS THIS HAPPENS... THE

DRYLINE MAY BE ABLE TO OVERCOME THE WEAKENING CAP AND BE THE

FOCUS FOR THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON AND MORE

LIKELY EARLY THIS EVENING. THIS INITIAL STORM DEVELOPMENT WILL

GENERALLY OCCUR FROM WARSAW SOUTHWEST THROUGH JOPLIN INTO

NORTHEAST OKLAHOMA.

STORM MOTION SHOULD BE TO THE NORTHEAST AND CLOSE TO BEING

PARALLEL TO THE DRYLINE. INSTABILITY WILL STILL LIKELY BE IN THE

1000J/KG TO 1500J/KG RANGE WHILE WIND SHEAR REMAINS SUFFICIENT FOR

ORGANIZED STORMS. A BRIEF PERIOD OF DISCREET CELLS WILL BE POSSIBLE

GIVEN THE WIND FIELDS. VERY STEEP LAPSE RATES WILL SUPPORT THE

POTENTIAL OF LARGE HAIL AND DAMAGING WINDS ALONG WITH A RISK FOR

ISOLATED TORNADOES. ALSO...

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