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July 22-27 Severe Potential


hm8

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Forecast low positions at 00z Thursday from 12z ECMWF, RGEM, and GFS40. 18z of the NAM20. NAM is the furthest south with teh low taking it through central lower MI, while the other 3 are trended more to the north. Will be interesting to see how things play out, or if the curse of 2012 will reign supreme!

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I don't know if this will be useful for tomorrow or not, but the three models that did the best for today over MN were the UKMET, ECMWF, and Gem Global, closely followed by the Nam, as far as short term High resolutions models I don't know, I left for work at Noon and got home at 10pm Central time. If anyone wants to see accumulated Precip for the UKMET go to the link below. The Ukie was really good 24-36 hours out. Hope you all get some rain.

http://meteocentre.c...&run=00〈=en

One more thing, the local model of the WRF that Duluth puts on it's website also did a good job this morning before I went to work, just can't remember if it was the 24/06z or 12z, that I viewed, and yes it is run 4 times per day according to their website.

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I am liking tomorrow's potential for WI, MI, North IN,OH, West PA, and Ontario, a decent threat of significant severe weather starting during the day lasting into the overnight hours, a MCS will cross MI, into Ontario with supercells possible along warm front into the Upper Ohio Valley

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Likewise, I will decide around noon for sure but as it stands I would be going out.

The NAM soundings for 00z tomorrow evening look really nice. The best looking soundings aren't co-located with the best instability, but at this point I'm somewhat confident that there will be an area of supercellular potential along the instability gradient. Hopefully something will fire on this side of the lake before dark tomorrow.

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New D1

day1.gif

day1.tornado.gif

day1.hail.gif

day1.wind.gif

AY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1251 AM CDT WED JUL 25 2012

VALID 251200Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE CENTRAL

PLAINS EWD TO THE UPPER MIDWEST AND GREAT LAKES...

..SYNOPSIS

UPPER LOW OVER SRN ALBERTA WILL MOVE SEWD TO NEAR THE U.S.-CANADIAN

BORDER BY 26/12Z RESULTING IN STRONGER WLY MID-LEVEL FLOW FROM THE

UPPER MIDWEST EWD INTO NEW ENGLAND. UPPER LEVEL HIGH PRESSURE AREAS

WILL BECOME ESTABLISHED OVER BOTH THE SOUTHWEST AND SOUTHEAST U.S.

SURFACE LOW PRESSURE WILL MOVE EAST ACROSS THE UPPER MS VALLEY/GREAT

LAKES WHILE A TRAILING COLD FRONT MOVES INTO THE CENTRAL/SRN HIGH

PLAINS. A WARM FRONT WILL MOVE NEWD ACROSS THE MIDWEST AND GREAT

LAKES AND THEN EXTEND SEWD INTO THE CAROLINAS.

..CENTRAL PLAINS/UPPER MIDWEST EAST ACROSS THE GREAT LAKES

AN MCS WITH STG/SVR TSTMS WILL LIKELY BE ON GOING AT 12Z WED ACROSS

PORTIONS OF MN/WI/UPPER MI DRIVEN BY ISENTROPIC LIFT ASSOCIATED WITH

A MODERATELY STRONG LOW-LEVEL JET. THIS COMPLEX MAY WEAKEN SOMEWHAT

DURING THE MORNING...HOWEVER RESIDUAL CLOUDS AND OUTFLOW SHOULD

REINFORCE THE WARM FRONT ACROSS THE GREAT LAKES REGION. INTENSE

DAYTIME HEATING WILL RESULT IN A VERY UNSTABLE BUT CAPPED AIR MASS

IN THE WARM SECTOR UNTIL LATE AFTN. AS HEIGHT FALLS OVERSPREAD THE

AREA SVR TSTMS WILL LIKELY DEVELOP/RE-INTENSIFY NEAR THE WARM FRONT.

SUPERCELLS MAY INITIALLY DEVELOP WITH A THREAT OF LARGE

HAIL/DAMAGING WINDS. A TORNADO THREAT MAY EXIST WITH ANY DISCRETE

STORM IN THE VICINITY OF THE WARM FRONT. WITH TIME UPSCALE GROWTH

INTO AN MCS APPEARS LIKELY WITH A CONTINUED SVR WIND/HAIL THREAT EWD

INTO WRN NY LATE WED NIGHT.

TSTM DEVELOPMENT SWWD ALONG THE COLD FRONT IS EXPECTED BY LATE

AFTN/EARLY EVENING IN A MODERATELY UNSTABLE AIR MASS WITH LARGE

DCAPE IN THE RANGE OF 1000-1500 J/KG. STRONG WIND GUSTS WILL BE THE

PRIMARY THREAT WITH ISOLATED LARGE HAIL ALSO POSSIBLE.

A SECONDARY COLD FRONT ASSOCIATED WITH THE ALBERTA UPPER LOW WILL

MOVE ACROSS NRN MN WITH ISOLATED STG/SVR STORMS POSSIBLE.

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SPC seems to be completely off on the tornado threat area, N OH/NW PA/MI are favorable for tornadoes and also a large part of the Ohio Valley is under a slight risk on thursday with mentions of a moderate risk due to widespread severe and all modes (hail,wind,tornadoes possible) for OH/PA area

GIVEN THE POTENTIAL FOR WIDESPREAD ORGANIZED SEVERE STORMS AN AREA FROM SRN OH ACROSS MUCH OF WRN/NRN PA INTO CNTRL NY MAY BE UPGRADED TO A MODERATE CATEGORICAL RISK IN LATER OUTLOOKS.
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looks like a long lasting storm has formed in MN, the real question is, could this lead to a Derecho as it moves along the northern extent of the greatest heat values, and thus the northern extend of the greatest instability, could it last all the way to the east coast and the affect the big cities of NY and Boston?

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12z NAM with a massive linear squall line from just south of Green Bay stretching back into the plains.

That would be best case scenerio for people looking for rain. The HRRR is kind of hinting at the same idea.

The MKX WRF has been pretty solid the past few days has convection blowing up in Iowa and spreading into Wisconsin.

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That outflow boundary near the western border of WI might do something interesting in coming hours, CAPE is ramping up ahead of it as the sun breaks through.

I guess the main event is now supposed to be late this evening looking at the 3 km HRRR, hail and wind threat.

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NSSL WRF has a really good idea as far as current convection goes. It's almost spot on.

It's showing Northern MI with the biggest system area tracking east right now, but indicates a fairly sharp right turn to the SE, with a second system developing over near Green Bay, also tracking SE, around 00Z. By 04Z the second MCS should be rocking areas from Jackson to Port Huron and northermost suburbs of Oakland county, heading toward DTX. Further developments begin to track more toward the east again, roughly from FNT northward.

We'll have to see how that verifies.

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HRRR keeps trying to fire action off that boundary in Iowa as it pushes into N IL and S WI later this afternoon ahead of the main show...I think it's out to lunch.

FWIW, it nailed the forecast for those storms yesterday morning.

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HRRR has a large MCS (possibly a derecho) crossing Michigan, and also a few supercells along the warm front in OH moving east, is it me, or does this reminds me a little bit of May 31st 1998, but will likely not be as strong as that one, but a similar set up

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FWIW, it nailed the forecast for those storms yesterday morning.

I guess...it also showed hours and hours of junk convection prior which never happened. I think we're dry until super late when we get a decaying line...chances look decent for far eastern LOT tomorrow.

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HRRR has a large MCS (possibly a derecho) crossing Michigan, and also a few supercells along the warm front in OH moving east, is it me, or does this reminds me a little bit of May 31st 1998, but will likely not be as strong as that one, but a similar set up

A bit early to be throwing around the pinnacle derecho event as a similarity....

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HRRR keeps trying to fire action off that boundary in Iowa as it pushes into N IL and S WI later this afternoon ahead of the main show...I think it's out to lunch.

I think it's possible, the cap is forecast to weaken throughout the day, so once the cap is sufficiently small the boundary would be where storms fire. The potential evening MCS is more interesting obviously.

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Agreed, the setup is not nearly as robust as that day...

The HRRR also shows it's structure breaking down rapidly by 03z. Also, the forward speed of the line seems pretty slow for a derecho.

TBH, I haven't checked lately, but there has been a very stubborn cap in place over the lower half of MI for some time now, which would really start beating this line up right about where the model shows it beginning to dissipate. Unless it can muster enough energy to overpower the capping, the model is probably quite accurate in it's outcome.

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I think turtleland back into central Iowa has the best shot of some high end severe weather...instability is going to be off the charts.

Current SPC mesoanalysis already has 3000 J/kg of CAPE over Madison. Temperature up to 86 °F at the airport, about 10 more degrees until we hit the convective temp. The outflow boundary is coming into view from the roof cam, probably won't fire before it passes Madison but I still think it has potential. Looks quite bubbly right now, trying hard to go through the cap. http://quad.aos.wisc...min_640x480.mov

14z HRRR brings the main squall through Madison at 7 pm. HRRR seems to be overdoing current convection near Minneapolis though.

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