Chicago Storm Posted June 27, 2012 Share Posted June 27, 2012 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1257 AM CDT WED JUN 27 2012 VALID 281200Z - 291200Z ..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF IA NRN IL AND FAR NW IND... ..CNTRL PLAINS/UPPER MS VALLEY/SRN GREAT LAKES AN UPPER-LEVEL RIDGE IS FORECAST TO MOVE EWD ACROSS THE GREAT LAKES REGION ON THURSDAY AS HIGH PRESSURE REMAINS DOMINANT ACROSS THE SCNTRL US. A SUBTLE UPPER-LEVEL TROUGH IS FORECAST TO MOVE ACROSS THE UPPER MS VALLEY. AT THE SFC...A SLOW MOVING BUT ILL-DEFINED COLD FRONT SHOULD BE IN PLACE FROM NRN NEB EXTENDING EWD ACROSS IA...SRN WI AND INTO LOWER MI. ALONG AND SOUTH OF THE BOUNDARY...SFC DEWPOINTS IN THE UPPER 60S AND LOWER 70S F SHOULD RESULT IN STRONG DESTABILIZATION BY AFTERNOON. THUNDERSTORM DEVELOPMENT COULD OCCUR ANYWHERE ALONG THE BOUNDARY BUT THE CONVECTION IN MANY AREAS COULD STRUGGLE DUE TO THE WARM AIR ALOFT. FORECAST SOUNDINGS AT 00Z/FRI ALONG THE BOUNDARY FROM CNTRL IA EWD TO NRN IL SHOW IMPRESSIVE THERMODYNAMICS WITH MLCAPE FROM 4000 TO 5000 J/KG. IN ADDITION...0-6 KM SHEAR IN THE DES MOINES AND CHICAGO AREAS ARE FORECAST TO BE IN THE 40 TO 50 KT RANGE. THIS SHOULD SUPPORT SUPERCELL DEVELOPMENT ALTHOUGH LARGE-SCALE ASCENT SHOULD REMAIN WEAK KEEPING STORM COVERAGE ISOLATED. ANY STORMS THAT CAN DEVELOP IN THE EXTREMELY UNSTABLE AIRMASS SHOULD HAVE A POTENTIAL FOR DAMAGING WIND GUSTS. ISOLATED LARGE HAIL WILL ALSO BE POSSIBLE. FURTHER TO THE WEST ACROSS THE CNTRL PLAINS...ISOLATED THUNDERSTORMS SHOULD ALSO DEVELOP ALONG THE BOUNDARY FROM FAR NE CO INTO CNTRL NEB. FORECAST SOUNDINGS ALONG THIS CORRIDOR SHOW MLCAPE VALUES FROM 3000 TO 4000 J/KG WITH 0-6 KM SHEAR AROUND 30 KT. THIS SHOULD SUPPORT A MARGINAL SEVERE THREAT WITH MULTICELLS THAT CAN DEVELOP IN SPITE OF THE WARM AIR ALOFT. Link to comment Share on other sites More sharing options...
tornadotony Posted June 27, 2012 Share Posted June 27, 2012 You know...if we hold on to, say 65-70 dewpoints right near the boundary Thursday evening, there'd easily be 4000J/kg of CAPE. Add in some pretty strong bulk shear, and you've got a recipe for a really intense HP supercell or two. The trick, as well-noted in the SWODY2, would be getting the storms to form in the first place. Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 27, 2012 Share Posted June 27, 2012 I'm flipping back and forth on this...I fully bought into the ample instability days ago, not the crazy GFS numbers but plenty and the noted shear is a bonus...so yeah the pump will be primed. The forcing is just giving me a hard time and at this time i'm leaning towards the cap holding...at least thursday. Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted June 27, 2012 Share Posted June 27, 2012 Man I really feel like we will stay capped on this one... Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 27, 2012 Share Posted June 27, 2012 latest SREF, NAM and GFS all develop an MCS Thursday night. EDIT: Hi-res NMM blows up an MCS late tonight across southern MN Link to comment Share on other sites More sharing options...
Stebo Posted June 27, 2012 Share Posted June 27, 2012 latest SREF, NAM and GFS all develope an MCS Thursday night. Of course they do, especially after my firm call of the cap not busting... Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 27, 2012 Share Posted June 27, 2012 Of course they do, especially after my firm call of the cap not busting... the current SPC day 2 discussion still talks about large scale ascent being on the weak side..it will be interesting to see which way they lean on the updated version this afternoon Link to comment Share on other sites More sharing options...
Stebo Posted June 27, 2012 Share Posted June 27, 2012 the current SPC day 2 discussion still talks about large scale ascent being on the weak side..it will be interesting to see which way they lean on the updated version this afternoon I do have to admit if these shortwaves that the NAM/GFS are showing verify that would be probably enough ascent to bust the cap, especially if we can realize the dews I had mentioned Monday (67-71) range, considering both here and there might be in the vicinity of 100-108. Link to comment Share on other sites More sharing options...
Stebo Posted June 27, 2012 Share Posted June 27, 2012 Looks like SPC decided to take out the slight for tomorrow... Link to comment Share on other sites More sharing options...
Hoosier Posted June 27, 2012 Share Posted June 27, 2012 New day 2 outlook DOMINANT UPPER HIGH WILL REMAIN IN PLACE ACROSS THE CONUS INTO THE DAY2 PERIOD WITH FLATTENING EXPECTED NEAR THE U.S. CANADIAN BORDER AS MB/ON SHORT-WAVE TROUGH TOPS THE RIDGE AND BEGINS TO DIGS SEWD LATE IN THE PERIOD. VERY WARM EML HAS OVERSPREAD MUCH OF THE COUNTRY AND A STRONG CAP WILL LIKELY PROVE HOSTILE TOWARDS DEEP CONVECTION...ESPECIALLY ORGANIZED ROBUST DEEP CONVECTION. ONE EXCEPTION WILL BE ALONG THE NERN EDGE OF THE STEEP LAPSE RATE PLUME WHICH HAS BEEN DISPLACED UNUSUALLY FAR DOWNSTREAM ACROSS THE GREAT LAKES/OH VALLEY. GIVEN THE VERY WARM MID LEVEL TEMPERATURES IT APPEARS SFC-BASED THUNDERSTORMS WILL STRUGGLE TO DEVELOP AS CONVECTIVE TEMPERATURES WILL LIKELY NOT BE REACHED AHEAD OF THE COLD FRONT. FOR SFC PARCELS TO FREELY CONVECT READINGS WILL NEED TO RISE WELL ABOVE 100F. ADDITIONALLY...LATEST MODEL GUIDANCE IS LIKELY TOO AGGRESSIVE REGARDING FORECAST SFC DEW POINTS IN THE MID 70S AHEAD OF THE WIND SHIFT. EVEN SO...THERE IS SOME CONCERN THAT FRONTAL ASCENT/WEAK WARM ADVECTION ALOFT WILL ENCOURAGE POST-FRONTAL ELEVATED CONVECTION THAT COULD ATTAIN ROBUST LEVELS GIVEN THE STEEP LAPSE RATES. THE MOST LIKELY AREA FOR THIS WILL BE ACROSS THE LOWER GREAT LAKES AFTER DARK WITH SUBSEQUENT SEWD MOVEMENT/DEVELOPMENT ALONG THE ERN EDGE OF STRONG EML THROUGH THE UPPER OH VALLEY INTO PORTIONS OF CNTRL PA BY MORNING. FOR THIS REASON HAVE EXPANDED 5% SEVERE PROBS TO ACCOUNT FOR STRONG ELEVATED TSTMS DURING THE LATTER HALF OF THE PERIOD. Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 27, 2012 Share Posted June 27, 2012 Hard to disagree with their thoughts, 12z hi-res runs certainly aren't impressive Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 27, 2012 Share Posted June 27, 2012 pretty decent little compact shortwave on the 18z NAM...something like that would do the trick (EDIT: it does on this run) Link to comment Share on other sites More sharing options...
Indystorm Posted June 27, 2012 Share Posted June 27, 2012 IWX Wed. afternoon AFD emphasizes that models are grossly overestimating dews this far east given dryness of soil and that will inhibit t storm formation in a pattern that would normally be favorable. They also mention that any MCS diving in from the NW would tend to dry up before reaching the Michiana area and give only a 10% chance of precip in the short term period. Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 27, 2012 Share Posted June 27, 2012 yeah, pretty much all local offices punting on thursday and skeptical beyond. Link to comment Share on other sites More sharing options...
snowlover2 Posted June 27, 2012 Share Posted June 27, 2012 ILN AFD mentions the potential of a high end damaging wind MCS event if everything comes together just right. BETTER SIGNAL FRIDAY/FRIDAY NIGHT...THAT IF WEAK SYSTEMS IN INCREASINGLY NWLY MID LEVEL FLOW CAN ERODE CAPPING...A HIGH END DAMAGING WIND MCS EVENT IS POSSIBLE...AS THE SYNOPTIC SETUP WILL BE AN IDEAL DERECHO TYPE ENVIRONMENT WITH EXTREME INSTABILITY ON THE EDGE OF THE CAP AND STRONG NWLY MID LEVEL FLOW. KEY WILL BE FORCING AND WHETHER IT WILL BE STRONG ENOUGH TO DO SO...AND STRONG ENOUGH TO MAINTAIN THROUGH VERY WARM EML. LOW CHANCE OF IT OCCURRING...BUT IF SOMETHING GOES...IT COULD BE SIGNIFICANT CONSIDERING MLCAPE/SHEAR PARAMETER SPACING ON FORECAST SOUNDINGS. Link to comment Share on other sites More sharing options...
tornadotony Posted June 28, 2012 Share Posted June 28, 2012 00z NAM is an overnight MCS for IA/WI/IL/IN/MI. Link to comment Share on other sites More sharing options...
chase_stormz Posted June 28, 2012 Share Posted June 28, 2012 00z NAM is an overnight MCS for IA/WI/IL/IN/MI. On friday night. I think tomorrow is going to stay capped. Link to comment Share on other sites More sharing options...
tornadotony Posted June 28, 2012 Share Posted June 28, 2012 On friday night. I think tomorrow is going to stay capped. Hmm nope, it has it tomorrow night. I personally don't think we'll know for sure until we get a good look at WV tomorrow to try and diagnose the strength of the embedded disturbances riding around the ridge tomorrow. It's easy to just blurt out that it's gonna be capped with H7 temps at 15C. But the NAM shows subtle CAA at H7 in the evening, and with such intense low-level heating, the cap won't quite as substantial as you think. Add in that H85 WAA will be ongoing (another forcing for acsent), a decent shortwave could do the trick. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted June 28, 2012 Share Posted June 28, 2012 00z NAM is an overnight MCS for IA/WI/IL/IN/MI. yep lights up the frontal boundary after 0z and they track east along/north of it. Link to comment Share on other sites More sharing options...
chase_stormz Posted June 28, 2012 Share Posted June 28, 2012 yep lights up the frontal boundary after 0z and they track east along/north of it. you're right, my fault. i hadn't had a chance to look at the 00z runs yet. I think both tomorrow night (thurs) and friday night have a good chance at a fairly substantial mcs threat. we shall see. like you said, would like to see the wv in the morning first. ps, my girlfriend goes to UAH tornadotony! Link to comment Share on other sites More sharing options...
tornadotony Posted June 28, 2012 Share Posted June 28, 2012 you're right, my fault. i hadn't had a chance to look at the 00z runs yet. I think both tomorrow night (thurs) and friday night have a good chance at a fairly substantial mcs threat. we shall see. like you said, would like to see the wv in the morning first. ps, my girlfriend goes to UAH tornadotony! Very cool! Yeah there is some pretty good potential for the next few days. Link to comment Share on other sites More sharing options...
chase_stormz Posted June 28, 2012 Share Posted June 28, 2012 Very cool! Yeah there is some pretty good potential for the next few days. I agree. Considering i've had a dud of a chase season, I will most likely be out every night there is potential. I need something. Link to comment Share on other sites More sharing options...
tornadotony Posted June 28, 2012 Share Posted June 28, 2012 In an odd twist from the norm, the WRF-ARW and NSSL WRF models are the most bullish of the high-res model suite, with the WRF-NMM and EMC WRF showing very little, the NSSL WRF showing a likely supercell to MCS transition, with initiation at the lake-breeze/frontal interface around 2200 UTC and moving SE through Chicago and NW IN, and the ARW showing a very intense MCS along the front tomorrow night initiating in IA. Link to comment Share on other sites More sharing options...
chase_stormz Posted June 28, 2012 Share Posted June 28, 2012 In an odd twist from the norm, the WRF-ARW and NSSL WRF models are the most bullish of the high-res model suite, with the WRF-NMM and EMC WRF showing very little, the NSSL WRF showing a likely supercell to MCS transition, with initiation at the lake-breeze/frontal interface around 2200 UTC and moving SE through Chicago and NW IN, and the ARW showing a very intense MCS along the front tomorrow night initiating in IA. The question is, who wins out lol... we shall see. Could you post the links to those sim radars? just curious if i found the same ones. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted June 28, 2012 Share Posted June 28, 2012 In an odd twist from the norm, the WRF-ARW and NSSL WRF models are the most bullish of the high-res model suite, with the WRF-NMM and EMC WRF showing very little, the NSSL WRF showing a likely supercell to MCS transition, with initiation at the lake-breeze/frontal interface around 2200 UTC and moving SE through Chicago and NW IN, and the ARW showing a very intense MCS along the front tomorrow night initiating in IA. Kinda looks like the NAM then turning it ESE as it makes it's way across IL during the early morning hours Friday. Link to comment Share on other sites More sharing options...
chase_stormz Posted June 28, 2012 Share Posted June 28, 2012 Kinda looks like the NAM then turning it ESE as it makes it's way across IL during the early morning hours Friday. I would love for that to happen Link to comment Share on other sites More sharing options...
Thundersnow12 Posted June 28, 2012 Share Posted June 28, 2012 I think we'll see a slight risk for today but don't know if we'll get it on the first outlook. Link to comment Share on other sites More sharing options...
tornadotony Posted June 28, 2012 Share Posted June 28, 2012 The question is, who wins out lol... we shall see. Could you post the links to those sim radars? just curious if i found the same ones. WRF-NMM: http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller?prevPage=Model&MainPage=index&model=HRW-NMM-EUS&area=EUS&areaDesc=Eastern+United+States&page=Model&prevModel=&prevArea=EUS&currKey=model&prevKey=model&cat=MODEL+GUIDANCE WRF-ARW: http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller?prevPage=Model&MainPage=index&model=HRW-ARW-EUS&area=EUS&areaDesc=Eastern+United+States&page=Model&prevModel=&prevArea=EUS&currKey=model&prevKey=model&cat=MODEL+GUIDANCE EMC WRF: http://www.emc.ncep.noaa.gov/mmb/mpyle/spcprod/00/ NSSL WRF: http://www.nssl.noaa.gov/wrf/ Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 28, 2012 Share Posted June 28, 2012 6z NMM comes around and blows up a monster cell over lake michigan. I'm still leaning against anything beyond hyper isolated convection in the LOT area and have a hard time arguing with local offices and the SPC. I'd probably favor a disorganized complex riding just north of the IL/WI border...maybe we'll get lucky and see the tail build south into the lake breeze convergence but that's an outside shot IMO. some isolated elevated showers have gone up along the waa in eastern iowa... ASOS/AWOS SITES ACROSS EASTERN IA REPORTING CLOUD BASES GENERALLY IN THE 9000-15000 FT RANGE...AND CEDAR RAPIDS RECENTLY REPORTED TSRA WITH CLOUD BASES AT 11000 FT! arizona style ftl Link to comment Share on other sites More sharing options...
Jim Martin Posted June 28, 2012 Share Posted June 28, 2012 NWS in Northern Indiana saying no severe weather at all overnight tonight... IN TERMS OF PRECIP POTENTIAL /AND POSSIBLE IMPACTS ON TEMPS TODAY/...THE HI RES MODELS CONTINUE TO BRING SEVERAL WEAK WAVES THROUGH THE FLOW SPARKING OFF MCS DEVELOPMENT TO THE WEST OF THE AREA AND MOVING ACROSS S LWR MI INTO N INDIANA. HOWEVER...WHERE THESE SAME MODELS ARE SHOWING CONVECTION SHOULD BE OCCURRING...CONDITIONS ARE PRESENTLY DRY. UNSTABLE CONDITIONS WILL BE IN PLACE...BUT 700 MB TEMPS IN THE +13 TO +16 CELSIUS RANGE DOES NOT BODE WELL FOR CONVECTIVE DEVELOPMENT IN THE ABSENCE OF STRONG FORCING OR UPPER LEVEL COOLING. THESE FACTORS COMBINED WITH PAST HISTORY OF RECENT MCS DEVELOPMENT EITHER FALLING APART AS THEY ENTER OR BYPASSING THE AREA TO THE NORTH...WARRANT GOING AGAINST SOME OF THE SURROUNDING OFFICES AND KEEPING A DRY FORECAST. THE SAME GUIDANCE THAT BRINGS IN MID 70 OR HIGHER DEWPTS BARELY HAS 30 POPS IN. That is from their AFD early this morning at 424am edt. Link to comment Share on other sites More sharing options...
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