Kaner88 Posted June 21, 2015 Share Posted June 21, 2015 Probably goes without saying at this point, but 12z NAM SHARPpy plots have a PDS TOR hazard type over ORD and DPA tomorrow evening. Just under 4000 j/kg CAPE, just under 400 m2/s2 0-3km SRH, close to 60 knots 0-6km shear (for ORD off the 12z NAM)... promising environment. Link to comment Share on other sites More sharing options...
homedis Posted June 21, 2015 Share Posted June 21, 2015 Probably goes without saying at this point, but 12z NAM SHARPpy plots have a PDS TOR hazard type over ORD and DPA tomorrow evening. Just under 4000 j/kg CAPE, just under 400 m2/s2 0-3km SRH, close to 60 knots 0-6km shear (for ORD off the 12z NAM)... promising environment. Yeah even if we get an MCS, our environment will easily soar to those numbers with the summer solstice just the day before... very strong heating will occur Link to comment Share on other sites More sharing options...
Hoosier Posted June 21, 2015 Share Posted June 21, 2015 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1232 PM CDT SUN JUN 21 2015 VALID 221200Z - 231200Z ...THERE IS AN ENH RISK OF SVR TSTMS GREAT LAKES AND UPPER MS VALLEY... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MIDWEST TO LOWER GREAT LAKES... ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE N-CNTRL/NE STATES... ..SUMMARY SCATTERED SEVERE STORMS ARE LIKELY ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES REGIONS...SOME OF WHICH SHOULD BE INTENSE...MAINLY FROM MIDDAY THROUGH THE EVENING ON MONDAY. ..UPPER MS VALLEY/GREAT LAKES STRONGLY CONSIDERED AN UPGRADE TO MODERATE RISK WITH POTENTIAL FOR CLUSTERS OF INTENSE SEVERE STORMS WITH ALL SIGNIFICANT SEVERE HAZARDS POSSIBLE. BUT WILL DEFER GIVEN ENOUGH UNCERTAINTY WITH REGARD TO EVOLUTION OF LATE D1 CONVECTION WITH ITS SUBSEQUENT EFFECT ON THE DEGREE OF DOWNSTREAM DIURNAL DESTABILIZATION...ALONG WITH TIMING OF THE PAIR OF MID-LEVEL SHORTWAVE IMPULSES WITH RESPECT TO PEAK HEATING. GUIDANCE IS CONSISTENT IN DEPICTING STRENGTHENING LOW/MID-TROPOSPHERIC FLOW IN RESPONSE TO A CONVECTIVELY-GENERATED MCV FROM LATE D1/EARLY D2 AND APPROACH OF AN UPSTREAM SHORTWAVE TROUGH CURRENTLY OVER THE SRN CANADIAN ROCKIES. THESE FEATURES WOULD ENHANCE LOW-LEVEL WAA OF THE RICHLY BUOYANT AIR MASS CURRENTLY PRESENT OVER THE LOWER MO VALLEY. AVAILABLE CAMS VARY MARKEDLY WITH THE DAYTIME EVOLUTION OF AN MCS EXPECTED TO BE ONGOING ACROSS PARTS OF SRN MN/NRN IA. IT SEEMS PLAUSIBLE THAT THIS ACTIVITY SHOULD PERSIST THROUGH THE DAY WITH AN ORGANIZED SEVERE RISK ON THE EDGE OF A ROBUST PLAINS EML. THIS TYPE OF SCENARIO MAY RESULT IN LEAD CONVECTION OUTPACING THE MORE FAVORABLE THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY RATHER STEEP MID-LEVEL LAPSE RATES AND VERY LARGE BUOYANCY. AT LEAST SCATTERED UPSTREAM TSTM DEVELOPMENT SHOULD OCCUR BY LATE AFTERNOON ALONG THE COLD FRONT FROM CNTRL/ERN WI SW TO THE IA/IL BORDER AREA AS CONVERGENCE ALONG THE FRONT AND DIABATIC HEATING OVERCOME INHIBITION DUE TO THE INITIALLY STOUT EML. SUPERCELLS ARE EXPECTED IN INITIAL STAGES OF DEVELOPMENT...WITH SOME OF THIS CONVECTION GROWING UPSCALE DURING THE EVENING. WITH LOW-LEVEL FLOW BECOMING INCREASINGLY VEERED IN THE WAKE OF THE LEAD MID-LEVEL IMPULSE...MAIN HAZARDS WITH SW EXTENT SHOULD BE VERY LARGE HAIL TRANSITIONING TO PREDOMINATELY SEVERE WIND. WHERE 850 MB WINDS CAN REMAIN QUITE STRONG WITH ENLARGED LOW-LEVEL HODOGRAPHS /MOST LIKELY IN ERN WI TO LOWER MI/...A RISK FOR STRONG TORNADOES AND/OR SIGNIFICANT SEVERE WIND GUSTS MAY DEVELOP. ..GRAMS.. 06/21/2015 Link to comment Share on other sites More sharing options...
Powerball Posted June 21, 2015 Share Posted June 21, 2015 Updated day 2 SPC outlook... Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted June 21, 2015 Share Posted June 21, 2015 Updated day 2 SPC outlook... You weren't kidding about them expanding it. Link to comment Share on other sites More sharing options...
jojo762 Posted June 21, 2015 Share Posted June 21, 2015 It's crazy to think that a couple years ago this would've only been seen as a "slight risk" on the SPC page when it definitely has way more potential than that.. The new category of ENH makes a big difference in public awareness/alertness imo.. Link to comment Share on other sites More sharing options...
homedis Posted June 21, 2015 Share Posted June 21, 2015 It's crazy to think that a couple years ago this would've only been seen as a "slight risk" on the SPC page when it definitely has way more potential than that.. The new category of ENH makes a big difference in public awareness/alertness imo.. What probabilities a Moderate consists of changed with the addition of the enhanced tho. Most likely this would be a moderate if enhanced didn't exist. Link to comment Share on other sites More sharing options...
Chicago Storm Posted June 21, 2015 Share Posted June 21, 2015 Both the NMM and ARW have a MCS moving across the prime area during the late morning and afternoon hours. Both do have redevelopment, but the risk would be questionable pending recovery. My biggest issues are the early day convection and capping, and I can see a scenario where the early day MCS(s) is the main show. We'll see... Link to comment Share on other sites More sharing options...
Indystorm Posted June 21, 2015 Share Posted June 21, 2015 When I started seeing those PDS tor probable hazards on those plots yesterday I already gave a heads up to family in the Chicago and NW In area, telling them to pay close attention to wx tomorrow since they are not usually weatherwise. Link to comment Share on other sites More sharing options...
rolltide_130 Posted June 21, 2015 Share Posted June 21, 2015 It's crazy to think that a couple years ago this would've only been seen as a "slight risk" on the SPC page when it definitely has way more potential than that.. The new category of ENH makes a big difference in public awareness/alertness imo.. I've got a feeling the only thing holding it back from being a moderate is the fact that the SPC has has so many day 2 moderates get busted wide open the day of the event so far this year. I may be a little bit pessimistic but I'm not going to get hyped up much until I see the Obs after the early MCS moves through. Link to comment Share on other sites More sharing options...
cyclone77 Posted June 21, 2015 Share Posted June 21, 2015 Down this way over eastern IA and western IL I'm less concerned about tornadoes, but the risk for very large hail is pretty scary. Tremendous cape associated with those steep mid-level LRs will produce some rather prolific hail makers down along the SW portion of the line. Gonna be a wild day tomorrow over a huge area from the looks of things. Link to comment Share on other sites More sharing options...
andyhb Posted June 21, 2015 Share Posted June 21, 2015 Both the NMM and ARW have a MCS moving across the prime area during the late morning and afternoon hours. Both do have redevelopment, but the risk would be questionable pending recovery. My biggest issues are the early day convection and capping, and I can see a scenario where the early day MCS(s) is the main show. We'll see... I can see a scenario where the early MCS splits into more discrete elements by the time it reaches MI given the intense directional shear present there. That would be an ugly outcome. Link to comment Share on other sites More sharing options...
A-L-E-K Posted June 21, 2015 Share Posted June 21, 2015 Both the NMM and ARW have a MCS moving across the prime area during the late morning and afternoon hours. Both do have redevelopment, but the risk would be questionable pending recovery. My biggest issues are the early day convection and capping, and I can see a scenario where the early day MCS(s) is the main show. We'll see... i've been thinking the same thing Link to comment Share on other sites More sharing options...
Hoosier Posted June 21, 2015 Share Posted June 21, 2015 Both the NMM and ARW have a MCS moving across the prime area during the late morning and afternoon hours. Both do have redevelopment, but the risk would be questionable pending recovery. My biggest issues are the early day convection and capping, and I can see a scenario where the early day MCS(s) is the main show. We'll see... Good catch. They seem more bullish with that MCS than most other guidance. Link to comment Share on other sites More sharing options...
Powerball Posted June 21, 2015 Share Posted June 21, 2015 I can see a scenario where the early MCS splits into more discrete elements by the time it reaches MI given the intense directional shear present there. That would be an ugly outcome. It would depend on how fast the higher instability advects NE. There could also be a scenario (which the Hi-Res models sort of show) where the early day MCS slows down the better moisture advection, which in effect diminishes the threat for some areas. Link to comment Share on other sites More sharing options...
Hoosier Posted June 21, 2015 Share Posted June 21, 2015 You can see how that MCS disturbs the wind field in N IL/IN etc if you flip through the hourlies here. Assuming enough recovery in time for a second round, would locally heighten the tornado threat http://mp1.met.psu.edu/~fxg1/COMPRAD4CENT_12z/wind30.html Link to comment Share on other sites More sharing options...
homedis Posted June 21, 2015 Share Posted June 21, 2015 Also don't forget to look at the probabilities for D2. The SIG Severe is further south than the actual enhanced Link to comment Share on other sites More sharing options...
andyhb Posted June 21, 2015 Share Posted June 21, 2015 It would depend on how fast the higher instability advects NE. There could also be a scenario (which the Hi-Res models sort of show) where the early day MCS slows down the better moisture advection, which in effect diminishes the threat for some areas. Well obviously, that has already been covered multiple times though. Link to comment Share on other sites More sharing options...
Powerball Posted June 21, 2015 Share Posted June 21, 2015 Well obviously, that has already been covered multiple times though. And that would explain, which many have been wondering, why the SPC has such a broad enhanced area and hasn't upgraded any one location to moderate risk yet. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted June 21, 2015 Share Posted June 21, 2015 i've been thinking the same thing Eh we will see. With such strong WAA at 925mb and 850mb, we should be able to destabilize fairly quickly even if EF do see a morning MCS here. Link to comment Share on other sites More sharing options...
homedis Posted June 21, 2015 Share Posted June 21, 2015 Eh we will see. With such strong WAA at 925mb and 850mb, we should be able to destabilize fairly quickly even if EF do see a morning MCS here. Yup! Thats what I have been thinking and saying. The time of year and situation we are in is prime for a rapid recovery and destabilization after the MCS. Link to comment Share on other sites More sharing options...
jojo762 Posted June 21, 2015 Share Posted June 21, 2015 Eh we will see. With such strong WAA at 925mb and 850mb, we should be able to destabilize fairly quickly even if EF do see a morning MCS here. yeah.. A day before the summer solstice and a strong S/SSW'ly LLJ in place.. Theta-E increases markedly after the MCS moves through, which in turn would cause a relatively quick warm up, and result in significant destabilization after the strong southerly/SSW'ly LLVL winds bring deep moisture back into the area.. Looking at the forecast soundings winds at the surface are even at 30+ kts Link to comment Share on other sites More sharing options...
Hoosier Posted June 21, 2015 Share Posted June 21, 2015 I agree with the comments above...as long as we don't get continuous redevelopment along the flanks of the MCS, the situation would seem to favor a fairly quick rebound given the strong low level winds tomorrow. Any boundary should not get pushed too far south of northern IL before it tries to retreat or wash out. Link to comment Share on other sites More sharing options...
Powerball Posted June 21, 2015 Share Posted June 21, 2015 This event does have some pretty impressive standard deviations. For the low pressure center, it's a standard deviation of -2 to -3 below normal. For moisture advection, it's a standard deviation of +2 to +3. For mid-level wind speeds, the standard deviations range from +3 to +4 above normal. Link to comment Share on other sites More sharing options...
chase.frankel1 Posted June 21, 2015 Share Posted June 21, 2015 The SPC forecaster didn't mention anything about a MDT. I'd imagine that could come with Day 1 if confidence becomes high in widespread coverage.Is the main threat damaging winds? What would give grounds for a moderate? Sent from my LG-V410 using Tapatalk Link to comment Share on other sites More sharing options...
Hoosier Posted June 21, 2015 Share Posted June 21, 2015 This event does have some pretty impressive standard deviations. For the low pressure center, it's a standard deviation of -2 to -3 below normal. For moisture advection, it's a standard deviation of +2 to +3. For mid-level wind speeds, the standard deviations range from +3 to +4 above normal. It's easy to get buried in the details of a given setup but at a more basic level, summer levels of instability with those deviations can be a bad combination. Link to comment Share on other sites More sharing options...
kystormspotter Posted June 21, 2015 Share Posted June 21, 2015 Is the main threat damaging winds? What would give grounds for a moderate? Sent from my LG-V410 It's about probabilities for given threats. You can have a high risk for just wind...http://www.spc.noaa.gov/misc/SPC_probotlk_info.html Link to comment Share on other sites More sharing options...
chase.frankel1 Posted June 21, 2015 Share Posted June 21, 2015 It's about probabilities for given threats. You can have a high risk for just wind...True. True. I was thinking more specifically to this situation. Seems to be a well rounded threat. But im not sure what is pushing probabilities so high. Sent from my LG-V410 using Tapatalk Link to comment Share on other sites More sharing options...
kystormspotter Posted June 21, 2015 Share Posted June 21, 2015 True. True. I was thinking more specifically to this situation. Seems to be a well rounded threat. But im not sure what is pushing probabilities so high. Sent from my LG-V410 Check link in my modified post Link to comment Share on other sites More sharing options...
homedis Posted June 21, 2015 Share Posted June 21, 2015 It's about probabilities for given threats. You can have a high risk for just wind... http://www.spc.noaa.gov/misc/SPC_probotlk_info.html Check link in my modified post He knows the probabilities and what makes a high end event but he is wondering which one of these probabilities (wind or tornado or hail) will be the ones to get the category tomorrow to the moderate risk. Link to comment Share on other sites More sharing options...
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