Hoosier Posted March 11, 2012 Share Posted March 11, 2012 Don't feel like posting a writeup but to me this looks like a slight risk event for parts of the Lakes, maybe as early as the new day 2 outlook although there are some lingering model differences in terms of instability and location of the best threat. Here is a NAM forecast sounding for Gary Indiana valid 00z Tue At this time, main threats with this event look to be hail/damaging winds, but some isolated tornadoes may also be possible. Link to comment Share on other sites More sharing options...
Stebo Posted March 11, 2012 Share Posted March 11, 2012 Don't feel like posting a writeup but to me this looks like a slight risk event for parts of the Lakes, maybe as early as the new day 2 outlook although there are some lingering model differences in terms of instability and location of the best threat. Here is a NAM forecast sounding for Gary Indiana valid 00z Tue At this time, main threats with this event look to be hail/damaging winds, but some isolated tornadoes may also be possible. I would agree on all accounts here. I think the GFS's climo bias is playing havoc with the temp/dew profile for this, and being that it is early season convective I would be riding the NAM/Euro on this, both of which have done very will with respect to the last few events in the region. Link to comment Share on other sites More sharing options...
Hoosier Posted March 11, 2012 Author Share Posted March 11, 2012 SPC holding off DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1124 PM CST SAT MAR 10 2012 VALID 121200Z - 131200Z ..NO SVR TSTM AREAS FORECAST ..GREAT LAKES LATEST MODEL GUIDANCE REMAINS QUITE CONSISTENT REGARDING THE INTENSE MID LEVEL HEIGHT FALLS THAT WILL OVERSPREAD THE MID/UPPER MS VALLEY REGION INTO THE GREAT LAKES WHERE 12HR VALUES WILL APPROACH 150-180M EARLY IN THE PERIOD. THE RESPONSIBLE SHORT-WAVE TROUGH WILL EXTEND FROM THE U.P. OF MI...SWD INTO EXTREME NRN IND BY 13/00Z WITH A FOCUSED SPEED MAX ORIENTED SW-NE ACROSS LOWER MI. NAM IS THE MOST AGGRESSIVE MODEL REGARDING DESTABILIZATION NORTH OF THE JET...ESPECIALLY GIVEN THE EXPECTED SFC HEATING AHEAD OF WIND SHIFT THAT WILL BE JUXTAPOSED BENEATH THE UPPER TROUGH AXIS. IF BOUNDARY LAYER CAN HEAT AS SUGGESTED BY THE NAM WITH READINGS INTO THE LOW-MID 60S THEN STEEP LAPSE RATES COULD SUPPORT A FEW ROBUST UPDRAFTS WITHIN AN OTHERWISE STRONGLY SHEARED ENVIRONMENT. THE LOW PROBABILITY FOR SEVERE TSTMS IS PREDICATED ON STRONG SFC HEATING PROVIDING ENOUGH BUOYANCY FOR SFC-BASED ACTIVITY PRIMARILY BETWEEN THE HOURS OF 20-00Z. Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 11, 2012 Share Posted March 11, 2012 Several potentially mitigating factors with this. MI probably has the best shot of anything as it looks ATT. Link to comment Share on other sites More sharing options...
Indystorm Posted March 11, 2012 Share Posted March 11, 2012 Vorticity lobe expected to be in eastern IA by 12Z Monday moving ne per SPC. Set up continuing to look favorable for possible svr. Link to comment Share on other sites More sharing options...
hm8 Posted March 11, 2012 Share Posted March 11, 2012 ...THERE IS A SLGT RISK OF SVR TSTMS FROM NERN IL INTO MUCH OF LOWER MI... ..SYNOPSIS A POTENT UPPER LOW WILL MOVE FROM IA/MN NEWD TOWARD LAKE SUPERIOR BY 00Z WITH A 70+ KT MIDLEVEL SPEED MAX AND SUBSTANTIAL HEIGHT FALLS SPREADING INTO LOWER MI. AT THE SURFACE...A BROAD LOW PRESSURE TROUGH WILL EXTEND FROM WRN WI INTO NRN IL BY AFTERNOON...PUSHING INTO LOWER MI THROUGH EARLY EVENING. THIS TROUGH WILL SERVE AS A FOCUS FOR SEVERE STORM DEVELOPMENT. TO THE S...A TRAILING FRONT WILL STALL FROM ERN MO INTO AR AND NRN TX. E OF THIS FRONT OVER THE WARM SECTOR...SLY LOW LEVEL FLOW WILL HELP BRING MID TO UPPER 50S F DEWPOINTS AS FAR N AS CHICAGO...WITH LOWER 60S F INTO THE LOWER OH VALLEY. ..NERN IL/SERN WI INTO LOWER MI WIDESPREAD MORNING RAIN WILL LIKELY EXIST FROM LOWER MI INTO IND...OH...AND ERN KY/TN ASSOCIATED WITH LOW LEVEL WARM ADVECTION. THIS ACTIVITY SHOULD LIFT RAPIDLY NEWD AS THE DRY SLOT SPREADS OVER MUCH OF IL AND IND BY MIDDAY. WITH COOL TEMPERATURES ALOFT AND DAYTIME HEATING...LAPSE RATE PROFILES WILL BE RELATIVELY STEEP...AND LITTLE CONVECTIVE INHIBITION SHOULD EXIST BY AFTERNOON. THERE ARE MODEL DIFFERENCES THAT LEND A DEGREE OF UNCERTAINTY TO THIS SEVERE SCENARIO. FOR EXAMPLE...THE GFS MODEL SUGGESTS MUCH LESS INSTABILITY...AND FASTER VEERING OF THE LOW LEVEL FLOW...RESULTING IN VERY LITTLE SEVERE THREAT OVER IL...AND PERHAPS ONLY ISOLATED INTO LOWER MI. HOWEVER...THE NAM/NAMKF SOLUTIONS INDICATE A SUBSTANTIAL THREAT OF SUPERCELLS...INCLUDING LARGE HAIL AND TORNADOES. GIVEN STRONG FORCING WITH THE UPPER SYSTEM...AT LEAST ISOLATED SEVERE THUNDERSTORMS APPEAR LIKELY...ALONG AND JUST AHEAD OF THE DEVELOPING SYNOPTIC COLD FRONT. TIMING OF SEVERE WEATHER WOULD BEGIN NEAR 21Z SRN WI/NRN IL...AND WOULD CONTINUE THROUGH ABOUT 03Z INTO LOWER MI. Link to comment Share on other sites More sharing options...
YHM Supercell Posted March 11, 2012 Share Posted March 11, 2012 Slight Risk now from the SPC on the latest Day 2 Link to comment Share on other sites More sharing options...
Indystorm Posted March 11, 2012 Share Posted March 11, 2012 http://wxcaster4.com...OS_STP_36HR.gif Current 12z NAM map for Monday evening. Link to comment Share on other sites More sharing options...
Hoosier Posted March 11, 2012 Author Share Posted March 11, 2012 SPC discussion sums it up nicely. GFS still much less unstable especially north of I-70. As always, watch the short term trends closely tomorrow. Link to comment Share on other sites More sharing options...
andyhb Posted March 11, 2012 Share Posted March 11, 2012 Considering the NAM verified much better with several of the past few systems, we could have something here. Link to comment Share on other sites More sharing options...
brettman320 Posted March 11, 2012 Share Posted March 11, 2012 It's probably just the Nam being the Nam but it will be interesting to see how this unfolds. I just hope I can get some thunder imby. We Don't get severe weather threats up here very often this early in the year. Link to comment Share on other sites More sharing options...
tornadotony Posted March 11, 2012 Share Posted March 11, 2012 The moisture is gonna have a long way to go to get up here in time... Link to comment Share on other sites More sharing options...
Jim Martin Posted March 12, 2012 Share Posted March 12, 2012 Wow... the 0z NAM really backs off on the severe potential to some degree for tomorrow... Link to comment Share on other sites More sharing options...
BrettenBailey Posted March 12, 2012 Share Posted March 12, 2012 http://hp6.wright-weather.com/wrf_nmmeast-radar-loop_1hour.gif Shows a potential squall line moving through. If we get the instability, I think we'll be seeing a broken line if everything. The Weather Channel as well as SPC seems to think any storms (if they fire) will fire in the Southwest portion of Michigan (as well as parts of Illinois & Indiana) and head east. Will be interesting see what goes on. At any rate, later this week may need to be watched as well. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 Wow... the 0z NAM really backs off on the severe potential to some degree for tomorrow... Umm no, if anything, it's more conducive for severe, with better moisture depicted than from previous runs. I'm still dubious of that, but verbatim, it actually looks better for severe wx. Link to comment Share on other sites More sharing options...
andyhb Posted March 12, 2012 Share Posted March 12, 2012 Bullseye of 0-3 km EHI over 3 near Bloomington tomorrow... Seems like the NAM didn't decrease the threat, just brought it further south/west. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 Bullseye of 0-3 km EHI over 3 near Bloomington tomorrow... Yeah but you never bullseye chase. Often, the bullseye for severe parameters is in a location with poor forcing for convection, and you can have all the EHI in the world but it won't mean a thing if you don't have a storm there. A trick to forecasting enhanced severe threats is to look for the GRADIENT of the parameters (EHI in this case). The gradient is where you'll often get your best combination of parameters and forcing. And tomorrow looks to be no different, with a tight vort lobe rounding the H5 low. And unfortunately, that gradient basically sets up along I-80 in the southern suburbs of Chicago and into northern Indiana (NAM verbatim). Again, I am skeptical about the moisture return the NAM is depicting, but if it verifies, then I'll be a bit nervous tomorrow afternoon. Link to comment Share on other sites More sharing options...
Hoosier Posted March 12, 2012 Author Share Posted March 12, 2012 NAM has a nice 0-3 km CAPE bullseye over NE IL/NW IN tomorrow evening. Link to comment Share on other sites More sharing options...
andyhb Posted March 12, 2012 Share Posted March 12, 2012 Yeah but you never bullseye chase. Often, the bullseye for severe parameters is in a location with poor forcing for convection, and you can have all the EHI in the world but it won't mean a thing if you don't have a storm there. A trick to forecasting enhanced severe threats is to look for the GRADIENT of the parameters (EHI in this case). The gradient is where you'll often get your best combination of parameters and forcing. And tomorrow looks to be no different, with a tight vort lobe rounding the H5 low. And unfortunately, that gradient basically sets up along I-80 in the southern suburbs of Chicago and into northern Indiana (NAM verbatim). Again, I am skeptical about the moisture return the NAM is depicting, but if it verifies, then I'll be a bit nervous tomorrow afternoon. Unless the bullseye is the entire warm sector of course like a couple of the events last year But, yeah, considering the problems we had with moisture advection today, it's probably going to take awhile to get enough up that far north in time to get the setup the NAM is projecting. lol apparently I need to get out of Hoosier's head. Link to comment Share on other sites More sharing options...
Hoosier Posted March 12, 2012 Author Share Posted March 12, 2012 Yeah but you never bullseye chase. Often, the bullseye for severe parameters is in a location with poor forcing for convection, and you can have all the EHI in the world but it won't mean a thing if you don't have a storm there. A trick to forecasting enhanced severe threats is to look for the GRADIENT of the parameters (EHI in this case). The gradient is where you'll often get your best combination of parameters and forcing. And tomorrow looks to be no different, with a tight vort lobe rounding the H5 low. And unfortunately, that gradient basically sets up along I-80 in the southern suburbs of Chicago and into northern Indiana (NAM verbatim). Again, I am skeptical about the moisture return the NAM is depicting, but if it verifies, then I'll be a bit nervous tomorrow afternoon. You're ignoring that tomorrow is March 12 - a date that has produced some pretty good severe weather events in the area. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 If something severe is going to happen tomorrow, it's likely going to be a supercell (maybe tornadic) along the I-80 corridor. I don't foresee the threat getting much farther N (especially with the cold lake). Link to comment Share on other sites More sharing options...
cyclone77 Posted March 12, 2012 Share Posted March 12, 2012 One thing I always like to look for is the nose of the theta-e ridge at the surface and at 925mb. This is usually near the northern edge of the best cape. I actually like the LaSalle/Peru area tomorrow based on the NAM. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 You're ignoring that tomorrow is March 12 - a date that has produced some pretty good severe weather events in the area. I know, and the big one in '76 I believe only had Tds in the 53-55°F range, but this is going to be a mesoscale driven event. We won't know really that it's going to happen until it happens. Link to comment Share on other sites More sharing options...
Hoosier Posted March 12, 2012 Author Share Posted March 12, 2012 Substantial differences between the NAM and GFS continue, although I guess we're getting to the point where we can look at other models. Link to comment Share on other sites More sharing options...
andyhb Posted March 12, 2012 Share Posted March 12, 2012 Either way, I feel this may be the prelude to something...bigger... Link to comment Share on other sites More sharing options...
hm8 Posted March 12, 2012 Share Posted March 12, 2012 RUC doesn't look like its biting. Link to comment Share on other sites More sharing options...
cyclone77 Posted March 12, 2012 Share Posted March 12, 2012 The NAM definitely is the slowest. The other models (including the long-range RUC) are quicker. The long-range RUC would favor areas closer to the Indiana border south of Kankakee IMO. GFS looks ugly with veered low-levels and less instability. Link to comment Share on other sites More sharing options...
OceanStWx Posted March 12, 2012 Share Posted March 12, 2012 Yeah but you never bullseye chase. Often, the bullseye for severe parameters is in a location with poor forcing for convection, and you can have all the EHI in the world but it won't mean a thing if you don't have a storm there. A trick to forecasting enhanced severe threats is to look for the GRADIENT of the parameters (EHI in this case). The gradient is where you'll often get your best combination of parameters and forcing. And tomorrow looks to be no different, with a tight vort lobe rounding the H5 low. And unfortunately, that gradient basically sets up along I-80 in the southern suburbs of Chicago and into northern Indiana (NAM verbatim). Again, I am skeptical about the moisture return the NAM is depicting, but if it verifies, then I'll be a bit nervous tomorrow afternoon. Couldn't have really said it any better myself. I don't know if you've noticed, but the new SPC parameter on the mesoanalysis page (probability of sig. tor.) seems to do well in showing this. It places the highest probabilities on the gradient rather than the bullseyes. Link to comment Share on other sites More sharing options...
Hoosier Posted March 12, 2012 Author Share Posted March 12, 2012 I know, and the big one in '76 I believe only had Tds in the 53-55°F range, but this is going to be a mesoscale driven event. We won't know really that it's going to happen until it happens. Td's were actually lower than that in some of the areas that were hit. ORD only had a dewpoint around 50 when the tornado passed near there. In terms of overall tornado production, that was an impressive event given the marginal moisture. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 Link to comment Share on other sites More sharing options...
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