HillsdaleMIWeather Posted December 20, 2015 Share Posted December 20, 2015 OK Folks, heres what we know: 23rd: This would lead to a potential decent severe event across this subforum (particularly the Southeastern) and a large-scale outbreak down south. 25th-27th Models are arguing over the exact details, but another severe event is possible the 26th, with rain in between. Link to comment Share on other sites More sharing options...
andyhb Posted December 20, 2015 Share Posted December 20, 2015 This would lead to a potential decent severe event across this subforum (particularly the Southeastern) and a large-scale outbreak down south. Which is why I said maybe this would be better on the general wx discussion board. Link to comment Share on other sites More sharing options...
Stebo Posted December 20, 2015 Share Posted December 20, 2015 You should probably looked at the other threads before posting this, we are still deciding where to start the thread with the multiple regions... Link to comment Share on other sites More sharing options...
nwburbschaser Posted December 20, 2015 Share Posted December 20, 2015 The modeled large warm sectors for these potential events really stand out to me. That seems impressive for this time of year. Link to comment Share on other sites More sharing options...
andyhb Posted December 20, 2015 Share Posted December 20, 2015 The modeled large warm sectors for these potential events really stand out to me. That seems impressive for this time of year. It is certainly highly anomalous, thanks to the 594 dm Bermuda ridge being progged, which is basically unheard of this late in the year. Link to comment Share on other sites More sharing options...
MattPetrulli Posted December 20, 2015 Share Posted December 20, 2015 NAM and GFS are being quite aggressive for Wednesday. SPC has introduced a 15% risk for a small area of MS,LA, and SE AR. Link to comment Share on other sites More sharing options...
MichelleH Posted December 20, 2015 Share Posted December 20, 2015 I agree that this thread needs to be on the main board. I had to hunt several of the regional forums to find it. Link to comment Share on other sites More sharing options...
buckeye Posted December 20, 2015 Share Posted December 20, 2015 12z gfs says if you live in n. ohio, you might hope to get a boat for xmas. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted December 20, 2015 Share Posted December 20, 2015 Change the thread title or move it. Link to comment Share on other sites More sharing options...
Hoosier Posted December 20, 2015 Share Posted December 20, 2015 Usually don't go to the main forum unless it looks high risk caliber. I haven't looked at this at all so I'm not sure about the threat level. Can always move it if necessary. Link to comment Share on other sites More sharing options...
Chitown Storm Posted December 20, 2015 Share Posted December 20, 2015 12z gfs says if you live in n. ohio, you might hope to get a boat for xmas. And if you live in S. MN or C/N WI you better fire up the snowblower. Complete change from the 6z run. Link to comment Share on other sites More sharing options...
Indystorm Posted December 20, 2015 Share Posted December 20, 2015 I've been watching both of these systems for several days now living in the Indpls area. IMBY concerns really argue for the weekend impact but could have some excitement down south. before then. If the main forum is only used for HIGH RISK situations (SPC definition?) we will rarely have a multi region system covered there. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted December 20, 2015 Author Share Posted December 20, 2015 The 12Z GFS increased the instability, with Supercell composites in Southwestern Lower MI of 3,hints at flash flooding particularly for Northern Ohio. For our southern friends lurking, instability increased for you guys as well. Link to comment Share on other sites More sharing options...
Hoosier Posted December 20, 2015 Share Posted December 20, 2015 I'm dubious about the northward extent of severe weather on the 23rd, but for the GFS to have 500 J/kg SBCAPE almost up to I-80 catches my attention. Will be interesting to see what the NAM has as it gets a better handle on this system. Link to comment Share on other sites More sharing options...
andyhb Posted December 20, 2015 Share Posted December 20, 2015 I'm dubious about the northward extent of severe weather on the 23rd, but for the GFS to have 500 J/kg SBCAPE almost up to I-80 catches my attention. Will be interesting to see what the NAM has as it gets a better handle on this system. You should probably take a glance at the Euro. It has >1000 J/kg CAPE in IL thanks to very cold air aloft. Link to comment Share on other sites More sharing options...
Hoosier Posted December 20, 2015 Share Posted December 20, 2015 You should probably take a glance at the Euro. It has >1000 J/kg CAPE in IL thanks to very cold air aloft. Yes, I was just coming back here to post that. I'm certainly not writing off a threat...I guess my natural tendency is to be skeptical of severe storms this far north in December, though I know it has happened. Link to comment Share on other sites More sharing options...
andyhb Posted December 20, 2015 Share Posted December 20, 2015 The Euro will probably catch that potential better since its mid level thermodynamics are more accurate than the GFS the vast majority of the time. Link to comment Share on other sites More sharing options...
Stebo Posted December 20, 2015 Share Posted December 20, 2015 Yes, I was just coming back here to post that. I'm certainly not writing off a threat...I guess my natural tendency is to be skeptical of severe storms this far north in December, though I know it has happened.Yeah in a year similar to this, 1957. The Euro has more realistic representation of the atmosphere, which has 1000-1500 j/kg across parts of IL. Link to comment Share on other sites More sharing options...
Stebo Posted December 20, 2015 Share Posted December 20, 2015 The Euro will probably catch that potential better since its mid level thermodynamics are more accurate than the GFS the vast majority of the time.Yeah no water loading in the sounding like the GFS. Link to comment Share on other sites More sharing options...
Hoosier Posted December 20, 2015 Share Posted December 20, 2015 Should be clear, when I'm talking about a threat this far north, I'm talking about the I-80 area, not the Ohio Valley. Though the Euro instability would probably be enough to get it that far north. Link to comment Share on other sites More sharing options...
Stebo Posted December 20, 2015 Share Posted December 20, 2015 Should be clear, when I'm talking about a threat this far north, I'm talking about the I-80 area, not the Ohio Valley. Though the Euro instability would probably be enough to get it that far north. Honestly with a setup like this 500 to 750 J/kg will get things going, which the GFS shows at 216 getting almost to Gary, and that is with bad GFS parameters. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted December 20, 2015 Author Share Posted December 20, 2015 18Z GFS looks a little closer to the ECMWF, has higher CAPE. Link to comment Share on other sites More sharing options...
Hoosier Posted December 20, 2015 Share Posted December 20, 2015 Honestly with a setup like this 500 to 750 J/kg will get things going, which the GFS shows at 216 getting almost to Gary, and that is with bad GFS parameters. I agree...if we can realize >500 J/kg then that should be enough for a decent wintertime threat. System has a number of favorable factors going for it and I like the pretty rapid deepening being shown on Wednesday. Do wish there was a bit more time for better northward moisture return (check the progs for Tuesday and you'll see what I'm talking about) but it's certainly workable and it could obviously be worse. Link to comment Share on other sites More sharing options...
Hoosier Posted December 20, 2015 Share Posted December 20, 2015 Here's some maps of December severe weather events in this region that I posted last year. As you can see, it's usually a south of I-80 thing, but not always. http://www.americanwx.com/bb/index.php/topic/44964-early-december-severe-potential/?p=3149100 Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted December 20, 2015 Share Posted December 20, 2015 Usually don't go to the main forum unless it looks high risk caliber. I haven't looked at this at all so I'm not sure about the threat level. Can always move it if necessary. NWS Birmingham suggests it could certainly be one of those events NOW ON TO THE POSSIBLE HIGH IMPACT PART OF THE FORECAST... MODELS ARE IN SIGNIFICANTLY BETTER AGREEMENT TODAY REGARDING THE EVOLUTION OF THE UPPER-AIR PATTERN FOR WEDNESDAY...AND IT IS NOT GOOD NEWS. SEVERAL HISTORIC COOL-SEASON SEVERE WEATHER ANALOGS ARE SHOWING UP BASED ON THE FORECAST UPPER-AIR PATTERN. MODELS HAVE TRENDED TOWARD THE ECMWF SOLUTION WITH MORE VORTICITY IN THE BASE OF THE TROUGH ACROSS THE SOUTHERN PLAINS. THIS WILL CAUSE STRONG SURFACE CYCLOGENESIS TO OCCUR TO OUR NORTHWEST AND SUBSTANTIAL PRESSURE FALLS FARTHER SOUTH ACROSS INTO OUR AREA...LEADING TO STRENGTHENING WIND FIELDS ACROSS A LARGE AREA. THE CONVECTIVE EVOLUTION WITH THIS SYSTEM REMAINS A BIT UNCLEAR...BUT IT APPEARS LESS LIKELY THAT COASTAL CONVECTION WILL BE A SIGNIFICANT INHIBITING FACTOR IN POLEWARD MOISTURE ADVECTION. ONE POSSIBLE SCENARIO IS THAT RAIN DEPARTS TO THE EAST DURING THE MORNING ON WEDNESDAY...ALLOWING UNUSUALLY RICH GULF MOISTURE TO MOVE INLAND FROM THE NORTHWESTERN GULF OF MEXICO. IF THIS OCCURS...CONDITIONS COULD BECOME RIPE FOR A TORNADO OUTBREAK FROM THE LOWER MS VALLEY EASTWARD INTO PARTS OF CENTRAL ALABAMA. FORECAST SOUNDINGS... PARTICULARLY ACROSS THE NORTHERN AND WESTERN PARTS OF OUR AREA... SHOW ABUNDANT LOW-LEVEL MOISTURE BENEATH STEEP MID-LEVEL LAPSE RATES AND NEARLY TEXTBOOK WIND SHEAR PROFILES. IF THIS OCCURS... SUPERCELLS WITH TORNADOES...DAMAGING WINDS...AND LARGE HAIL WOULD BE POSSIBLE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. IT IS IMPOSSIBLE TO KNOW EXACTLY HOW MUCH GULF COAST CONVECTION WILL BE PRESENT ON WEDNESDAY...AND IT MAY MAKE OR BREAK THIS FORECAST. Anyway... I like the trends for our region. Last time we had a winter severe event was February 2014... been way too long. But the potential down south is really impressive. ILN didn't say anything about severe potential other than isolated t-storms are possible. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted December 20, 2015 Author Share Posted December 20, 2015 NWS Birmingham suggests it could certainly be one of those events Anyway... I like the trends for our region. Last time we had a winter severe event was February 2014... been way too long. But the potential down south is really impressive. ILN didn't say anything about severe potential other than isolated t-storms are possible. Agreed there brother, we could have a Enhanced Risk event up here if trends go the way of the ECMWF. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted December 20, 2015 Share Posted December 20, 2015 Agreed there brother, we could have a Enhanced Risk event up here if trends go the way of the ECMWF. I guess it's possible if enough CAPE verifies. I think we'd need like 500 j/kg to have a better chance of an enhanced. When GFS is showing even decent potential, you know you have reason to be optimistic about seeing something. Here's an 18z GFS sounding for Cincinnati. I think there's something wrong with their SRH calculation... I can't imagine how a hodograph like that only equates to 286 m2/s2. But this looks decent for some low-topped action here. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted December 20, 2015 Author Share Posted December 20, 2015 I guess it's possible if enough CAPE verifies. I think we'd need like 500 j/kg to have a better chance of an enhanced. When GFS is showing even decent potential, you know you have reason to be optimistic about seeing something. Here's an 18z GFS sounding for Cincinnati. I think there's something wrong with their SRH calculation... I can't imagine how a hodograph like that only equates to 286 m2/s2. But this looks decent for some low-topped action here. From the data, that calculation has to be off. Link to comment Share on other sites More sharing options...
MattPetrulli Posted December 20, 2015 Share Posted December 20, 2015 Seems like if IF this verifies, we could see a decent tornado outbreak. Link to comment Share on other sites More sharing options...
andyhb Posted December 20, 2015 Share Posted December 20, 2015 From the data, that calculation has to be off. Not really. The wind profile profile, despite some veering with height, is fairly unidirectional. That isn't going to lead to the super high SRH values. Link to comment Share on other sites More sharing options...
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