ClicheVortex2014 Posted December 22, 2015 Share Posted December 22, 2015 Hey forumers I live in northwest Alabama and I see Dr Forbes has us with a Torcon of 7 for Wednesday (what is it about Wednesdays?!). Every time really severe weather hits, I lose electricity and cable for days. As with the 4/27/2011 outbreak, I was in the dark about what happened until May 1st when I was able to access this board and catch up. You guys were amazing! If we get it again, I hope I can depend on your intelligence and diligence once again. Have a good day! BMX just updated their AFD... they mention your area is the best area to see tornadic supercells. They sound very worried; they even mentioned the possibility of an EF4+ tomorrow. Good luck and stay safe! NATIONAL WEATHER SERVICE BIRMINGHAM AL318 PM CST TUE DEC 22 2015 ...SEVERE WEATHER OUTBREAK MAY AFFECT PARTS OF CENTRAL ALABAMA ON WEDNESDAY AFTERNOON INTO EARLY THURSDAY... .DISCUSSION... WITH DISRUPTIVE GULF CONVECTION OUR OF THE PICTURE...THE MAIN QUESTION AT THIS POINT IS RELATED TO STORM COVERAGE ON WEDNESDAY. FORTUNATELY STORMS WILL PROBABLY BE VERY ISOLATED AS THE STRONGEST FORCING BRUSHES BY TO THE NORTH. MODELS HAVE TRENDED MORE AGGRESSIVE WITH THE RAPID NORTHWARD SURGE OF A WARM SECTOR WEDNESDAY MORNING BEHIND A WAVE OF EARLY MORNING SHOWERS AND STORMS. AT LEAST A FEW MODELS INDICATE THE POSSIBILITY OF NEAR 70 DEGREE DEWPOINTS AS FAR NORTH AS BIRMINGHAM BY EARLY TOMORROW AFTERNOON. SEVERAL LOW-LEVEL CONFLUENCE BANDS ARE EXPECTED TO BE PRESENT IN THE WAKE OF THE MORNING CONVECTION AS IT MOVES RAPIDLY TO THE NORTHEAST. AN ISOLATED TORNADIC SUPERCELL CANNOT TOTALLY BE RULED OUT ANYWHERE ACROSS THE AREA THROUGH THE EARLY AFTERNOON...BUT THE HIGHEST CHANCE FOR TORNADIC SUPERCELLS WILL OCCUR DURING THE EVENING AND INTO THE NIGHT GENERALLY NORTHWEST OF INTERSTATE 59 AS A STRONG LOW-LEVEL JET AXIS SHIFTS EASTWARD INTO ALABAMA. THE LIMITING FACTORS TO THIS SETUP ARE TIED TO A TENDENCY FOR 500 MB HEIGHT RISES AND A LACK OF LIFT. 200 MB DIVERGENCE AND LOW-LEVEL CONVERGENCE SHOULD BE SUFFICIENT FOR AT LEAST A FEW SUPERCELLS FOCUSED IN THE NORTHWEST PART OF THE FORECAST AREA. THE ISOLATED NATURE OF THESE STORMS MAY ALLOW THEM TO BECOME INTENSE NEAR THE BEST CAPE/SHEAR OVERLAP...WITH THE POSSIBILITY OF STRONG AND LONG-TRACK TORNADOES. A VIOLENT TORNADO CANNOT BE RULED OUT IF ALL OF THE RIGHT SEVERE WEATHER INGREDIENTS COME TOGETHER. Link to comment Share on other sites More sharing options...
andyhb Posted December 22, 2015 Share Posted December 22, 2015 This 18z 4 km NAM image valid 3z Thursday is scary, for lack of a better word, note the supercells over S IN. To see this popping 60 dBZ cores with those things in TN and KY is unreal for December. Link to comment Share on other sites More sharing options...
Hoosier Posted December 22, 2015 Share Posted December 22, 2015 so, yeah Link to comment Share on other sites More sharing options...
OSUmetstud Posted December 22, 2015 Share Posted December 22, 2015 How good is the 4km NAM at predicting instability? Link to comment Share on other sites More sharing options...
Stebo Posted December 22, 2015 Share Posted December 22, 2015 A couple things to note, most places today were warmer than forecast in the region. Detroit for example was +5 off of the forecast and furthermore the dew points haven't dropped off as quickly as originally thought. If we are starting ahead of the forecast. With more cloud cover moving in tonight with the moisture advection expecting to begin overnight, we shouldn't drop off much tonight as well. These higher values the NAM is pumping out, might not be as unrealistic as we originally thought. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted December 22, 2015 Author Share Posted December 22, 2015 Sounding in Tennessee at max paramaters per NAM 18Z Sounding in Southern MI: Link to comment Share on other sites More sharing options...
Stebo Posted December 22, 2015 Share Posted December 22, 2015 so, yeah ilx.png Well, expect that to be crushed. Link to comment Share on other sites More sharing options...
Stebo Posted December 22, 2015 Share Posted December 22, 2015 How good is the 4km NAM at predicting instability? It tends to be a bit high, but in strong moisture advection regimes it tends to not be too far off of the truth. It is usually more overzealous in the summer though, in cold season events it isn't too far off from reality. Link to comment Share on other sites More sharing options...
andyhb Posted December 22, 2015 Share Posted December 22, 2015 How good is the 4km NAM at predicting instability? It tends to be pretty good in the cold season from what I've seen. It did very well on 11/16. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted December 22, 2015 Share Posted December 22, 2015 This 18z 4 km NAM image valid 3z Thursday is scary, for lack of a better word, note the supercells over S IN. To see this popping 60 dBZ cores with those things in TN and KY is unreal for December. I don't even... How good is the 4km NAM at predicting instability? Probably not so good overall... I doubt it's an outlier at this point. Even Euro has 1000+ CAPE crossing the Michigan border. Link to comment Share on other sites More sharing options...
andyhb Posted December 22, 2015 Share Posted December 22, 2015 Should add that the 4 km NAM is not the only model suggesting appreciable CAPE further north, practically everything but the GFS has pockets of >1000 J/kg in spots. Link to comment Share on other sites More sharing options...
Hoosier Posted December 22, 2015 Share Posted December 22, 2015 Well, expect that to be crushed. MUCAPE record for December is like 950 J/kg. Of course some of this comes down to having the right timing to get it on the observed sounding and the timing tomorrow looks good. Link to comment Share on other sites More sharing options...
OSUmetstud Posted December 22, 2015 Share Posted December 22, 2015 I don't even... Probably not so good overall... I doubt it's an outlier at this point. Even Euro has 1000+ CAPE crossing the Michigan border. Yeah I showed forky the sounding in southern Illinois for 12z. Straight loaded gun. Steep lapse rates and all. 1600 elevated cape at that time. Link to comment Share on other sites More sharing options...
OSUmetstud Posted December 22, 2015 Share Posted December 22, 2015 12z K1H2 Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted December 22, 2015 Share Posted December 22, 2015 Damn! Loaded guns are a thing of beauty. This is also in south Illinois... 4km NAM Link to comment Share on other sites More sharing options...
Hoosier Posted December 22, 2015 Share Posted December 22, 2015 Locally, the morning into afternoon activity does have me mildly concerned as far as how much instability will build in its wake (whether we can reach the higher end of progs), but most models agree on sufficient recovery. It may be tempting to write things off around midday tomorrow but an important factor in this setup is the steepening mid level lapse rates with time, which should allow surface based instability to continue to build even after sunset as nocturnal cooling is offset by the strong southerly flow. Link to comment Share on other sites More sharing options...
Indystorm Posted December 22, 2015 Share Posted December 22, 2015 Per SPC meso there is a 986mb low over eastern CO at present. And this thing is supposed to deepen further as it moves ne? Yikes! Link to comment Share on other sites More sharing options...
kperk014 Posted December 22, 2015 Share Posted December 22, 2015 BMX just updated their AFD... they mention your area is the best area to see tornadic supercells. They sound very worried; they even mentioned the possibility of an EF4+ tomorrow. Good luck and stay safe! I live about 25 north of Phil Campbell. When I was told to drive down there to see if I could help, I had no idea what I was going to see since I had lost my electricity and cable that morning. I feel sick thinking it could happen again. Link to comment Share on other sites More sharing options...
Stebo Posted December 22, 2015 Share Posted December 22, 2015 Per SPC meso there is a 986mb low over eastern CO at present. And this thing is supposed to deepen further as it moves ne? Yikes! 4mb stronger than NAM 12, 2mb stronger than NAM4/GFS off 18z runs. Link to comment Share on other sites More sharing options...
MattPetrulli Posted December 22, 2015 Share Posted December 22, 2015 This setup keeps reminding me of 4/28. Link to comment Share on other sites More sharing options...
PGM Posted December 22, 2015 Share Posted December 22, 2015 This setup keeps reminding me of 4/28.Except 4/28's severe activity was mostly in the southeast subforum...... Could be way more action with this event for IL,IN,MI,KY.Sent from my XT1563 using Tapatalk Link to comment Share on other sites More sharing options...
MattPetrulli Posted December 22, 2015 Share Posted December 22, 2015 Except 4/28's severe activity was mostly in the southeast subforum...... Could be way more action with this event for IL,IN,MI,KY. Sent from my XT1563 I mean there's no forum about this in the Southeast subforum. I personally think it should be on the main forum though. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted December 22, 2015 Share Posted December 22, 2015 I mean there's no forum about this in the Southeast subforum. I personally think it should be on the main forum though. There's one in the TN valley subforum but it's pretty much dead Link to comment Share on other sites More sharing options...
Chambana Posted December 22, 2015 Share Posted December 22, 2015 When it's December and we are 8 pages deep in a SEVERE threat. Lol Link to comment Share on other sites More sharing options...
PGM Posted December 22, 2015 Share Posted December 22, 2015 I mean there's no forum about this in the Southeast subforum. I personally think it should be on the main forum though.Yeah, I'm surprised w the lack of discussion in the se forum. Psbl major tornado event less than a day away and they're talking mundanely about winter.... I am interested to see what the Day 1 outlook from the SPC will look like.. Sent from my XT1563 using Tapatalk Link to comment Share on other sites More sharing options...
PGM Posted December 22, 2015 Share Posted December 22, 2015 When it's December and we are 8 pages deep in a SEVERE threat. LolAnd it looks like the most impressive threat we've had this year!!!! 2015 smhSent from my XT1563 using Tapatalk Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted December 22, 2015 Author Share Posted December 22, 2015 I think moving this thread or making a new one on the man page is reasonable. Local mets on the news were talking about how they thought forecasts were too conservative Link to comment Share on other sites More sharing options...
Superstorm93 Posted December 22, 2015 Share Posted December 22, 2015 We have to see if the 00z follows the 18z in showing a slightly slower and slightly deeper solution like some of the offices suggested yesterday. This would obliviously give a chance for whatever junk convection there is to clear out and for another round of destabilization to occur. Like others have said, while the 4km NAM usually overdoes CAPE in the warm season, I don't think its playing things up all that much in this event. Even if we cut the instability by a quarter or so, we still have more than enough given the extreme shear and good upper level support. Link to comment Share on other sites More sharing options...
PGM Posted December 22, 2015 Share Posted December 22, 2015 4k NAM has a pretty intense squall line from Chicago down to central Arkansas at 15z. It moves about 250 miles or so northeast in six hours and is over central Indiana and western Lower Michigan at 21z. 4k NAM fires up discrete supercells to the southwest of this across western Tennessee and northern Mississippi. Am wondering if the supercell threat has shifted east a bit into Indiana and Ohio for wed evening. Will we see supercells behind this squall line in Illinois? Sent from my XT1563 using Tapatalk Link to comment Share on other sites More sharing options...
Chinook Posted December 22, 2015 Share Posted December 22, 2015 Instability is increasing in east Texas right now. SPC mesoanalysis predicts 1500J/kg surface cape (capped) up to Dallas in 6 hours. Maybe some isolated severe weather reports in the late night. Link to comment Share on other sites More sharing options...
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