Hoosier Posted November 12, 2013 Share Posted November 12, 2013 Between blasts of cold air, it looks like there will be a strong system with the potential to produce a severe weather outbreak at least into the Ohio Valley and quite possibly farther north. Too early for a lot of details but various solutions generally agree on a substantial surface low moving from the Plains to the Lakes late weekend/early next week with good moisture return for this time of year. Situation bears watching.Discuss. Link to comment Share on other sites More sharing options...
Stebo Posted November 12, 2013 Share Posted November 12, 2013 Both the GFS and Euro show an initial system lifting out on Saturday that will help draw the warmth and moisture Northward with the second system for Sunday into Monday bringing the cold front through. I do agree this bears watching as there could be a decent potential of severe weather with the cold front, too early to get specific in the details though. Link to comment Share on other sites More sharing options...
andyhb Posted November 12, 2013 Share Posted November 12, 2013 12z Euro looked quite impressive (as in potentially significant severe weather event) from 120-144 hrs. Considering the Euro has had better run to run continuity over the past few cycles, this certainly bears monitoring. 300 mb (@132): 500 mb (@132): Link to comment Share on other sites More sharing options...
Hoosier Posted November 12, 2013 Author Share Posted November 12, 2013 Both the GFS and Euro show an initial system lifting out on Saturday that will help draw the warmth and moisture Northward with the second system for Sunday into Monday bringing the cold front through. I do agree this bears watching as there could be a decent potential of severe weather with the cold front, too early to get specific in the details though. Some pretty notorious events have been preceded by a lead system...a sacrifical lamb. Not saying this is gonna be the outbreak of the century or anything like that but it's an important factor. Don't want that first one to get too strong though. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted November 12, 2013 Share Posted November 12, 2013 The 12z Euro did indeed look quite impressive on Sunday. Link to comment Share on other sites More sharing options...
Stebo Posted November 12, 2013 Share Posted November 12, 2013 Some pretty notorious events have been preceded by a lead system...a sacrifical lamb. Not saying this is gonna be the outbreak of the century or anything like that but it's an important factor. Don't want that first one to get too strong though. Yes, a system to prime the pump for the region. Link to comment Share on other sites More sharing options...
andyhb Posted November 13, 2013 Share Posted November 13, 2013 A significant majority of the 18z GFS ensemble members have trended towards the 12z Euro verbatim regarding Sunday. Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 13, 2013 Share Posted November 13, 2013 Sunday/night looks like the only potentially interesting day. 60F DP's into WI/MI in mid-November is good start. Link to comment Share on other sites More sharing options...
Hoosier Posted November 13, 2013 Author Share Posted November 13, 2013 Couldn't help myself and took a peek at some forecast soundings for the Ohio Valley off the 00z GFS. Needless to say, pretty impressive, especially if adjusted for what surface conditions may be like. Link to comment Share on other sites More sharing options...
andyhb Posted November 13, 2013 Share Posted November 13, 2013 00z Euro still looking impressive over a substantial coverage area on Sunday. Link to comment Share on other sites More sharing options...
Stebo Posted November 13, 2013 Share Posted November 13, 2013 Couldn't help myself and took a peek at some forecast soundings for the Ohio Valley off the 00z GFS. Needless to say, pretty impressive, especially if adjusted for what surface conditions may be like. The wind profiles are exceptional on the GFS, obviously the 60-65 temps are being way underdone, it will be interesting to see once this gets into the range of the NAM what temperature profiles we will be seeing. The part that interests me the most however, is that the Euro, GGEM and especially the Ukie are much stronger with the low pressure system for the region, that would have huge implications with respect to the strength of the wind field and the moisture transport and warm air advection into the region. Link to comment Share on other sites More sharing options...
hm8 Posted November 13, 2013 Share Posted November 13, 2013 The wind profiles are exceptional on the GFS, obviously the 60-65 temps are being way underdone, it will be interesting to see once this gets into the range of the NAM what temperature profiles we will be seeing. The part that interests me the most however, is that the Euro, GGEM and especially the Ukie are much stronger with the low pressure system for the region, that would have huge implications with respect to the strength of the wind field and the moisture transport and warm air advection into the region. 06z GFS pushes 70s up to Lincoln, IL Link to comment Share on other sites More sharing options...
nwohweather Posted November 13, 2013 Share Posted November 13, 2013 Should bode real well for the Lower GL if this Low really surges all the way into Lake Superior. Setup reminds me of November 10, 2002 a lot really, where it was very chilly to start the month and then heated up to almost 70 that day Link to comment Share on other sites More sharing options...
Hoosier Posted November 13, 2013 Author Share Posted November 13, 2013 Area has been outlined for day 5 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0351 AM CST WED NOV 13 2013 VALID 161200Z - 211200Z ..DISCUSSION ALTHOUGH CONSIDERABLE SPREAD PERSISTS WITHIN THE MEDIUM RANGE MODEL ENSEMBLE DATA...AND UNCERTAINTIES LINGER...THERE DOES APPEAR REASONABLE AGREEMENT BETWEEN AT LEAST THE GFS AND ECMWF ENSEMBLE MEANS CONCERNING LARGE-SCALE PATTERN DEVELOPMENTS LATE THIS WEEKEND INTO EARLY NEXT WEEK. THIS EXTENDS...AT LEAST TO SOME EXTENT...TO THEIR RESPECTIVE 13/00Z DETERMINISTIC RUNS...AND IT APPEARS INCREASINGLY LIKELY THAT SIGNIFICANT SURFACE CYCLOGENESIS WILL TAKE PLACE ALONG A SOUTH SURGING COLD FRONT TO THE LEE OF THE ROCKIES...FROM THE CENTRAL PLAINS INTO THE GREAT LAKES REGION. BEFORE THE COLD INTRUSION CUTS OFF MOISTURE RETURN FROM THE GULF OF MEXICO...A WINDOW OF OPPORTUNITY DOES APPEAR TO EXIST FOR THE DEVELOPMENT OF A CORRIDOR OF SUBSTANTIVE BOUNDARY LAYER DESTABILIZATION...IN THE PRESENCE OF STRONG DEEP LAYER SHEAR AND MID/UPPER FORCING FOR ASCENT...SUPPORTIVE OF THE RISK FOR SEVERE STORMS. THIS CURRENTLY SEEMS MOST LIKELY LATE SUNDAY AFTERNOON THROUGH SUNDAY NIGHT...FROM THE VICINITY OF THE ARKLATEX NORTHEASTWARD INTO THE MIDDLE MISSISSIPPI/LOWER OHIO VALLEY REGION...INCLUDING THE POTENTIAL FOR DAMAGING WIND GUSTS AND TORNADOES. ..KERR.. 11/13/2013 Link to comment Share on other sites More sharing options...
Hoosier Posted November 13, 2013 Author Share Posted November 13, 2013 12z Euro really goes to town with this. 980 mb low near the Lake Superior/Canada border at 120 hours. IMO, the ceiling with this one is higher than what we saw on Halloween as this one at least looks like it could have somewhat greater instability. Link to comment Share on other sites More sharing options...
nwohweather Posted November 13, 2013 Share Posted November 13, 2013 12z Euro really goes to town with this. 980 mb low near the Lake Superior/Canada border at 120 hours. IMO, the ceiling with this one is higher than what we saw on Halloween as this one at least looks like it could have somewhat greater instability. That location and the strength is really the kicker here. We really had almost no instability here on Halloween and Ohio had quite a few severe reports, this seems very promising especially with a track into Lake Superior which almost always leads to good fortunes for the Lower GL Link to comment Share on other sites More sharing options...
Stebo Posted November 13, 2013 Share Posted November 13, 2013 12z Euro really goes to town with this. 980 mb low near the Lake Superior/Canada border at 120 hours. IMO, the ceiling with this one is higher than what we saw on Halloween as this one at least looks like it could have somewhat greater instability. I'd agree especially considering that the Halloween event had roughly 500-750 J/kg max and there were 46 tornadoes with that event. The Euro is pumping out 800-1200 J/kg along the front on Sunday already, and that is probably a bit underdone. Link to comment Share on other sites More sharing options...
A-L-E-K Posted November 13, 2013 Share Posted November 13, 2013 looking like a solid event in the making Link to comment Share on other sites More sharing options...
andyhb Posted November 13, 2013 Share Posted November 13, 2013 One thing that really gets my attention is if the 12z Euro verbatim slows even by just 6 hrs, then you have something like the following occurring around peak heating for MO/IL and perhaps the D5 area (which with given the forecast temps and dewpoints probably means around 1000-2000 J/kg of CAPE over at least some of the area). Analysis of COD/wundermaps also shows southerly/backed sfc winds and a very impressive wind profile overall, with winds veering/increasing strongly with height. Link to comment Share on other sites More sharing options...
Hoosier Posted November 13, 2013 Author Share Posted November 13, 2013 looking like a solid event in the making Gil's take Sunday is an eye-opener. Models portray nearly 60 degree dewpoints coming into the area by Sunday afternoon, as a strong cold front approaches our area. Moisture levels 3 standard deviations above average this time of year should always raise eyebrows, but what it will do will bring us lots of clouds. I am concerned that if we---or areas southwest of us---get into some sunshine, somehow, on Sunday...there would be enough instability and more than enough shear for severe thunderstorms. The Storm prediction Center has that risk over southern Illinois: http://www.spc.noaa.gov/products/exper/day4-8/ That could spread farther north if the European model has its way. But, it's way too early to tell, and quite frankly, forecasting a late-November severe weather event for our area is about as easy as carving a Thanksgiving turkey blindfolded...while standing on a high-wire rope during a windy day. So for now, I just went for thunderstorms on Sunday...and will keep watching the trends. http://weather.admin.niu.edu/forecast.txt Link to comment Share on other sites More sharing options...
Hoosier Posted November 13, 2013 Author Share Posted November 13, 2013 One thing that really gets my attention is if the 12z Euro verbatim slows even by just 6 hrs, then you have something like the following occurring around peak heating for MO/IL and perhaps the D5 area (which with given the forecast temps and dewpoints probably means around 1000-2000 J/kg of CAPE over at least some of the area). Analysis of COD/wundermaps also shows southerly/backed sfc winds and a very impressive wind profile overall, with winds veering/increasing strongly with height. We're in big trouble if we're talking about CAPE like that. Link to comment Share on other sites More sharing options...
andyhb Posted November 13, 2013 Share Posted November 13, 2013 We're in big trouble if we're talking about CAPE like that. St. Louis forecast high on Sunday is 73˚F with 60-65˚F tds. I'd be interested in seeing the H5/H7 temps on the Euro. Link to comment Share on other sites More sharing options...
Stebo Posted November 13, 2013 Share Posted November 13, 2013 We're in big trouble if we're talking about CAPE like that. 1000 to 1500 J/kg certainly looks possible, especially if you were to modify soundings to the forecast highs by NWS, models are undercutting them by as much as 4 to 7 degrees. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted November 13, 2013 Share Posted November 13, 2013 It will be interesting to see how much that lead wave impacts things on Sunday. Also the GFS is showing LI's of -4 already in IL on Sunday, impressive for this range. Link to comment Share on other sites More sharing options...
RCNYILWX Posted November 13, 2013 Share Posted November 13, 2013 We're in big trouble if we're talking about CAPE like that. 1000 to 1500 J/kg certainly looks possible, especially if you were to modify soundings to the forecast highs by NWS, models are undercutting them by as much as 4 to 7 degrees. Also, all there really needs to be is sufficient 0-3 km CAPE. Gino remarked today at work the similarities to setups in previous cold season tor episodes in the LOT CWA, but then that this one has a much stronger synoptic system. So if things come into line track/timing/mesoscale, ceiling is at least as high as 1/7/08 and 11/22/10. Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2013 Author Share Posted November 14, 2013 One November event that is fairly recent that popped into my head is 11/15/05. Seems like a fair number of similarities to the upcoming setup but I'll have to do more digging. Edit: surface low on 11/15/05 was farther south Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2013 Author Share Posted November 14, 2013 I'm not sure if this is SB/ML/MU CAPE but whatever it is it's pretty impressive for 12z in November. Link to comment Share on other sites More sharing options...
Hoosier Posted November 14, 2013 Author Share Posted November 14, 2013 I'm not sure if this is SB/ML/MU CAPE but whatever it is it's pretty impressive for 12z in November. Looks like the MUCAPE map at COD. Link to comment Share on other sites More sharing options...
hm8 Posted November 14, 2013 Share Posted November 14, 2013 00z GFS is deeper with the first low..and then doesn't end up developing the second one further SW Link to comment Share on other sites More sharing options...
andyhb Posted November 14, 2013 Share Posted November 14, 2013 The system as a whole is less amplified and much more progressive than the 12z/18z runs. The second vort max is less intense and doesn't end up becoming independent of the lead wave. Since the best dynamics are leaving the instability axis behind, this run would likely imply a significantly lessened threat. That said, the GFS has been having run-to-run continuity problems to a significantly greater degree than the Euro with this so we'll see if it holds water when the counterparts come out later. HPC's early model diagnostic discussion tosses this verbatim: ...LONGWAVE TROUGH AMPLIFYING OVER THE WESTERN U.S. AND PLAINS SATURDAY AND SUNDAY... PREFERENCE: 12Z ECMWF/12Z ECENS MEAN BLEND CONFIDENCE: AVERAGE THE MODELS SHOW THE DEVELOPMENT OF A ROBUST LONGWAVE TROUGH OVER THE WESTERN U.S. THIS WEEKEND WHICH WILL BE GRADUALLY IMPACTING THE PLAINS. THE HEIGHT FALLS BY IN LARGE WILL BE DRIVEN BY STRONG REINFORCING SHORTWAVE/JET ENERGY DIGGING ACROSS THE NORTHWEST BY SAT. THE 12Z GEM GLOBAL AND 12Z UKMET ARE SOMEWHAT WEAKER/FASTER WITH THE ENERGY...COMPARED TO THE DEEPER 00Z NAM. THE 00Z GFS AND 12Z ECMWF SPLIT THE DIFF WITH THE LONGWAVE TROUGH DETAILS...BUT THE 00Z GFS APPEARS TOO ROBUST/PROGRESSIVE WITH A LEAD SHORTWAVE IT HAS EJECTING OUT ACROSS THE PLAINS BY SAT NIGHT. CONSEQUENTLY...THE GFS APPEARS TOO STRONG WITH ITS SURFACE LOW DRIVING UP TOWARD THE UPPER MIDWEST SAT NIGHT/SUN. THE 18Z GEFS MEAN AND 12Z ECENS MEAN SUPPORT THE 12Z ECMWF WITH LOW PRESSURE FOCUSED MORE BACK OVER THE PLAINS. WILL FAVOR A BLEND OF THE 12Z ECMWF AND 12Z ECENS MEAN. 18z GFS valid 96 hrs: 00z GFS valid 90 hrs: Link to comment Share on other sites More sharing options...
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