brettjrob Posted March 10, 2012 Share Posted March 10, 2012 Looks like an overall trend toward the slower progression with today's 12z suite... most notably on the op GFS. The op ECMWF essentially keeps the mean trough axis around 115-120 W for several days while really pumping the ern ridge back into the Midwest, creating a somewhat blocky look. By D+10, there's a monster closed low in the Mojave Desert that could spell trouble for the High Plains as it begins to progress. That said, a fair number of GEFS members still want to progress the first trough with the potential for an event Sat-Sun. Link to comment Share on other sites More sharing options...
Amped Posted March 10, 2012 Share Posted March 10, 2012 Does look like stormyness day 9-10 for the West. Probably rain down to SOCal and a severe outbreak in CO-NB. Link to comment Share on other sites More sharing options...
andyhb Posted March 10, 2012 Share Posted March 10, 2012 Looks like an overall trend toward the slower progression with today's 12z suite... most notably on the op GFS. The op ECMWF essentially keeps the mean trough axis around 115-120 W for several days while really pumping the ern ridge back into the Midwest, creating a somewhat blocky look. By D+10, there's a monster closed low in the Mojave Desert that could spell trouble for the High Plains as it begins to progress. That said, a fair number of GEFS members still want to progress the first trough with the potential for an event Sat-Sun. 12z GFS ensemble mean is virtually identical to the 00z run. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 10, 2012 Author Share Posted March 10, 2012 Looks like an overall trend toward the slower progression with today's 12z suite... most notably on the op GFS. The op ECMWF essentially keeps the mean trough axis around 115-120 W for several days while really pumping the ern ridge back into the Midwest, creating a somewhat blocky look. By D+10, there's a monster closed low in the Mojave Desert that could spell trouble for the High Plains as it begins to progress. That said, a fair number of GEFS members still want to progress the first trough with the potential for an event Sat-Sun. Well given the ECMWF and the complete change to a slower trend on the op GFS (which had been the fastest solution to begin with even among its ensembles), it is seems safe to suggest a deep longwave trough with an equatorward oriented jet like this will more than likely dig relatively far S. Slow and south seems more likely, but even the ECMWF op seems rather extreme. It does seem the forecast evolution of the longwave will be somewhat dependent upon low amplitude cyclones along the cyclonic side of the jet axis over the NE Pacific, when and how much they bomb out, and the ensuing cold air advective patterns they incite (i.e., how equatorward oriented is the CAA and the ensuing upper height falls). While the ECMWF seems to favor only one of those cyclones through day 6 deepening significantly off the NW US coast, GFS/CMC suggest the potential for multiple smaller scale perturbations off the NW US coast. For now won't buy any solution as small scale perturbations long the jet won't be resolved or modeled well at this juncture. Slow seems the way to go though. Link to comment Share on other sites More sharing options...
andyhb Posted March 10, 2012 Share Posted March 10, 2012 Talking more immediately, I think there is definitely some potential tomorrow in LA northward through the Ozarks if some of the progged dewpoint readings I'm seeing verify. DAY 2 CONVECTIVE OUTLOOKNWS STORM PREDICTION CENTER NORMAN OK 1121 AM CST SAT MAR 10 2012 VALID 111200Z - 121200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE ARKLATEX INTO THE OZARKS... ...SYNOPSIS... AN UPPER LOW WILL EJECT NEWD ACROSS THE SRN AND CNTRL PLAINS INTO THE MID TO UPPER MS VALLEY THROUGH THE PERIOD. MID TO UPPER LEVEL WIND FIELDS WILL INCREASE OVER MUCH OF THE REGION WITH THE ENTRANCE REGION OF THE UPPER JET MOVING ACROSS AR AND MO DURING THE AFTERNOON AND EVENING. AT THE SURFACE...PRESSURES WILL FALL BUT A CONSOLIDATED SURFACE LOW IS NOT FORECAST TO DEVELOP. NEITHER WILL THERE BE A STRONG COLD FRONT...BUT SUBTLE CONFLUENCE WILL EXIST ACROSS THE ENTIRE WARM SECTOR. BROAD SWLY 850 MB FLOW ON THE ORDER OF 40-50 KT WILL HELP BRING MOISTURE RAPIDLY NWD WITH BOUNDARY LAYER DEWPOINTS INTO THE LOWER 60S INTO CNTRL AR BY AFTERNOON. ...ARKLATEX INTO THE OZARKS... WIDESPREAD RAIN AND EMBEDDED THUNDERSTORMS WILL BE ONGOING OVER MUCH OF ERN TX...OK...KS...SWRN MO AND WRN AR SUN MORNING AS MOISTURE STREAMS NWD IN THE WARM CONVEYOR. AS THE UPPER TROUGH AND ASSOCIATED HEIGHT FALLS DEVELOP NEWD...THE WRN EDGE OF THE EARLY ACTIVITY SHOULD SHARPEN AND CONSOLIDATE INTO AN ORGANIZED BAND OF THUNDERSTORMS...WITH INCREASING INTENSITY WITH TIME....BEGINNING OVER FAR ERN OK AND NERN TX. SHEAR PROFILES WILL STRENGTHEN OVER AR WITH THE LOW LEVEL JET EXCEEDING 50 KT BY 00Z. FORECAST HODOGRAPHS ARE LARGE AND SMOOTH IN THE LOW LEVELS AND WOULD BE FAVORABLE FOR TORNADIC SUPERCELLS. MAIN MITIGATING FACTORS TO A MORE SUBSTANTIAL THREAT ARE SUBTLE WARM SECTOR FORCING...ONGOING AREAS OF RAIN AND SOMEWHAT MARGINAL LEVELS OF INSTABILITY...AT LEAST FOR STRONG TORNADOES. WITH NO CAPPING ACROSS THE WARM SECTOR AND INCREASING DEWPOINTS BY AFTERNOON...SW-NE ORIENTED BANDS OF DEEP CONVECTION MAY ALSO FORM AHEAD OF THE MAIN LINE OF STORMS. SINCE THE MODELS ARE IN VERY GOOD AGREEMENT WITH THE LOCATION OF THE BEST INSTABILITY AND SHEAR...HAVE ADDED A SMALL 30 PERCENT AREA ACROSS CNTRL AR. IN ADDITION TO TORNADOES...DAMAGING WINDS WITH SMALL BOWING LINE SEGMENTS ALSO APPEAR LIKELY. ..JEWELL.. 03/10/2012 Timmer is going to be out tomorrow trying to make up for his running out of gas mistake on 3/2 I'm not sure with the subtle warm sector forcing being a mitigating factor point, given the fact that there will likely be little capping, that may actually increase the risk for discrete convection. Link to comment Share on other sites More sharing options...
JoMo Posted March 10, 2012 Share Posted March 10, 2012 Talking more immediately, I think there is definitely some potential tomorrow in LA northward through the Ozarks if some of the progged dewpoint readings I'm seeing verify. Timmer is going to be out tomorrow trying to make up for his running out of gas mistake on 3/2 I'm not sure with the subtle warm sector forcing being a mitigating factor point, given the fact that there will likely be little capping, that may actually increase the risk for discrete convection. I don't think it'll make it all the way up this way, but Arkansas may have some problems. Or, there may just be a lot of crapvection throughout the day. Link to comment Share on other sites More sharing options...
andyhb Posted March 10, 2012 Share Posted March 10, 2012 Right now with the 8+ day threat on 18z GFS, it appears the resolution change is doing a number on how it wants to translate the upper level/mid level energy associated with the trough, considering it looks a bit unrealistically different in terms of trough setup between 192 and 204 hrs. Basically, it looks very broad based at 192 and then all of the sudden it is very sharp and amplified at 204. The way the upper jet digs on the West Coast in the 168-192 hr period and the way the trough forms from 204 on doesn't really make a lot of sense. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 11, 2012 Author Share Posted March 11, 2012 Right now with the 8+ day threat on 18z GFS, it appears the resolution change is doing a number on how it wants to translate the upper level/mid level energy associated with the trough, considering it looks a bit unrealistically different in terms of trough setup between 192 and 204 hrs. Basically, it looks very broad based at 192 and then all of the sudden it is very sharp and amplified at 204. The way the upper jet digs on the West Coast in the 168-192 hr period and the way the trough forms from 204 on doesn't really make a lot of sense. GFS/GEFS has definitely backed off its early ejection scenario...which makes sense given the pattern. It now looks much more similar to the EC even though they develop the trough in a much different manner. Both essentially develop a deep 4 corners semi-cutoff upper low which is more or less kicked out into the plains. This scenario would be a potential fireworks show...and for those looking for severe, this would likely support much more vigorous severe DMC than a slow moving positive/neutral tilt trough like some earlier GEFS runs were doing. Right now we are back to day 9+ again. Link to comment Share on other sites More sharing options...
andyhb Posted March 11, 2012 Share Posted March 11, 2012 00z GFS would be a scary verbatim for the Plains eastward into the Mid MS Valley, and then the GL/OV gets pummelled the next day...wow... Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 11, 2012 Author Share Posted March 11, 2012 This is going to be an incredible torch. Not even discussing the severe scenario, which keeps getting pushed back a day with each passing day it seems, dewpoints in the mid 60s across MN in March? Crazy. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 11, 2012 Author Share Posted March 11, 2012 ECMWF digs the upper trough through northern Mexico and has what would likely be a slow moving 546 dm 500 hpa bowling ball across Texas. Bizarre. Link to comment Share on other sites More sharing options...
andyhb Posted March 11, 2012 Share Posted March 11, 2012 00z GFS OP is quite a bit of a western outlier on the ensembles at 192 (and man, you know its a torch when you see the 576 line in Ontario in March on an ensemble mean): Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 11, 2012 Share Posted March 11, 2012 ECMWF digs the upper trough through northern Mexico and has what would likely be a slow moving 546 dm 500 hpa bowling ball across Texas. Bizarre. Block-ish at the end of the run. Nice 582dm+ ridge over Ontario. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 11, 2012 Author Share Posted March 11, 2012 Block-ish at the end of the run. Nice 582dm+ ridge over Ontario. Yeah huge block, ECMWF completely closes the upper high. Feels like July/August 2011 all over. Bringing back bad memories of the 600 dm subtropical death ridge. That said, a weird setup. Not even sure that the 0Z ECMWF scenario verbatim would be much of any sig severe. Link to comment Share on other sites More sharing options...
Stebo Posted March 11, 2012 Share Posted March 11, 2012 Yeah huge block, ECMWF completely closes the upper high. Feels like July/August 2011 all over. Bringing back bad memories of the 600 dm subtropical death ridge. That said, a weird setup. Not even sure that the 0Z ECMWF scenario verbatim would be much of any sig severe. Yeah that would be an extremely unusual pattern, not saying it isn't possible but the Euro does have its bias of closing off systems in the SW, which could be the case here. Of course that being said it is a 8-10 day model projection which will change with time, so it would be silly to nitpick right now. Link to comment Share on other sites More sharing options...
brettjrob Posted March 11, 2012 Share Posted March 11, 2012 The trend toward uber-blockiness is definitely a concern for severe potential. That said, while I don't have access to the precip maps or CAPE/CIN, I thought that D+9 (00z Tue Mar 20) on the op Euro looked like a potential event for the High Plains. It's right on the verge of being too meridional for anything big, but with the strong surface low and backed H85 flow, I wouldn't rule it out. With low-mid 60s dew points progged to be available east of the dryline all the way to or past 100 W this early in the spring, I feel it would take a lot going wrong (most likely the trough never fully ejecting in one piece) to avoid sig svr. Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 11, 2012 Share Posted March 11, 2012 Yeah that would be an extremely unusual pattern, not saying it isn't possible but the Euro does have its bias of closing off systems in the SW, which could be the case here. Several GFS ENS members have something at least somewhat similar. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 11, 2012 Author Share Posted March 11, 2012 Personally, I hate dewpoints greater than 55 degrees. Perfect time for me to be heading to Oklahoma today. Seeing dews in the mid to upper 60s for later in the week disgusts me. Link to comment Share on other sites More sharing options...
andyhb Posted March 11, 2012 Share Posted March 11, 2012 Talk about high octane for March... Even with the Euro's exceedingly strange solution, I'd have to think there would be potential in TX with that bowling ball UL low, although we may start running into problems that come with vertically stacked/closed upper systems. Link to comment Share on other sites More sharing options...
Stebo Posted March 11, 2012 Share Posted March 11, 2012 Several GFS ENS members have something at least somewhat similar. Yeah I see that some do, the thing is once again it is a 8-10 day forecast so a lot of things can and probably will change between now and then. I am not denouncing the solution as being impossible but I think it is one of many possible outcomes. Link to comment Share on other sites More sharing options...
andyhb Posted March 11, 2012 Share Posted March 11, 2012 12z GFS puts the North Central CONUS on the weekend in the crosshairs with a powerful initial wave...talk about a LLJ and large extent of moisture: Link to comment Share on other sites More sharing options...
wxmx Posted March 11, 2012 Share Posted March 11, 2012 ECMWF digs the upper trough through northern Mexico and has what would likely be a slow moving 546 dm 500 hpa bowling ball across Texas. Bizarre. Talking about bizarre... snow in L.A.? Link to comment Share on other sites More sharing options...
andyhb Posted March 11, 2012 Share Posted March 11, 2012 Another thing to watch would be if that lead wave retrogrades the ridge in the East a bit, allowing the less blocking of the later system and allowing more mid/upper level energy to eject eastward, possibly allowing it to eject in one piece. 12z GFS is actually pretty close to merging the two systems at around 150-168 hrs. Link to comment Share on other sites More sharing options...
andyhb Posted March 11, 2012 Share Posted March 11, 2012 18z GFS brings the trough through much more consolidated (the 192+ hr system) The lead wave looks nasty for the regions I mentioned earlier. Huge LLJ, due south/slightly backed sfc winds and upper/mid level support from incoming jet streak to the west. The warm sector is titanic in size in front of both systems. Link to comment Share on other sites More sharing options...
Derek30 Posted March 11, 2012 Share Posted March 11, 2012 Initial wave would give me a slight chance at some elevated convection, at least. Can't believe I'm talking about a threat of convection up here in early-mid March. Quite something. NWS Grand Forks has mentioned the thunder threat in the last few discussions. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted March 12, 2012 Share Posted March 12, 2012 I posted this on the Minnesota Forecaster site, you can goggle it, but please dumb it down, that site is really about grading our local weather forecaster's. There is a huge difference between 700mb temps on the Euro and the GFS, at around the 180-240hr time frame. The GFS has it near °c the Euro around 6 or 7. The Euro basically caps us. Any way this is what I posted there, and I think it's close to being right. Rember that I am based in MN. "As far as severe weather goes. I don't believe the GFS around the 180hr to 216hr, it breaks down the surface ridge way to fast. The Euro is showing it's bias by stalling out the 500mb low over the SW US and taking it's time ejecting it to the NE. I think the proper solution is somewhere in between. The GFS to fast, the Euro to slow. When the Eastern surface ridge starts to break down it will be most notable over the mid to south Mississippi Valley, that will use up most of the Convective Available Potential Energy (CAPE) and we will be left with some rain, but not enough to break our drought. I really thought that we may have a chance at severe Wx around the 17th to 21st, but I getting more and more convinced that will not happen. As a matter of fact I wonder if we will get much precip at all." Link to comment Share on other sites More sharing options...
andyhb Posted March 12, 2012 Share Posted March 12, 2012 I posted this on the Minnesota Forecaster site, you can goggle it, but please dumb it down, that site is really about grading our local weather forecaster's. There is a huge difference between 700mb temps on the Euro and the GFS, at around the 180-240hr time frame. The GFS has it near °c the Euro around 6 or 7. The Euro basically caps us. Any way this is what I posted there, and I think it's close to being right. Rember that I am based in MN. "As far as severe weather goes. I don't believe the GFS around the 180hr to 216hr, it breaks down the surface ridge way to fast. The Euro is showing it's bias by stalling out the 500mb low over the SW US and taking it's time ejecting it to the NE. I think the proper solution is somewhere in between. The GFS to fast, the Euro to slow. When the Eastern surface ridge starts to break down it will be most notable over the mid to south Mississippi Valley, that will use up most of the Convective Available Potential Energy (CAPE) and we will be left with some rain, but not enough to break our drought. I really thought that we may have a chance at severe Wx around the 17th to 21st, but I getting more and more convinced that will not happen. As a matter of fact I wonder if we will get much precip at all." The bigger severe threat for your area may end up being around 138-168 hrs, with the lead wave... Except that this is, as you mentioned, 180-216 hrs out, I agree that the main svr threat with the second system is probably farther south. Link to comment Share on other sites More sharing options...
Minnesota Meso Posted March 12, 2012 Share Posted March 12, 2012 The bigger severe threat for your area may end up being around 138-168 hrs, with the lead wave... Except that this is, as you mentioned, 180-216 hrs out, I agree that the main svr threat with the second system is probably farther south. 138- 168 I'm not buying it , the GFS is showing low K index values. Link to comment Share on other sites More sharing options...
andyhb Posted March 12, 2012 Share Posted March 12, 2012 138- 168 I'm not buying it , the GFS is showing low K index values. Ignoring K-Index values, there's 750+ J/kg CAPE into Central Minnesota, keep in mind this is 144 hrs out on a model that commonly underdoes surface temperatures and therefore instability. Here, check this little write up on stability indicators. http://weather.cod.edu/sirvatka/si.html Link to comment Share on other sites More sharing options...
Chinook Posted March 13, 2012 Share Posted March 13, 2012 Talking about bizarre... snow in L.A.? 168 hours-- Snow in Phoenix, 60 degrees at the Hudson Bay maybe? I'd laugh if either happened. Link to comment Share on other sites More sharing options...
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