Thundersnow12 Posted November 6, 2011 Share Posted November 6, 2011 Link to comment Share on other sites More sharing options...
Amped Posted November 6, 2011 Share Posted November 6, 2011 Big test for the new NAM Link to comment Share on other sites More sharing options...
Jim Martin Posted November 7, 2011 Share Posted November 7, 2011 The CAPE is starting to increase in western north Texas for tomorrow at 21z. Link to comment Share on other sites More sharing options...
tornadotony Posted November 7, 2011 Share Posted November 7, 2011 As I'm going through looking at the setup, I don't know how initial mode isn't going to be supercells with the shear vectors perpendicular to the dryline tomorrow afternoon...and probably supercells for several hours... Link to comment Share on other sites More sharing options...
andyhb Posted November 7, 2011 Share Posted November 7, 2011 As I'm going through looking at the setup, I don't know how initial mode isn't going to be supercells with the shear vectors perpendicular to the dryline tomorrow afternoon...and probably supercells for several hours... Do you think we'll see a MDT risk in the upcoming Day 1? Link to comment Share on other sites More sharing options...
David Reimer Posted November 7, 2011 Author Share Posted November 7, 2011 Do you think we'll see a MDT risk in the upcoming Day 1? In my opinion, if model guidance continues the trend that it has for the past several runs, then we will see a moderate risk issued. The 18Z NAM has over 2,500 Joules of surface based instability tomorrow afternoon across Northwest Texas. That is almost unheard of in these high-shear events. Personally, the last time I remember chasing an event that had this much shear and instability over 2,500 J/Kg was April 24, 2010 out in Mississippi. If the instability values do get as high as some models are suggesting, tomorrow could be a hell of a day. Link to comment Share on other sites More sharing options...
tornadotony Posted November 7, 2011 Share Posted November 7, 2011 This is what I wrote for an AFD for my synoptics class (this is for Wichita Falls). A significant severe weather episode is likely on Monday in the Red River Valley region. Vort max currently over the Great Basin region will continue to advect eastward during the overnight hours and will be moving over the plains by Monday morning. In response, the lee cyclone already evident in NE NM will begin to move eastward. Ahead of the lee cyclone, WAA already occurring in the low-levels will continue, with the current stationary front beginning to lift N as a warm front. As this occurs, sfc dewpoints will rapidly rise across north Texas owing to the large moisture reservoir that has been established to the S. Meanwhile aloft, an EML is evident on the 12z soundings from OUN, AMA, and DFW. In these areas, 700-500-hPa lapse rates are roughly on the order of 7.0°C/km. These lapse rates will likely maintain through the day Monday, allowing for destabilization of the atmosphere as temps rise through the day. The 18z NAM indicates CAPE upwards of 2000J/kg is possible over North Texas tomorrow afternoon. Even more alarmingly, the low-level CAPE progs from the NAM are predicted to be very high, with values potentially exceeding 250-300J/kg. The exact amount of destabilization will depend on how much clearing occurs in the warm sector during the day, as WAA convection will likely be occurring during the morning hours. However, as main zone of isentropic lift moves N along with warm front, I expect to see some clearing during the late morning and early afternoon hours, allowing for sufficient destabilization for significant severe storms. If instability does indeed verify to be sufficient, then the stage will be set for a severe weather outbreak. 0-6km bulk shear will be on the order of 40-50kt, with vectors perpendicular to the dryline that will be established west of Wichita Falls tomorrow afternoon. The approaching shortwave trough will result in large-scale rising motion over the forecast area. The combination of these two factors should lead to the development of several supercell thunderstorms tomorrow afternoon along the dryline. The NAM hints at the formation of a dryline bulge during the afternoon hours, which would serve as the likely initiation point and is something to watch closely. These supercells will likely be quite dangerous. Combination of strong instability (for November) and rather low wet-bulb zero heights (about 3km) will lead to the likelihood of very large hail. Additionally, low-LCLs, strong low-level CAPE, and 0-1km SRH of 200m^2s^-2 would be supportive of tornadoes, a couple of which may be strong. Eventually, activity will grow upscale due to isentropic forcing from the low-level jet as well as the ejection of the main trough onto the plains, causing the formation of a potentially intense QLCS, capable of producing wind damage, isolated tornadoes, and some hail. Link to comment Share on other sites More sharing options...
andyhb Posted November 7, 2011 Share Posted November 7, 2011 In my opinion, if model guidance continues the trend that it has for the past several runs, then we will see a moderate risk issued. The 18Z NAM has over 2,500 Joules of surface based instability tomorrow afternoon across Northwest Texas. That is almost unheard of in these high-shear events. Personally, the last time I remember chasing an event that had this much shear and instability over 2,500 J/Kg was April 24, 2010 out in Mississippi. If the instability values do get as high as some models are suggesting, tomorrow could be a hell of a day. Yeah, blending these types of shear profiles with that much instability almost always equals trouble... Btw, nice analysis on your site, David. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted November 7, 2011 Share Posted November 7, 2011 As I'm going through looking at the setup, I don't know how initial mode isn't going to be supercells with the shear vectors perpendicular to the dryline tomorrow afternoon...and probably supercells for several hours... This. I didn't understand why SPC was questioning mode in the day 2 from this afternoon. Link to comment Share on other sites More sharing options...
tornadotony Posted November 7, 2011 Share Posted November 7, 2011 This. I didn't understand why SPC was questioning mode in the day 2 from this afternoon. I think part of all of it is just the extreme climatological rarity of a setup like this in November. I was going through the Oklahoma archive and the last time I can find a significant tornado event in SW OK in November is 11/17/58. Additionally, the ONLY November tornado on record in OUN's North Texas counties was an F2 on that same date. Needless to say, you don't see this kind of setup every year... Link to comment Share on other sites More sharing options...
scoresman Posted November 7, 2011 Share Posted November 7, 2011 Too bad I couldnt get Monday off to chase instead of Tuesday.... Oh well Link to comment Share on other sites More sharing options...
David Reimer Posted November 7, 2011 Author Share Posted November 7, 2011 I think part of all of it is just the extreme climatological rarity of a setup like this in November. I was going through the Oklahoma archive and the last time I can find a significant tornado event in SW OK in November is 11/17/58. Additionally, the ONLY November tornado on record in OUN's North Texas counties was an F2 on that same date. Needless to say, you don't see this kind of setup every year... Frankly, I can't blame them. I'm still having issues wrapping my mind around tomorrow's setup. i know this is going to sound out there, but I think I'm in 'shock' at how good tomorrow is looking and how uncharacteristic it is for November. I keep thinking there has to be something I'm missing that makes tomorrow look like every other fall setup. I'm concerned with morning precipitation right now, but if that isn't an issue by noon tomorrow, then I'll throw my cards in. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 7, 2011 Share Posted November 7, 2011 3 km Helicity looking good for tomorrow as well. Link to comment Share on other sites More sharing options...
JoMo Posted November 7, 2011 Share Posted November 7, 2011 Gets dark too dang early. Might be able to catch something in SW OK according to the 00z NAM. Everything shifted north a slight bit. Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 7, 2011 Share Posted November 7, 2011 2750 J/KG SB CAPE and 0-1km SRH of 200 on this run. Near Hobart tomorrow evening... Link to comment Share on other sites More sharing options...
andyhb Posted November 7, 2011 Share Posted November 7, 2011 2750 J/KG SB CAPE and 0-1km SRH of 200 on this run. Near Hobart tomorrow evening... Very impressive veering of the winds there... and wow at the SB CAPE reading... Link to comment Share on other sites More sharing options...
Hoosier Posted November 7, 2011 Share Posted November 7, 2011 I think part of all of it is just the extreme climatological rarity of a setup like this in November. I was going through the Oklahoma archive and the last time I can find a significant tornado event in SW OK in November is 11/17/58. Additionally, the ONLY November tornado on record in OUN's North Texas counties was an F2 on that same date. Needless to say, you don't see this kind of setup every year... Yeah I just went through the database too and I found the same thing. That is pretty amazing. Link to comment Share on other sites More sharing options...
brettjrob Posted November 7, 2011 Share Posted November 7, 2011 Here's a closer look at that HBR sounding, featuring a truly classic Plains tornado hodo. At this point, I think it basically comes down to early convection or lack thereof. At the end of its cycle, the latest HRRR shows a nasty line approaching the area of concern around 14-16z. Will there be time for recovery if that happens? Will other precipitation persist into the afternoon? If we can get cleared out by 12-1pm, it does look as though the tornado potential is fairly substantial. Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 7, 2011 Share Posted November 7, 2011 2750 J/KG SB CAPE and 0-1km SRH of 200 on this run. Near Hobart tomorrow evening... I take a bigger part of Oklahoma seems to be at play, as compared to the previous 0Z and the 12Z NAM. Link to comment Share on other sites More sharing options...
JoMo Posted November 7, 2011 Share Posted November 7, 2011 21z SREF (h24) for 21z tomorrow Link to comment Share on other sites More sharing options...
Thundersnow12 Posted November 7, 2011 Share Posted November 7, 2011 love the way the sfc winds respond to the p-falls in southwest OK and REALLY back and they are strong too..15-20kts. sfc low on this run right over CDS at 0z with a bit of a DL bulge just northeast of there. Link to comment Share on other sites More sharing options...
Chicago Storm Posted November 7, 2011 Share Posted November 7, 2011 Link to comment Share on other sites More sharing options...
Thundersnow12 Posted November 7, 2011 Share Posted November 7, 2011 beat me to it lol Link to comment Share on other sites More sharing options...
tornadotony Posted November 7, 2011 Share Posted November 7, 2011 Impressive suite of 00z model runs. I'm dubious of the HRRR. In my experience, it tends to blow a lot of things out of proportion by overestimating the effects of a certain amount of forcing. I don't know what the forcing for the nasty line from 14z to 16z would be. Overall, I almost think you have to go moderate risk at this point if you're issuing a forecast. All of the trends are for a pretty significant event to transpire over N TX and wrn OK. The biggest question to me right now is regarding how far N the biggest threat gets. I'm not sure I buy it getting to I-40, but if it does, it adds a lot of towns into the threat region. Link to comment Share on other sites More sharing options...
andyhb Posted November 7, 2011 Share Posted November 7, 2011 I'm dubious of the HRRR. In my experience, it tends to blow a lot of things out of proportion by overestimating the effects of a certain amount of forcing. I don't know what the forcing for the nasty line from 14z to 16z would be. Really one of the only times I've seen it even close to spot-on was the April 27th outbreak, which a lot of people could see the potential far before the runs ever came out for that afternoon (And it was kind of hard to overestimate the dynamics for that one). Link to comment Share on other sites More sharing options...
thewxmann Posted November 7, 2011 Share Posted November 7, 2011 A few previous NAM runs have hinted at morning convection stabilizing things across ctrl TX, so I wouldn't discount the HRRR just yet. Now whether that will affect how things evolve invof the Red River later in the day, that remains to be seen. Link to comment Share on other sites More sharing options...
tornadotony Posted November 7, 2011 Share Posted November 7, 2011 A few previous NAM runs have hinted at morning convection stabilizing things across ctrl TX, so I wouldn't discount the HRRR just yet. Now whether that will affect how things evolve invof the Red River later in the day, that remains to be seen. ? Tonight's run looks very similar to the last several runs of the NAM... Link to comment Share on other sites More sharing options...
andyhb Posted November 7, 2011 Share Posted November 7, 2011 wxmann trolling fwiw, the main threat never really was in Central Texas. Link to comment Share on other sites More sharing options...
thewxmann Posted November 7, 2011 Share Posted November 7, 2011 ? Tonight's run looks very similar to the last several runs of the NAM... I haven't looked at the current run of the NAM, but a few prior runs did hint at some convective-related stabilization across ctrl TX. I just mentioned it as a reason not to completely discount the HRRR just yet, so no I am not trolling. Link to comment Share on other sites More sharing options...
SmokeEater Posted November 7, 2011 Share Posted November 7, 2011 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1159 PM CST SUN NOV 06 2011 VALID 071200Z - 081200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SRN AND CNTRL PLAINS... ..SRN AND CNTRL PLAINS A VIGOROUS UPPER-LEVEL TROUGH WILL MOVE EWD INTO THE FOUR CORNERS REGION TODAY AS A 60 TO 75 KT MID-LEVEL JET EJECTS NEWD INTO THE SRN AND CNTRL PLAINS. AHEAD OF THE APPROACHING UPPER-LEVEL SYSTEM...MOISTURE ADVECTION WILL INCREASE MARKEDLY AS A PRONOUNCED LOW-LEVEL JET STRENGTHENS. SCATTERED THUNDERSTORMS SHOULD BE ONGOING ON THE NOSE OF THE LOW-LEVEL JET THIS MORNING WHERE A THREAT FOR HAIL LIKELY EXISTING IN THE ERN TX PANHANDLE...NORTHWEST TX AND SW OK. AS THE UPPER-LEVEL TROUGH APPROACHES THE SRN PLAINS THIS AFTERNOON...CONDITIONS SHOULD BE IN PLACE FOR A SEVERE WEATHER EVENT ACROSS WRN OK AND NW TX. AS THE MORNING CONVECTION MOVES EWD LATE THIS MORNING...THE STRONGEST SFC HEATING SHOULD TAKE PLACE IN ITS WAKE ON THE WRN SIDE OF THE LOW-LEVEL JET FROM WRN OK SSWWD INTO THE LOW-ROLLING PLAINS. FORECAST SOUNDINGS ACROSS THE REGION BY EARLY AFTERNOON SUGGEST AN AXIS OF MODERATE INSTABILITY SHOULD BE IN PLACE WITH MLCAPE VALUES RANGING FROM 1000 TO 1500 J/KG. IN ADDITION...0-6 KM SHEAR VALUES ARE FORECAST TO INCREASE GRADUALLY INTO THE 45 TO 55 KT RANGE AS THE EXIT REGION OF THE MID-LEVEL JET SPREADS NEWD INTO THE SRN PLAINS. THE AMOUNT OF SHEAR ALONG WITH STEEP MID-LEVEL LAPSE RATES SHOULD SUPPORT THE DEVELOPMENT OF SUPERCELLS WITH LARGE HAIL AS STORMS INCREASE IN COVERAGE THIS AFTERNOON. HAIL GREATER THAN 2 INCHES IN DIAMETER WILL BE POSSIBLE WITH SUPERCELLS THAT ARE LOCATED NEAR THE GREATEST INSTABILITY WITH THE MOST LIKELY LOCATION FOR VERY LARGE HAIL FROM I-40 IN WRN OK SWD INTO NW TX WHERE A HATCHED THREAT FOR HAIL IS INCLUDED. IN ADDITION...0-1 KM SHEAR OF 30-35 KT...STRONGLY CURVED HODOGRAPHS AND LOW LCL HEIGHTS WITH SFC DEWPOINTS IN THE LOW TO MID 60S F SHOULD ALSO SUPPORT TORNADO DEVELOPMENT WITH THE MORE DOMINANT SUPERCELL STORMS. THE ENVIRONMENT MAY ALSO SUPPORT A STRONG TORNADO OR TWO. A SMALL SIGNIFICANT TORNADO THREAT AREA HAS BEEN ADDED FROM NEAR CLINTON OK SWD TO JUST SOUTHWEST OF WICHITA FALLS TX. AS STORM COVERAGE INCREASES DURING THE LATE AFTERNOON...MODEL FORECASTS DEVELOP A SQUALL-LINE EXTENDING FROM FAR SRN KS SSWWD INTO NW TX SUGGESTING A WIND DAMAGE THREAT WILL ALSO EXIST. HOWEVER...THE MAGNITUDE OF THE WIND DAMAGE THREAT REMAINS UNCERTAIN AND WILL BE DEPENDENT UPON IF A NEARLY CONTINUES SQUALL-LINE CAN BECOME WELL-ORGANIZED AND MOVE QUICKLY EWD. THE NAM AND GFS SOLUTIONS DIFFER ON THE LOCATION OF THE LINE THIS EVENING WITH THE GFS FASTER AND MUCH FURTHER EAST. THIS SUGGESTS A SEVERE THREAT MAY CONTINUE EWD INTO ECNTRL OK AND NORTH TX DURING THE OVERNIGHT PERIOD ALTHOUGH WEAKENING INSTABILITY SHOULD RESULT IN A MARGINALIZED THREAT BY LATE EVENING. ..BROYLES.. 11/07/2011 Link to comment Share on other sites More sharing options...
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