andyhb Posted March 18, 2012 Share Posted March 18, 2012 That updraft path in the Eastern TX Panhandle is similar to the beginning of the April 9th, 1947 event in the area, just wanted to put some historical perspective on that. Obviously not expecting anything like that. Remember that surface wind response to the height falls moving in from the west may still be being underestimated by the models, which would only enhance boundary layer moisture and the already sky-high low level shear. Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 Day 2, 30% hatched, mentions a couple of tornadoes, although I'd tend to disagree if they expect supercells in the types of STI indicators that Tony posted as well as the favorable shear profiles and low level shear I'm seeing on both models: DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT SUN MAR 18 2012 VALID 191200Z - 201200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MO VALLEY AREA SWD/SSWWD TO THE LOWER RIO GRANDE VALLEY... ...SYNOPSIS... HIGHLY AMPLIFIED UPPER FLOW FIELD TO CONTINUE ACROSS THE U.S. THIS PERIOD...AS A VERY LARGE TROUGH MOVES SLOWLY OUT OF THE ROCKIES TOWARD THE GREAT PLAINS. MEANWHILE...A CORRESPONDING DOWNSTREAM RIDGE WILL AFFECT BASICALLY THE ENTIRE ERN U.S. E OF THE MS VALLEY. AT THE SURFACE...HIGH PRESSURE WILL PREVAIL OVER THE ERN AND WRN PORTIONS OF COUNTRY...WHILE A N-S COLD FRONT ASSOCIATED WITH THE ADVANCING TROUGH CROSSES THE PLAINS STATES THROUGH THE PERIOD. THIS FRONT WILL BE THE FOCUS FOR A N-S ZONE OF STORMS EXTENDING FROM THE CANADIAN TO THE MEXICAN BORDER. ...MID MO VALLEY SSWWD TO THE LOWER RIO GRANDE VALLEY... SHOWERS AND STORMS -- AND POSSIBLY ONGOING SEVERE POTENTIAL -- SHOULD EXTEND ACROSS PARTS OF KS/OK/TX AT THE START OF THE PERIOD...WITH WEAKER CONVECTION EXTENDING NNEWD INTO THE MID MO VALLEY REGION. THE ONGOING PRECIPITATION AND CLOUD COVER -- BEING CARRIED CONTINUALLY NNEWD BY THE STRONG SLY/MERIDIONAL FLOW ALOFT -- SHOULD HINDER DESTABILIZATION POTENTIAL...AND THUS LIKEWISE LIMIT ASSOCIATED SEVERE WEATHER POTENTIAL N OF THE SRN PLAINS WHERE LOWER PROBABILITY THREAT FOR HAIL/WIND IS EXPECTED. THE FOCUS FOR GREATER SEVERE POTENTIAL REMAINS FROM ROUGHLY ERN KS/MO SWD -- PARTICULARLY INTO SERN OK/WRN MO AND SWD ACROSS E TX ON THE SERN FRINGE OF ONGOING STORMS. AS AFTERNOON DESTABILIZATION PUSHES MIXED-LAYER CAPE INTO THE 1000 TO 2000 J/KG RANGE ACROSS THIS REGION...STORMS WILL INTENSIFY/REDEVELOP ACROSS THIS AREA THROUGH PEAK HEATING. AS STRONG /60 TO 70 KT/ SWLY FLOW AT MID LEVELS OVERSPREADS THE MOIST/UNSTABLE BOUNDARY LAYER FEATURING SSELY PRE-FRONTAL WINDS...DEVELOPING STORMS WITHIN THE FAVORABLY SHEARED ENVIRONMENT WILL QUICKLY BECOME SEVERE/SUPERCELLULAR...WITH VERY LARGE HAIL AND LOCALLY DAMAGING WINDS POSSIBLE. A COUPLE OF TORNADOES MAY ALSO OCCUR -- GIVEN AMPLE LOW-LEVEL SHEAR AND THE MOIST BOUNDARY LAYER FORECAST IN THIS REGION. OVERNIGHT...INCREASINGLY LINEAR ORGANIZATION OF THE CONVECTION IS EXPECTED ALONG THE SLOWLY ADVANCING FRONT. WHILE SEVERE THREAT CONTINUES INTO THE OVERNIGHT HOURS...THREAT FOR HEAVY RAIN SHOULD ALSO INCREASE GIVEN OVERALL SLOW MOVEMENT OF THE CONVECTIVE BAND AND POTENTIAL FOR TRAINING CONVECTION. ..GOSS.. 03/18/2012 Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 18, 2012 Share Posted March 18, 2012 00Z ECMWF still initiates quite a bit of dryline activity as early as mid afternoon. Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 00Z ECMWF still initiates quite a bit of dryline activity as early as mid afternoon. For tomorrow or Monday? Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 18, 2012 Share Posted March 18, 2012 For tomorrow or Monday? Tomorrow. Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 Tomorrow. Thanks. Link to comment Share on other sites More sharing options...
ZackH Posted March 18, 2012 Share Posted March 18, 2012 Sorry about the misunderstanding. I latched onto your statement "I hope we see something surprising" and should have read the rest of your post more carefully. Our thoughts probably aren't too far apart... I'm just a touch more bullish for now. Its okay man... I can see how that statement could have been misconstrued. I was referring to us chasing mainly... that I hope we see something surprising. No probs here, I just wanted to make it clear that tornadoes, even a couple strong tornadoes would not be surprising to me at all tomorrow. And for the record, I too am scratching my head at the Day 1. Will be interested to see what different forecasters say in the morning. Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 I think it is liable to say that if we do get that cap broken sufficiently, we are likely to have a powder keg waiting to go off underneath it. Link to comment Share on other sites More sharing options...
ZackH Posted March 18, 2012 Share Posted March 18, 2012 The only thing that stil concerns me is the upper level wind profile... BUT this is a pretty easy thing to overcome with all of the other ingredients in place. Just we could get that great directional shear all the way up in a consistent area. Link to comment Share on other sites More sharing options...
brettjrob Posted March 18, 2012 Share Posted March 18, 2012 00Z ECMWF still initiates quite a bit of dryline activity as early as mid afternoon. If you have AWIPS access right now, I'd be curious to know its SBCAPE output along and ahead of the dryline. Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 The only thing that stil concerns me is the upper level wind profile... BUT this is a pretty easy thing to overcome with all of the other ingredients in place. Just we could get that great directional shear all the way up in a consistent area. As Tony mentioned, the veering in the upper levels is pretty marginal at best, at most around 10-15 degrees, which really shouldn't have much influence at all in terms of storm mode, I honestly think the only things we really have to worry about right now is the cap, and perhaps a few minor LCL issues, but if the soundings on the NAM verify like Tony said, we have a big problem on our hands, as both of those issues would likely be resolved at the same time. That sounding at Woodward he posted is nuts in terms of the lack of an inversion. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 18, 2012 Share Posted March 18, 2012 If you have AWIPS access right now, I'd be curious to know its SBCAPE output along and ahead of the dryline. I would help you out, but I am just online at home. Link to comment Share on other sites More sharing options...
tornadotony Posted March 18, 2012 Author Share Posted March 18, 2012 NSSL's WRF paints a major cell with extremely intense updraft helicity forming in the the NE TX panhandle around 00z and moving NNE across the ern OK panhandle and into srn KS. Impressive output for this model. http://www.nssl.noaa.gov/wrf/ Link to comment Share on other sites More sharing options...
tornadotony Posted March 18, 2012 Author Share Posted March 18, 2012 I think a hatched tor would have been more than acceptable given the incredible low level shear and near dry adiabatic lapse rates through such a deep layer. Coverage wise, at least in my opinion, seems to be the bigger question. I would agree with this. 10% hatched would have been a far superior forecast, IMO, than the current one. It may be a one big-dog night tomorrow night. Link to comment Share on other sites More sharing options...
brettjrob Posted March 18, 2012 Share Posted March 18, 2012 FWIW at this range (likely not a whole lot): Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 WRF-NMM pops a bunch of discrete convection in the butter zone between 00 and 06z. Link to comment Share on other sites More sharing options...
Srain Posted March 18, 2012 Share Posted March 18, 2012 I sense a special sounding from CLL coming for Monday with the current setup... Link to comment Share on other sites More sharing options...
brettjrob Posted March 18, 2012 Share Posted March 18, 2012 I promise I'm done model spamming until the morning after this, but the 5km WRF run on WxCaster.net suggests several discrete supercells from about DDC to LTS during the 21-03z timeframe. http://www.wxcaster.com/wrfcentralnojava.htm Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 Day 3, Tuesday looks like it wants to join the party too, although I find it funny how the wording is stronger than either tomorrow's or Monday's threat: DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0229 AM CDT SUN MAR 18 2012 VALID 201200Z - 211200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF AR SWD INTO COASTAL SERN TX/SRN LA... ..SYNOPSIS AS THE LARGE UPPER TROUGH MOVING OUT OF THE ROCKIES CONTINUES A SLOW ADVANCE THIS PERIOD...EVOLUTION OF THE SYSTEM INTO A CLOSED LOW IS FORECAST...WITH THE LOW EXPECTED TO RESIDE OVER ERN PORTIONS OF THE SRN PLAINS BY THE END OF THE PERIOD. ELSEWHERE...RIDGING IS FORECAST TO PREVAIL OVER BOTH THE ERN U.S. AND ALSO THE SOUTHWEST...TO THE S OF FAST WSWLY FLOW EXPECTED OVER THE NWRN CORNER OF THE CONUS. AT THE SURFACE...SLOW EWD ADVANCE OF THE FRONT ASSOCIATED WITH THE UPPER TROUGH WILL CONTINUE THROUGH THE FIRST HALF OF THE PERIOD...BUT EVENTUAL UPPER LOW DEVELOPMENT OVER TX/OK MAY DRIVE FRONTAL CYCLOGENESIS INVOF OK. DEPENDING UPON THE STRENGTH OF THIS LOW DEVELOPMENT...SOME WWD RETREAT OF THE FRONT IN A WARM-FRONTAL FASHION MAY OCCUR N OF THE LOW...WHILE SLOW EWD ADVANCE OF A COLD FRONT TOWARD THE LOWER MS VALLEY WOULD CONTINUE S OF THIS FEATURE. ..MID AND UPPER TX COAST EWD ACROSS SRN LA AND NWD INTO AR WIDESPREAD SHOWERS AND THUNDERSTORMS WILL BE ONGOING ALONG THE WRN FRINGE OF THE OUTLOOK AREA AT THE START OF THE PERIOD...AHEAD OF THE ADVANCING COLD FRONT. ONGOING SEVERE THREAT SHOULD RAMP UP THROUGH THE AFTERNOON FROM ROUGHLY THE OZARKS SWD TO THE SERN TX/SRN LA GULF COASTS...AS LIMITED HEATING OF THE VERY MOIST GULF AIRMASS RESULTS IN AIRMASS DESTABILIZATION. ONCE AGAIN...THE NRN EXTENT OF THE SEVERE THREAT SHOULD AGAIN BE LIMITED DUE TO WIDESPREAD PRECIPITATION/CLOUD COVER AND THUS MODEST INSTABILITY. HOWEVER...FARTHER S...SERN TX AND LA IN PARTICULAR MAY EXPERIENCE MORE WIDESPREAD/HIGHER END SEVERE POTENTIAL -- INCLUDING THE POSSIBILITY OF TORNADOES GIVEN THE VERY MOIST BOUNDARY LAYER AND FAVORABLY STRONG LOW-LEVEL SHEAR. CONVECTION SHOULD SHIFT SLOWLY ACROSS LA THROUGH THE SECOND HALF OF THE PERIOD...WITH SEVERE THREAT LIKELY TO CONTINUE THROUGH THE OVERNIGHT HOURS. ..GOSS.. 03/18/2012 Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 I promise I'm done model spamming until the morning after this, but the 5km WRF run on WxCaster.net suggests several discrete supercells from about DDC to LTS during the 21-03z timeframe. http://www.wxcaster....ntralnojava.htm Good lord... It initiates a second round after that as well, btw. Uh oh: Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 Repost from the Texas/LA general/obs. thread: There are some ugly looking parameters Monday evening/overnight and early Tuesday morning across Southern/Central TX on the southern end of the line and ahead of it, which on the 06z NAM's composite reflectivity, looks to have semi-discrete/discrete convection. This includes many of the major metros along the I-10 and I-35 corridors, basically in an area south of a line from Brownwood to Lufkin. All of this area is located within the current 30%/hatched area on the Day 2, except for the immediate Gulf Coast. I mean look at this hodograph for Corpus Christi at 3:00 in the morning on Tuesday (and they only get worse further NE). This is the result of a secondary, 40-70 kt LLJ developing as the upper level low closes off and the surface low developing in southern TX strongly backs the surface winds. Even if the discrete convection doesn't manage to form, I can see the line being full of embedded supercells and LEWPs given the LL shear in place. Keep in mind there is still plenty of boundary layer moisture and instability into Monday overnight/Tuesday morning, and the cap is gone. GFS coming in with some positively monster hodographs (even bigger than the NAM) in this area around the same time frame as the NAM, with H5 shear vectors oriented WSW/SW. This is certainly something to watch as it includes some very highly populated areas. Link to comment Share on other sites More sharing options...
andyhb Posted March 18, 2012 Share Posted March 18, 2012 Note the intensity of the sfc cyclogenesis, this will be key in terms of getting better heights falls later on, it's already a lot stronger than the 06z NAM progged it to be at this time: Link to comment Share on other sites More sharing options...
OceanStWx Posted March 18, 2012 Share Posted March 18, 2012 This is 06z west of Woodward. To have that little of an inversion progged at 06z on the plains is ABSURD! Good Lord, if this verifies... To your point, the 18/00z NAM maintains 50-100 J/kg of 0-3 km CAPE from around Dodge City to Miami through 06z tonight. There is plenty of potential left in the boundary layer after dark. Link to comment Share on other sites More sharing options...
OceanStWx Posted March 18, 2012 Share Posted March 18, 2012 Not a bad morning sounding from AMA. A lot of cloud debris over the eastern Texas panhandle, but it is beginning to slowly push east now. Link to comment Share on other sites More sharing options...
brettjrob Posted March 18, 2012 Share Posted March 18, 2012 If the departure of those morning clouds is timed correctly, it could serve to keep a "lid" on the boundary layer and reduce the time over which moisture tries to mix out this afternoon. With the RUC indicating widespread temperatures in the lower 80s by late afternoon, I'd definitely sacrifice several degrees T in order to save a couple degrees Td. By far, the most concerning trend on the modeling this morning for chasers is the lack of any storms/precip signals lasting more than a couple hours on the RUC and HRRR. It seems the upper system might be a touch slower than expected last night, which may (or may not) have significant implications. The environment should be there, with the RUC showing widespread 0-1 km EHI values of 5-8 by 00z along and 2-3 counties east of the dryline. Tough day; if there's going to be only one isolated beast, I see little signal along the entire CDS-DDC corridor that favors one area over another, right now. Link to comment Share on other sites More sharing options...
OceanStWx Posted March 18, 2012 Share Posted March 18, 2012 If the departure of those morning clouds is timed correctly, it could serve to keep a "lid" on the boundary layer and reduce the time over which moisture tries to mix out this afternoon. With the RUC indicating widespread temperatures in the lower 80s by late afternoon, I'd definitely sacrifice several degrees T in order to save a couple degrees Td. By far, the most concerning trend on the modeling this morning for chasers is the lack of any storms/precip signals lasting more than a couple hours on the RUC and HRRR. It seems the upper system might be a touch slower than expected last night, which may (or may not) have significant implications. The environment should be there, with the RUC showing widespread 0-1 km EHI values of 5-8 by 00z along and 2-3 counties east of the dryline. Tough day; if there's going to be only one isolated beast, I see little signal along the entire CDS-DDC corridor that favors one area over another, right now. I was thinking this as well, a way to artificially lower LCLs without increasing the moisture per se. However, as you noted this will probably require more forcing to break the cap, and probably why hi-res models are struggling to maintain precip. Link to comment Share on other sites More sharing options...
OceanStWx Posted March 18, 2012 Share Posted March 18, 2012 Modifying that AMA sounding for an 80 degree high and dewpoints nearing 60 (as they should to the east) yields about 4500 J/kg. Link to comment Share on other sites More sharing options...
OceanStWx Posted March 18, 2012 Share Posted March 18, 2012 Even 75/60 is about 3900 CAPE, but also -40 CIN. Link to comment Share on other sites More sharing options...
Superstorm93 Posted March 18, 2012 Share Posted March 18, 2012 SBCAPE near 3700j/kg SBCIN Link to comment Share on other sites More sharing options...
OceanStWx Posted March 18, 2012 Share Posted March 18, 2012 13z HRRR showing a little more in the way of convection around KCDS, we'll see if it becomes a trend over the next couple of runs. Link to comment Share on other sites More sharing options...
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