YHM Supercell Posted March 2, 2012 Share Posted March 2, 2012 Interesting AFD from KBUF this evening, I am from Hamilton,Ontario which is on the edge of the current slight risk and very close to KBUF's western CWA. SPEAKING OF CONVECTION...THE NAM IS STILL SUGGESTING ELEVATED CAPE VALUES OF 200-500 J/KG DURING THE OVERNIGHT HOURS (ESP. OVER THE WRN COUNTIES) WITH MID LEVEL LAPSE RATES EXCEEDING 8 DEG C/KM AND PLENTY OF SPEED SHEAR (LEADING TO EXTENDED HODOGRAPH). THESE ARE NOT ONLY FAVORABLE PARAMETERS FOR CONVECTION...BUT ARE BASELINE VARIABLES FOR WHAT LOCAL RESEARCH HAS FOUND FOR COLD SEASON DERECHO'S IN OUR REGION. NOT ONLY ARE THESE WIND AND THERMAL PROFILES SOMEWHAT IMPRESSIVE...BUT THE MERE SYNOPTIC FORCING WILL BE STRONG. THIS IN ITSELF IS PROBABLY THE LARGEST CONTRIBUTOR TO THE PROCESS. Link to comment Share on other sites More sharing options...
PatrickSumner Posted March 2, 2012 Share Posted March 2, 2012 NAM going south... Link to comment Share on other sites More sharing options...
andyhb Posted March 2, 2012 Share Posted March 2, 2012 NAM going south... Widespread 0-1 km SRH in excess of 300 m2/s2 by 18z. Link to comment Share on other sites More sharing options...
PatrickSumner Posted March 2, 2012 Share Posted March 2, 2012 Widespread 0-1 km SRH in excess of 300 m2/s2 by 18z. Where??? Link to comment Share on other sites More sharing options...
andyhb Posted March 2, 2012 Share Posted March 2, 2012 Where??? Whoops, that was on 0-3 km, but its 200+ across much of KY southward into N AL and MS. Link to comment Share on other sites More sharing options...
PatrickSumner Posted March 2, 2012 Share Posted March 2, 2012 Whoops, that was on 0-3 km, but its 200+ across much of KY southward into N AL and MS. How about farther north into Southern IN? Link to comment Share on other sites More sharing options...
LouWX Posted March 2, 2012 Share Posted March 2, 2012 Have some concerns that before the warm air intrusion at 700MB caps things off until FROPA there could be some surface rooted storms on the advancing warm front which is right on the nose of the LLJ from along the OH River mid to late morning northward to near I-70 early in the PM. Thoughts? Link to comment Share on other sites More sharing options...
hm8 Posted March 2, 2012 Share Posted March 2, 2012 Pretty impressive radar forecast from the RUC Link to comment Share on other sites More sharing options...
andyhb Posted March 2, 2012 Share Posted March 2, 2012 Worrying and detailed BMX AFD, edited for emphasis: .DISCUSSION...BEGINNING TO WATCH THE 02/00Z NAM MODEL COME INTO OUR SYSTEM. CERTAINLY AT FIRST GLANCE...IT APPEARS TO ONLY WORSEN THE THREAT FOR SEVERE WEATHER TOMORROW AFTERNOON AND EVENING. THE TREND IS COMING IN LINE MORE WITH THE FASTER SOLUTIONS THAT WE HAVE SEEN...FROM GFS...ETC. THE FIRST CELLS COULD BEGIN TO FORM NEAR THE NORTHWESTERN STATE LINE EARLY...AT AROUND 3PM...AS INDICATED BY THE TIMING MAP ON OUR HOMEPAGE...WITH THE LINEAR FEATURE CLOSER TO 9PM OR SO. THERE HAVE BEEN A LOT OF QUESTIONS ABOUT MODE OF CONVECTION...WHICH ARE UNDERSTANDABLE GIVEN THE LOW LEVEL WIND FIELDS. THE NEW NAM COMING IN IS STARTING TO SHOW EVEN MORE EVIDENCE OF THE LOW LEVEL PROFILES BEGINNING TO BACK AROUND OR STAY BACKED WITH TIME...AS THE SURFACE LOW TO THE NORTH RAPIDLY DEEPENS FROM 993 TO 986 MB IN SIX HOURS ACROSS THE OHIO VALLEY. NOT THAT INTUITIVE THIS TIME AROUND CONSIDERING THE MODELS HAVE NOT REALLY SHOWN ANY KIND OF SECONDARY LOW FORMING FURTHER SOUTH ALONG THE FRONT. IF THAT WERE TO HAPPEN THINGS WOULD GO FROM BAD TO WORSE. FOR THE MOST PART...THE MODELS HAVE NOT SHOWN THE LOW LEVEL WINDS TO BE AGEOSTROPHIC...BUT THAT HAS SLOWLY CHANGED WITH TIME AND TRENDS AS THE SURFACE WINDS FROM AROUND 00 TO 06Z HAVE BACKED SLIGHTLY. MESOSCALE FOLKS WILL HAVE TO BE ON THIS TOMORROW...HOT AND HEAVY. MY GOTO PRODUCT FOR THE PAST YEAR OR MORE HAS BEEN THE 0 TO 6 KM BULK SHEAR...NOT ONLY THE MAGNITUDE...BUT THE ANGLE DIRECTION AND ORIENTATION TO THE FRONTAL BOUNDARY. THE NEW RUN HAS THE DIRECTIONAL DIFFERENCE AT ABOUT 25 DEGREES AT 03Z...HOWEVER...IT INCREASES TO 32 DEGREES BY 06Z...MAINLY DUE TO THE INFLUENCE OF THE LOW LEVEL JET NOSING IN AHEAD OF THE FRONT. THE PERFECT ANGLE WOULD BE 45 DEGREES DIFFERENCE...SO WE ARE HEADING THAT WAY ACROSS THE NORTHERN HALF OF THE CWA. ONE SHOULD USE EXTREME CAUTION WHEN THINKING IN TERMS OF SUN GOING DOWN EQUALS LINEAR MODE OF CONVECTION. YES...IT VERY WELL COULD BE LINEAR...BUT WITH THOSE VECTOR DIFFERENCES INCREASING WITH TIME IT IS LIKELY TO BE FULL OF EMBEDDED BOWING SEGMENTS AND SUPERCELLS. WE HAVE TO GET OUT OF THE MINDSET OF SQUALL LINE/QLCS AND START CONTEMPLATING BROKEN SQUALL WITH SUPERS AND BOWS. TO HELP...CONTINUE WATCHING THE BULK SHEAR ORIENTATION. LONG TRACKED STORMS WILL BE A GIVEN THAT THE 0 TO 10 KM BULK SHEAR VALUES ARE OFF THE CHART AT FROM 100 TO 120 KTS. THE FINAL ELEMENT...INSTABILITY...SHOULD NOT BE MUCH OF AN ISSUE. AS TEMPS INCREASE TO NEAR 80 OR ABOVE AND THE DEWPOINTS WELL INTO 60S...TALL AND FAT CAPE PROFILES WILL BE THE NORM. CAPES UP AROUND 2000 J/KG WILL BE LIKELY. THE CONCERN CONTINUES TO CENTER AROUND THE LOW LEVEL CAPE PROFILES WHICH ARE SHORT AND FAT. OLD SCHOOL FOLKS WILL TELL YOU THAT THE LOW LEVEL CAPE PROFILES FROM EITHER 0 TO 1 KM OR MORE LIKE THE 0 TO 3 KM ARE WAY IMPRESSIVE...SO UPDRAFT INTENSITY WILL BE AT A MAX FOR EARLY MARCH. MOST OF MY CONCERN CENTERS FROM AN AREA FROM A LINE ALONG AND NORTHWEST OF LIVINGSTON TO CENTREVILLE TO GADSDEN. THIS WOULD INCLUDE ALL OF THE TCL AND BHM METRO AREAS. NONETHELESS...IF YOU LIVE ANYWHERE IN THE STATE OF ALABAMA...YOU NEED TO TAKE THE MORNING TO PREPARE YOURSELVES FOR LIKELIHOOD OF A SEVERE WEATHER OUTBREAK. GET YOUR PLANS TOGETHER...AND DO WHATEVER NECESSARY TO PROTECT YOUR LIFE AND PROPERTY! 17/KLAWS Link to comment Share on other sites More sharing options...
thewxmann Posted March 2, 2012 Share Posted March 2, 2012 I'm also skeptical that this will end up being a major tornado outbreak. The lead impulse and the associated sfc reflection is traveling too fast... low-lvl winds veer out too quickly. I think QVectorman has a point in that there might be some subsidence in the wake of early morning convection over the SE. The important thing to keep in mind there is that if convective initiation is delayed to 21Z or later, the veering low-level flow would seriously reduce the temporal window for significant tornadoes to occur. Link to comment Share on other sites More sharing options...
Superstorm93 Posted March 2, 2012 Share Posted March 2, 2012 Seems like BMX wants the significant threat moved more south. The new outlook will be very intreresting. Link to comment Share on other sites More sharing options...
ineedsnow Posted March 2, 2012 Share Posted March 2, 2012 Whatever happens down there stay safe you guys Link to comment Share on other sites More sharing options...
it*has*an*i Posted March 2, 2012 Share Posted March 2, 2012 Seems like BMX wants the significant threat moved more south. The new outlook will be very intreresting. The 30%+ Hatched area already extends along the I-20/I-59 areas which the Livingston-Centerville-Gadsden line is on so hopefully that is what the were referring to and it won't need to be moved any further south (I don't want it). Link to comment Share on other sites More sharing options...
Ed Lizard Posted March 2, 2012 Share Posted March 2, 2012 Just reading the SigTor thing from SPC. 2.6 was the mean STP, 75% occur with SigTor at 4.5, and 90% occur at or below 6.7, and the 21Z SREF median is over 6 and 70% of the members are >=5 near the same area. Not all that far from the 0Z NAM max EHI values either at 3 pm CST/4pm EST. #s based on RUC proximity soundings previous hour, so it isn't exactly apples to apples, but its close. Link to comment Share on other sites More sharing options...
JoMo Posted March 2, 2012 Share Posted March 2, 2012 New Day 1 is out: http://www.spc.noaa.gov/products/outlook/day1otlk.html Link to comment Share on other sites More sharing options...
Ed Lizard Posted March 2, 2012 Share Posted March 2, 2012 New Day 1 is out: http://www.spc.noaa....k/day1otlk.html Moderate, but all modes hatched. Link to comment Share on other sites More sharing options...
TNE Posted March 2, 2012 Share Posted March 2, 2012 Model Analysis: (use below images for reference) I am happy that I have not commented earlier for the Saturday severe threat / East Coast. The NAM trends toward the GFS, and both models have trended toward a faster cold front and less ridging for this event.The result is a suppressed warm front and convective energy (in the warm sector) being directed toward Cape Hatteras instead of Delaware and New Jersey. The guidance between the NAM and the GFS in terms of where the energy propagates is solid at this point. Why? Because we are 36hrs away and both models are showing almost identical propagation of this convective energy in the warm sector. The energy along the leading front propagates from Alabama (Late Friday) toward Cape Hatteras @ 15Z/ 10AM Saturday.Look at the below images (Under '2') for reference. Can it change? Sure, nothing is 100 percent in weather. Is it likely to change? No. The wrong idea the NAM had before is for stronger ridging at the Coast (specifically in the Mid-Atlantic region), and it allowed the warm front to go into New York City at 15Z (10AM).. The result for this previous NAM run is as follows: Slower moving cold front , which comes across at about 15-18z (10AM-1PM) as opposed to 12-15Z. Another result of a slower moving cold front is the convective energy being directed toward our area instead of Cape Hatteras. Refer to the below image (Under '3') for reference. The most likely scenario is for the cold front to move in faster. The cold front as forecasted by the 00z models to move in right after 12z (7AM) - (10AM)...building thereafter. With less ridging present at the coast like on the 00z Model Runs, and the warm front on the 00z will most likely have a hard time getting past Central New Jersey . The 00z NAM is showing the warm front not making it past Central New Jersey at 7AM (12z NAM has the warm front moving over NYC by 15z, with 60s spreading into Jersey by 18z). Most of the convective energy in the warm sector based on the current NAM & GFS runs is directed from Alabama toward Cape Hatteras, NC. My conclusion: Severe threat looks very limited in the Northern Mid-Atlantic. If the warm front does make it past NYC and if the northerly/westerly wind shift does not occur until 18z (1PM) like on the 12z NAM, there might be a chance for the severe weather in the northern areas. The chance for that is low. The severe threat in the South along the cold front seems limited based on the fact that the leading edge of the cold front is already at Cape Hatteras at 15z/10AM. Limited instability due to insufficient timing of cold front might limit the severe threat. At this point I am not impressed by the severe threat on Saturday. Images: 1.These two model maps (one from 12z NAM and the other from the 00z NAM) show how the NAM model trended toward a faster solution (by about 3hrs) and the impact of RIDGING in the Northern Mid-Atlantic States. 12z: 00z: 2.The next images show the CURRENT consensus of the convective energy in the warm sector--The energy moving from Alabama toward Cape Hatteras (as opposed to the 12z NAM shown under '3'): 3. This is what the 12z NAM is showing (old data)---Cold Front moving in slower ( at 18z) and the convective energy in the warm sector propagating all the way toward New Jersey from Alabama: PLEASE NOTE: Convective energy in the way I am using it refers to the area most likely to see storm development and instability. The area I decided to use is in the warm sector and along the cold front, which is depicted on the 850 vorticity maps I posted above. The first reference is to the "convective energy" moving from AL to Cape Hatteras, and the other reference (shown using the 12z NAM) is of the "convective energy" moving from AL to NJ. Both of these references based on the 850 vorticity map is occurring along the cold front and in the warm sector. I used the 850 vorticity because it helps depict the area where storm development is likely to occur given a sufficient warm sector (or potential instability) and a sufficient cold front (lift)...thus I termed the vorticity as "convective energy." Link to comment Share on other sites More sharing options...
RCNYILWX Posted March 2, 2012 Share Posted March 2, 2012 TNE, just had to point out, 850 mb vorticity is not convective energy. The yellow and orange areas are maxima of positive vorticity at the 850 mb level of the atmosphere. Vorticity refers to rotation and positive vorticity is counterclockwise rotation. That's why the most notable 850 mb vort max is in the 850 mb low center northeast of Lake Huron in the images you posted. Vorticity maxima at the lower and mid levels can obviously aid in forcing upward motion, but it is not convective energy, or Convective Available Potential Energy (CAPE), which refers to the amount of instability present in the atmosphere. You most certainly do not need instability to have vorticity. Link to comment Share on other sites More sharing options...
Cheeznado Posted March 2, 2012 Share Posted March 2, 2012 The surface low is already deeper than the earlier models, the 06Z NAM has ramped up the LL SRH again, I really think there will be some very nasty violent tornadoes in central TN to Central KY from 21-0Z. Link to comment Share on other sites More sharing options...
tmagan Posted March 2, 2012 Share Posted March 2, 2012 08Z Observations, MSLP, streamlines. Link to comment Share on other sites More sharing options...
andyhb Posted March 2, 2012 Share Posted March 2, 2012 PUBLIC SEVERE WEATHER OUTLOOKNWS STORM PREDICTION CENTER NORMAN OK 0309 AM CST FRI MAR 02 2012 ...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS LATER TODAY AND TONIGHT... THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE DEVELOPMENT OF A FEW STRONG...LONG-TRACK TORNADOES OVER PARTS OF THE OHIO AND TENNESSEE VALLEYS LATER TODAY AND TONIGHT. THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE CENTRAL AND NORTHERN ALABAMA NORTHERN GEORGIA SOUTHERN ILLINOIS SOUTHERN INDIANA KENTUCKY EAST CENTRAL AND NORTHEAST MISSISSIPPI SOUTHWEST OHIO TENNESSEE WESTERN WEST VIRGINIA ELSEWHERE...SEVERE STORMS ARE ALSO POSSIBLE FROM THE UPPER OHIO VALLEY AND CENTRAL APPALACHIANS SOUTHWESTWARD TO THE LOWER MISSISSIPPI VALLEY. A STRONG UPPER-LEVEL STORM SYSTEM AND ASSOCIATED SURFACE LOW PRESSURE CENTER OVER KANSAS...OKLAHOMA...AND MISSOURI THIS MORNING WILL MOVE QUICKLY NORTHEASTWARD TO LOWER MICHIGAN BY THIS EVENING...WHILE A TRAILING COLD FRONT PROGRESSES EASTWARD INTO THE OHIO/TENNESSEE VALLEYS. MOISTURE WILL SPREAD QUICKLY NORTHEASTWARD FROM THE SOUTHERN STATES TO THE OHIO VALLEY BY THIS AFTERNOON IN ADVANCE OF A COLD FRONT...PROVIDING THE FUEL FOR SEVERE THUNDERSTORM DEVELOPMENT. IN ADDITION...WINDS AND ALL LEVELS OF THE ATMOSPHERE WILL INCREASE THROUGH THE DAY ACROSS THE MODERATE RISK AREA...SETTING THE STAGE FOR LONG-LIVED SEVERE THUNDERSTORMS. THE MOST DANGEROUS TORNADO RISK AREA IS EXPECTED FROM MIDDLE AND EASTERN TENNESSEE NORTHWARD ACROSS KENTUCKY TO THE OHIO RIVER THIS AFTERNOON...WHERE A FEW LONG-TRACK/DESTRUCTIVE TORNADOES WILL BE POSSIBLE...ALONG WITH DAMAGING WINDS AND LARGE HAIL. FARTHER SOUTH INTO MISSISSIPPI AND ALABAMA...ADDITIONAL SEVERE STORM DEVELOPMENT IS EXPECTED LATE THIS AFTERNOON INTO TONIGHT NEAR AND AHEAD OF THE COLD FRONT. THESE STORMS WILL SPREAD ACROSS CENTRAL AND NORTHERN MISSISSIPPI/ALABAMA AND NORTHERN GEORGIA THIS EVENING INTO THE OVERNIGHT HOURS...WITH AN ACCOMPANYING RISK FOR TORNADOES...DAMAGING WINDS...AND LARGE HAIL. STATE AND LOCAL EMERGENCY MANAGERS ARE MONITORING THIS DEVELOPING SITUATION. THOSE IN THE THREATENED AREA ARE URGED TO REVIEW SEVERE WEATHER SAFETY RULES AND TO LISTEN TO RADIO...TELEVISION...AND NOAA WEATHER RADIO FOR POSSIBLE WATCHES...WARNINGS...AND STATEMENTS LATER TODAY. ..THOMPSON.. 03/02/2012 Link to comment Share on other sites More sharing options...
QVectorman Posted March 2, 2012 Share Posted March 2, 2012 So here is my brief assessment as asked for...since there isn't a very clear agreement on a solution with the NAM/WRF/GFS/RUC wrt to placement of thermodynamics/dynamics any where. It makes it alot harder to say specifically where what will happen. This is really a crap shoot to me. I usually like to see a "little" more agreement between them all. But I will put more weight in the NAM since the RUC generates a similar solution. But will cover what I see out of the NAM/WRF/GFS. 18z nam I see a slight risk for storms for northern MS just east of MS river if they do develop they would probably be borderline svr and very slight risk of any tornadoes. I also see a slight risk for NE AL into N GA if they do develop they would probably be below svr limits and very slight risk of any tornadoes. If storms do develop/cross over cn. tenn. at 18z I think the storms will be near or at severe limits but will have issues producing tornadoes since -vv are progged over the area so it will be hard to maximize the updrafts. It may be able to squeak out one or two spin ups. Western KY also looks like svr. limit convection would be retarded due to -vv. Eastern KY no storms at this time. 18z WRF Best possibility for svr wx on WRF...South central KY and West TN...so a bit of a difference compared to the NAM 18z GFS Seeing hindrance reaching svr./tornadic limit over south central TN due to subsidence over head. In Tennessee from the vertical MS/AL line east...great shear/CAPE though but low CAPE/shear and good +VV in east TN Part of extremely east southern Indiana has subsidence over it so storms would be borderline svr but probably not not tornadic. SLIGHT risk for severe storms and tornadoes at the fork of IN/IL 21z nam strong to near svr storms in northern AL and slight risk of tornadoes. Central TN again appears under subsidence so storms would stay just under/near svr limit and limited tornado threat. I see a slight risk of strong storms for E KY and slight risk of tornadoes. Southern central KY by state line directly below the IN/OH line a decent chance for the storms to make it to svr limits and slight chance to produce a spin up or two. 21z WRF storms stay at or below svr limit with very slight risk of tornaodoes for Cn. KY 0z NAM This is where things get interesting and solutions of the NAM/RUC diverge greatly.... High risk of very strong storms strengthening to svr or above svr limits and good chance of strong tornadoes east of Columbia TN and around I-65 Moderate chance of strong storms strengthen to svr limits Lafayette TN westward to around I-65 westward. This will be a tricky area b/c it will be on the eastern edge of the best dynamics. At 0z northern MS/East TN&KY would not have any issues. RUC doesn't match up over this area for good storms. TN would be non svr all the way according to the RUC. I believe there would be a decent chance of strong to severe storms btwn Cin. and Georgetown OH and moderate risk for tornadoes but this will be a very close call...all or nothing in this area depending on arrival time of the squall line. RUC matches this threat. 0z WRF best chances n. MS through East KY but mainly Eastern KY 0z GFS really kills CAPE so it would be a bust by 0z on strong storms. slight risk KY/TN/VA border So a couple things if I were to chance and put all my eggs in one basket using the NAM during the time of 18z to 0z I would take TN areas outlined above as having the best opportunity for seeing very strong storms and the best chance of producing tornadoes. But since the RUC disagrees with this the second best spot I like is by Cincinnati since there is some agreement there, but that area is completely at the mercy of when the squall line arrives. Lastly, 0z could be a complete wash if the GFS is correct... Also, my definition of severe/strong isn't used as the same context as the SPC definition. I am loosing using it based on damage reports...multiple reports of wind damage, hail etc from the same storm. because I'm sure most of these storms will have warnings issued on them. So my definition of svr would be more based on the reports rather than verification based on a svr t'storm warning issued on the storm. Lastly, I am super tired so if you find errors in this I apologize and I'm sure it becomes a little rambley by the end and some things/thoughts may not be completely coherent. Just took the time to write it out for you guys to critique. I think that's it, if I forgot something or have to add clarification please allow me to add it tomorrow Link to comment Share on other sites More sharing options...
beneficii Posted March 2, 2012 Author Share Posted March 2, 2012 MEG: THUNDERSTORMS ARE NOW DEVELOPING ACROSS THE MIDSOUTH WITH THE ANTICIPATION OF A VERY ACTIVE DAY IN THE MAKING. DEW POINTS CONTINUE TO INCREASE ACROSS THE MIDSOUTH AS A STRONG WARM FRONT SURGES NORTH. AT 330AM IT WAS POSITIONED ACROSS THE MISSOURI BOOTHEEL TO JUST NORTH OF JACKSON MISSISSIPPI...BUT SHOULD BE NORTH OF THE ENTIRE MIDSOUTH WITHIN THE NEXT COUPLE OF HOURS PLACING THE ENTIRE FORECAST AREA IN THE WARM SECTOR OF A POWERFUL SPRING STORM SYSTEM. 60+ DEGREE READINGS ENCOMPASS MOST OF THE AREA WITH THE EXCEPTION OF PORTIONS OF WEST TENNESSEE...MAINLY NORTH AND EAST OF A LINE FROM BLYTHEVILLE TO JACKSON. PORTIONS OF THE DELTA...SOUTH OF MEMPHIS HAVE SEEN DEW POINTS CLIMB INTO THE MIDDLE 60S. AS A RESULT OF THIS WARM MOIST AIRMASS LAPS CAPE VALUES RANGE FROM 200 TO 800 J/KG WITH GENERALLY -1 TO -2C LIFTED INDICES. INSTABILITY WILL ONLY INCREASE FURTHER TODAY AS ADDITIONAL ENERGY IS GAINED FROM DAYTIME HEATING. EXPECTING 1500 TO 3000 J/KG THIS AFTERNOON DURING PEAK HEATING...GREATEST EAST OF THE MISSISSIPPI RIVER. IN ADDITION...A VERY STRONG JET STREAK ORIENTED FROM NORTHEAST OKLAHOMA ACROSS SOUTH MISSOURI WILL BRING PLENTY OF DYNAMIC ENERGY TO THE MIDSOUTH. AS THIS JET FEATURE SHIFTS ACROSS SOUTHERN ILLINOIS AND SOUTH INDIANA...IT WILL PLACE MUCH OF WEST TENNESSEE AND NORTH MISSISSIPPI IN THE RIGHT REAR ENTRANCE QUADRANT FAVORING SEVERE THUNDERSTORM DEVELOPMENT. HODOGRAPHS ARE STRONGLY CURVED BELOW 3000 FEET...ESPECIALLY BEFORE 18Z RESULTING IN 0-3KM SRH BETWEEN 300 AND 500 M2/S2. AFTER 18Z...SHEER DIMINISH A BIT AS HODOGRAPHS STRAIGHTEN...BUT SPEED SHEER WILL REMAIN PLENTY TO KEEP THE THREAT OF TORNADOES IN THE FORECAST THROUGH AT LEAST 00Z. ANY DISCRETE SUPERCELLS THAT FORM AFTER NOON ACROSS WEST TENNESSEE OR NORTHEAST MISSISSIPPI WILL HAVE THE GREATEST POTENTIAL TO PRODUCE TORNADOES. LARGE HAIL AND DAMAGING WIND WILL BE A THREAT WITH ANY STORMS TODAY. STORM MOTION SHOULD BE TO THE EAST NORTHEAST AT AROUND 35 MPH. WITH TIME...SPECIFICALLY CLOSER TO 00Z AND AFTER...ENHANCED CONVERGENCE ALONG THE FRONT WILL FAVOR THE DEVELOPMENT OF A SQUALL LINE JUST AHEAD OF THE WIND SHIFT/COLD FRONT. DRY AIR ALOFT WILL ACT TO ENHANCE DOWNDRAFTS RESULTING IN A GREATER POTENTIAL FOR WIDESPREAD DAMAGING WIND. DAMAGING WIND WILL BE MOST FAVORED ALONG LINE SEGMENTS. Link to comment Share on other sites More sharing options...
Roger Smith Posted March 2, 2012 Share Posted March 2, 2012 I am assessing this as a PDS and high risk scenario. The rapid deepening of the low is probably a more significant factor than many other variables under consideration. Also there is a large geomagnetic energy peak (lunar northern max). Just on raw climatology this system looks ominously similar to 3-18-1925 and I suspect it could have a similar evolution -- early and rapid intensification to major squall line from e MO and s IL curved southwest into AR, followed by multiple tornadic supercells moving northeast at high rates of speed through IL, IN, OH, KY, TN, AL, MS, AR, LA and e TX. ... I believe there is a high risk of F4 or even F5 intensity with some storms later today, but expect numerous F2-3 along the line. The focus of severe storms by evening will be more confined to the TN-AL-MS portion moving into Carolinas and Georgia. Less destructive severe weather can also be expected in s MI, sw ON as a strong cold front develops and brings straight-line wind gusts to 60kt and F1-2 tornadic potential (mostly in MI). A squall line is likely to race east through eOH, PA and NY overnight with borderline severe conditions. The more severe activity in the southeast may take most of the night to extinguish. Let's hope that warnings are effective because I could foresee this being a very destructive day, hopefully all states in the high risk area will have extensive media coverage of developments. Would stress the early peak of development, this won't wait for late day. Link to comment Share on other sites More sharing options...
Superstorm93 Posted March 2, 2012 Share Posted March 2, 2012 SPC Briefing. http://www.spc.noaa.gov/products/outlook/pwo.mp4 Link to comment Share on other sites More sharing options...
Sunny and Warm Posted March 2, 2012 Share Posted March 2, 2012 So here is my brief assessment as asked for...since there isn't a very clear agreement on a solution with the NAM/WRF/GFS/RUC wrt to placement of thermodynamics/dynamics any where. It makes it alot harder to say specifically where what will happen. This is really a crap shoot to me. I usually like to see a "little" more agreement between them all. But I will put more weight in the NAM since the RUC generates a similar solution. But will cover what I see out of the NAM/WRF/GFS. Also, my definition of severe/strong isn't used as the same context as the SPC definition. I am loosing using it based on damage reports...multiple reports of wind damage, hail etc from the same storm. because I'm sure most of these storms will have warnings issued on them. So my definition of svr would be more based on the reports rather than verification based on a svr t'storm warning issued on the storm. Lastly, I am super tired so if you find errors in this I apologize and I'm sure it becomes a little rambley by the end and some things/thoughts may not be completely coherent. Just took the time to write it out for you guys to critique. I think that's it, if I forgot something or have to add clarification please allow me to add it tomorrow Q-man, I appreciate your expertise in this matter, tired or not. Thank you... Link to comment Share on other sites More sharing options...
SmokeEater Posted March 2, 2012 Share Posted March 2, 2012 High risk issued. Link to comment Share on other sites More sharing options...
BrentO Posted March 2, 2012 Share Posted March 2, 2012 lokks like just east of Evansville, In, to louisville, lexington, bowling green and south to Nashville. wow not good Link to comment Share on other sites More sharing options...
baroclinic_instability Posted March 2, 2012 Share Posted March 2, 2012 193 ACUS01 KWNS 021301 SWODY1 SPC AC 021259 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0659 AM CST FRI MAR 02 2012 VALID 021300Z - 031200Z ...THERE IS A HIGH RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR EXTREME SRN INDIANA...CENTRAL KY... AND NRN MIDDLE TN... ..THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK FOR MUCH OF THE OH/TN VALLEYS... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY TO THE UPPER OH VALLEY AND APPALACHIANS... --SIGNIFICANT SEVERE WEATHER OUTBREAK EXPECTED THIS AFTERNOON INTO TONIGHT ACROSS MUCH OF THE OH/TN VALLEY REGION...INCLUDING THE POTENTIAL FOR LONG-TRACK/STRONG TORNADOES-- ..SYNOPSIS A 130 KT JET STREAK ALOFT NOW OVERSPREADING NW OK PER PROFILER PLOTS WILL CONTINUE NEWD TO MO/IL/INDIANA BY THIS EVENING. A COUPLING OF LOW-LEVEL WAA/DECREASING STATIC STABILITY AND DIVERGENCE IN THE LEFT EXIT REGION OF THE MID-UPPER JET STREAK WILL PROMOTE DEEPENING OF A SURFACE CYCLONE WHICH WILL MOVE NEWD FROM MO TO CENTRAL IL BY MIDDAY...AND SRN LOWER MI BY THIS EVENING. A WARM FRONT WILL MOVE QUICKLY NWD TODAY IN ADVANCE OF THE CYCLONE...AND A TRAILING COLD FRONT WILL SWEEP EWD ACROSS THE MID MS AND OH VALLEY REGION. A RESERVOIR OF L0W-MID 60S BOUNDARY LAYER DEWPOINTS NEAR AND S OF I-40 WILL SURGE NEWD INTO THE OH VALLEY BY MID-LATE AFTERNOON...WHICH WILL CONTRIBUTE TO SUBSTANTIAL NEWD EXPANSION OF THE UNSTABLE WARM SECTOR IN THE WAKE OF MORNING ELEVATED CONVECTION IN THE WARM ADVECTION REGIME. ..TN/OH VALLEY REGION TODAY THROUGH THIS EVENING THE INITIAL ELEVATED SEVERE STORMS NEAR STL /JUST AHEAD OF THE SURFACE CYCLONE/ WILL CONTINUE TO SPREAD ENEWD OVER CENTRAL IL/INDIANA WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING GUSTS. THE MORE SERIOUS SEVERE STORM/TORNADO RISK WILL BEGIN TO MATERIALIZE IMMEDIATELY E OF THE MS RIVER BY MIDDAY. A BROKEN BAND OF STORMS WILL LIKELY FORM ALONG THE COLD FRONT BY EARLY AFTERNOON...WITH ADDITIONAL STORM DEVELOPMENT EXPECTED FARTHER E IN THE UNSTABLE/WEAKLY CAPPED WARM SECTOR. AS SURFACE TEMPERATURES WARM INTO THE UPPER 60S TO MID 70S AND MOISTURE LIKEWISE INCREASES...MLCAPE WILL INCREASE TO 1500-2000 J/KG AS FAR NE AS NRN KY BY LATE AFTERNOON. THE DESTABILIZATION WILL BE COINCIDENT WITH AN INCREASE IN DEEP-LAYER FLOW/VERTICAL SHEAR...WITH EFFECTIVE BULK SHEAR NEAR 70 KT AND EFFECTIVE SRH OF 300-400 M2/S2. THE VERY STRONG VERTICAL SHEAR...MODERATE INSTABILITY...A MOIST LOW-LEVEL ENVIRONMENT...AND THE LIKELIHOOD OF A FEW DISCRETE WARM SECTOR SUPERCELLS / AND SUPERCELLS WITHIN THE LINE ALONG THE FRONT/...ALL APPEAR SUPPORTIVE OF A POTENTIALLY SIGNIFICANT TORNADO EPISODE WITH A FEW LONG-TRACK/STRONG TORNADOES. THE MOST PROBABLE AREA FOR DAMAGING TORNADOES WILL BE SE OF THE SURFACE LOW TRACK IN THE MORE ESTABLISHED WARM SECTOR...OR NEAR AND S OF THE OH RIVER FROM EXTREME SRN INDIANA INTO CENTRAL KY/NRN MIDDLE TN. BOTH PRE-FRONTAL AND FRONTAL SUPERCELLS ARE MOST PROBABLE IN THE HIGH RISK AREA...AND SOME OF THESE STORMS COULD SPREAD AS FAR NE AS SW OH AND WRN WV BEFORE EXITING THE WARM SECTOR THIS EVENING. OTHERWISE...DAMAGING WINDS AND LARGE HAIL CAN ALSO BE EXPECTED WITH THE PRE-FRONTAL AND FRONTAL STORMS THROUGH THIS EVENING. ..MS/AL/GA LATE THIS AFTERNOON INTO TONIGHT THE MOIST/UNSTABLE WARM SECTOR IS ALREADY ESTABLISHED ACROSS THE GULF COAST STATES THIS MORNING. THIS AREA WILL REMAIN A LITTLE S OF THE STRONGEST DEEP-LAYER FLOW...AND THE STRONGEST LLJ CORE WILL DEVELOP NEWD TO THE OH VALLEY IN CONJUNCTION WITH THE UPPER JET STREAK AND SURFACE CYCLONE. STILL...INSTABILITY AND VERTICAL SHEAR WILL BE FAVORABLE FOR SUPERCELLS WITHIN IN ONE OR MORE BANDS OF CONVECTION ALONG AND AHEAD OF THE COLD FRONT BEGINNING LATER THIS AFTERNOON AND CONTINUING INTO TONIGHT. RISKS WILL INCLUDE A FEW TORNADOES...DAMAGING WINDS...AND LARGE HAIL THROUGH TONIGHT. ..THOMPSON/LEITMAN.. 03/02/2012 Link to comment Share on other sites More sharing options...
Srain Posted March 2, 2012 Share Posted March 2, 2012 193 ACUS01 KWNS 021301 SWODY1 SPC AC 021259 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0659 AM CST FRI MAR 02 2012 VALID 021300Z - 031200Z ...THERE IS A HIGH RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR EXTREME SRN INDIANA...CENTRAL KY... AND NRN MIDDLE TN... ..THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK FOR MUCH OF THE OH/TN VALLEYS... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY TO THE UPPER OH VALLEY AND APPALACHIANS... --SIGNIFICANT SEVERE WEATHER OUTBREAK EXPECTED THIS AFTERNOON INTO TONIGHT ACROSS MUCH OF THE OH/TN VALLEY REGION...INCLUDING THE POTENTIAL FOR LONG-TRACK/STRONG TORNADOES-- ..SYNOPSIS A 130 KT JET STREAK ALOFT NOW OVERSPREADING NW OK PER PROFILER PLOTS WILL CONTINUE NEWD TO MO/IL/INDIANA BY THIS EVENING. A COUPLING OF LOW-LEVEL WAA/DECREASING STATIC STABILITY AND DIVERGENCE IN THE LEFT EXIT REGION OF THE MID-UPPER JET STREAK WILL PROMOTE DEEPENING OF A SURFACE CYCLONE WHICH WILL MOVE NEWD FROM MO TO CENTRAL IL BY MIDDAY...AND SRN LOWER MI BY THIS EVENING. A WARM FRONT WILL MOVE QUICKLY NWD TODAY IN ADVANCE OF THE CYCLONE...AND A TRAILING COLD FRONT WILL SWEEP EWD ACROSS THE MID MS AND OH VALLEY REGION. A RESERVOIR OF L0W-MID 60S BOUNDARY LAYER DEWPOINTS NEAR AND S OF I-40 WILL SURGE NEWD INTO THE OH VALLEY BY MID-LATE AFTERNOON...WHICH WILL CONTRIBUTE TO SUBSTANTIAL NEWD EXPANSION OF THE UNSTABLE WARM SECTOR IN THE WAKE OF MORNING ELEVATED CONVECTION IN THE WARM ADVECTION REGIME. ..TN/OH VALLEY REGION TODAY THROUGH THIS EVENING THE INITIAL ELEVATED SEVERE STORMS NEAR STL /JUST AHEAD OF THE SURFACE CYCLONE/ WILL CONTINUE TO SPREAD ENEWD OVER CENTRAL IL/INDIANA WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND DAMAGING GUSTS. THE MORE SERIOUS SEVERE STORM/TORNADO RISK WILL BEGIN TO MATERIALIZE IMMEDIATELY E OF THE MS RIVER BY MIDDAY. A BROKEN BAND OF STORMS WILL LIKELY FORM ALONG THE COLD FRONT BY EARLY AFTERNOON...WITH ADDITIONAL STORM DEVELOPMENT EXPECTED FARTHER E IN THE UNSTABLE/WEAKLY CAPPED WARM SECTOR. AS SURFACE TEMPERATURES WARM INTO THE UPPER 60S TO MID 70S AND MOISTURE LIKEWISE INCREASES...MLCAPE WILL INCREASE TO 1500-2000 J/KG AS FAR NE AS NRN KY BY LATE AFTERNOON. THE DESTABILIZATION WILL BE COINCIDENT WITH AN INCREASE IN DEEP-LAYER FLOW/VERTICAL SHEAR...WITH EFFECTIVE BULK SHEAR NEAR 70 KT AND EFFECTIVE SRH OF 300-400 M2/S2. THE VERY STRONG VERTICAL SHEAR...MODERATE INSTABILITY...A MOIST LOW-LEVEL ENVIRONMENT...AND THE LIKELIHOOD OF A FEW DISCRETE WARM SECTOR SUPERCELLS / AND SUPERCELLS WITHIN THE LINE ALONG THE FRONT/...ALL APPEAR SUPPORTIVE OF A POTENTIALLY SIGNIFICANT TORNADO EPISODE WITH A FEW LONG-TRACK/STRONG TORNADOES. THE MOST PROBABLE AREA FOR DAMAGING TORNADOES WILL BE SE OF THE SURFACE LOW TRACK IN THE MORE ESTABLISHED WARM SECTOR...OR NEAR AND S OF THE OH RIVER FROM EXTREME SRN INDIANA INTO CENTRAL KY/NRN MIDDLE TN. BOTH PRE-FRONTAL AND FRONTAL SUPERCELLS ARE MOST PROBABLE IN THE HIGH RISK AREA...AND SOME OF THESE STORMS COULD SPREAD AS FAR NE AS SW OH AND WRN WV BEFORE EXITING THE WARM SECTOR THIS EVENING. OTHERWISE...DAMAGING WINDS AND LARGE HAIL CAN ALSO BE EXPECTED WITH THE PRE-FRONTAL AND FRONTAL STORMS THROUGH THIS EVENING. ..MS/AL/GA LATE THIS AFTERNOON INTO TONIGHT THE MOIST/UNSTABLE WARM SECTOR IS ALREADY ESTABLISHED ACROSS THE GULF COAST STATES THIS MORNING. THIS AREA WILL REMAIN A LITTLE S OF THE STRONGEST DEEP-LAYER FLOW...AND THE STRONGEST LLJ CORE WILL DEVELOP NEWD TO THE OH VALLEY IN CONJUNCTION WITH THE UPPER JET STREAK AND SURFACE CYCLONE. STILL...INSTABILITY AND VERTICAL SHEAR WILL BE FAVORABLE FOR SUPERCELLS WITHIN IN ONE OR MORE BANDS OF CONVECTION ALONG AND AHEAD OF THE COLD FRONT BEGINNING LATER THIS AFTERNOON AND CONTINUING INTO TONIGHT. RISKS WILL INCLUDE A FEW TORNADOES...DAMAGING WINDS...AND LARGE HAIL THROUGH TONIGHT. ..THOMPSON/LEITMAN.. 03/02/2012 Link to comment Share on other sites More sharing options...
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