yoda Posted March 27, 2020 Share Posted March 27, 2020 disco talks about giant hail possible Link to comment Share on other sites More sharing options...
snowlover2 Posted March 27, 2020 Share Posted March 27, 2020 15% tornado area too. Quote DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT FRI MAR 27 2020 VALID 281200Z - 291200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTH-CENTRAL AND NORTHWEST ILLINOIS... ..SUMMARY A SIGNIFICANT SEVERE WEATHER OUTBREAK IS POSSIBLE FOR PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY ON SATURDAY. THE THREATS WITH THE STRONGER STORMS INCLUDE TORNADOES, A FEW WHICH MAY BE SIGNIFICANT, LARGE TO VERY LARGE HAIL, AND SEVERE GUSTS. ..SYNOPSIS AN INTENSE 150-KT UPPER SPEED MAX OVER THE SOUTHERN GREAT PLAINS SATURDAY MORNING WILL QUICKLY MOVE INTO THE MIDDLE MS VALLEY BY MID AFTERNOON, AS A NORTHEAST-MIGRATING MID-LEVEL LOW MOVES FROM THE CENTRAL HIGH PLAINS INTO THE UPPER MIDWEST. AN INTENSE BELT OF SOUTHWESTERLY 500MB FLOW (100+ KT) WILL CONCURRENTLY MOVE FROM OK INTO IL BY SATURDAY EVENING AND INTO THE SOUTHERN GREAT LAKES BY EARLY SUNDAY MORNING. A 990MB SURFACE LOW WILL DEVELOP NORTHEAST AND DEEPEN FURTHER INTO NORTH-CENTRAL IA BY EARLY EVENING BEFORE BECOMING OCCLUDED OVER WI BY DAYBREAK SUNDAY. ..MID MS VALLEY ---CONFIDENCE IS INCREASING FOR A POTENTIALLY POTENT SEVERE WEATHER SETUP AS INGREDIENTS NEEDED FOR THIS ARE APPEARING TO FAVORABLY ALIGN ON SATURDAY.--- A CLUSTER OF ELEVATED THUNDERSTORMS WILL LIKELY BE ONGOING SATURDAY MORNING ACROSS THE MID MS VALLEY ASSOCIATED WITH WARM AIR ADVECTION NEAR A NORTHWARD-ADVANCING WARM FRONT. STRONG SOUTHERLY FLOW WILL TRANSPORT LOW-LEVEL MOISTURE NORTHWARD DURING THE DAY WITH SURFACE DEWPOINTS EXPECTED TO REACH THE MID 60S SOUTH OF THE WARM FRONT. AN ELEVATED MIXED LAYER WITH STEEP 700-500 MB LAPSE RATES (7.5-8 DEG C/KM) WILL ADVECT NORTHEAST INTO THE REGION WITH AN ASSOCIATED CAPPING INVERSION INHIBITING SURFACE-BASED THUNDERSTORM DEVELOPMENT THROUGH THE MORNING. BY MIDDAY, STRONG HEATING WILL RESULT IN MODERATE BUOYANCY DEVELOPING TO THE EAST OF A DRYLINE/PACIFIC FRONT. SCATTERED DISCRETE THUNDERSTORMS ARE FORECAST TO DEVELOP FROM NEAR THE SURFACE LOW SOUTHWARD ALONG THE BOUNDARY AND MOVE TO THE NORTHEAST WITHIN A DESTABILIZING AIRMASS AND STRENGTHENING LOW-LEVEL SHEAR. FORECAST HODOGRAPHS INDICATE LONG-TRACK, DISCRETE SUPERCELLS ARE PROBABLE GIVEN THE INTENSE SHEAR COUPLED WITH MODERATE INSTABILITY. THE SEVERE THREAT WILL LIKELY PEAK DURING THE AFTERNOON AND PERSIST INTO THE EARLY EVENING. IT APPEARS THE TORNADO RISK WILL FOCUS IN THE WARM SECTOR TO THE SOUTHEAST OF THE SURFACE LOW, ESPECIALLY WITH SUPERCELLS INTERACTING WITH VORTICITY RICH LOW LEVELS NEAR THE WARM FRONT. LARGE TO GIANT HAIL IS POSSIBLE WITH EITHER LEFT OR RIGHT-SPLITTING SUPERCELLS. ELEVATED STRONG TO SEVERE STORMS ARE POSSIBLE NORTH OF THE WARM FRONT ACROSS THE GREAT LAKES WITH MAINLY A HAIL RISK. STORMS MAY CONTINUE WELL INTO THE EVENING ACROSS PARTS OF THE OH VALLEY/SOUTHERN GREAT LAKES POSING A SEVERE RISK. ..LOWER MS VALLEY INTO THE TN VALLEY MODELS SHOW THE DEVELOPMENT OF MODERATE INSTABILITY DURING THE DAY ACROSS THE LOWER MS VALLEY WITH ISOLATED TO SCATTERED DIURNAL STORM ACTIVITY. RECENT MODEL TRENDS IMPLY STORM DEVELOPMENT PERHAPS INITIATING IN THE VICINITY OF LOW-LEVEL CONFLUENCE BANDS DURING PEAK HEATING. STRONG DEEP-LAYER SHEAR WILL FAVOR ORGANIZED STORMS WITH THE MORE ROBUST UPDRAFTS. HAIL/WIND APPEAR TO BE THE PRIMARY HAZARDS BUT A TORNADO RISK COULD MATERIALIZE WITH ADEQUATE LOW-LEVEL SHEAR FORECAST. SOME OF THIS ACTIVITY MAY LINGER INTO THE OVERNIGHT HOURS AND SPREAD EAST/NORTHEAST INTO PARTS OF THE TN VALLEY LATE. ..SMITH.. 03/27/2020 Link to comment Share on other sites More sharing options...
Indystorm Posted March 27, 2020 Share Posted March 27, 2020 Wow... a jump past enhanced to moderate.....will bear watching closely this Saturday. And it is only March. Have we had moderate risk yet this year? Yep. Jan. 10, 2020 in Arkansas and Louisiana.... Link to comment Share on other sites More sharing options...
Sydney Claridge Posted March 27, 2020 Share Posted March 27, 2020 With that drastic risk increase, I am getting more concerned that a scenario comparable to the November 17, 2013 tornado outbreak could be within the realm of possibilities, at least for Illinois. Link to comment Share on other sites More sharing options...
Hoosier Posted March 27, 2020 Share Posted March 27, 2020 4 minutes ago, BrandonC_TX said: With that drastic risk increase, I am getting more concerned that a scenario comparable to the November 17, 2013 tornado outbreak could be within the realm of possibilities, at least for Illinois. (keep in mind that 11/17/13 had a MDT as far east as Buffalo, NY; I believe this was due to the risk for a serial derecho) It is a pretty good setup, but 11/17/13 had a larger area of better tornado potential than this does. I am not sure I agree with the comparison even if we limit it to Illinois, but you can make a better case with that vs a larger regional comparison. Link to comment Share on other sites More sharing options...
Sydney Claridge Posted March 27, 2020 Share Posted March 27, 2020 1 minute ago, Hoosier said: It is a pretty good setup, but 11/17/13 had a larger area of better tornado potential than this does. I am not sure I agree with the comparison even if we limit it to Illinois, but you can make a better case with that vs a larger regional comparison. I agree with that. April 9, 2015 may be the better comparison here, especially with the similarities in expected areal coverage for significant tornadoes. 11/17/13 was generally further east with the favorable area for tornadoes extending across Indiana and even into Ohio (though few tornadoes occurred in OH, several touched down in northern IN). Link to comment Share on other sites More sharing options...
hlcater Posted March 27, 2020 Share Posted March 27, 2020 Euro just popped a CA of 60. Quite a step up from previous runs and the NAM with CAs of 35-40. Link to comment Share on other sites More sharing options...
Indystorm Posted March 27, 2020 Share Posted March 27, 2020 April 9, 2015 1630 outlook was enhanced with a 10 % hatched tor area over nw IL. Link to comment Share on other sites More sharing options...
LansingWeather Posted March 27, 2020 Share Posted March 27, 2020 Is it possible to chase this with the lockdown in Illinois? Link to comment Share on other sites More sharing options...
CoalCityWxMan Posted March 27, 2020 Share Posted March 27, 2020 Just now, LansingWeather said: Is it possible to chase this with the lockdown in Illinois? Technically yes. Just as long as you’re smart & avoid gathering in groups while waiting, being smart while getting gas (gloves, hand sanitizer, etc) & just being smart it should be fine. Planning on heading out but am gonna bring all my own food and water 1 Link to comment Share on other sites More sharing options...
LansingWeather Posted March 27, 2020 Share Posted March 27, 2020 1 minute ago, CoalCityWxMan said: Technically yes. Just as long as you’re smart & avoid gathering in groups while waiting, being smart while getting gas (gloves, hand sanitizer, etc) & just being smart it should be fine. Planning on heading out but am gonna bring all my own food and water I would be coming from Michigan, not sure if crossing into states is permitted or not. I guess I will need to do some reading. Link to comment Share on other sites More sharing options...
Sydney Claridge Posted March 27, 2020 Share Posted March 27, 2020 06z HRRR has a major storm complex moving through Illinois, Indiana, and Ohio (and even into SW PA/N WV) during the morning hours on Saturday (overnight/early morning in IL), before the main action would get started in Illinois. While generally elevated, some of this complex is modeled to get fairly close to some SBCAPE. If this complex verifies we might see outflow boundaries come into play later in the day, but my experience with HRRR models is that they are quite bullish. Link to comment Share on other sites More sharing options...
Radtechwxman Posted March 27, 2020 Share Posted March 27, 2020 DVN is being majorly conservative: THE LIKELY SPEED OF THE LINE (POTENTIALLY 45-50 MPH) MEANS DAMAGING WINDS AND LARGE HAIL ARE EXPECTED. IF LOW LEVEL WIND FIELDS BECOME FAVORABLE THEN ISOLATED TORNADOES CANNOT BE RULED OUT. Link to comment Share on other sites More sharing options...
A-L-E-K Posted March 27, 2020 Share Posted March 27, 2020 it's my birthday tomorrow, would like to see some tors please 1 Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 27, 2020 Share Posted March 27, 2020 I’m not going to post a bunch of images, but take a look at the 9z RAP for Saturday... . Link to comment Share on other sites More sharing options...
crossbowftw3 Posted March 27, 2020 Share Posted March 27, 2020 Some pretty impressive parameters setting up tomorrow. Regional outbreak with multiple strong tornadoes seems like a solid bet. Link to comment Share on other sites More sharing options...
A-L-E-K Posted March 27, 2020 Share Posted March 27, 2020 10 minutes ago, Chicago Storm said: I’m not going to post a bunch of images, but that a look at the 9z RAP for Saturday... . Link to comment Share on other sites More sharing options...
nwohweather Posted March 27, 2020 Share Posted March 27, 2020 Best setup I've seen in years for you guys. I would absolutely be driving from OH to IL if I still lived there but I digress. I'm REALLLLLYYYYYY impressed with lapse rates for tomorrow. While chasing would be cool, you have to take into account that there will be some giant hail tomorrow. This kind of explosive growth should aid supercell development tremendously, and bring strong downdrafts down leading to quite a few tornadoes. A sub-990 mb low and dry line is some serious stuff for this area. Promising but kind of terrifying considering the possibilities it may bring. Would not shock me to see multiple long track tornadoes tomorrow in IL leading into a fierce MCV-Bow Echo that blows through IN/OH Link to comment Share on other sites More sharing options...
crossbowftw3 Posted March 27, 2020 Share Posted March 27, 2020 3 minutes ago, nwohweather said: Best setup I've seen in years for you guys. I would absolutely be driving from OH to IL if I still lived there but I digress. I'm REALLLLLYYYYYY impressed with lapse rates for tomorrow. While chasing would be cool, you have to take into account that there will be some giant hail tomorrow. This kind of explosive growth should aid supercell development tremendously, and bring strong downdrafts down leading to quite a few tornadoes. A sub-990 mb low and dry line is some serious stuff for this area. Promising but kind of terrifying considering the possibilities it may bring. Would not shock me to see multiple long track tornadoes tomorrow in IL leading into a fierce MCV-Bow Echo that blows through IN/OH Wouldn't shock me if SPC goes high and/or expands that MDT area. All going to be dependent on morning convection. Link to comment Share on other sites More sharing options...
DanLarsen34 Posted March 27, 2020 Share Posted March 27, 2020 From earlier this morning. Link to comment Share on other sites More sharing options...
janetjanet998 Posted March 27, 2020 Share Posted March 27, 2020 the 12z HRRR is interesting to say the least Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 27, 2020 Share Posted March 27, 2020 the 12z HRRR is interesting to say the least . 1 Link to comment Share on other sites More sharing options...
crossbowftw3 Posted March 27, 2020 Share Posted March 27, 2020 The HRRR greatly oversold 5/20 so YMMV 1 Link to comment Share on other sites More sharing options...
Bob's Burgers Posted March 27, 2020 Share Posted March 27, 2020 Posted for documentation purposes. 1 Link to comment Share on other sites More sharing options...
crossbowftw3 Posted March 27, 2020 Share Posted March 27, 2020 HRRR STP values give me flashbacks Link to comment Share on other sites More sharing options...
Bob's Burgers Posted March 27, 2020 Share Posted March 27, 2020 Nam Nest has a similar idea, just farther west Link to comment Share on other sites More sharing options...
A-L-E-K Posted March 27, 2020 Share Posted March 27, 2020 smart money says west is the way to go Link to comment Share on other sites More sharing options...
andyhb Posted March 27, 2020 Share Posted March 27, 2020 26 minutes ago, crossbowftw3 said: The HRRR greatly oversold 5/20 so YMMV This one is a bit different where basically every CAM is in agreement on a string of pearls ahead of that front. We have a very clear focus for initiation this time in the warm sector. I do believe the HRRR parameters may be a bit overblown in terms of instability, but its wind profiles are extremely impressive. 1 1 Link to comment Share on other sites More sharing options...
crossbowftw3 Posted March 27, 2020 Share Posted March 27, 2020 8 minutes ago, andyhb said: This one is a bit different where basically every CAM is in agreement on a string of pearls ahead of that front. We have a very clear focus for initiation this time in the warm sector. I do believe the HRRR parameters may be a bit overblown in terms of instability, but its wind profiles are extremely impressive. That they are. This one seems a bit less obvious than 5/20 at first but seems more probable to verify. Do they go high? It still boils down to what kind of boundaries morning convection leaves/how fast atmosphere recovers. Link to comment Share on other sites More sharing options...
andyhb Posted March 27, 2020 Share Posted March 27, 2020 Quote Turning to Saturday`s potentially higher end severe risk, there are some lingering uncertainties to consider. Continued strong isentropic ascent across the warm frontal zone could keep elevated showers and some embedded thunder threat going into the morning, though likely less t-storm coverage than Friday night-early Saturday. The 00z guidance continued to offer a rather classic synoptic pattern for upper echelon severe weather potential, with a sub 990 mb low occluding into the evening, warm front with rich boundary layer moisture lifting northward, and an arcing Pacific front/dryline. These surface features will be topped by extremely impressive wind fields, including south-southwesterly 40-50+ kt at 850 mb, southwesterly 90-100+ kt at 500 mb, and 150+ kt 250-300 mb upper level jet core, along with still steep mid- level lapse rates. The main uncertainties with this set-up are the northward progress of the warm front, owing to the possibly slowing progression east-northeastward of the surface low, threat for continued convection (non-zero severe hail risk) north of the warm front that could temporarily reinforce the front, and likelihood of extensive cloud cover that hindering insolation and perhaps destabilization. While there is overall agreement in the big picture in the guidance, any further slowing of the warm front and then Pac front/dry line advancing from the psuedo-triple point could shift severe risk a bit farther west and threat into the CWA a bit later, likely into the evening. The ECMWF and UKMET indicated this sort of possibility. That all being said, with the inherent uncertainties aside, the set-up has the hallmarks of a classic midwest severe weather producer. Advection and kinematics will play a large role in compensating for likely lacking insolation, with advancing warm sector conditions featuring temps around 70/low 70s, with dew points into the 60s, and aforementioned steep lapse rates driving moderate instability (1000-1500 j/kg MLCAPE). The impressive wind fields will support extreme deep layer bulk shear and favorable sufficiently orthogonal orientation to likely support discrete or semi-discrete supercells erupting from the Pacific front. Supercells with time to mature south of the warm front will pose greatest risk into the CWA, with strong low level shear (ample speed shear) and sufficient veering from southerly at the surface to south-southwest at 850 mb for hodograph curvature that could support tornadoes, some possibly strong, along with large hail and damaging wind risks inherent to supercells. Storm motions will be very fast off to the northeast, with right moving vectors over 60 mph. At this time, do have concerns with how far north and east into the CWA the more ominous severe risk will be realized given aforementioned uncertainties. However, given the available data and recent trends, placement of SPC Day 2 Moderate Risk into the western CWA appears reasonable given the upper level jet core intersecting the advancing low level theta-e axis favorably in western Illinois and into north central Illinois. ENH extending east-southeast marks possible warm front progress uncertainty, keeping higher probabilities south of city of Chicago for now. Exact timing of cold front will determine how long into the early evening higher coverage of numerous storms extends, with severe risk then quickly ending with frontal passage. While discussion focused on potential for slower/farther west trend with convective initiation, certainly can`t rule out a faster outcome, such as was depicted on the 00z HREF CAM suite. Will continue to highlight given the range in possible outcomes, a timing of severe threat being roughly 4-10pm. Posting LOT’s discussion for posterity because it is a beast. 2 Link to comment Share on other sites More sharing options...
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