CUmet Posted April 11, 2012 Share Posted April 11, 2012 Wow, the 00z ECMWF would be a blockbuster outbreak across the Plains, as would the 00Z UKMET run. As mentioned before, it looks like the GFS is on its own island now w.r.t. not ejecting a piece of the trough on Saturday. Still 4 days out, so there's a lot of details to be resolved, and those details are going to be important because the ejection of the vort max is necessary to amplify the low-level wind fields for the low-level shear. But the Saturday event in particular has a very high ceiling IMO. Link to comment Share on other sites More sharing options...
David Reimer Posted April 11, 2012 Share Posted April 11, 2012 While on the discussion about Saturday, I feel it relevant to point out we have several high-profile events ongoing this weekend in D/FW. One of those events is NASCAR at Texas Motor Speedway, which is northwest of Fort Worth. Link to comment Share on other sites More sharing options...
andyhb Posted April 11, 2012 Author Share Posted April 11, 2012 While on the discussion about Saturday, I feel it relevant to point out we have several high-profile events ongoing this weekend in D/FW. One of those events is NASCAR at Texas Motor Speedway, which is northwest of Fort Worth. That doesn't sound good. Link to comment Share on other sites More sharing options...
MnWeatherman Posted April 11, 2012 Share Posted April 11, 2012 Thursday looks awesome. Large hodos and dryline/warm front setup can't get any better. SPC feeling a bit timid...should beef it up by tomorrow. Link to comment Share on other sites More sharing options...
andyhb Posted April 11, 2012 Author Share Posted April 11, 2012 Thursday looks awesome. Large hodos and dryline/warm front setup can't get any better. SPC feeling a bit timid...should beef it up by tomorrow. One word >> Moisture. But yeah if that possible caveat works itself out, (like the NAM suggests) then Thursday could be big in the region where some of those soundings were pulled earlier. Either way, this is the type of setup with fast moving Plains storms where I become very concerned regarding chaser convergence, since if that Saturday setup verifies, the amount of chasers out is going to be insane. I mean, a possible significant outbreak in prime chaser country, on the weekend... Link to comment Share on other sites More sharing options...
JoMo Posted April 11, 2012 Share Posted April 11, 2012 yeah, not looking forward to this weekend. Timmer seems excited. Link to comment Share on other sites More sharing options...
andyhb Posted April 11, 2012 Author Share Posted April 11, 2012 Friday. Timmer should also be concerned considering these things could be targeting where he lives. ...OK/KS...A DRY LINE IS EXPECTED TO EXTEND SWD FROM THE NEB SURFACE LOW THROUGH CENTRAL KS...WRN OK...THEN SWWD INTO SW TX AT 12Z FRI. GFS/ECMWF SUGGEST THIS BOUNDARY SHIFTS A LITTLE EWD FRI MORNING... BUT BACKING/STRENGTHENING LOW LEVEL WINDS IN RESPONSE TO SURFACE PRESSURE FALLS WITH THE LEE TROUGH ARE EXPECTED TO SUPPORT MOISTURE RETREATING WNWWD. SURFACE DEWPOINTS IN THE LOWER 60S SHOULD EXTEND INTO WRN/NWRN OK BY LATE FRI AFTERNOON AND THEN INTO CENTRAL KS FRI EVENING AS THE SLY LLJ UNDERGOES FURTHER STRENGTHENING. MOST MODELS INDICATED CONVECTION/TSTM DEVELOPMENT COULD OCCUR PRIOR TO PEAK HEATING /BY 18Z/ ACROSS THE WARM SECTOR FROM N TX THROUGH OK TO ERN KS. INCREASING INSTABILITY AND SUFFICIENT DEEP LAYER SHEAR WOULD SUPPORT ORGANIZED STRONG TO SEVERE STORMS WITH THIS ACTIVITY. ADDITIONAL TSTM DEVELOPMENT IS THEN EXPECTED WNWWD LATER FRI AFTERNOON AS THE BOUNDARY LAYER MOISTENS ALONG AND E OF THE RETREATING DRY LINE. STRONG SURFACE HEATING INVOF THIS BOUNDARY AND BENEATH STEEP MIDLEVEL LAPSE RATES SHOULD ALLOW FOR STRONGER INSTABILITY. STRENGTHENING SWLY MIDLEVEL AND SLY LOW LEVEL WINDS ACROSS WILL RESULT IN EFFECTIVE BULK SHEAR UP TO 50 KT ORIENTED PERPENDICULAR TO THE DRY LINE LINE...SUPPORTING THE POTENTIAL FOR TORNADIC SUPERCELLS WITH ADDITIONAL THREATS FOR VERY LARGE HAIL AND DAMAGING WINDS. GIVEN THE STRENGTHENING WIND FIELDS INTO THE EVENING...SEVERE WEATHER THREATS ARE EXPECTED TO PERSIST AFTER DARK INCLUDING A THREAT FOR TORNADOES. THE EARLY WAVE AND IMPACT OF THE MORNING/EARLY AFTERNOON STORMS COULD AFFECT OVERALL DESTABILIZATION...AND THUS LOWER PROBABILITIES WILL BE MAINTAINED...BUT HIGHER PROBABILITIES MAY BE NEEDED IN LATER OUTLOOKS. ..PETERS.. 04/11/2012 Link to comment Share on other sites More sharing options...
andyhb Posted April 11, 2012 Author Share Posted April 11, 2012 And the latest Day 4-8 maintains a large area for Saturday. DAY 4-8 CONVECTIVE OUTLOOKNWS STORM PREDICTION CENTER NORMAN OK 0400 AM CDT WED APR 11 2012 VALID 141200Z - 191200Z ...DISCUSSION... THE GFS/ECMWF EACH MAINTAIN A TROUGH IN THE WEST WITH SWLY FLOW EXPECTED TO BE STRONGER THAN D3/FRI ACROSS OK/KS TO MO/IA...WHILE THE STRONGEST FLOW ON D5/SUN GENERALLY EXTENDS FROM W TX INTO KS. THE GFS CLOSES A LOW ACROSS THE FOUR CORNERS REGION ON D4 SHIFTING IT ENEWD INTO CO/NM ON D5/SUN...WHILE THE ECMWF MAINTAINS THE SRN EXTENT OF THE WRN TROUGH AS AN OPEN WAVE. DESPITE THESE DIFFERENCES...THE OVERALL MOISTURE DISTRIBUTION WITHIN THE WARM SECTOR IS SIMILAR FOR D4 WITH A SURFACE LOW LOCATED ACROSS WRN KS IN AGREEMENT WITH THE MREF. GIVEN THESE SIMILARITIES FOR D4 WITH EACH MODEL INDICATING STRONG VERTICALLY VEERING WIND FIELDS...A REGIONAL SEVERE WEATHER THREAT AREA WILL BE MAINTAINED FOR SAT APR 14 FROM N TX THROUGH MUCH OF OK...CENTRAL/ERN KS INTO NWRN MO/SWRN IA/SERN NEB. TORNADIC SUPERCELLS ALONG WITH VERY LARGE HAIL AND DAMAGING WINDS CAN BE EXPECTED ACROSS THIS REGION. MODEL DIFFERENCES BEYOND D5 PRECLUDE THE INCLUSION OF ANY ADDITIONAL REGIONAL SEVERE WEATHER THREAT AREAS AS THE WRN TROUGH SHIFTS EWD. STRONG TO SEVERE STORMS MAY OCCUR EACH DAY AS EXTENSIVE CONVECTION IS EXPECTED FROM PARTS OF TX THROUGH THE LOWER-MID MS VALLEY TO OH VALLEY THROUGH EARLY NEXT WEEK. ..PETERS.. 04/11/2012 Link to comment Share on other sites More sharing options...
OceanStWx Posted April 11, 2012 Share Posted April 11, 2012 SREF significant tornado ingredients probabilities each evening, Thursday through Saturday. It is now starting to hint at the dry line in Kansas for tomorrow. Link to comment Share on other sites More sharing options...
jdrenken Posted April 11, 2012 Share Posted April 11, 2012 This is why the SPC is holding back on highlighting areas after Day 4. It's also another reason why I've been on the mindset that the NHC needs to continue Pacific Flights during the severe weather season. No sampling means model variability! Link to comment Share on other sites More sharing options...
Srain Posted April 11, 2012 Share Posted April 11, 2012 This is why the SPC is holding back on highlighting areas after Day 4. It's also another reason why I've been on the mindset that the NHC needs to continue Pacific Flights during the severe weather season. No sampling means model variability! The NHC does not task flights for the Pacific for severe weather or winter storms. Also with budget constraints, NOAA G-IV missions are becoming very difficult to come by. Edit to add: We probably need to extend the severe threat for the 16th as well... Link to comment Share on other sites More sharing options...
OceanStWx Posted April 11, 2012 Share Posted April 11, 2012 Here is an overlay I have of 0-4 km theta-e lapse rates and 300 mb jet speed. Generally speaking the overlap in the two is good for severe weather. This is the 11/06z GFS run, and it is the first to really show the overlap along the warm front in Iowa into Illinois. Between 70 and 90 knots on the southern fringe of the main jet core over the top of -4 to -5 deg/km would be more than sufficient for warm frontal action. Link to comment Share on other sites More sharing options...
CoastalWx Posted April 11, 2012 Share Posted April 11, 2012 Although it's the 16th, eastern TX could be kind of interesting with that setup. Link to comment Share on other sites More sharing options...
Srain Posted April 11, 2012 Share Posted April 11, 2012 Although it's the 16th, eastern TX could be kind of interesting with that setup. I agree. The local chatter (EWX/HGX/FWD/LCH/SHV) has been rather interesting for several days for points along and E of the I-35 Corridor. Link to comment Share on other sites More sharing options...
LocoAko Posted April 11, 2012 Share Posted April 11, 2012 Here is the Hill City, KS 0z NAM sounding valid at 7pm cdt Thursday evening. I know I'm late on this, but wow. I haven't seen as many soundings as many others here but that is astounding... Not incredibly amazing on the instability front but the wind profile looks as good as it possibly could. Link to comment Share on other sites More sharing options...
David Reimer Posted April 11, 2012 Share Posted April 11, 2012 12Z NAM: Kinsley, Kansas at 0Z Friday Link to comment Share on other sites More sharing options...
JoMo Posted April 11, 2012 Share Posted April 11, 2012 09z SREF for Sat continues to increase the sigtor Link to comment Share on other sites More sharing options...
Thundersnow12 Posted April 11, 2012 Share Posted April 11, 2012 popping at 30 at this range is impressive. Link to comment Share on other sites More sharing options...
OceanStWx Posted April 11, 2012 Share Posted April 11, 2012 09z SREF for Sat continues to increase the sigtor Showing a warm frontal extension of higher probabilities to the east as well. Link to comment Share on other sites More sharing options...
Ed Lizard Posted April 11, 2012 Share Posted April 11, 2012 While on the discussion about Saturday, I feel it relevant to point out we have several high-profile events ongoing this weekend in D/FW. One of those events is NASCAR at Texas Motor Speedway, which is northwest of Fort Worth. Verbatim, Euro QPF is nuisance rains until after the race should be over Saturday night. AFW is the location for looking up forecast soundings, only ~5 miles from TMS. I'm glass half full optimistic that the races themselves will be ok. The large crowd that attends in motor homes and will no doubt stay at least until Sunday morning might be another issue. Link to comment Share on other sites More sharing options...
David Reimer Posted April 11, 2012 Share Posted April 11, 2012 The 12Z NAM is pretty scary for Texas, Oklahoma, and Kansas on Saturday... Link to comment Share on other sites More sharing options...
brettjrob Posted April 11, 2012 Share Posted April 11, 2012 I'm in awe of the 12z NAM. I've never seen a multi-day event quite like this forecast for the southern Plains, no matter the time of year. Saturday has the makings of a monster day that could find its way onto lists with impressive company. Confidence in that sort of outcome is beginning to increase, too, with prior convective evolution the only major caveat I see right now. I think if a student were asked to draw a classic OK/KS outbreak scenario and traced the kinematics and thermodynamics from the 12z NAM for 00z Sunday, they'd get extra credit. Link to comment Share on other sites More sharing options...
CoastalWx Posted April 11, 2012 Share Posted April 11, 2012 Even that tongue of instability moving into NE looks nice. Don't have the giant CAPE but enough shear and CAPE possibly..along with upslope flow sometimes forms those fast moving mesos. Link to comment Share on other sites More sharing options...
OceanStWx Posted April 11, 2012 Share Posted April 11, 2012 Hodograph from the vicinity of the warm front in southeastern Nebraska late afternoon Saturday. Nice curvature in the lower 1.5 km, often times very important signature for significant tornadoes. Link to comment Share on other sites More sharing options...
aurora Posted April 11, 2012 Share Posted April 11, 2012 While we're talking about high profile events, the Oklahoma Sooners have their Red & White spring football game at 2 p.m. on Saturday, so about 30,000 extra people will be in Norman... Link to comment Share on other sites More sharing options...
Ed Lizard Posted April 11, 2012 Share Posted April 11, 2012 I'm in awe of the 12z NAM. I've never seen a multi-day event quite like this forecast for the southern Plains, no matter the time of year. Saturday has the makings of a monster day that could find its way onto lists with impressive company. Confidence in that sort of outcome is beginning to increase, too, with prior convective evolution the only major caveat I see right now. I think if a student were asked to draw a classic OK/KS outbreak scenario and traced the kinematics and thermodynamics from the 12z NAM for 00z Sunday, they'd get extra credit. Kansas I-35 corridor, >2000 J/Kg MUCape, 25 m/s (~50 knots) deep layer shear, and backed low level winds, I almosr regret being away from the TV/computer Saturday evening. Link to comment Share on other sites More sharing options...
Chad A Posted April 11, 2012 Share Posted April 11, 2012 While we're talking about high profile events, the Oklahoma Sooners have their Red & White spring football game at 2 p.m. on Saturday, so about 30,000 extra people will be in Norman... Same deal in Lincoln, Nebraska. Nebraska Cornhuskers football Spring game - kickoff at 1 pm. Add another 50,000 or so to Lincoln, all trying to drive home to various places in Omaha, Grand Island, Hastings, Kansas City, etc... at 5 pm. Link to comment Share on other sites More sharing options...
andyhb Posted April 11, 2012 Author Share Posted April 11, 2012 Confidence in that sort of outcome is beginning to increase, too, with prior convective evolution the only major caveat I see right now. With the strength of theta-e inflow I'm not sure how much that is going to negatively affect this, there also could be major OFB problems here. I just saved that image that Ed posted, that is disgusting... Link to comment Share on other sites More sharing options...
brettjrob Posted April 11, 2012 Share Posted April 11, 2012 This fairly well summarizes the NAM's position on Saturday's event, I think: Link to comment Share on other sites More sharing options...
David Reimer Posted April 11, 2012 Share Posted April 11, 2012 This fairly well summarizes the NAM's position on Saturday's event, I think: Looks like our yearly OKC Tornado Outbreak is coming early this year. The chaser convergence is going to be unbelievable and apparently law enforcement is already planning to do their rolling road blocks. Link to comment Share on other sites More sharing options...
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