baroclinic_instability Posted April 10, 2012 Share Posted April 10, 2012 0Z GFS is definitely going to be beefier with the Saturday wave by the way it is deepening the ULL across the west. It is also slower. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 Trouble...NAM does the same thing at the end of its run too. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted April 10, 2012 Share Posted April 10, 2012 I guess I spoke too soon. The GFS ejection looks weird from 114-126. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 Still has a sub 995 mb low in a very favorable position and a powerful LLJ overlapping the warm sector, better than the 18z run. Link to comment Share on other sites More sharing options...
MnWeatherman Posted April 10, 2012 Share Posted April 10, 2012 Thursday looks fairly interesting across western KS on the NAM, but I'm concerned about the moisture situation. It pools lower 60s dew points, but indicates nasty moisture holes developing farther south, with low-mid 50s prevalent down the dryline in the Panhandles. In my experience, this often means the moisture will end up mixing out farther north anyway, too. If some of the forecast soundings did verify for areas like DDC-GCK and points north up to I-70, there would definitely be a tornadic supercell threat, though. I agree. Thursday COULD be the best setup for tornadoes. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 I agree. Thursday will be the best setup for tornadoes. I think, like CUmet mentioned, that Saturday has the most potential out of any of the days here. Link to comment Share on other sites More sharing options...
tornadotony Posted April 10, 2012 Share Posted April 10, 2012 I agree. Thursday will be the best setup for tornadoes. Way too early to say that. Way too early. Link to comment Share on other sites More sharing options...
Chicago Storm Posted April 10, 2012 Share Posted April 10, 2012 I guess I spoke too soon. The GFS ejection looks weird from 114-126. Too many moving parts. S/w trough ejects too late and/or the PV over the Hudson swings around too early. Link to comment Share on other sites More sharing options...
nwburbschaser Posted April 10, 2012 Share Posted April 10, 2012 I agree. Thursday will be the best setup for tornadoes. Last year on April 9th I went to sleep ready to wake up and chase in Northern Illinois in a High Risk area, and when I woke up the target area had shifted about 250 miles north and was not nearly the outbreak that had been predicted the night before. I clearly remember an outlook on Saturday night saying that an upgrade to High Risk is likely, and it ended up with a downgrade in Illinois. Just saying that it is really early to predict. Link to comment Share on other sites More sharing options...
wx_chip Posted April 10, 2012 Share Posted April 10, 2012 The best upper level energetics are still offshore via nam 0z but with such a broad trough in place, upper level support exists Thurs. With this much moisture already in place, many episodes of convective weather will occur during the entire forecast period. By Fri or Sat many chasers will find roads washed out from the day before and difficult conditions. Flooding will be a serious issue. Link to comment Share on other sites More sharing options...
wx_chip Posted April 10, 2012 Share Posted April 10, 2012 This time last year I was just now calling off the chase having witnessed 7 tornadoes, all at night! (sorry, off topic) Yes things can and will change, quickly at times. Convection will occur...somewhere and some time! Chip Link to comment Share on other sites More sharing options...
nwburbschaser Posted April 10, 2012 Share Posted April 10, 2012 This time last year I was just now calling off the chase having witnessed 7 tornadoes, all at night! (sorry, off topic) Yes things can and will change, quickly at times. Convection will occur...somewhere and some time! Chip That was supposed to be the prelude to Sunday, and in my opinion Saturday night in Iowa was the main show. The cap never broke around here on Sunday though. Just goes to show how much things can change. Link to comment Share on other sites More sharing options...
thewxmann Posted April 10, 2012 Share Posted April 10, 2012 I agree. Thursday COULD be the best setup for tornadoes. Probably not, especially with the way the moisture's been trending. Not unusual for models to overestimate moisture depth and quality by a significant margin this time of year. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 Probably not, especially with the way the moisture's been trending. Not unusual for models to overestimate moisture depth and quality by a significant margin this time of year. Agreed for Thursday, but with the way the trajectories out of the Gulf and Caribbean are setting up, the amount of moisture doesn't seem very unrealistic, at least for Friday and Saturday. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 00z GGEM is going towards its 12z verbatim, btw. Euro is a more GFS-like scenario, but with stronger surface cyclogenesis. Link to comment Share on other sites More sharing options...
CUmet Posted April 10, 2012 Share Posted April 10, 2012 The 00z ECMWF taken verbatim would probably be a major tornado outbreak Saturday over the Central Plains. A 80+ kt 500 mb jet punches right into the warm sector, with a strong LLJ associated with a pretty decent low level cyclone. 60s dewpoints all the way up to southern MN. A very impressive run. Link to comment Share on other sites More sharing options...
thewxmann Posted April 10, 2012 Share Posted April 10, 2012 Agreed for Thursday, but with the way the trajectories out of the Gulf and Caribbean are setting up, the amount of moisture doesn't seem very unrealistic, at least for Friday and Saturday. Oh yeah, for sure. My post was only referring to Thursday. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 Oh yeah, for sure. My post was only referring to Thursday. Cool, understood. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 Thursday. ...CENTRAL/SRN PLAINS...HEIGHT FALLS CONTINUING OVER THE PLAINS STATES ON THU AS THE LEAD SHORTWAVE TROUGH LIFTS NEWD INTO THE NRN PLAINS WILL ALLOW THE LEE TROUGH/DRY LINE TO SHIFT EWD INTO SWRN NEB...WRN KS...ERN TX PANHANDLE AND THEN TRAIL SWWD INTO SW TX BY MID-LATE THU AFTERNOON. MULTI-MODEL ANALYSIS OF THE GFS/ECMWF/NAM DURING THE LAST 24 HOURS SHOWS LOW VARIABILITY IN THE AFOREMENTIONED PLACEMENT OF THE DRY LINE. ELEVATED TSTMS MAY BE ONGOING AT THE START OF D3 ACROSS ERN PARTS OF KS/NEB WITHIN A CORRIDOR OF WAA ALONG A SSWLY LLJ. WHILE THIS ACTIVITY COULD PERSIST THROUGH THE DAY...A GREATER THREAT FOR SEVERE STORMS IS EXPECTED FARTHER W/SW ALONG THE N-S ORIENTED DRY LINE. SLY LOW LEVEL FLOW ACROSS WRN PORTIONS OF THE CENTRAL/SRN PLAINS WILL MAINTAIN NWD MOISTURE ADVECTION WITH SURFACE DEWPOINTS IN THE LOWER 60S REACHING SWRN-SOUTH CENTRAL KS. THIS COMBINED WITH STRONG SURFACE HEATING AND STEEP MIDLEVEL LAPSE RATES SHIFTING EWD ATOP THE DRY LINE WILL SUPPORT A NARROW CORRIDOR OF MODERATE INSTABILITY. EFFECTIVE BULK SHEAR OF 35-50 KT WITH VECTORS ORIENTED PERPENDICULAR TO THE SURFACE BOUNDARY WILL RESULT IN SUPERCELLS CAPABLE OF PRODUCING HAIL...SOME VERY LARGE...AND A TORNADO THREAT. 00z Ukie too: Link to comment Share on other sites More sharing options...
baroclinic_instability Posted April 10, 2012 Share Posted April 10, 2012 UKMET would be nasty too. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 Yeah a 982 mb sfc low with a 80-100+ kt H5 jet punching directly into a weakly capped and moist warm sector can never end well... I'm not so sure we can discount some warm frontal action on both Friday and Saturday as well. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 ICT really beefing up the wording for Friday/Saturday: THURSDAY-SATURDAY:THE MEDIUM RANGE MODELS WERE IN DECENT OVERALL AGREEMENT ON PLACEMENT OF UPPER LEVEL AND LOW-LEVEL SYNOPTIC FEATURES DURING THE PERIOD. THE NAM AND GFS WERE FURTHER WEST WITH THE DRYLINE AND INSTABILITY AXIS THURSDAY AFTERNOON/EVENING AND ARE PREFERRED OVER THE ECMWF. THE SURFACE INSTABILITY AXIS SHOULD LIE WEST OF OUR AREA CLOSER TO THE DRYLINE THURSDAY. SBCINH WILL LIKELY BE HIGH IN OUR AREA THURSDAY PM/NIGHT GIVEN STRONG MOISTURE ADVECTION...EXTENSIVE LOW CLOUDS...AND WIDESPREAD RAIN/THUNDER POTENTIAL. HAVE CUT BACK ON HIGHS THURSDAY. EVEN IF A FEW SUPERCELLS GET GOING NEAR THE DRYLINE THURS PM/EVE TO OUR WEST...THEY WILL LIKELY DISSIPATE OR BECOME ELEVATED BY THE TIME THEY REACH OUR WESTERN COUNTIES. FRIDAY AND SATURDAY LOOK TO BE THE TWO DAYS WITH THE BIGGEST SEVERE WEATHER POTENTIAL IN OUR AREA. A CLASSIC WARM SECTOR SEVERE WEATHER SETUP WILL BE IN PLACE WITH A DRYLINE FROM CENTRAL KS TO WESTERN OK. MODERATE-STRONG INSTABILITY WILL BE IN PLACE EAST OF THE DRYLINE...WITH 50-65 KT DEEP LAYER SHEAR VECTORS CUTTING NEARLY PERPENDICULAR ACROSS THE DRYLINE FAVORING SUPERCELL-TYPE STORMS WITH HIGH-END SEVERE POTENTIAL. TSA: THE FRONT IS EXPECTED TO HAVE CLEARED THE FORECAST AREA BYTHURSDAY EVENING PLACING THE AREA WITHIN THE WARM SECTOR AHEAD OF THE APPROACHING WESTERN TROUGH. WHILE DETAILS WILL GRADUALLY EVOLVE...THERE IS LIKELY TO BE SEVERAL SHORTWAVE TROUGH EJECTING ACROSS THE PLAINS FROM LATE WEEK THROUGH NEXT WEEKEND. EACH WAVE WILL LIKELY SPARK ONE OR MORE AREAS OF SEVERE CONVECTION IN OR NEAR THE AREA. ALSO...THE DRYLINE AND/OR COLD FRONT WILL WORK STEADILY EASTWARD WITH SATURDAY AND SUNDAY APPEARING MOST LIKELY FOR THE MORE WIDESPREAD SEVERE EVENT ACROSS THE FORECAST AREA. TOP: WHILE OPERATIONAL MODELS DIVERGE ON THE SPECIFICS DURING THISPERIOD...AND WITH THE FORECASTING NATURE OF CONVECTIVE WEATHER POTENTIAL SEVERAL DAYS OUT...MUCH IS LEFT TO STILL RESOLVE THAT WILL PLAY A SUBSTANTIAL ROLE IN THE EVOLUTION OF EACH CONVECTIVE EPISODE...IT APPEARS LIKELY THAT ACTIVE WEATHER CAN BE EXPECTED THURSDAY THROUGH SATURDAY. THE POTENTIAL FOR SOME FORM OF SEVERE WEATHER EACH DAY (THU-SAT) AND EVENTUALLY SOME FLOODING CONCERNS ARE ALSO IN THE WORKS WITH THIS SLOW MOVING AMPLIFIED SYSTEM. BOTH FRIDAY AND SATURDAY ARE OF PARTICULAR INTEREST WITH REGARDS TO SEVERE WEATHER OVER PORTIONS OF THE CWA...WITH FORECASTED ENVIRONMENTAL PARAMETERS SUGGESTING THE POSSIBILITY OF SUPERCELLS AND SOME TORNADO RISK. Link to comment Share on other sites More sharing options...
andyhb Posted April 10, 2012 Author Share Posted April 10, 2012 And the latest Day 4-8 maintains the threat for both days and already mentioning tornadic supercells... DAY 4-8 CONVECTIVE OUTLOOKNWS STORM PREDICTION CENTER NORMAN OK 0400 AM CDT TUE APR 10 2012 VALID 131200Z - 181200Z ...DISCUSSION... A LARGE PACIFIC TROUGH WILL CONTINUE TO AMPLIFY SEWD ACROSS CA/NV ON D4/FRI INTO THE SWRN STATES/NRN MEXICO DURING D5/SAT AND D6/SUN RESULTING IN DEEPENING OF THE WRN U.S. LONGWAVE TROUGH. THIS WILL SUSTAIN A SWLY FLOW REGIME EXTENDING FROM NM THROUGH OK/KS TO THE GREAT LAKES REGION DURING FRI-SUN. ON D4...THE GFS DIFFERS WITH THE ECMWF INDICATING A STRONGER SHORTWAVE TROUGH TRACKING ACROSS THE CENTRAL PLAINS TO THE UPPER MS VALLEY. DESPITE THIS DIFFERENCE...EACH MODEL CONTINUES TO MAINTAIN A SIMILAR WARM SECTOR MOISTURE DISTRIBUTION EXTENDING NWD ACROSS OK AND CENTRAL/ERN KS ON D4 AND SHIFTED SLIGHTLY EWD AND EXPANDED IN AREAL COVERAGE ON D5. THE REGIONAL SEVERE WEATHER THREAT AREAS REMAIN SIMILAR FROM PREVIOUS FORECASTS FOR FRI APR 13 AND SAT APR 14. SWLY MIDLEVEL WINDS ARE EXPECTED TO STRENGTHEN ON D4 TO 50-70 KT WITH A FURTHER INCREASE ON D5 AS A 70-90 KT JET MOVES FROM THE BASE OF THE WRN TROUGH INTO THE CENTRAL PLAINS TO THE UPPER MS VALLEY. THESE WINDS COMBINED WITH A STRONG SLY LLJ MAINTAINING RICH LOW LEVEL MOISTURE INTO THE OUTLOOK AREAS WILL RESULT IN A MODERATELY-STRONGLY UNSTABLE WARM SECTOR. VERTICALLY VEERING WIND PROFILES WILL PROMOTE THE POTENTIAL FOR TORNADIC SUPERCELLS ALSO PRODUCING LARGE HAIL AND DAMAGING WINDS. BEYOND D5...MEDIUM RANGE MODELS SUGGEST THE WRN LONGWAVE TROUGH WILL BECOME PROGRESSIVE SHIFTING EWD...BUT MODELS TEND TO DIFFER IN THE TRACK AND TIMING OF THIS TROUGH. STRONG STORMS WILL BE POSSIBLE AGAIN ON D6/SUN ACROSS THE SRN PLAINS...THOUGH WIDESPREAD CONVECTION MAY TEND TO LIMIT A REGIONAL SEVERE WEATHER THREAT. ..PETERS.. 04/10/2012 Link to comment Share on other sites More sharing options...
jdrenken Posted April 10, 2012 Share Posted April 10, 2012 I'm hoping that the warm front plays nice for us here in MO. My friend and I have been watching for a possible chase on Saturday in Northern MO. Link to comment Share on other sites More sharing options...
Superstorm93 Posted April 10, 2012 Share Posted April 10, 2012 I'm hoping that the warm front plays nice for us here in MO. My friend and I have been watching for a possible chase on Saturday in Northern MO. If the HPC is right, you'll be in good shape. http://www.hpc.ncep.noaa.gov/medr/9khwbgpre.gif Link to comment Share on other sites More sharing options...
BryanB Posted April 10, 2012 Share Posted April 10, 2012 Definitely looks like one of the more substantial severe weather risks in and around Kansas City that we have seen in the last couple of years. Link to comment Share on other sites More sharing options...
OceanStWx Posted April 10, 2012 Share Posted April 10, 2012 GFS and ECMWF are in generally good agreement about placement of the jet heading into the late week/weekend. ECMWF is a little muted on the low level instability, but that is usually the case. GFS is pretty bullish on the theta-e lapse rates in the lowest 4 km Friday, and especially Saturday, across the warm sector. Link to comment Share on other sites More sharing options...
tornadotony Posted April 10, 2012 Share Posted April 10, 2012 GFS and ECMWF are in generally good agreement about placement of the jet heading into the late week/weekend. ECMWF is a little muted on the low level instability, but that is usually the case. GFS is pretty bullish on the theta-e lapse rates in the lowest 4 km Friday, and especially Saturday, across the warm sector. It's been a long time, if ever, since I've seen the GFS be as aggressive on instability in the low-levels as it is with this system. It's a bit unnerving. Link to comment Share on other sites More sharing options...
SquatchinNY Posted April 10, 2012 Share Posted April 10, 2012 SPC mentions a tornado threat for THU. THIS COMBINED WITH STRONG SURFACE HEATING AND STEEP MIDLEVEL LAPSE RATES SHIFTING EWD ATOP THE DRY LINE WILL SUPPORT A NARROW CORRIDOR OF MODERATE INSTABILITY. EFFECTIVE BULK SHEAR OF 35-50 KT WITH VECTORS ORIENTED PERPENDICULAR TO THE SURFACE BOUNDARY WILL RESULT IN SUPERCELLS CAPABLE OF PRODUCING HAIL...SOME VERY LARGE...AND A TORNADO THREAT. http://www.spc.noaa.gov/products/outlook/day3otlk.html Link to comment Share on other sites More sharing options...
OceanStWx Posted April 10, 2012 Share Posted April 10, 2012 It's been a long time, if ever, since I've seen the GFS be as aggressive on instability in the low-levels as it is with this system. It's a bit unnerving. It's not necessarily an outlier either. There is at least large scale agreement with the ECMWF, Ukie and NAM (though it is at the end of its range). The CMC is the only guidance that I've seen that takes the jet more meridional. Link to comment Share on other sites More sharing options...
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