RCNYILWX Posted April 7, 2015 Share Posted April 7, 2015 Here's the sounding for near RFD on the 00z NAM at 00Z Thursday evening: Link to comment Share on other sites More sharing options...
cyclone77 Posted April 7, 2015 Share Posted April 7, 2015 I'm not too concerned about the uni-flow above H8, as the stretching above that level, combined with incoming vorticity advection, and lowering LCLs with ongoing sups should help to enhance supercell characteristics. With the crosswise vorticity above the BL it may take a split to kick the dominant right storm into tor mode, but that's splitting hairs at this point lol. EDIT: No pun intended lol Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 7, 2015 Share Posted April 7, 2015 Big shift on the 00z GFS toward a more NAM like solution regarding surface low track and timing and more backing of the surface winds between 21 and 00z (SW to closer to due south) on Thursday over northern IL. 00z GFS at 00z: 18z GFS at 21z Thursday (frontal passage in progress at 00z Thursday on 18z run): Link to comment Share on other sites More sharing options...
OceanStWx Posted April 7, 2015 Share Posted April 7, 2015 With things slowing down for Wednesday to the west, things in our subforum are actually looking a bit up for Thursday compared to previous runs. I like Eastern IA/Northern IL a lot actually on the latest runs. My interest is piqued for sure, especially if we can get a surface low track similar to the NAM/GFS/GEM. Link to comment Share on other sites More sharing options...
A-L-E-K Posted April 7, 2015 Share Posted April 7, 2015 stoked for my rapidly weakening linear mcs looks dope out cyclone way Link to comment Share on other sites More sharing options...
huronicane Posted April 7, 2015 Share Posted April 7, 2015 And the GFS takes it back to looking much more linear. Link to comment Share on other sites More sharing options...
Indystorm Posted April 7, 2015 Share Posted April 7, 2015 06NAM has STP of 6-7 just west of Chicago in the Fox river valley at 00z Friday. STP of 4 in the city near the lake. Link to comment Share on other sites More sharing options...
Tim from Springfield (IL) Posted April 7, 2015 Author Share Posted April 7, 2015 Might as well add today's marginal threat to this thread--Severe Thunderstorm Watch issued an hour ago for most of the St. Louis metro, and SW IL until 2PM: http://www.spc.noaa.gov/products/watch/ww0027.html Link to comment Share on other sites More sharing options...
Gilbertfly Posted April 7, 2015 Share Posted April 7, 2015 12z 12k goes down to 993 with what looks like some discrete action Link to comment Share on other sites More sharing options...
Chicago Storm Posted April 7, 2015 Share Posted April 7, 2015 Link to comment Share on other sites More sharing options...
A-L-E-K Posted April 7, 2015 Share Posted April 7, 2015 nice look, timing is crap for the city but should still see some decent sloppy seconds Link to comment Share on other sites More sharing options...
Chicago Storm Posted April 7, 2015 Share Posted April 7, 2015 nice look, timing is crap for the city but should still see some decent sloppy secondsAs long as all goes well, I think you're underplaying it.It's not like it'll be coming through at 5AM. It'll be around 0z. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 7, 2015 Share Posted April 7, 2015 As long as all goes well, I think you're underplaying it. It's not like it'll be coming through at 5AM. It'll be around 0z. Exactly my thoughts per the 4km and 12km NAM. The next sim ref frame, valid at 00z on the 4km, is still a broken line of discrete supercells headed for the metro. You can see the individual cell tracks on the 3hr precip valid at 00z. Given the strong kinematics with a deepening low, severe/tornado threat will last longer beyond sunset than is typical, and in this case it'll be right after sunset, so the city would certainly be in the game if something like the NAM happened. Link to comment Share on other sites More sharing options...
chase_stormz Posted April 7, 2015 Share Posted April 7, 2015 Exactly my thoughts per the 4km and 12km NAM. The next sim ref frame, valid at 00z on the 4km, is still a broken line of discrete supercells headed for the metro. You can see the individual cell tracks on the 3hr precip valid at 00z. Given the strong kinematics with a deepening low, severe/tornado threat will last longer beyond sunset than is typical, and in this case it'll be right after sunset, so the city would certainly be in the game if something like the NAM happened. Any chance that could be posted? Link to comment Share on other sites More sharing options...
Thundersnow12 Posted April 7, 2015 Share Posted April 7, 2015 As long as all goes well, I think you're underplaying it. It's not like it'll be coming through at 5AM. It'll be around 0z. He is. Has been a sig tor bullseye over the city at 0z for a few runs now just as storms over into the heart of the metro. Link to comment Share on other sites More sharing options...
huronicane Posted April 7, 2015 Share Posted April 7, 2015 Will have to see how the earlier in the day convection moves out. If there's good clearing and heating between the two rounds...look out. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 7, 2015 Share Posted April 7, 2015 Any chance that could be posted? Link to comment Share on other sites More sharing options...
Hoosier Posted April 7, 2015 Share Posted April 7, 2015 Internet running really slow for me for some reason so doing a dprog/dt would take extra time but if anything, it seems like the 12z NAM sped up a little compared to 00z, which would put Chicago proper into a greater risk zone. Link to comment Share on other sites More sharing options...
Gilbertfly Posted April 7, 2015 Share Posted April 7, 2015 Internet running really slow for me for some reason so doing a dprog/dt would take extra time but if anything, it seems like the 12z NAM sped up a little compared to 00z, which would put Chicago proper into a greater risk zone. and also maintained strength of the SLP a little longer too...which could also provide for some longer maintenance if things "work out" Link to comment Share on other sites More sharing options...
Thundersnow12 Posted April 7, 2015 Share Posted April 7, 2015 Internet running really slow for me for some reason so doing a dprog/dt would take extra time but if anything, it seems like the 12z NAM sped up a little compared to 00z, which would put Chicago proper into a greater risk zone. yeah looks like it did speed up to me when comparing sfc low locations at 21z Thursday to previous runs. Link to comment Share on other sites More sharing options...
Chargers09 Posted April 7, 2015 Share Posted April 7, 2015 Any chance for some warm front action in Michigan before the main show with the cold front late? Link to comment Share on other sites More sharing options...
IWXwx Posted April 7, 2015 Share Posted April 7, 2015 Any chance for some warm front action in Michigan before the main show with the cold front late? The simulated NAM reflectivity that Ricky posted above depicts discrete cells in West Central Lower MI at 0z Friday. Link to comment Share on other sites More sharing options...
Stebo Posted April 7, 2015 Share Posted April 7, 2015 Any chance for some warm front action in Michigan before the main show with the cold front late? I think the west side of the state has some chances, though I wouldn't write off the entire warm front. I do think there will be some morning convection as well. Link to comment Share on other sites More sharing options...
Stebo Posted April 7, 2015 Share Posted April 7, 2015 Internet running really slow for me for some reason so doing a dprog/dt would take extra time but if anything, it seems like the 12z NAM sped up a little compared to 00z, which would put Chicago proper into a greater risk zone. Yeah the 4km nam is looking pretty stout for west of Chicago and into Chicago between 21z-00z Link to comment Share on other sites More sharing options...
Powerball Posted April 7, 2015 Share Posted April 7, 2015 Not saying much, but this will probably be Detroit's best shot for severe weather thus far. Timing and placement of the synoptic features is unfavorable as things stand right now, but we're still 2-3 days out. It will ultimately be the mesoscale features from the previous day's convection that determines how widespread the severe t'storms are and where they develop/track. One thing's for sure, I'd rather not be on the far western and northern edge of the higher risk area this far out. Link to comment Share on other sites More sharing options...
huronicane Posted April 7, 2015 Share Posted April 7, 2015 LOT tosses out the O word Link to comment Share on other sites More sharing options...
Chitown Storm Posted April 7, 2015 Share Posted April 7, 2015 Some nice hail reports in those cells south of Mankato, MN Link to comment Share on other sites More sharing options...
Stebo Posted April 7, 2015 Share Posted April 7, 2015 GRR's thoughts on Thursday: THE PRIMARY FOCUS IS ON THE SEVERE WEATHER POTENTIAL FOR THURSDAYINCLUDING DAMAGING WINDS AND LARGE HAIL. A TORNADO THREAT LOOKS TOEXIST AS WELL. CURRENT GUIDANCE INDICATES THAT THE MAIN THREAT ISLATER IN THE DAY... PARTICULARLY 21Z-03Z. A LOT OF KEY SYNOPTICINGREDIENTS FOR SEVERE WEATHER APPEAR TO BE PRESENT LATE THURSDAYBUT INSTABILITY AND THE FINER DETAILS ARE STILL BIG WILDCARDS.THERE IS A COUPLED UPPER LEVEL JET STRUCTURE THURSDAY WITH A POTENTMID LEVEL SHORTWAVE AND DEEPENING SFC LOW LIFTING NORTHEAST THROUGHTHE WESTERN GRTLKS REGION. A 75-90 KT H5 MID LEVEL JET AND A 50 KTH8 LOW LEVEL JET LEAD TO DEEP LAYER SHEAR IN EXCESS OF 40 KTS.PLENTY OF SHEAR IS ALSO PROGGED DOWN LOW WITH 0-3KM AND 0-1KM SHEARVALUES NEAR OR IN EXCESS OF 30 KTS. IT SHOULD BE NOTED THAT THEECMWF IS NOT AS AMPLIFIED WITH THE MID LEVEL SHORTWAVE AND HAS AMUCH WEAKER AND FARTHER EAST SFC LOW.IT SEEMS MUCH OF THE SEVERE WX THREAT HINGES ON HOW LONG CLOUDS ANDPRECIP LINGER ON THURSDAY AND HOW QUICKLY THE WARM SECTOR CAN SURGENORTH. FREQUENTLY IN THESE TYPE OF SET UPS THE ELEVATED CONVECTIONNORTH OF THE WARM FRONT THROUGH THE DAY CAN HINDER THE NORTHWARDPROGRESS OF THE SFC WARM FRONT. GUIDANCE CURRENTLY SUGGEST THAT ITMAY TAKE UNTIL AFTER 21Z THURSDAY TO DEVELOP SUFFICIENT SFC BASEDCAPE IN THE WARM SECTOR... LEAVING A ONLY A RELATIVELY NARROW PERIODTO WORK WITH WHEN BOTH THE SHEAR AND INSTABILITY ARE PRESENTTOGETHER. Link to comment Share on other sites More sharing options...
Kaner88 Posted April 7, 2015 Share Posted April 7, 2015 Impressive/ominous AFD out of LOT. .LONG TERM...327 PM CDTTHURSDAY NIGHT THROUGH TUESDAY...PRIMARY TROUGH IS STILL PROGGED TO MOVE QUICKLY EASTWARD AND INTOTHE MIDWEST BY THURSDAY AFTERNOON. GUIDANCE VARIES SOME WITH RESPECTTO TIMING/INTENSITY OF THIS SYSTEM WITH 12Z ECMWF ON THEFASTER/WEAKER END OF THE GUIDANCE SPECTRUM AND THE NAM/GEM ON THESLOWER DEEPER END OF THE SPECTRUM. OFTEN TIMES THE SLOWER GUIDANCEENDS UP VERIFYING BETTER WITH THESE STRONGER SYSTEMS...SO TRENDEDTHE GRIDS TOWARD THE NAM/GEM SOLUTION. THE GFS SUPPORTS THE IDEA OFSTRONGER SYSTEM BUT SUSPECT IT IS A BIT TOO FAST.SYNOPTICALLY SPEAKING THE LARGE SCALE PATTERN AND EVOLUTION OF THISCYCLONE CONTINUE TO RAISE RED FLAGS FOR THE POTENTIAL OF ASIGNIFICANT SEVERE WEATHER EPISODE IN THE REGION THURSDAY AFTERNOONAND EVENING. THE KINEMATIC FIELDS ARE EXTREMELY IMPRESSIVE WITH 90-100KT UPPER LEVEL JET NOSING INTO THE REGION IN THE AFTERNOON WITH40KT+ LOW LEVEL JET RESULTING IN VERY FAVORABLE DEEP LAYER SHEARPROFILE FOR SEVERE WEATHER. THE MAGNITUDE OF LOW LEVEL SHEAR WHICHWILL PLAY A ROLE IN THE MAGNITUDE OF A TORNADO THREAT VARIESDEPENDING ON THE MODEL. THE DEEPER SOLUTIONS HAVE A MORE BACKEDSURFACE FLOW AND LARGER LOW LEVEL HODOGRAPHS AND WOULD BE MUCH MOREWORRISOME REGARDING TORNADO THREAT.THE LATEST MODEL RUNS THIS MORNING ALSO SUGGEST AN UNUSUALLYIMPRESSIVE PLUME OF STEEP MID LEVEL LAPSE RATES FOR SO FAR EASTWARDBECOME JUXTAPOSED OVER TOP A WARM AND HUMID AIR MASS WITH SURFACEDEWPOINTS LIKELY IN THE 60S WITHIN THE WARM SECTOR. GIVEN THEPROGGED INTENSITY OF THE SYSTEM SUSPECT THAT EVEN MORNING CONVECTIONWILL NOT BE ENOUGH TO PREVENT THE WARM FRONT FROM BLASTING NORTH ANDPLACING ENTIRE CWA IN THE HUMID/UNSTABLE WARM SECTOR BY AFTERNOON.OBVIOUSLY THERE ARE A TON OF MESOSCALE DETAILS THAT CANNOT BERESOLVED AT THIS DISTANCE...INCLUDING STORM MODE AND COVERAGE. THEREIS A LOT THAT CAN CHANGE BETWEEN NOW AND THURSDAY SO A SIGNIFICANTSEVERE WEATHER EVENT IS FAR FROM A SURE THING...BUT GIVEN THE TRENDSIN MODEL GUIDANCE AND SYNOPTIC PATTERN THERE IS DEFINITELY REASONFOR CONCERN ABOUT THE SEVERE WEATHER AND TORNADO POTENTIAL THURSDAYAFTERNOON AND EVENING. Link to comment Share on other sites More sharing options...
Gilbertfly Posted April 7, 2015 Share Posted April 7, 2015 Thursday is going to be one of those days where I see those low level clouds hauling arse north...typically leads to some decent storm potential in and around the area... 18z 12k holds serve with some discrete action into the metro 4k brings her down to 991 in SW Wisco at 21Z with discrete action starting to rip Link to comment Share on other sites More sharing options...
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