snowstormcanuck Posted February 25, 2011 Share Posted February 25, 2011 A lot of reasons--but convection played a huge role--so it does seem it was not negative convective feedback that the NCEP (NAM/GFS) were hitting on. It was such a tough forecast for this reason. We knew convection would play a role in strong pressure falls--just how much that would "drive" storm track was unclear. It does seem convection is playing a large role with this storm heading a bit more E though. speak of the devil. Link to comment Share on other sites More sharing options...
Stevo6899 Posted February 25, 2011 Share Posted February 25, 2011 A lot of reasons--but convection played a huge role--so it does seem it was not negative convective feedback that the NCEP (NAM/GFS) were hitting on. It was such a tough forecast for this reason. We knew convection would play a role in strong pressure falls--just how much that would "drive" storm track was unclear. It does seem convection is playing a large role with this storm heading a bit more E though. Makes sense. I thought the more convection the better chance it would go more north because I thought convection might signal strength. Thanks for the input Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 25, 2011 Share Posted February 25, 2011 That was a much more vigorous upper level system that was able to curl the sfc system NW as it intensified. H5 with this system is fairly meager, which has allowed that deep convection developing over the lower MS valley to dictate the direction of the sfc low. That's my layman's interpretation of what b_i was saying yesterday. Maybe he could illuminate you further. No illuminating needed. You pretty much said it. The upper level wave configuration was completely different and that system was a partial phase job with a deep elongated polar vortex intruding into the CONUS. That storm was essentially a deepening negative tilt longwave trough after phasing with a boatload more of potential energy and much deeper tropospheric deep baroclinity. This is mainly an upper tropospheric wave, positive tilt, with a much "shallower" overall depth that the groundhog storm. The groundhog day storm had the mother of all coupled jet circulations too--historic storm for a reason. The potential energy with this storm--as impressive as it is--is probably an order of magnitude less than the GroundHogs Day beast. Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 25, 2011 Share Posted February 25, 2011 Makes sense. I thought the more convection the better chance it would go more north because I thought convection might signal strength. Thanks for the input Well were this negative tilt it would have been different--but strong pressure falls along the triple point/warm front (this surface low will track along the warm front essentially with only minimal lifting of the front--mainly as the storm heads eastward and the upper wave amplifies a bit more) associated with convection means this takes a more latitudinal track than a meridional track since negative tilt storms typically have warm fronts/advection patterns that develop much farther N and even wrap around the system if the storm is intense enough (TROWAL = Trough Of Warm Air Aloft). Link to comment Share on other sites More sharing options...
cheezemm Posted February 25, 2011 Share Posted February 25, 2011 31.6 degrees IMBY here in Akron area......will be interesting to see if the cold air holds strong. Should I expect a slight rise in temperature as the low approaches or will precip cool the column? Link to comment Share on other sites More sharing options...
Stevo6899 Posted February 25, 2011 Share Posted February 25, 2011 Well were this negative tilt it would have been different--but strong pressure falls along the triple point/warm front (this surface low will track along the warm front essentially with only minimal lifting of the front--mainly as the storm heads eastward and the upper wave amplifies a bit more) associated with convection means this takes a more latitudinal track than a meridional track since negative tilt storms typically have warm fronts/advection patterns that develop much farther N and even wrap around the system if the storm is intense enough (TROWAL). So basically the lack of a northern stream or energy is not allowing this to go negative. Also it's taking longer to intensify which is lamens terms for why it's going more east. The more in depth info explains the reasoning behind that. So much going on it's hard to process it all. Appreciate the reasoning. Link to comment Share on other sites More sharing options...
CoastalWx Posted February 25, 2011 Share Posted February 25, 2011 Snow looks like it's following the classic mid level frontogenesis and deformation areas of se Iowa. Link to comment Share on other sites More sharing options...
LizardMafia Posted February 25, 2011 Share Posted February 25, 2011 Currently sitting at 34F IMBY. Winds have definitely picked up over last couple of hours. Not much can do, so might as well embrace the snow! Link to comment Share on other sites More sharing options...
Trent Posted February 25, 2011 Share Posted February 25, 2011 Through 9 am. Link to comment Share on other sites More sharing options...
hawkeye_wx Posted February 25, 2011 Share Posted February 25, 2011 AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 718 PM CST THU FEB 24 2011. UPDATE... SENT UPDATE TO LOWER SNOW AMOUNTS. FIRST PROBLEM IS MASSIVE DRY WEDGE SEEN ON KDVN 00Z RAOB AND STRENGTHENING LOW LEVEL NORTHEAST WINDS... WHICH HAS KEPT SNOW AT BAY FOR MUCH OF THE AREA. HAVE BEEN SEEING SNOW INCREASE FROM NEAR TO SOUTH OF KCID TO KAWG IN REGION OF STRONG 600 MB FRONTOGENETICAL FORCING... AND SOME MOSTLY LIGHTER SNOW INTO SOUTHEAST IA AND NORTHEAST MO AHEAD OF 850 MB AND 700 MB LOWS IN PERSISTENT WARM ADVECTION. PROBLEM THERE IS TEMPS HAVE BEEN AT OR JUST ABOVE FREEZING MARK THUS SNOW UNLESS HEAVY HAS BEEN MELTING OR COMPACTING IF ANY ACCUM. ANOTHER PROBLEM IS MAIN MOIST CONVEYOR EXPECTED TO FEED SIGNIFICANT SNOWFALL CONTINUES SHIFTING EASTWARD THROUGH DOWNSTATE IL... AS SUPPORTED BY PRESSURE FALLS... AND NOT MOVING NORTHWARD THUS CWA IS MISSING THE STRONGEST MOISTURE FEED. EVEN SO... WILL SEE SNOW MOST OF AREA BETWEEN COMBINATION OF MID LEVEL FRONTOGENESIS AND DEFORMATION SWEEPING THROUGH SOUTHEAST 1/2 TO 2/3 OF CWA... WITH SNOW MODERATE TO LOCALLY HEAVY AT TIMES. BUT DUE TO SLOWER ONSET...BETTER MOISTURE AND DYNAMICS SOUTH...HAVE LOWERED SNOW AMOUNTS AND WILL BE WATCHING TRENDS FOR NEEDING TO POSSIBLY LOWER SOME MORE. INCREASINGLY CONCERNED THAT COMBINATION OF VERY DRY AIR 900-700 MB AND WEAKENING MID LEVEL FRONTOGENESIS MAY RESULT IN NOT MUCH IN WAY OF SNOW FOR AREAS FROM QUAD CITIES NORTHEASTWARD. HAVE CANCELLED ADVISORY FOR CARROLL COUNTY. RADAR TRENDS BEARING OUT THE SNOW/NO SNOW LINEFROM JUST NORTH OF KCID AIRPORT TO NEAR KFEP. Link to comment Share on other sites More sharing options...
michsnowfreak Posted February 25, 2011 Share Posted February 25, 2011 Hit 36 today, snow compacted about an inch. Depth now a very heavy 7" (water content 1.2"). Getting excited. Will miss the heaviest snow to the south, but its a special night as Detroit will be snowing its way into the record books. February 2011 will become just the 4th calendar month on record (131 years) to have 30+ inches of snow officially. Link to comment Share on other sites More sharing options...
afterimage Posted February 25, 2011 Share Posted February 25, 2011 Through 9 am. red dots look like MBY Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 25, 2011 Author Share Posted February 25, 2011 LOT just cancelled the WWA for the northern tier of counties in their CWA. Link to comment Share on other sites More sharing options...
snowstormcanuck Posted February 25, 2011 Share Posted February 25, 2011 NAM weaker and south. Surprise surprise. Link to comment Share on other sites More sharing options...
Toronto4 Posted February 25, 2011 Share Posted February 25, 2011 NAM weaker and south. Surprise surprise. Completely different from the 00z RUC. This one is going down to the wire. It's either boom or bust. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 25, 2011 Share Posted February 25, 2011 LOT just cancelled the WWA for the northern tier of counties in their CWA. You and I are cancelling it for Kane co. lol Link to comment Share on other sites More sharing options...
snowstormcanuck Posted February 25, 2011 Share Posted February 25, 2011 Completely different from the 00z RUC. This one is going down to the wire. It's either boom or bust. We'll have to see over the next couple of hours. Low track south of the OH river, we're toast. Hugs or north, we're ok. Link to comment Share on other sites More sharing options...
CoastalWx Posted February 25, 2011 Share Posted February 25, 2011 Baroclinic_Instability, where do you get those great tropopause maps? I love those. Link to comment Share on other sites More sharing options...
michsnowfreak Posted February 25, 2011 Share Posted February 25, 2011 Wow the NAM has an insane gradient now. It has Monroe county solidly in the 0.5+ qpf zone (something it didnt have at 12/6z), Im still looking good...but the cutoff NW of Detroit is scary. Hope its not such a sharp cutoff. Link to comment Share on other sites More sharing options...
Harry Posted February 25, 2011 Share Posted February 25, 2011 Completely different from the 00z RUC. This one is going down to the wire. It's either boom or bust. Yeah i would not write this off yet if i were as far east as you guys are. Out this way? Oh heck yeah. I have never ever seen anything work out with the surface low taking a track so far south and i full expect a near shutout with 2-3 max if i am very lucky. This has shades of March 08 written all over it ( just a slight bit farther to the nw this go around ) and that was a shut out here. BTW. The euro did kinda sh!t the bed with this as did it's ensembles. See the start of the thread and last one and see how many runs of both brought better snows up this way and tracked the surface low to near Cleveland. Gonna be one of the bigger euro/euro ensemble busts i have seen recently in it's supposed hot zone of day 2-3/5. However i did warn that this system touched on a euro weak spot and thus see the northern system that brought the convective snows up this way last night. That ended up stronger and pushed the confluence etc zone a little farther south as the GFS/NAM had been hinting at. Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 25, 2011 Author Share Posted February 25, 2011 LOT: 736 PM CST SOME ADJUSTMENTS TO THE GOING HEADLINES TONIGHT. OPEN WAVES HAVE A TENDENCY TO POSE SIGNIFICANT CHALLENGES TO FORECASTS...WHICH IS THE CASE THIS EVENING IN REGARDS TO THE PRECISE PLACEMENT AND TRACK OF THE LOW PRESSURE. HI-RES GUIDANCE CONTINUES TO INDICATE A SLIGHTLY FURTHER SOUTH PATH OF THE SFC LOW PRESSURE...ACROSS EXTREME SOUTHERN IL/IN WITH THE 850MB LOW DISPLACED JUST TO THE NORTHWEST. A WEAK FRONTOGENETIC BAND THIS EVENING WAS LOCATED ACROSS WINNEBAGO COUNTY STRETCHED SOUTHWEST THROUGH CENTRAL IA...HOWEVER CURRENT RADAR TRENDS HAS BEEN SHOWING WEAKENING TO THIS BAND AND A SOUTHEAST TREND. GUIDANCE SUGGESTS THAT SNOWFALL TOTALS WILL NOT BE AS HIGH FURTHER NORTH ALONG THE FAR NORTHERN ROW OF COUNTIES IN IL...THUS HAVE CANCELLED THE ADVISORY FOR THESE LOCATIONS WHERE IT APPEARS 1 TO 3 INCHES IS NOW EXPECTED. ELSEWHERE A SECOND DEFORMATION ZONE APPEARS TO BE TRYING TO FORM ACROSS CENTRAL IL SLIDING NORTHEAST THROUGH A PORTION OF THE CURRENT WARNING AREAS OF OUR CWFA. THE WILDCARD CONTINUES TO BE A DRY WEDGE THAT LATEST GUIDANCE IS NOW BEGINNING TO HAVE A BETTER HANDLE ON. 21Z SREF CONTINUES TO PROG A LARGE REGION OF A POTENT EASTERLY/NORTHEASTERLY JET OF 40KT ACROSS MUCH OF CENTRAL/SOUTHERN CWFA. WRAP AROUND MOISTURE AND FORCING SHOULD AID IN ENHANCING SNOWFALL OVERNIGHT FOR CENTRAL/SOUTHERN PORTIONS OF THE CWFA WHERE THE HEADLINES WILL REMAIN UNTOUCHED. ACROSS THE SOUTHERN TIER TEMPERATURES WILL CONTINUE TO DYNAMICALLY COOL...AS ONSET OF PRECIP WILL BE A MIX OF RA/IP BEFORE BECOMING ALL SN. ISOALLOBARIC PRES CHG FROM RUC/NAM CONTINUE TO SHOW A 3HR PRES CHG OF 3-5MB BETWEEN 06-09Z...WHICH CONTINUES TO SUPPORT THE WIND GUSTS OF 25 TO 30 MPH...WITH OCCASIONAL GUSTS TO 35MPH ESPECIALLY ALONG THE IMMEDIATE LAKESHORE. Link to comment Share on other sites More sharing options...
snowstormcanuck Posted February 25, 2011 Share Posted February 25, 2011 Yeah i would not write this off yet if i were as far east as you guys are. Out this way? Oh heck yeah. I have never ever seen anything work out with the surface low taking a track so far south and i full expect a near shutout with 2-3 max if i am very lucky. This has shades of March 08 written all over it ( just a slight bit farther to the nw this go around ) and that was a shut out here. BTW. The euro did kinda sh!t the bed with this as did it's ensembles. See the start of the thread and last one and see how many runs of both brought better snows up this way and tracked the surface low to near Cleveland. Gonna be one of the bigger euro/euro ensemble busts i have seen recently in it's supposed hot zone of day 2-3/5. However i did warn that this system touched on a euro weak spot and thus see the northern system that brought the convective snows up this way last night. That ended up stronger and pushed the confluence etc zone a little farther south as the GFS/NAM had been hinting at. If the 0z NAM track verifies, the sfc low track will end closer to the GFS than the EURO. So I retract what I said earlier about giving the EURO the gold. Not sure if I wrote that before the 12z models had come out, because I was somewhat cocky about them coming back NW. Link to comment Share on other sites More sharing options...
STL Posted February 25, 2011 Share Posted February 25, 2011 I've been under green on the radar for a good hour in Macomb, Il. It hasn't even snowed yet. The dry air is really eating things up. They were calling for 7-11 earlier and now are down to 4-6 Link to comment Share on other sites More sharing options...
Stevo6899 Posted February 25, 2011 Share Posted February 25, 2011 Yeah i would not write this off yet if i were as far east as you guys are. Out this way? Oh heck yeah. I have never ever seen anything work out with the surface low taking a track so far south and i full expect a near shutout with 2-3 max if i am very lucky. This has shades of March 08 written all over it ( just a slight bit farther to the nw this go around ) and that was a shut out here. BTW. The euro did kinda sh!t the bed with this as did it's ensembles. See the start of the thread and last one and see how many runs of both brought better snows up this way and tracked the surface low to near Cleveland. Gonna be one of the bigger euro/euro ensemble busts i have seen recently in it's supposed hot zone of day 2-3/5. However i did warn that this system touched on a euro weak spot and thus see the northern system that brought the convective snows up this way last night. That ended up stronger and pushed the confluence etc zone a little farther south as the GFS/NAM had been hinting at. Yea while the euro was a bit off, it still wasn't that bad. More than not, it's usually right. I think most models struggle with analyzing of northern streams and where and how strong the confluence ends up. A lot of bad timings with northern streams pushing southern streams east, northern energy suppressing strong southern lows, or southern energies robbing moisture of a decently strong northern stream. Some worked out some didn't. Link to comment Share on other sites More sharing options...
Harry Posted February 25, 2011 Share Posted February 25, 2011 If the 0z NAM track verifies, the sfc low track will end closer to the GFS than the EURO. So I retract what I said earlier about giving the EURO the gold. Not sure if I wrote that before the 12z models had come out, because I was somewhat cocky about them coming back NW. It will take a miracle to get this thing to end up anywhere near where the euro and it's ensembles tracked it. Thus just north of the river to Cleveland. No dice there. Now it is more of a matter of where and or when does this thing turn more towards the ne/nne or whatever? Or will it even do that? Link to comment Share on other sites More sharing options...
toronto blizzard Posted February 25, 2011 Share Posted February 25, 2011 It will take a miracle to get this thing to end up anywhere near where the euro and it's ensembles tracked it. Thus just north of the river to Cleveland. No dice there. Now it is more of a matter of where and or when does this thing turn more towards the ne/nne or whatever? Or will it even do that? Do you think the 00z RUC is correct Harry? Link to comment Share on other sites More sharing options...
Chicago WX Posted February 25, 2011 Share Posted February 25, 2011 IND updated and expanded the WWA's south to now include Indy and the I-70 corridor in central Indiana. 0z NAM raw data has 0.68" falling in LAF in six hours (6z to 12z). Total storm QPF of 0.80". Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 25, 2011 Share Posted February 25, 2011 Baroclinic_Instability, where do you get those great tropopause maps? I love those. Univ. of Utah has GFS maps for pretty much the world, lol. I love them too--just a basic DT/925 theta combo--but they do the job. http://weather.utah....fs004&r=NH&d=DT SPC has the potential vorticity maps for the mesoanalysis too. This guy has DT maps on theta surfaces--but the graphics are kinda corny. Still works though. http://www.atmos.alb...els/gfs_dt.html Link to comment Share on other sites More sharing options...
Harry Posted February 25, 2011 Share Posted February 25, 2011 Yea while the euro was a bit off, it still wasn't that bad. More than not, it's usually right. I think most models struggle with analyzing of northern streams and where and how strong the confluence ends up. A lot of bad timings with northern streams pushing southern streams east, northern energy suppressing strong southern lows, or southern energies robbing moisture of a decently strong northern stream. Some worked out some didn't. Yeah and as i mentioned this touched on one of the few weak spots the euro has which is with northern energy like that stuff last night. The other models did do a better job with it. Rare but it happens. Thus see what baro said about the models and how they have done with it and past systems etc. On the whole it is not a massive shift but it never was gonna be a massive shift but small ones which for *some* ( see here/LAF etc ) could be huge and it looks to be that way. Still rare to see the euro show what it did for here and several other locations and end up being alot different and thus why i say one of the bigger euro busts recently. Link to comment Share on other sites More sharing options...
npcougar Posted February 25, 2011 Share Posted February 25, 2011 <br />IND updated and expanded the WWA's south to now include Indy and the I-70 corridor in central Indiana.<br /><br />0z NAM raw data has 0.68" falling in LAF in six hours (6z to 12z). Total storm QPF of 0.80".<br /><br /><br /><br />You have any numbers for Indy? TIA Link to comment Share on other sites More sharing options...
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