ILSNOW Posted February 16, 2014 Share Posted February 16, 2014 LOT UPDATE AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL310 PM CST SUN FEB 16 2014.DISCUSSION...308 PM CSTSHORT TERM...TONIGHT THROUGH TUESDAY...THE MAIN FORECAST CONCERNS WITH MONDAYS WINTER STORM IS ON ACTUALSNOW AMOUNTS ACROSS THE AREA...AND LESS ON PRECIP TYPES. I CONTINUETO FAVOR A SLOWER SOLUTION CLOSER TO THE MORE CONSISTENT 12 UTCECMWF. THIS SLOWER SOLUTION IS PREFERRED DUE TO THE EXPECTED NEGATIVETILT OF THE MID LEVEL WAVE AND THE DOWN STREAM SHORT WAVE RIDGINGAHEAD OF RETREATING EAST COAST TROUGH. ALL OF THIS POINTS TO ASLIGHTLY SLOWER PROGRESSION OF THE SYSTEM ON MONDAY.OVERALL...THIS SYSTEM PROMISES TO BE GOOD SNOW MAKER FOR THE AREA.MY CURRENT SNOWFALL TOTALS ARE NEARLY 6 INCHES FOR AREAS ACROSSNORTHERN ILLINOIS. HOWEVER...I DID NOT FEEL CONFIDENT ENOUGH TOUPGRADE THE ADVISORY TO A WARNING FOR 6+ INCHES AMOUNTS...BUT IT MAYBE CLOSE...ESPECIALLY ACROSS NORTHERN ILLINOIS. THE ONLY CHANGE TOGOING HEADLINES WAS TO PUSH BACK THE START TIME OF THE ADVISORY ACOUPLE HOURS ACROSS THE EASTERN HALF OF MY AREA. THE SNOW COULDBEGIN ACROSS NORTHEASTERN ILLINOIS A BIT PRIOR TO THIS TIME ASISENTROPIC ASCENT TRIES TO SATURATE THE COLUMN. HOWEVER...THE BETTERSNOWFALL SHOULD HOLD OFF IN THESE AREAS UNTIL LATE MORNING AND INTOTHE AFTERNOON.GUIDANCE CONTINUES TO SUGGEST THAT THE SPLIT MID/UPPER LEVELWAVE...CURRENTLY MOVING ACROSS THE NORTHERN ROCKIES...WILL PROGRESSEASTWARD ACROSS THE AREA BY LATE MONDAY. DUE TO THE LIKELIHOOD OFTHIS SHORT WAVE BECOMING NEGATIVELY TILTED ACROSS THE AREA...THEREWILL LIKELY BE VERY GOOD DYNAMIC FORCING ACROSS THE AREA WITH THISEVENT. AS SUCH...SOME PERIODS OF HEAVY SNOW APPEAR TO BE A GOOD BETACROSS MUCH OF THE AREA...ESPECIALLY DURING THE AFTERNOON MONDAY.AREA MODEL CROSS SECTIONS ACROSS NORTHERN ILLINOIS INDICATE A BANDOF STRONG MID LEVEL FGEN WITHIN AND JUST BENEATH A LAYER OF NEGATIVEEPV. THIS STRONG BAND OF FRONTOGENESIS WILL ALSO LIKELY COINCIDE WITHTHE IMPRESSIVE LARGE SCALE Q-VECTOR CONVERGENCE ASSOCIATED WITH THEAPPROACHING MID-LEVEL WAVE. THIS WILL LIKELY SUPPORT A PERIOD OFDEEP ASCENT THROUGH THE DGZ. THIS COMBINED WITH THE VERY STEEP MIDLEVEL LAPSE RATES...SHOULD SUPPORT BANDS OF HEAVY SNOW ACROSS THEAREA DURING THE AFTERNOON...WITH SNOW RATES AROUND AN INCH PER HOURAT TIMES PROBABLE. ANOTHER ASPECT SUPPORTIVE OF HEAVY SNOW IS THATTHE MODEL SOUNDINGS ARE INDICATING SOME ELEVATED CAPE FOR PARCELSLIFTED ABOVE 600MB. THIS COULD SUPPORT CONVECTIVE SNOW. HOWEVER...IDECIDED TO LEAVE THUNDER OUT OF THE FORECAST AS THE MOST UNSTABLEPARCEL IS AROUND -10 C...WHICH IS A LITTLE ON THE COOL SIDE FOR GOODCHARGE SEPARATION.ALTHOUGH THIS SYSTEM WILL HAVE EXCELLENT DYNAMICS...AND WILL LIKELYPRODUCE SOME HEAVY SNOW ACROSS THE AREA...I DID NOT CHOSE TO UPGRADEAN AREAS TO A WARNING...MAINLY DUE TO THE SYSTEMS RELATIVELYPROGRESSIVE NATURE. EVEN A SLOWER SOLUTION IS STILL RELATIVELYPROGRESSIVE. AS A RESULT...IT APPEARS THE HEAVIEST SNOW BANDS MAYONLY LAST OVER ANY GIVEN AREA FOR A COUPLE HOUR PERIOD...AND AS SUCHTOTAL SNOWFALL AMOUNTS MAY STILL ONLY END UP GETTING INTO THE 4 TO 6INCH RANGE. HOWEVER...ANY CONVECTIVE NATURE TO THE SNOW COULD EASILYLEAD TO SOME AMOUNTS SLIGHTLY HIGHER. MOST OF THE ACCUMULATING SNOWWILL LIKELY FALL IN A 6 TO 8 HOUR PERIOD. I WILL LET THE OVERNIGHTSHIFT GET ANOTHER LOOK AT THINGS TO SEE IF A SHORTER FUSED WARNINGMAY BE NEEDED FOR PORTIONS OF THE AREA...POSSIBLY EVEN FOR THEIMPACTS OF A FEW HOURS OF HEAVY SNOW. Link to comment Share on other sites More sharing options...
Central Illinois Posted February 16, 2014 Share Posted February 16, 2014 Freezing rain and sleet before noon, then rain, freezing rain, and sleet. High near 34. Southeast wind 13 to 15 mph becoming west in the afternoon. Winds could gust as high as 21 mph. Chance of precipitation is 90%. New ice accumulation of less than a 0.1 of an inch possible. New sleet accumulation of 1 to 2 inches possible. ILX hitting the sleet hard in the p&c forecast Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 16, 2014 Share Posted February 16, 2014 Really good AFD from LOT, almost upgraded. Link to comment Share on other sites More sharing options...
Hoosier Posted February 16, 2014 Share Posted February 16, 2014 18z RGEM bullseyes LAF. Link to comment Share on other sites More sharing options...
Chicago WX Posted February 16, 2014 Share Posted February 16, 2014 18z RGEM bullseyes LAF. 6-7"? Low chances of that happening, but... Link to comment Share on other sites More sharing options...
RJSnowLover Posted February 16, 2014 Share Posted February 16, 2014 GFS has caved. Link to comment Share on other sites More sharing options...
Chicago WX Posted February 16, 2014 Share Posted February 16, 2014 Hmmm, 18z GFS went wetter for quite a few. Good hit for northern Indiana. Link to comment Share on other sites More sharing options...
Brewers Posted February 16, 2014 Share Posted February 16, 2014 The GFS with over .4" of qpf over S WI. Looks pretty likely we see over .3" of qpf and probably closer to .4" with the NAM the only model under .3". Link to comment Share on other sites More sharing options...
Hoosier Posted February 16, 2014 Share Posted February 16, 2014 Hmmm, 18z GFS went wetter for quite a few. Good hit for northern Indiana. Also a bit warmer for us. Link to comment Share on other sites More sharing options...
afterimage Posted February 16, 2014 Share Posted February 16, 2014 6-7"? Low chances of that happening, but... You have to admit, it does seem, at least in these parts of Indiana these systems have over performed...the now casts have ended up being better than what first appears...it has been a nice season Link to comment Share on other sites More sharing options...
Hoosier Posted February 16, 2014 Share Posted February 16, 2014 18z NAM and GFS for LAF valid 18z Monday. Large differences in thermal profiles this close in from 750 mb down Link to comment Share on other sites More sharing options...
Chicago WX Posted February 16, 2014 Share Posted February 16, 2014 Also a bit warmer for us. Tis true. Funny thing is I've noticed the GFS running too warm this winter at times. Totally not its usual MO. Regardless, we're still at risk for mixing for sure. You have to admit, it does seem, at least in these parts of Indiana these systems have over performed...the now casts have ended up being better than what first appears...it has been a nice season No doubt. We'll see if this one can continue the theme. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 16, 2014 Share Posted February 16, 2014 Point has 4" for tomorrow here. Looks spot on to me. Now looks to be 100% snow, with onset pingers staying just south. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 16, 2014 Share Posted February 16, 2014 Quite the increase on the GFS 12z run gave me about 3.5" 18z with 5-6" so obviously it's showing some good ratios. Link to comment Share on other sites More sharing options...
Powerball Posted February 16, 2014 Share Posted February 16, 2014 DTX adjusted my grid down to 2-4". Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 16, 2014 Share Posted February 16, 2014 5.3" in my hourly and heavy snow wording now for tomorrow Link to comment Share on other sites More sharing options...
Powerball Posted February 16, 2014 Share Posted February 16, 2014 No changes on the 18z GEM. Link to comment Share on other sites More sharing options...
Geos Posted February 16, 2014 Share Posted February 16, 2014 18z GFS Close call for LAF. RPM at noon. 3pm Link to comment Share on other sites More sharing options...
chances14 Posted February 16, 2014 Share Posted February 16, 2014 dtx snowfall map Link to comment Share on other sites More sharing options...
Powerball Posted February 16, 2014 Share Posted February 16, 2014 15z SREF mean for DTW fell to about 4.5". A much better clustering below the mean this time. The vast majority of the members are at/below 5". Link to comment Share on other sites More sharing options...
Powerball Posted February 16, 2014 Share Posted February 16, 2014 dtx snowfall map lol. That would probably explain why my grid is down from 3-5" to 2-4". Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 16, 2014 Share Posted February 16, 2014 Mid level heights really tank here, gotta think we get some convective snows Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 16, 2014 Share Posted February 16, 2014 Mid level heights really tank here, gotta think we get some convective snows NMM was really hinting at as much during earlier runs but backed off, we'll see if 0z ramps back up. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 16, 2014 Share Posted February 16, 2014 Latest HPC. Link to comment Share on other sites More sharing options...
Chicago WX Posted February 16, 2014 Share Posted February 16, 2014 15z plumes snowfall for IND. Quite a bit of spread this close in, with pretty much two camps... ...but then we look at the mean p-type map and it's quite clear why...despite a fairly narrow total QPF range (0.30-0.50"). Fun stuff. Link to comment Share on other sites More sharing options...
cyclone77 Posted February 16, 2014 Share Posted February 16, 2014 RAP looking pretty jacked for tomorrow morning. Link to comment Share on other sites More sharing options...
stormtrackertf Posted February 16, 2014 Share Posted February 16, 2014 Random burst of +SN going on right now. Not sure exactly where this is coming from. Link to comment Share on other sites More sharing options...
huronicane Posted February 16, 2014 Share Posted February 16, 2014 Phil Schwarz going low: Link to comment Share on other sites More sharing options...
Thundersnow12 Posted February 16, 2014 Share Posted February 16, 2014 Phil Schwarz going low: Must of asked Alek lol Link to comment Share on other sites More sharing options...
A-L-E-K Posted February 16, 2014 Share Posted February 16, 2014 Must of asked Alek lol we lunched Link to comment Share on other sites More sharing options...
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