And so it begins...

well I've had moderate to heavy snow falling since about 5:15pm and have 0.5" down so far. things will only get worse as the night goes on into the overnight hours when the heaviest snow is expected to fall.

there have already been reports of 5-12" in northern/northeast MO as the storm continues to ramp up. rates in northern MO/western IL have been impressive at 1-1.5"/hr this afternoon. rain has been reported in the southern suburbs and closer to the lake but has since gone over to snow at most places including ORD and MDW

here is an image taken off the 23z RUC, it has slowly been bumping up QPF for the overnight hours with some places picking up 0.3-0.5" QPF in 3 hours!



and here is a national radar loop of our storm

http://radar.weather.gov/Conus/full_loop.php

just in...

0646 PM SNOW OTTAWA 41.35N 88.84W
02/21/2010 M1.2 INCH LA SALLE IL TRAINED SPOTTER

SNOW FELL IN ONE HOUR AND IS THE TOTAL SO FAR. HEAVY
SNOWFALL CONTINUES.

will have another update around 10pm


Matt

storm update, 19z sunday

well the models have continued to trend drier with QPF and the have placed the heaviest snow band further to the southeast. snowfall amounts will be a bit less then thought yesterday but will still be a significatn snowfall for the area with totals ranging from 5-9" locally 10" possible in some areas. the dynamics and moisture with this system will aid in some impressive snowfall rates at or above 1"/hr at times in the heaviest snow bands.

the heaviest snow will fall from late this evening through the overnight hours and shut off pretty quickly during the mid morning hours as the low pressure slides off to to the east.

here is a image taken off the LSW WRF for early monday morning at 6z



LOT has upgraded parts of the area north of I-80 and west of dupage county to a winter storm warning starting at 9pm this evening and going through the day tomorrow.

It will be interesting to watch this system unfold tonight.


Matt

Storm Update

There have been no drastic changes but the 0z runs did nudge the main band a bit further south with less QPF but dont know if Im buying into that yet. waiting for the hi-res models to come in now. going to be intesting if the trend continues. the hi-res NMM holds its ground.

think chicagoland area from 1-88 on north will see around 6-10" with locally higher amounts taper down to 2-4" across the far southern counties due to having mixing problems. some pretty impressive returns going on right now down south in TX and OK with some thunderstorms. whats pretty cool is the WAA precip all the way in western IL with the ULL still back in the southwest.

http://radar.weather.gov/Conus/full_loop.php

here is an image from the SPC 4km WRF showing a very intense snow band from southeast IA to chicago



and this from the hi-res NMM



if things hold true then a snow day for parts of the area could be a real possibility given the heaviest snow will be falling during the overnight hours into the morning.

and lastly here is the text from the winter storm watch from the chicago office...

WINTER STORM WATCH REMAINS IN EFFECT FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON...A WINTER STORM WATCH REMAINS IN EFFECT FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON.

* TIMING...SNOW IS EXPECTED TO DEVELOP ACROSS NORTHERN ILLINOIS BY SUNDAY EVENING. AREAS NORTH OF THE INTERSTATE 80 CORRIDOR WILL RECEIVE MAINLY SNOW FROM THIS SYSTEM. THE SNOW MAY BECOME HEAVY SUNDAY NIGHT INTO EARLY MONDAY MORNING...WITH ACCUMULATION RATES OF AN INCH PER HOUR EXPECTED.

* ACCUMULATIONS...TOTAL ACCUMULATIONS OF 8 TO 12 INCHES ARELIKELY...GENERALLY ALONG AND NORTH OF INTERSTATE 88...TAPERING TO AROUND 6 INCHES TO THE SOUTH WHERE PRECIPITATION MAY MIX WITH SLEET AT TIMES. THE SNOW SHOULD BEGIN TO DIMINISH FROM THE WEST AROUND MID DAY MONDAY.


Matt

Yet another snowstorm, maybe some TSSN??

Another winter storm is on its way into northern IL for sunday night into monday with a good possibility of it dumping significant amounts of snow across the chicagoland area. unlike like the last snow event that went on for over 30 hours, this one will not be as long-lived but will pack quite a punch when it does get here. this storm will also be wetter and our southern counties could have to worry about possible mixing issues down along and south of I-80. It is still a bit early to say where the rain/snow line will set up. snow ratios will be lower which will mean a heavier snow to shovel aka "heart attack snow" but given the dynamics of this sucker and possible convection, they could be higher maybe nearing 12:1 or so.

as usual, I will start with the WV loop to get a quick look at whats currently going on. we had the weak wave move through overnight dumping near an inch in places across the area. our attention now turns the trof coing down the western U.S and the big guy at the base of that trof spinning off the southern CA coast and moving onshore into CA and the baja.

http://weather.cod.edu/loops/US-WV24.loop.html

WAA snow is already breaking out in KS in association with the upper level low over baja and will continue to develop. this is just the beginning of this major storm.

as the ULL kicks out and moves into the southern plains this will create a surface refletion and an area of low pressure will develop and begin to move ENE and deepen slowly. the progs are coming into better agreement on the track but there is still some uncertainty on the exact track but it looks to head into MO and then through central IL and into IN with an area of heavy snowfall to the north and west of the surface low.

here the where the vort is located at 36 hours as it moves NE into MO by early monday morning.



and then by monday morning at 12z its over IL/IN.



here is where the sfc low is progged to be early monday morning at 6z, looks to be over the st. louis area



and then by 12z monday morning its in east central IL now down to 999mb moving NE.



this storm is going to have a good amount of moisture with it and tons of lift to help produce some hefty snowfall rates and wouldn't suprise me if we were to see some TSSN reports as this thing really gets going given the amount of the omega in the DGZ. here is a map showing the amount of lift at 700mb



what is going to be a problem for the soutern counties and down towards the kankakee area is going to be the warm nose at 925mb and 850mb with strong WAA that is going to create mixing issues down there but up here will should remain all snow. here is the winds at 850mb showing the impressive wind fields.



so as all this is going on, the storm will be strengthening and heavy snow will begin to break out in MO and streak into western IL and eventually our area by late sunday night and the deformation begins to take shape which will produce heavy snow rates overnight sunday and through the morning and afternoon hours on monday.

here is where the defo band is located overnight sunday, really starting to ramp up.



and then by rush hour monday morning, we are getting blasted.



The chicago office has a Winter Storm Watch in effect for the area north of I-80 from sunday evening to monday evening for 6-10". I think there will be some areas that hit a foot or more when all is said and done, heaviest being the further north and west you go. with the heavier rates, the snow should stack up pretty quick, even more if there can be some thundersnow. some models are spitting out near 1.25" QPF for ORD and even with 10:1 ratios, that would yield 12" of snow.

here is a image I just took off the LSX hi-res WRF, this is for overnight sunday as the heavy snow is now over the area.



and just took this off the new 12z hi-res NMM showing the impressive omega as this thing ramps up tomorrow evening



I will probably do an update later tonight after the 0z runs come out but there will most likely not be many changes. some other notes, the hi-res NMM takes the surface low down to 996mb along the IL/IN border sw of INDY by monday morning, and im really impressed with the omega showing up throughout the storm as well.

hopefully in a few months I will be able to see a few of these if we ever get out of this pattern

Big Snowstorm taking aim on the Chicagoland area

The chicago area is bracing for the biggest winter storm in about a month that will begin tomorrow evening and last through the early hours of wednesday morning. A southern stream vort will track out of the central plains that is currently producing some moderate snow to heavy snow in KS/MO/IA out ahead of the southern piece of energy. There was actually just a report of a few places with 1"/hr rates. This southern vort will track eastward before phasing with a very compact intense vort associated with the northern stream as it dives into the midwest from the northwest. You can see both pieces currently on WV.

http://weather.cod.edu/loops/US-WV24.loop.html

First there will be an intial push of WAA snow with the southern wave that will start the snow off tomorrow evening dropping several inches of snow. then the northern vort will continue to dig further south and eventually east, deepening along the way which will create a surface low with the help of the southern stream. this area of low pressure will track from MS northeastward up to southern IN and into OH creating another, more intense band of snow across the area. also, as the storm wraps up to the east we will have winds between 20-30mph which will be more then enough to cause blowing and drifting of the powdery snow.

Here you can see both the southern and northern stream vorts and their positions tomorrow evening.



Here is a closer look at the very intense ULL associated with the northern stream as it begins to head ESE across IA/IL.



6 hours later, its deepening as it heads east, as well as the 700mb and 850mb lows.



This system is going to have a ton of lift associated with it all overlapping up to 500mb, here are the VV maps from 500mb and 700mb.





as the system moves off to the east it deepens and this will create a very nice trowal across the area which will give us most of our snow and possibly heavy snow at that, here you can see the increase in lift at the 700mb and 850mb level





This will create a heavy snow axis from northern IL across lake michigan into portions of southern MI. Here is a image of where the heaviest snow would be tuesday evening and late that night. You can clearly see the heavier snow developing as the sfc low and ULL deepen and lift increases.





Another good advantage for significant snow amounts is the deep DGZ for a long period of time which will allow for maximum snow growth aloft and also in play will be the high snow ratios possibly nearing 20:1 or even higher that will allow the snow to fluff up easily. and to keep going on the advantage train, we will have favorable winds for lake enhancement to take place with good delta T's around 13 which will allow for added moisture into the trowal in northeast IL. here are a few soundings for tuesday morning showing the deep DGZ.





LOT has a Winter Storm Watch out for the area from tomorrow evening through late tuesday night for accumulations of 8-10" with the highest occuring near the lake due to the enhancement. I think we will see some amounts near a foot or even higher where better banding sets up as well as the lake enhancement. The only concern I think is the amount of moisture that gets north but hopefully the very impressive dynamics will help offset that. There is just so much working for this event.

The one thing I really love about this storm is the long duration of it, It should snow for atleast 24 hours, possibly nearing 30 hours. overall im really giddy over this storm and will be a fun one to track.


Matt