Old Man Winter...."I'm Back"

Well we have got off to a late start in the snow department here in northern IL so far but it seems like as we turn the page to December we really start seeing the snow flying. After the first measurable snow the other day of 0.1" we should blow way past that total with this snow system coming for tomorrow night into saturday. This is our first sizeable snowfall of the season

This is a clipper like system but not a real clipper as its not going up around the ridge and the sfc low diving southeast pretty quickly like a typical clipper des. Its more of the 850mb low and the track of that with the sfc low being further south moving southeast to ESE across the central plains and into MO and then KY with band of snow on the northside closer to where the 850mb low is.

sfc low track



As this sytem is getting its act together warm air advection will be taking place and running up and over the cold air causing snow to break out in a northwest to southeast oriented band streaking to the southeast along the 850mb low track and into our area by late tomorrow night with the heaviest snow falling from about 10pm to the late morning hours on saturday with possible lake enhanced/lake effect snowfall after that in the afternoon and evening.





There are things working for this system and things not working to help create a good snowfall. Its going to be a quick hitter, probably a good 12 hour period of moderate snow but the snow ratios will be around 13/14:1 which will be a powdery type. There will also be good snow growth given the depth of the DGZ. There is also could be some nice fronto banding which would aid in heavier snowfall rates.

here is an image showing the amount of lift going on in our snow system




this is a map showing the probability of the depth of the DGZ being greater than 100mb allowing for good snow growth



Another thing to watch for is a possible meso low forming out over lake michigan and even coming onshore which could enhance snowfall amounts near the lake saturday afternoon and evening. meso lows are more favorable in weak synoptic flow environments, which is what we will have on the north and northeast side of the 850mb low. The flow from surface to 800mb is weak easterly to northeasterly flow, with no significant flow above that until you get up to about 600mb.

here you can see the LSX WRF picking op on a possible meso low moving down the lake and actually comes onshore in northeast IL



as for amounts, Im still riding my 3-6" call from yesterday for area wide with heaviest near the lake due to lake enhancement/lake effect snow and guess LOT will go with a winter weather advisory for tomorrow night into saturday afternoon. here is an image of total QPF run off a hi res WRF

First heavy snow event!!

Well I haven't posted in quite awhile and there has sure been some events where I should have, but now we have snowstorms to forecast and watch and this is what I love doing, being up to my neck in data. So even though the first good snow event of the winter, or should I say fall...(with temps in the 60's and 70's here this week) isn't over northern IL, I am still geeking out of this system because it is fairly impressive and should have some moderate to heavy snow accumulations associated with it beginning tonight and through the day tomorrow from northwest IA to southern/central MN to to norhwest WI by tomorrow night.

Like always I will start with the 24 hour WV loop

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

We currently have our upper level trof moving into the midwest with well defined vort max over the NE/IA border reflected by the closed 700mb low. this system has been moving northeast throughout the evening and intensifying nicely as it does so. precip has also been steadily increasing in coverage and intensity from northeast KS up to the MN/IA border. The temperatures in the area have been dropping throughout the afternoon and evening but are marginal for snow but due to some good CAA going on and the intense precip rates, rain has been able to changeover to snow in some areas and has been quite heavy at that with a few lightning strikes in the OAX area earlier due to CCB's

At the time before that, the temps were above freezing up to 800mb but due to the insane amount of insentropic ascent going on, the 925mb temps crash 3 to 4 degrees in an hour which lead the the BL temps to cool below freezing to allow for snow to reach the surface. This is what happened this morning in AMA where they had +TSSN with the column not supportive of snow but due to the amount of convection, it was able to make it all the way down.

Here is the 0z OAX sounding..



Over the past few hours the deformation band has really began to take off and areas have began to changeover to snow and the temps/dew points slowly drop to near or below freezing. There is a really nice moisture plume that is feeding northwestward into the colder air. It looks like the snow axis will follow the H85-H7 frontogenesis axis. Also, the dry slot was filling in with precip from southeast NE up into southwest NE.



The deformation band will continue to move northeast overnight into southern/central MN where there are currently winter storm warnings in place for 6-10" of snow. I wouldn't be suprised if there ended up being a total near a foot given the intense precip rates/possible thundersnow due to it being pretty unstable aloft, and the dynamics this thing has going for it. all in all, a nice, intense first snow system to forecast for.




Hopefully this is a sign of things to come this winter!


Matt

tuesday potential on the home turf??

well tuesday looks very interesting looking at the new NAM. MCS moves across western/central IL during the morning/early afternoon hours most likely laying out a nice boundary with storms going on that in the evening. mid-level flow is alright between 25kt-35kts but the low level shear is quite good given the strong 850's in the area and you add big amounts of instability and upper 70's dew points with a sfc low in southeast IA and you got a problem. have already looked at some soundings and the GBG and PIA soundings are quite nice with good turning. the CAP might be a problem with H7 temps between 12-14 and CIN at -49 on the GBG sounding at 0z.

will post more later on the setup.

will not be able to chase though due to work.

write up for tues/weds severe and tornado potential

Well as much as it hurts to look at the forecast models for the next few days since I can't chase I still will do it anyways cause I love to forecast these events. Weds looks to be the bigger of the two days but tues still looks pretty descent in the dakotas.

As a upper trof moves in from the west with better mid and upper level winds associated with it, moisture will begin to return from the south and west as a dryline sets itself up in the dakotas and further south into NE. As Victor and I were just discussing tomorrow looks tough as it looks like maybe two possible targets. One being down possibly in NE where the better instability and moisture is being pegged but away from the better mid-level winds or playing further north in eastern SD under the better winds but less juice but still sufficient. I personally like the northern target with the better wind profiles but as Victor said further south "big CAPE kicks big ass"

500mb speeds at 0z


MLCAPE at 0z



As a target for tomorrow I like Mitchell with possibility of heading north.

Now comes the fun part or day for that matter. I will just go out and say it, play nw KS on weds! It would take some real kahonas to blow off MN/IA and do that :) but I wouldn't considering this setup is going to be a repeat of 6/17 in the AEL area. This setup just looks "good day" 50kts from the WSW at H5, good strong SW H85 winds and nicely backed sfc winds into southern/southeast MN and northern/northeast IA. As Victor pointed out, there looks to be a diffuse warm front from southern MN down across northeast IA. The wind profiles in that area are mmmm good. 0-1 SRH AOA 200 in northeast IA at 0z and only gets better as time goes on.

12z NAM showing CAPE values AOA 3500 j/kg with dew points in the mid 70's possibly nearing 80!


thank you corn!


just look at that theta-e! wow!


Target for weds- sit in AEL to possibly head east on 90 or south on 35 to head into northern or northeast IA.

One last images to look at for tornado potential off the 9z SREF for 21z on Weds. last time a 50 was shown...4/22...5/10...6/5




Matt

sleeper day in CO??

The new 12z WRF is showing a nice signal for the TX PH but I really dont like the weak upper level winds as well as what the LCL's will be in that area. Its going to take quite a bit of convergence along the dryline to get something to go. The H7 temps are progged to be quite high. I wouldn't rule out that area for an isolated storm later this evening but I like the northeast CO play alot more.

Like the Brush to Yuma area for supercells later this afternoon. dew points are already in the low 50's in nw KS/ne KS/nw NE per the 16z obs. The shear is amazing in the area with really nice low level hodographs. will be interesting to see if a denver cyclone can develop later this afternoon.


We are leaving Garden City now.

4 tornadoes in TX Panhandle on Tuesday!!

This day had alot of promise in the TX PH with upper level flow finally kicking out into the plains with a trof coming in with descent moisture streaming into the PH with moderate instability in the area with a wave progged to move in during the late afternoon hours. We headed to Dalhart, TX for our intial target where we ate lunch at decided to sit there for awhile thinking that was a good area. We decided to headed a bit northwest west to Clayton, NM where we could get a better view out to the west where we thought CI would occur with the wave coming in. On our way there we noticed some TCU in the clearing to our southeast near Channing, TX. A few minutes later echoes started showing up on radar and it was going up fast. We decided to bust south to it not knowing what it would do but it was in a good environment for development. We caught up to east east of Channing and pulled off the road past some of the Vortex 2 crew to watch it.



It was developing into a very nice supercell rather fast right in front of us and had good inflow into it most of the time. It was sucking up alot of scud with a nice RFD to our west and soon began to develop a wall cloud with numerous areas of interest.



It really started to get its act together as it started raining but soon had rain falling into its updraft so we headed east to give it time. About 3 minutes after leaving this location some people spotted a tornado back to our west as we were driving east we spotted a tornado coming down. Only a few got pictures of it as it was brief but was tornado number one. After this is when all the hordes of chasers. There were so many chasers between Vortex 2, locals, the Discovery Channel idiots, tour groups, and others out.

We ended up southwest west of Dumas, TX and pulled over to continue to watch its development. At this point it never screamed tornado and never had the classic clear slot RFD occlusion. Most of the time it looked shelfish as it looked like a HP mess for awhile with it raining into the mesocyclone.



After this we headed through Dumas and then east. This took quite awhile with so many people out and having to go through a town. As we got onto the road out of town we spotted a small tornado back to our WSW. There were reports of a large tornado in Dumas but we didnt see it and dont believe it considering the one we saw was small and brief and just south of town. We continued east with other chasers to get a good view of it and went probably about 10 miles east of Dumas and stopped and were rewarded to amazing structure with the supercell, It was amazing in its own.



After about 5 minutes at this location, hail began to fall out east of the storm due to the strong upper level winds. We headed back east for a few miles and went south of the main road where all the chasers were to get a nice view of the storm by ourselves with nobody around.


On Tuesday our target was the TX PH as we left LBB in the morning and headed for

This thing was turning into a HP mess with alot of rain falling into the updraft as time went on which meant you had to be on the northeast side of the meso to see anything. We continued to follow it to Stinnett where it was a mess with alot of chasers.



We decided to leave this storm for a rapidly developing supercell near Romero, TX. We busted back west and finally caught up to it just northeast of Dalhart at right when it became dark and was throwing out cold air....so with crappy lightning we decided to leave and head to the hotel but as we were heading east low level rotation increased quite a bit and inflow picked up so about after 10 seconds of looking north while driving for lightning flashes, someone saw what looked to be a tornado off to our north illuminated by the lightning. It ended up being a pretty good size tornado a mile from us. It was on the ground for around 5 minutes before lifting. It was so great getting my first night tornado I couldn't of been more giddy.

We went east again with a supercell northwest of Stratford showing descent rotation show we went north to check it out but were having data problems but were still able to get radar on Victor's phone. The area of interest was pretty close to us as we were nearing the town. We stopped to get gas where hail was covering the ground and we were actually not allowed in the gas station due to the weather im guessing.



The storm slowly moved south and we were just south of town when the storm was just east of town when someone spotted a tornado thanks to the lightning behind us. We got out and sure enough a large tornado was on the ground with inflow winds probably around 40mph! That was the 4th tornado of the day! It was my best chase day and was so much fun.

Write up for the next day in OK coming soon!


Matt

day by day...by day...finally we have better UL support

The last few days we have been playing around with ok storms in southeast NM and southwest TX. Yesterday we were around I-10 and fort stockon to sanderson killing storms that were already crappy. Today was the best day so far as we caught a few nice storms near Carlsbad, NM. They were big hailers which we stayed out of but did give us some descent structure to enjoy and well as some good lightning, was nice to be actually chasing again.



The problem with each day has been the overnight stupid convection that has went through the area and scouring out everything and making it harder to recover the next day. this past saturday looked great the day before but due to an MCS it sucked. As with the setup for tomorrow, that is going to be the problem once again. We finally have a nice trof coming into the plains with good mid level winds and a dryline at the surface but the new NAM is breaking out alot of precip during the morning and early afternoon from southern CO to eastern NM/TX PH. This cutting down on the amount of destabilization to occur and moisture return.

500mb flow tomorrow evening



Weds looks like a good day in OK and possibly northern TX around the childress to wichita falls area but what happens tomorrow night will have an effect on the next day. Thursday looks like a travel day further north with more chasing once again friday and saturday before heading home on sunday.

dew points weds evening

Lets see what happens, maybe some big HP's??

We left Wichita Falls about 45 mins ago and are currently heading south to I-20 to decide if we want to go west or south.

Thanks to a million storms yesterday and overnight, there is alot of rain cooled air across the area with the front pretty far south with tons of fog currently across southwest TX. the shear is there later for supercells and a few tornadoes but question remains if we can destabilize the atmosphere and get the instability we need. Will probably end up somewhere down near I-10 later this afternoon.

There will be storms just a matter of iff we get supercells. If so, they will be big, wet and scary looking. monster HP's probably. lots of standing water everywhere down here. Would think the dirt roads are complete mud so will probably be staying off those today.

Is some dry air aloft in the area looking at a WV image.



next few days look ok and then next week is showing promise but the models have been struggling if a trof kicks out into the plains or not, lets hope so.


Matt

BIG Monday on tap for the plains!

Well tomorrow is looking like possibly the best looking setup of the year with every chaser, there mom and dog in KS and OK tomorrow afternoon. I unfortunately will not be able to chase this do to school and work but leave friday for 10 days of chasing hopefully with no down days!! Will probably be doing a blog over the next few days on the long range forecast for the trip. The new 0z NAM has come in a bit different for further north by keeping the warm front further south as it seems a cold wedge as the surface is preventing its movement. It also looks like the surface low is a tad weaker on this run.

s/w at 0z tomorrow evening



The player for this setup is the s/w trof currently over southern nevada looking at a WV loop...http://weather.cod.edu/loops/US-WV24.loop.html....This shortwave will head over the four corners region then move ENE which will aid in CI in the danger zone monday afternoon and evening

As this wave moves out, surface frontogenesis will begin to increase in the mid afternoon in the area of the best thermal/moist advection northeast of the surface low where moisture will start to pool as CAPE should begin to increase and it wont take much to get storms going as the s/w will be moving into the area. I think this area in northwest KS is another target for supercells and tornadoes but not the obvious play so im sure some chasers will be playing this area but most should be in southern KS or down into OK which the new NAM favors.



There will be ongoing convection in parts of OK/KS in the morning tomorrow associated with the strong LLJ going up and over the front overnight and into the morning. It will be interesting to see how this plays out during the day tomorrow and if an OFB can be put out for later on. As the day goes on the warm front will be lifting north (or atleast trying to). The new NAM held it further south making the warm sector smaller. Would like to see it lift north allowing for a bigger warm sector so storms dont run away from the instability. the new NAM is pooling dew points at 70 on the dryline in OK which I dont know if I believe they will get that high but does look possible as dew points are in the upper 40's/low 50's in OK where they have went up between 5-10 degrees since early this afternoon and will be on the increase.



This setup has gotten tones of hype the last several days being compared to historic tornado days from the past. No matter how tomorrow plays out, the hype IMO is deserved given the setup/parameters its cranking out and I wont be shocked at all if SPC ends up going high risk. CAPE values around 3000 j/kg with 0-1 SRH at 300. THE OKC sounding off the 12z NAM earlier today was just stupid. Given the insane parameters and also the nice LCL heights, strong to violent tornadoes are a good possibility tomorrow in the moderate risk area.

CAPE as 0z



0-1 SRH



The dynamics for tomorrow are just insane with 500mb flow between 70-90kts with 700mb winds at or above 50kts. This is going to create pretty fast storm motion which means there are going to be hundreds of chasers trying to keep up with fast moving tornadic supercells which could create a dangerous situation.

Wont pick a target area until the morning given the uncertainties on the front position and ongoing convection but like somewhere in OK along the dryline north of I-40 given the fact that the mid level cooling has increased in model land which would aid in breaking the cap allowing for rubust convection further south along the dryline. hopefully there will be a few nice supercells to spread the chasers out. the shear vectors tomorrow are nearly perpendicular to the dryline which will promote discrete storm mode. Hoping for storms here in northern IL later monday night into tuesday morning so its not a total loss.

Overall it is looking like a big day tomorrow and I only with I was out there.


Matt

Thinking cap on...what went wrong??

Well the major tornado outbreak did not happen and now comes the fun part of trying to figure out what happened to not allow for tornadoes to come out of the many supercells that were in AR this evening. I was fully expecting AR to go completely insane with full out supercells with big tornadoes in them all evening. That was not the case. There is a discussion going on ST and this is what my thoughts were:

"Could it have been due to a warm layer aloft? The lapse rates were just not that great. There was quite of bit of supercells at the onset with a good number of left movers that were interacting with other storms.

As Skip said, the storms were moving with the mean wind most of the time but when that storm west of Wynne, AR made a right turn the LL rotation substantially increased with a good meso from 3,000ft to 13,000ft and then started putting down tornadoes.

The storm further south looked pretty good on radar but just could never get that LL rotation even when the LLJ picked up later in the evening. And with pertains to both storms, I would of thought the further north storm would of had problems with inflow and rotation due to the southern storm but it backwards with the northern storm being the dominate one.

Im pretty shocked with the lack of tornado reports with this setup given the storms were able to stay discrete. Would of been nice to have V2 on these storms to see what the near storm environments were like"

Too add to that, looking at radar tonight it just looked like the storms were more LP in nature where they actually looked more wet and HPish on the cameras that were out there this afternoon/evening.

It was just a weird evening watching things unfold. But that is what makes this fun and interesting and why its my love and passion. To learn from each event!


Matt

Go west young man....after work.

Well after a nice supercell today along the KS/NE border with a thousand chasers and there mom on....they should be alittle bit more spread out tomorrow given the wider area at risk for severe weather tomorrow as the trough continues its way east along with the amazing dynamics of this system. I have never seen this strong a jet in the month of april. 100kts at 500mb is just stupid.




Tomorrow has possibilities but with most setups around here there are the problems that could hamper the possibility of tornadic supercells on the cold front tomorrow in IA/MO and possibly IL. But there are also some good things like the shear storms are going to have to work with. I am kind of concerned with the moisture and low to mid 60 dew points are going to get up here in time, we shall see.

1. Ongoing convection as usual will have to be watched in the morning tomorrow and if it will move out of the area with enough time to get destabilization to occur. If there is alot of clouds then were not going to get enough instability for thunderstorms later on. The one plus about this is that there is the possibility of an OFB being left out.

2. Clearing- Tomorrow could be one of those days where the area is socked in clouds but one small area could see some sun for a few hours and that will be it, going to have to watch vis sat alot tomorrow to see what is going on.

3. Storm motions- These bad boys are going to be hauling tomorrow between 40-50kts which means staying on them is going to be very tough. going to have to sit east of where CI takes place and let them come to you if you want to have a shot.

4. Mode- There is quite a bit of forcing tomorrow and the question if and how long storms can remain discrete. If they can remain discrete they will go supercellular given the shear they are going to have to work with but if there is alot of forcing its going to be a honkin squall line with possible embedded supercells.

Here is an image taken off the 21z SREF showing tornado ingredients which combines different parameters which are needed for tornadoes.



The new SPC day 1 outlook just came out and showing the best risk west of the Miss. river in IA/MO which I had suspected. Its going to be interesting to see if things are linear or discrete. Everything should form into a line and move into northern IL before weakening overnight.



I will not be able to chase until after work at 4 or 4 30pm so im hoping the CF is a bit faster and the storms get here sooner then expected but Im not so confident in that happening.

If I was able to chase with more time and get to a target Id head to IA be somewhere in the Oskaloosa to Iowa City to Fairfield triangle.


Matt

easy choice for a title......HIGH RISK!!

Well SPC has pulled out the high risk with the 6z outlook (pretty large area for the first outlook of the day). For the past week it seems weather geeks and forecasters have been talking about the potential for severe weather outbreak in the south and now were in the morning of getting ready for a possible historic tornado outbreak in parts of AR/TN/LA/MS/AL.



Today was somewhat of a bust givn the 15% hatched tornado probs put out but tomorrow has alot higher confidence but there still are a few things that could play havoc on this setup that I have been looking at tonight.

1. The current convection in eastern TX working its way eastward could stabilize the warm sector and not allow for good enough heating later in the day limiting the risk of potential long track, violent tornadoes.

2. The track of the surface low and how quickly it deepens. A further north and west track would lessen the amount of forcing in the warm sector early on which would mean not as much junk convection to hamper heating.

3. The mid level dry punch, I think this is going to be the key player on what plays out tomorrow. If this can happen during the day tomorrow and allow surface temps to really warm up, then some high amounts of instability coupled with insane amounts of shear (both bulk shear and low level shear) is a deadly combination for cyclic supercells tomorrow in the warm sector producing alot of tornadoes, potentially violent ones at that.

forecast offices have been comparing past outbreaks in the late 90's to this setup and writing amazing AFD's that were just through the roof good on the potential this thing had and letting people know ahead of time. If things play out right tomorrow (or wrong for that matter) then we could be looking at a major tornado outbreak across the south.

here is the text from the new day 1 from SPC....I will probably be doing updated throughout the day with radar images and such as Im geeking out watching this potential tornado outbreak unfold.


...LOWER MS VALLEY...MID-SOUTH AND TN VALLEY REGIONS...
TSTMS SHOULD BE INCREASING IN COVERAGE/INTENSITY AROUND BEGINNING OF
PERIOD OVER E TX...LA AND ARKLATEX REGION. FOREGOING AIR MASS --
ALREADY MOISTENED/DESTABILIZED FAVORABLY BY PRIOR/OVERNIGHT THETAE
ADVECTION...WILL FURTHER DESTABILIZE AMIDST SFC DIABATIC HEATING.
AMOUNT OF HEATING IS SOMEWHAT IN QUESTION BECAUSE OF POTENTIAL FOR
CLOUD/ANVIL DEBRIS SPREADING DOWNSTREAM IN MID-UPPER LEVELS FROM
EARLY CONVECTION...PERHAPS INCLUDING TEMPORAL EXTENSION OF ACTIVITY
NOW OVER S TX. STILL...AWAY FROM EXISTING CONVECTION...EVERY
REASONABLE SCENARIO INDICATES THAT MLCINH GENERALLY WILL WEAKEN WITH
NWD EXTENT FROM GULF COAST...SUPPORTING EARLY AND RAPID DEVELOPMENT
AND INTENSIFICATION OF TSTMS FROM MID-MORNING THROUGH
MID-AFTERNOON...AND SUSTAINED THREAT SHIFTING EWD AND NEWD ACROSS
OUTLOOK AREA INTO EVENING/OVERNIGHT HOURS.

INTENSE VERTICAL WIND PROFILES WILL SPREAD ACROSS BROAD WARM/MOIST
SECTOR TODAY...MUCH OF WHICH ALREADY IS IN PLACE ACROSS MUCH OF
LA...MS AND COASTAL AL. THIS AIR MASS WILL SPREAD INLAND TOWARD TN
VALLEY AS CONVECTION/PRECIP NOW OVER TN/AL/GA SHIFTS NEWD. SFC DEW
POINTS WILL BE 70S INVOF GULF COAST...TRANSITIONING TO UPPER 60S AS
FAR N AS TN AND LOW-MID 60S TO OH VALLEY. WEAKENING LAPSE RATES
ALOFT AND BUOYANCY WITH NWD EXTENT...FROM TN VALLEY TO OH VALLEY AND
GREAT LAKES...RENDER PROGRESSIVELY MORE CONDITIONAL NATURE TO SVR
THREAT...THOUGH KINEMATIC PROFILES WILL BECOME FAVORABLE OVER VERY
LARGE AREA S OF GREAT LAKES BY EVENING/OVERNIGHT HOURS.

MULTIPLE CONVECTIVE EPISODES AND STORM MODES ARE EXPECTED IN THIS
SITUATION...AGGREGATE OF WHICH SHOULD YIELD DENSE CONCENTRATION OF
SVR EVENTS BY END OF PERIOD ACROSS MDT/HIGH CATEGORICAL RISK AREAS.
THOUGH DISCRETE/CYCLIC TORNADIC SUPERCELLS ARE MOST POTENTIALLY
DANGEROUS THREAT...ESPECIALLY OVER HIGH RISK AREA...CLUSTERED AND
QUASI-LINEAR CONVECTIVE ELEMENTS WITH EMBEDDED BOW/LEWP FORMATIONS
AND SUPERCELLS ALSO APPEAR PROBABLE. STRENGTHENING DEEP-LAYER WINDS
AND RELATED FAST STORM MOTIONS PORTEND LONG TRACKS FOR SUPERCELLS
AND FOR SOME OF THEIR TORNADOES...AS WELL AS FOR SWATHS OF DAMAGING
WIND WITH ANY BOW/LEWP FEATURES. THIS SUPPORTS RATHER ROBUST
PROBABILITIES FOR ALL SEVERE MODES.

PARAMETER SPACES IN FCST SOUNDINGS OVER HIGH RISK AREA -- SHIFTING
NEWD FROM LATE MORNING THROUGH AFTERNOON -- INCLUDE 50-60 KT LLJ
SUPPORTING VERY LARGE HODOGRAPHS WITH 0-1 AND 0-1 KM SRH 300-600
J/KG. ALSO EXPECT 50-60 KT EFFECTIVE SHEAR MAGNITUDES BENEATH
110-140 KT 250 MB JET MAX AND 60-90 KT 500 MB WINDS...POTENTIALLY
JUXTAPOSED WITH MLCAPE 1500-2500 J/KG.

getting my weather swerve on!

Well tornado season really got cranking this afternoon and evening in CO to KS down into the TX PH where 30 tornadoes have been reported so far and that number should continue to go up. Today was only the start of it and tomorrow and saturday look to be just as big if not bigger.

I cant chase tomorrow but if I was I would target Falls City, NE where the triple point/warm front is going to setup. The new NAM is showing H5 winds greater then 50kts out of the southwest nosing up into the area by late afternoon into the evening with southerly 850's and backed sfc winds up against the WF with nice convergence.

Storms will be ongoing in the morning but should clear out by the afternoon as the dry intrusion moves into the area and allows for destabilization to occur with CAPE values approaching 2500 j/kg by 0z with dew points nearing the mid 60s into the triple point and bumping up against the warm front with a nice theata-e axis.

Look for storms to fire during the afternoon hours between 20-22z with all modes of severe weather possible with any supercells that do form. could see some pretty large hail given the steep lapse rates. tornadoes will also be a pretty sizeable threat given the amount of shear that will be in place


Going to be an active day even though I wont be out and then we get to saturday....



Matt

What are the odds?? I will have to chase new orleans while I'm there haha

Im leaving to head down to New Orleans thursday morning and was just looking at the new 0z run of the GFS and started laughing when looking at the forecast for saturday afternoon down there and the severe weather potential it was showing. would be a nice consolation prize for not being able to chase the possible good setup the day before most likely in TX.

The system that will aid in the severe weather the day before saturday will continue moving eastward with an ULL centered western AR during the afternoon on saturday if this were the perfect prog, which its not, would have southwesterly flow near 40kts.



we also have nice low level winds at 850mb out of the SSW near 30-35kts pumping in some good moisture off the gulf with 850mb Td's nearing 15.



The moisture is for sure there with dew points in the mid 60's with backed surface winds up into the surface low further north across MO/AR.



here is a image showing the nice area of instability feeding up into the sfc low with CAPE values nearing 1500 j/kg.



and lastly, here is a forecast sounding for 18z on saturday showing the nice turning with height and descent hodograph.



the last time I believe new orleans was hit by a tornado was 2/12/07, which is when we had a pretty good snowstorm beginning that day.


Matt

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