Nasty, raw Halloween weekend

[OHweather]

Euro just a tick east at 0z. Overall wouldn't make a huge difference across the region, but it's interesting that the model that led the super amped trend in Tuesday's runs is now ticking back the other way.

 

[Thunder Road]

Edit:  GGEM goes ape with the lake precip.  Wow.  And it has the max far inland...like Newton county lol.  Looking at more for fun than anything although I do take the RGEM more seriously when it gets in range.

Wow, you aren't kidding! Now that's what I call a LES signal!

QPF just from 0z Sat to 0z Sun:

That's a maximum of 15+ mm (~0.6"). The total is 20+ mm (0.8+ ") but most of that additional 0.2" is porobably synoptic.

And yes, it produces snow too:

 

 

7.5 mm (0.3") liquid equivalent max.  Though obviously we can't actually trust precip type algorithms in such a marginal set-up.

[Thunder Road]

Do you remember off the top of your head how much directional shear that event had? That could also contribute to the broadening of the band.

 

Regardless, it still looks like a marginal (but potentially interesting) situation downwind of Lake MI. For kicks, the NAM shows 925mb temps getting down below 0C around 0z Friday even in the lake effect band it tries depicting...although it takes until after 3z to get them down closer to -2C, which is probably what it would take to get good accums with the lack of "terrain" in NW IN unless a really strong band develops earlier. Instability numbers and equilibrium levels are essentially limitless in term of lake effect potential for the first few hours Friday evening before slowly coming down through the night...however, EL's don't look to become prohibitive for potentially accumulating snow in an organized band until close to sunrise Saturday. Things look pretty dry before that, but with all of Lake MI to work with I'd have to imagine that isn't as prohibitive as it is off of my small Great Lake. It's a short window of eye popping lake effect parameters in the evening when low level temps are iffier, followed by ok parameters for the rest of the night with better low level temps.

 

It would be nice if the winds weren't so strong Friday evening, as that would be the potential period to rack up some decent accums given the parameters if a good band can develop and compensate for the marginal looking low level temps. Any band that develops will probably slowly drift west later at night as the winds slowly veer. The instability numbers and 850mb temps Friday evening make me want to get excited for a decent early season LES event in parts of NW Indiana, but if the winds are too strong to get a good band that does work and dynamically cools the lower levels in the evening that may not happen, and then later at night when it's colder things gradually become more and more marginal for good lake effect snow due to lower inversions and increasing dry air, and perhaps a moving band.

 

It's still a few days out, so we'll see what the models say as we get closer. Prospects off of Lake Erie look lack luster now unless a pretty big shift east starts occurring soon, but it would be nice for someone to get a nice little bit of LES out of this somewhere.

 

I want to say winds were pretty unidirectional, but I wouldn't swear to it.

 

Also, fantastic job with these write-ups!

[Hoosier]

Might be too early to bring this up but in areas that flip to snow and get within a couple degrees of freezing, it won't take much to start to cause issues with power outages.  During the early Oct 2000 event, there were literally thousands of outages from a couple inches of slop.  The leaf drop is farther along this time but a significant amount of leaves are still on the trees, and I don't remember the winds being as strong in 2000.

[A-L-E-K]

zero chance of flakes here but it looks like an absolute pisser of a day in the making

[A-L-E-K]

looking forward to ice cold lake effect thundershowers

 

[Brewers]

Looks like there will be a potential ~3hr period for 50mph gusts behind the front.

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[Hoosier]

LOT already calling for 18 foot waves on southern parts of the lake.

[A-L-E-K]

LOT already calling for 18 foot waves on southern parts of the lake.

 

dunes on friday will be a nice place to experience the oregon coast vibe.

[Jonger]

dunes on friday will be a nice place to experience the oregon coast vibe.

 

These are the days I wish I didn't have kids... I'd love to go drive out there and check it out. No-can-do..... Trick R Treating bonanza in the cold.

[Chicago WX]

Should be nasty indeed. Slight chance of snow in the hourly forecast graph for LAF too. Very nice.

 

[OHweather]

12z NAM is more progressive...through 66 hours, hasn't closed that bad boy off at 500mb

[Hoosier]

Should be nasty indeed. Slight chance of snow in the hourly forecast graph for LAF too. Very nice.

 

laf 10:31 forecast.png

 

 

I'm wondering if we might get in on that lake band at some point.  Low level flow could carry some of that stuff pretty far south and being almost 100 miles inland, we would escape the marine puke air and have a better shot at snow.  It might drift too far west though.  Something to watch anyway. 

[Chicago WX]

I'm wondering if we might get in on that lake band at some point.  Low level flow could carry some of that stuff pretty far south and being almost 100 miles inland, we would escape the marine puke air and have a better shot at snow.  It might drift too far west though.  Something to watch anyway. 

 

Probably silly of me for posting it, but the 12z NAM has that scenario...where the LER/S band scrapes/misses us to the west.

 

EDIT: a "better" look. Short drive though.

 

[Hoosier]

Probably silly of me for posting it, but the 12z NAM has that scenario...where the LER/S band scrapes/misses us to the west.

 

10:29 12z nam 63 hour reflectivity.gif

 

 

If I were chasing this one I'd probably have an initial target in southern Lake/northern Newton county and adjust northward depending on how pronounced the marine influence is.  Given the strength of the low level flow, I think those areas will be able to get in on a good amount of precip. 

 

It's little more than a guessing game at this point as to exactly how far inland the marine air will be a detriment.  I went back and read a writeup on the October 2006 Buffalo event and it was interesting to see the forecasts from that morning compared to what happened.  The marine influence in that case was muted due to the well-organized band and prolific convective elements.  I'm not making a direct comparison between the two but the same basic question applies here. 

[Hoosier]

Lake effect band has a pretty cellular appearance on the NAM, at least early on.  Precip type plot verbatim shows that it's trying to mix in some snow during the afternoon.

 

 

[Gilbertfly]

1035+ vs. sub 1010 isn't insane...but def gets some style points...noon friday to noon saturday looks quite late novemberish as modeled now for mby

[Hoosier]

Early guess on the lake effect situation Friday into Saturday.  This is a really borderline one as has been discussed.  Lots of uncertainty on thermal profiles and how long it takes to get a well-organized band going.  Band placement seems to be getting narrowed down for the most part but obviously could see minor shifts. 

 

The dark blue area touches the red area by design, as that zone a few miles inland is tough to figure and has a range of plausible outcomes.

 

 

[A-L-E-K]

[Hoosier]

LOT increased the wave heights on the afternoon update.  These values would be similar to what happened with the remnants of Sandy IIRC.

 

 

FRIDAY  NORTH WINDS TO 45 KT. STORM FORCE GUSTS TO 50 KT  POSSIBLE. RAIN OR SNOW SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS.  WAVES QUICKLY BUILDING TO 20 TO 25 FT OCCASIONALLY TO 30 FT IN THE  AFTERNOON.  

[Hoosier]

part of LOT afternoon afd

OVERALL...THIS LOOKS TO   SET UP TO STRONG PRESSURE RISES...POSSIBLY IN EXCESS OF 6 MB/6HR   PERIOD...ESPECIALLY ACROSS LAKE MICHIGAN AND ADJACENT AREAS OF   NORTHEASTERN ILLINOIS AND NORTHWESTERN INDIANA. THIS COMBINED WITH   THE STRONG PUSH OF MUCH COLDER AIR...SHOULD DRIVE SOME VERY STRONG   WINDS. MODEL SOUNDINGS INDICATE MEAN LAYER FLOW IN EXCESS OF 45 KT   OVER SOUTHERN LAKE MICHIGAN...WITH AROUND 50 KT OF FLOW AT THE TOP   OF THE MIXING LAYER. IT APPEARS THAT THE STRONGEST WINDS WITH THIS   SYSTEM WILL BE DURING THE LATE MORNING AND AFTERNOON ON FRIDAY   FOLLOWING THE PASSAGE OF THE UPPER LEVEL VORT MAX. THE TRACK OF THIS   SYSTEM ALSO SUGGESTS THAT THE STRONGEST WINDS WILL ALSO BE OVER   APPROXIMATELY THE EASTERN HALF OF MY CWA...ROUGHLY FROM THE CHICAGO   METRO AREA AND POINTS EASTWARD. THESE AREAS COULD REACH WIND   ADVISORY CRITERIA WITH WIND GUSTS UP TO 50 MPH.      THE STRONG NORTHERLY WINDS COMING IN OFF THE LAKE COULD ALLOW WIND   GUSTS TO APPROACH 50KT FOR AREAS NEAR THE LAKE SHORE...ESPECIALLY IN   NORTHWESTERN INDIANA. VERY HIGH CRASHING WAVES IN EXCESS OF 18 FT   ALSO APPEAR LIKELY FOR THE INDIANA AND PORTIONS OF THE ILLINOIS   SHORELINES...WHICH COULD RESULT IN SOME LAKE SHORE FLOODING CONCERNS   FRIDAY.     IT APPEARS MUCH OF THE PRECIPITATION WITH THIS SYSTEM WILL BE   FAVORED ACROSS AREAS NEAR THE LAKE ON FRIDAY AND FRIDAY EVENING.   HOWEVER...AS THE MAIN UPPER IMPULSE MOVES OVER THE AREA THURSDAY   NIGHT INTO EARLY FRIDAY...IT COULD DRIVE A SHORT PERIOD OF SHOWERS    ACROSS MUCH OF THE AREA. HOWEVER...DRIER AIR AND LARGE SCALE FORCING   FOR DECENT SHOULD OVERSPREAD MOST INLAND AREAS ACROSS NORTHERN   ILLINOIS BY FRIDAY AFTERNOON...LIKELY ENDING THE THREAT OF PRECIP.   HOWEVER...AREAS NEAR THE LAKE IN FAR NORTHEASTERN ILLINOIS AND MY   NORTHWESTERN INDIANA COUNTIES WILL LIKELY CONTINUE TO EXPERIENCE   PRECIPITATION FRIDAY AFTERNOON AND INTO THE EVENING AS THERMODYNAMICS   OVER LAKE MICHIGAN WILL BECOME VERY FAVORABLE FOR LAKE EFFECT   PRECIPITATION THROUGH FRIDAY EVENING. LAKE INDUCED EQUILIBRIUM LEVELS   LOOK TO EXCEED 16,000 FEET WITH LAKE SURFACE TEMPERATURE TO 850 MB   TEMPERATURE DIFFERENCES OF 18-19 DEGREES C. THE OVERALL DEPTH OF   THIS LAKE INDUCED INSTABILITY COULD ALSO ALLOW FOR SOME CHARGE   SEPARATION SUPPORTING THUNDER AND LIGHTENING ACROSS SOUTHERN   PORTIONS OF THE LAKE AND POSSIBLY INTO NORTHWESTERN INDIANA FRIDAY.   SO I HAVE INCLUDED A MENTION OF SUCH IN THE FORECAST.     THE MAIN QUESTION WITH THIS EVENT REMAINS AS TO WHEN THE PRECIP TYPE   COULD MIX WITH OR CHANGE TO SNOW. IT APPEARS THAT WITH 850 MB   TEMPERATURES AROUND -8 DEGREES C...THAT A TRANSITION OVER TO LAKE   EFFECT SNOW SHOWERS APPEARS TO BE A DECENT BET BY LATE FRIDAY   AFTERNOON AND INTO THE EVENING. HOWEVER...DUE TO THE POTENTIAL FOR   CONVECTIVELY DRIVEN HEAVY SHOWERS OVER THE LAKE...DYNAMIC COOLING   COULD BECOME STRONG ENOUGH TO RESULT IN AN EARLY TRANSITION TO SNOW   OVER NORTHWESTERN INDIANA. WITH THIS IN MIND CONFIDENCE ON TIMING OF   ANY TRANSITION TO SNOW ON FRIDAY IS LOW...THOUGH THERE IS THE   POTENTIAL FOR SOME HEAVIER RAIN/SNOW SHOWERS WHICH COULD RESULT IN   SOME ACCUMULATIONS ACROSS PORTIONS OF NORTHWESTERN INDIAN IN SPITE   OF WARM GROUND TEMPS. THE STRONG WINDS COULD ALSO ALLOW THESE   SHOWERS TO GET WELL INLAND ACROSS NORTHWESTERN INDIANA. THE THREAT   OF SNOW SHOULD COME TO END OVERNIGHT FRIDAY AS INVERSION HEIGHTS   TANK IN RESPONSE TO BUILDING UPPER LEVEL HEIGHTS AND WARMING MID   LEVEL TEMPERATURES.

[Thundersnow12]

Will be interesting to see if any precip can survive till Saturday morning  as high pressure builds in on the west side of the lake as the NAM keeps showing but sounds like LOT is favoring the GFS in that regard. 

[Thunder Road]

Early guess on the lake effect situation Friday into Saturday.  This is a really borderline one as has been discussed.  Lots of uncertainty on thermal profiles and how long it takes to get a well-organized band going.  Band placement seems to be getting narrowed down for the most part but obviously could see minor shifts. 

 

The dark blue area touches the red area by design, as that zone a few miles inland is tough to figure and has a range of plausible outcomes.

 

 

whattheheckamidoing.png

 

I would pretty much agree with this map.  Maybe expand the red area southward just a bit.

[Hoosier]

pound town, and lol at the 1"+ making it into Tippecanoe county 

 

 

[Thunder Road]

Per Evan at IWX,

 

Lake surface temps on 11/11/2013, the day before our early-season LES event last year, were an average of 51.3 F.  At the moment we're averaging around 57 F or so, so that marine layer really can't be ignored.

 

The good news is that, at least from the 18z NAM in BUFKIT, the freezing level at SBN drops all the way to 600 ft by 0z.  

 

Also... using a lake surface temp of 54 F, you get a max lake-induced CAPE of 1011 J/kg.

[Geos]

Friday afternoon for sure I'll be checking out the wave action along the lake. Sounding like the wind will be strong enough to kick up the sand and sent it airborne!

 

18Z GFS winds at the surface and just above the surface at 0z 11/1.

 

 

[Hoosier]

Per Evan at IWX,

 

Lake surface temps on 11/11/2013, the day before our early-season LES event last year, were an average of 51.3 F.  At the moment we're averaging around 57 F or so, so that marine layer really can't be ignored.

 

The good news is that, at least from the 18z NAM in BUFKIT, the freezing level at SBN drops all the way to 600 ft by 0z.  

 

Also... using a lake surface temp of 54 F, you get a max lake-induced CAPE of 1011 J/kg.

 

 

 

Ah, thanks for mentioning that one from last year.  I hadn't thought of it.  Here's IWX's writeup:

 

http://www.crh.noaa.gov/iwx/?n=20131112_les

 

Interesting to see no reduction in totals near the shore.  However, there are some key differences as 850 mb temps with that event got down to around -12C, so besides having a colder lake it was also a colder airmass.

 

I'm just fascinated by this setup (as if no one could tell).  Having spent many years living near the lake and tracking things from afar in my years not living there, it's hard to recall many this early that at least had a chance to produce something decent.  I really feel like we're teetering between a very minor thing that coats the ground and something like a half foot+ paste job that makes it a memorable Halloween night for a lucky few, and the thing is, you could probably make a good argument for either of those outcomes.

[IWXwx]

Just read IWX's afternoon discussion (written by IND) and all I can say that you can tell that there is not a Great Lake near IND.AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE NORTHERN INDIANAISSUED BY NATIONAL WEATHER SERVICE INDIANAPOLIS IN409 PM EDT WED OCT 29 2014...AS OF RIGHT NOW...IT APPEARS A TENTH OR TWO OFACCUMULATION MIGHT BE POSSIBLE ON GRASSY AREAS BY SATURDAY MORNING.THE EXCEPTION WILL BE AREAS ALONG THE SHORES OF LAKE MICHIGAN THATCOULD SEE MAYBE HALF AN INCH...

30-35 MPH winds and 35° temps are going to feel awful.

[Geos]

Couldn't help but notice the 18z NAM putting Hammond and the IN/IL stateline in the LE core signal.

 

[OHweather]

pound town, and lol at the 1"+ making it into Tippecanoe county

ptot60.gif

Don't look at the 18z hi-res NAM snow map

I think the question for Friday PM into Friday evening when temps are marginal but parameters are extreme isn't whether a band will form but more along the lines of if it's a consolidated an extremely intense band or a broader band with weaker precip rates. Even during Friday afternoon and evening I'd have to imagine a consolidated band would dynamically cool things enough to get snow to stick just inland from the lake and possibly accumulate a relatively significant amount in a very small area, but the wind speeds during that timeframe make it questionable if a more consolidated band can form.