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Fascinating very detailed update from Chi NWSO explaining how difficult this forecast is:UPDATE ISSUED AT 944 PM CST SUN NOV 9 2025 HAVE EXPANDED THE WINTER WEATHER ADVISORY TO INCLUDE FORD AND BENTON COUNTIES, OTHERWISE NO CHANGES TO THE MANY, MANY HEADLINES IN EFFECT. ALSO, NO BIG CHANGES TO THE FORECAST GRIDS THIS EVENING. CONVECTIVE ALLOWING MODELS (CAMS) OFTEN STRUGGLE WITH THE EXACT DETAILS OF LAKE EFFECT SNOW, MUCH LIKE THEY DO WITH SPECIFICS OF SUMMERTIME CONVECTION. THIS WAS THE CASE THIS EVENING WITH THE MOVEMENT AND TIMING OF THE LAKE INDUCED/ENHANCED MESO-LOW, WHICH MOVED INLAND INTO NORTHERN IN HOURS EARLIER THAN MOST CAM GUIDANCE HAD BEEN INDICATING. THE FASTER AND FARTHER EAST TRACK OF THIS MESOLOW HAS RESULTED IN CAMS BEING WRONG IN THEIR DEPICTION OF A LARGE INITIAL WESTWARD SURGING LAKE EFFECT SNOW PLUME WELL INLAND INTO NORTHEASTERN IL LATE THIS EVENING. RATHER, THIS MESOLOW HAS BECOME NEARLY STATIONARY OVER NORTH CENTRAL INDIANA WITH A COHERENT, INTENSE SINGLE BAND OF LAKE EFFECT SNOW EXTENDING NORTHWEST THEN NORTH UP THE SPINE OF THE LAKE FROM THIS MESOLOW. SURFACE OBSERVATIONS DEPICT A SHARP SURFACE TROUGH EXTENDING NORTHWEST FROM THE MESOLOW ACROSS SOUTHERN LAKE MICHIGAN. THIS TROUGH AXIS HAS BEEN STEADILY MOVING SOUTHWARD DOWN THE LAKE, WITH THE STRONG LOW LEVEL NORTHEASTERLY FLOW IN THE WAKE OF THIS TROUGH HELPING PUSH THE LAKE EFFECT PLUME STEADILY WESTWARD. AS THIS TROUGH CONTINUES TO PUSH SOUTH OF THE LAKE, ANTICIPATE THAT WESTWARD PROGRESSION OF THE LAKE PLUME SHOULD PUSH IT INTO NORTHEAST IL BETWEEN 11 PM AND MIDNIGHT. CONFIDENCE IS LOW IN HOW FAR WEST THIS PLUME WILL GET INTO NE IL BEFORE BECOMING QUASI-STATIONARY FOR A TIME, THEN LIKELY SHIFTING BACK EASTWARD TOWARD AND ACROSS NORTHWEST IN MONDAY. REALLY NOT PUTTING A TON OF STOCK IN CAM GUIDANCE AT THIS POINT, SO ONCOMING MIDNIGHT SHIFT WILL BE NOWCASTING THIS BAND THROUGH THE NIGHT BASED ON OBSERVATIONAL TRENDS. NO CHANGE TO THE MAGNITUDE OF INSTABILITY, WHICH IS CONFIRMED BY A SPECIAL 0030Z VALPARAISO UNIVERSITY SOUNDING FROM THIS EVENING. STILL ANTICIPATE SNOWFALL RATES OF AT LEAST 2-3 INCHES PER HOUR WITHIN THE HEAVIEST ELEMENTS OF THIS BAND. DEPENDING ON HOW LONG THE BAND BECOMES QUASI-STATIONARY, IT IS CERTAINLY POSSIBLE THAT WE COULD SEE ISOLATED TOTALS PUSHING OR EVEN EXCEEDING A FOOT BEFORE THE BAND BEGINS SHIFTING EASTWARD. CURRENT TRENDS WOULD SEEM TO SUGGEST THAT LAKE OR COOK COUNTY IL COULD BE THAT WESTWARD TERMINUS THAT SEES SOME OF THE HEAVIER TOTALS. WHERE EVER THE BAND IS DURING RUSH HOUR TOMORROW MORNING, TRAVEL CONDITIONS WILL BE VERY DIFFICULT TO NEARLY IMPOSSIBLE. - IZZI

The massive meso-low currently at the southern tip of the lake is just cranking. Can't recall seeing something to that magnitude before around here.

Looks pretty good out there over the layke atm

@Torch Tiger all set check your personal messages.

finally,some rain to keep the leaf piles from blowing away tomorrow.

Down to 33. The roads are very wet, liable to be some icy travel if we get down to 24 as predicted.

Looks like it will be a relatively short punch here downwind in Jasper County. Not bought into the deterministic output for snow accumulation. But that’s just experience talking vs any science applied. Still think there’s a shot of an inch or so. Looking forward to seeing what comes of this further north and west into the city.

@mreaves all set - check your personal messages.

Giving us that Xtra westerly push?

Any good webcams out of Chicago ?

Gnarly storms for this time of year. Jumped at a couple of these sudden bolts.

One of many… But this particular meso-low earlier this afternoon was quite significant.

Yep, periods of rain here with thunder and loud thunder 56f humidity 98% Looks like fairly strong thunderstorms in Delaware Bay in a line moving into south Jersey.

@WxWatcher007 all set - check your personal messages.

Still having trouble seeing their forecast.

Yeah not happening

We missed being out in all the rain in the city thankfully!

His mother was a mudah

Thunder and lightning here. Not as crazy as where @CAPE is located, but much more rain than forecasted. Still more to arrive from my SW shortly.

Increasing loud thunder and 70F here in Greenville, N.C. as storms are moving rapidly from SW to NE. I take it this is the first of the two cold fronts moving through. Possible snow showers late tomorrow night which would be crazy for this time of year.

^Ok, I've plotted Tropical OLR and found that subsurface temperature anomalies near the thermocline (associated with sea level height) are actually more impactful. You see the correlation increase to almost double and the same goes for vs 850mb wind, 250mb wind, sea-level pressure. Matching Tropical Pacific OLR though, which is "Weak La Nina-like" right now, comes out to a -NAO in Nov and Dec then switches to +NAO for Jan and Feb. Curious how he got -NAO for Jan and Feb.

Keep on a pushing...

Paul Roundy @PaulRoundy1 · 13h The algorithm is based entirely on outgoing longwave radiation data in the tropics. The OLR diagnostic algorithm is explained and assessed here: https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.962 And the association with the extratropical circulation is diagnosed through the method of constructed analogs: https://journals.ametsoc.org/view/journals/mwre/141/7/mwr-d-12-00223.1.xml Since the algorithm does not include any explicit information about the ocean (it includes what is implicit in OLR anomalies), and since the OLR signal is projected forward based on how similar OLR signals moved in the past, it will do poorly when the ocean subsurface is undergoing strong changes. In the short term (e.g., next 2 months), the results are reasonable, but in this particular event, there is risk of El Niño being forced by strong subseasonal variability (February through May). Should that occur, the verification data would diverge from the forecast.