beavis1729

.LONG TERM...(Saturday through Wednesday) Issued at 236 PM EST Thu Jan 24 2019 ...Winter storm and pipe freezing cold on the way... Track of potent upstream amplifying wave late Sun predicated on how quickly deep low south of James Bay ejects out ahead of sewd peeling PV dropping through cntrl Canada. Regardless of specific solution track, intense warm advection wing expected to emanate ese of deepening cyclone as leading strong moisture push off the Gomex hits eroding swrn flank of arctic wedge. 12Z deterministic consensus shifted south again and holds retreating arctic wedge in longer yet still some threat exists for a mix far s/se. Wrn OH valley sourced pivot point would portent a prolonged duration of snow as deformation zone overlaps leading warm advection zone and likely hefty snow amounts given sharp baroclinic zone in place. Nevertheless strong flow inadvance and behind this system promise a mess with the addition of considerable blowing/drifting snow. Thereafter a brutishly cold airmass entrenched through nrn Canada will blast south commensurate with PV swing through Michigan. Many long standing records will no doubt fall and threaten all-time cold records as raw 2m guidance sits in unseen territory across the nrn OH valley.

6AM Jan 25: 6 AM Jan 30:

Agree completely...and it will also help if the Sunday-Monday clipper adds some fresh snow cover to help offset any potential UHI effects. Even if ORD "only" hits -20, it would be the coldest since January 1994 (Feb 1996 hit -19 at ORD, I believe). 12z GFS continues the insanity...only 6 days out now:

Records in play for Chicago. Note some of the data prior to 1928 may be a bit off, as I only did a quick scan of ORD/MDW official data and LOT record pages. All-time coldest temps -27, 1/20/1985 -26, 1/10/1982 -25, 1/16/1982 -25, 12/24/1983 -23, 1/19/1985 -22, 1/21/1984 All-time low max temp -11, 12/24/1983 -11, 1/18/1994 -10, 1/25/1897 -9, 1/15/1972 All-time coldest daily mean temp -18, 12/24/1983 -16, 1/18/1994 -15.5, 1/20/1985 -15, 1/10/1982 Coldest 2-day mean temp -15.75, 12/23/1983 to 12/24/1983 -12.25, 1/25/1897 to 1/26/1897 -12, 1/18/1994 to 1/19/1994 -11.25, 2/2/1996 to 2/3/1996 Coldest 3-day mean temp -14.2, 12/23/1983 to 12/25/1983 -9.5, 2/2/1996 to 2/4/1996 -8.5, 1/17/1994 to 1/19/1994 Daily records Jan 30: low max 3 (2004); min -15 (1966) Jan 31: low max 1 (1971); min -12 (1985)

Nice! I'm surprised the record low H85 temp at DVN is "only" -27.7C. I would have thought closer to -30 or -32C. That makes the current model output even more impressive. Would like to get this within 5 days...but even so, those incredibly low EPS mean heights are very telling that it's probably the real deal. Yeah, the 18z GFS was wild. 468 dm thickness at INL and H85 temps below -40C.

URGENT - WINTER WEATHER MESSAGE National Weather Service Chicago IL 220 PM CST Wed Jan 23 2019 ...Dangerously Cold Wind Chills Possible Thursday night into Friday Morning... ILZ003>006-008-010>012-019-020-240430- /O.NEW.KLOT.WC.A.0001.190125T0000Z-190125T1800Z/ Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-DeKalb-Kane-La Salle- Kendall- Including the cities of Rockford, Belvidere, Woodstock, Waukegan, Oregon, Dixon, DeKalb, Aurora, Elgin, Ottawa, and Oswego 220 PM CST Wed Jan 23 2019 ...WIND CHILL WATCH IN EFFECT FROM THURSDAY EVENING THROUGH FRIDAY MORNING... * WHAT...Dangerously cold wind chills possible. Wind chills as low as 30 below zero possible. * WHERE...Portions of north central and northeast Illinois. * WHEN...From Thursday evening through Friday morning. * ADDITIONAL DETAILS...The cold wind chills could cause frostbite on exposed skin in as little as 30 minutes. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Wind Chill Watch means there is the potential for a combination of very cold air and the wind to create dangerously low wind chill values. Monitor the latest forecasts and warnings for updates on this situation.

Taken from the TN sub-forum. The pink area is 48+ degrees below normal.

Yikes, and it's only Day 7. Those are sub-486 H5 heights in WI, not thicknesses. That is insane.

NWS DLH Area Forecast Discussion National Weather Service Duluth MN 1145 AM CST Wed Jan 23 2019 .SHORT TERM...(Today through Thursday) Issued at 322 AM CST Wed Jan 23 2019 A very strong cold front will bring strong winds followed by a return to frigid arctic temperatures tonight into Thursday morning. Today will almost certainly be the warmest day until the end of January as arctic air returns this weekend through much of next week. A warm front briefly builds east from the northern Great Plains into the Upper Midwest today with a ridge of high pressure ahead of the front helping to create some weak subsidence that will suppress some of the stratus and associated flurries across the Northland today, leading to a mix of sun and clouds today before clouds increase from the west ahead of the cold front that will move in tonight. Widespread light snow develops along and ahead of the frontal boundary this evening into tonight resulting in up to an inch of so of fluffy snow across far northern Minnesota into parts of northwest Wisconsin. Late tonight into early Thursday morning the greatest impact of this cold front will occur as very strong northwest winds of 20 to 30 mph with gusts up to 40 mph roll through northern and central Minnesota due to the very strong pressure and thermal gradient between the seasonable airmass ahead of the front (850mb temps around -5C, surface temps in the teens above zero) to the Arctic air behind the front (850mb temps falling to -25 to -30C, surface temps struggling to reach above zero on Thursday afternoon). The strongest winds will likely only occur for a few hours as the front moves through, with breezy winds of 15 to 20 mph lingering into much of the day Thursday. Skies will clear out from west to east as the arctic surface high builds in from the west on Thursday afternoon, centered over the Dakotas around 18z, building southeast towards Iowa Thursday evening. Surface pressure will increase rapidly with this front, from around 1010mb 06z Thurs to 1025mb 18z Thurs, a ~15mb rise in 12 hours. The cold air will filter in behind the front through the day Thursday resulting in the high temps on Thursday occurring in the morning hours - temps will in the single digits to low teens around midnight, single digits above and below zero at daybreak, then most locations in the single digits below zero Thursday afternoon. As temperatures fall and winds remain breezy, wind chill values will fall to 25 to 35 below zero, likely prompting the need for a wind chill advisory on Thursday. .LONG TERM...(Thursday night through Tuesday) Issued at 322 AM CST Wed Jan 23 2019 The coldest temperatures are yet to come. January will end with continued arctic intrusions, with near-record cold temperatures possible towards the middle of next week. On the synoptic scale the pattern remains fairly consistent over the next seven days with longwave ridge off the west coast and a longwave trough over much of the central and eastern CONUS, which will allow for two distinct rounds of arctic air impacting the Upper Great Lakes as air as cold as -40C tracks south from the arctic circle across northwest Ontario and across northeast Minnesota and Lake Superior resulting in what will likely be the coldest days of the winter yet - perhaps the coldest of this season considering we have just passed the climatologically coldest time of the year. Late this week a round of colder air builds in from the north with low/mid level moisture and the persistent north-northwest winds at low to mid levels leading to a prolonged period of lake effect snow showers along the south shore. Then this weekend, a potent upper low and associated arctic air will track south-southeast across northwest Ontario towards the Upper Great Lakes. While the strongest broad-scale lift and precip chances will be further to the east, this upper low will bring 850mb temps of -35C to -40C to northeast Minnesota, reinforcing the already cold airmass over the region. The surface high pressure associated with this Arctic air will be over central Manitoba late Saturday then weaken as it builds eastward into northwest Ontario on Sunday. To the west, an elongated mid/upper level shortwave trough will track south across the Canadian Rockies into the northern Great Plains, producing strong broad-scale forcing along a warm frontal zone in the Dakotas. This warm front will then build eastward into the Upper Mississippi River Valley, being forced to take a southeasterly trajectory around much of the Northland due to the arctic high over northwest Ontario on Sunday into Monday. Depending on the trajectory precipitation may impact all or none of the Northland as the main shortwave trough axis swings across the Upper Midwest, but chances are likely there will be at least some light snow on Sunday into Sunday night, though the best chance for any measurable accumulating will be greatest across central and southern Minnesota. A brief break from the worst of the cold early next week before another upper low and arctic airmass approach from the north, this time with an origin farther to the west over Manitoba Monday before moving into the northern Great Plains and Upper Midwest towards mid- week. While there will be a chance for some light precipitation associated with this upper low, the primary sensible weather impact will be the frigid cold temperatures this next round of arctic air produces, with temperatures as cold or colder than the Arctic outbreak last weekend. With the very cold air expected, wind chill advisories or warnings will likely be needed nearly every night for the rest of the month.

0z Euro H85 temps at Day 7. -30C in northern IA, -35C in northern MN, and the infamous -40C in southern Manitoba.

at the Euro. The 6z FV3 also shows the arctic outbreak for Jan 30-31. Not quite as intense as the 0z Euro, but still very cold. Verbatim, it looks like -20s in IA and -30s in MN.

Word has it that today’s 12z Euro has wind chills in the -30s in the Chicago area on days 9-10, with -40s in the upper Midwest.

Dewpoint at ORD increased from -6 to 20 during the past 15 hours. Of course, it was very low to begin with...and there's still a ways to go to get near freezing.

With the new snow cover expected in N IL, NWS Chicago has dropped the temps significantly for Friday and Saturday. Now forecasting a low of -12 on Friday morning at RFD, with highs barely above 0 on Friday afternoon. Could see a wind cill advisory soon; I believe the criteria is -20. Could see temps near -30 in northern MN again, but with more wind this time.

Didn't realize that LOT issued a warning overnight for the NW part of the FA, including Rockford. URGENT - WINTER WEATHER MESSAGE National Weather Service Chicago IL 324 AM CST Tue Jan 22 2019 ...Freezing Rain and Snow Expected Today into Wednesday Morning... ILZ003-004-008-221800- /O.UPG.KLOT.WW.Y.0005.190122T1500Z-190123T0000Z/ /O.NEW.KLOT.WS.W.0003.190122T1500Z-190123T1800Z/ Winnebago-Boone-Ogle- Including the cities of Rockford, Belvidere, and Oregon 324 AM CST Tue Jan 22 2019 ...WINTER STORM WARNING IN EFFECT FROM 9 AM THIS MORNING TO NOON CST WEDNESDAY... * WHAT...Heavy snow expected through Wednesday morning, mixing with freezing rain this afternoon. Total snow accumulations of 4 to 7 inches expected. Total ice accumulations of up to one tenth of an inch expected this afternoon. * WHERE...Winnebago, Boone and Ogle Counties. * WHEN...From 9 AM this morning to noon CST Wednesday.

Yeah...and ORD has a dewpoint of -7. Hard to fathom the Td increasing by 35+ degrees over the next 24 hours. Normally you'd lean against it, but the model support seems overwhelming. Hopefully the Ukie and NAM can win out...but, unfortunately, WAA can overwhelm everything if the conditions are right.

Looks like the coldest weekend temp was -42, at Babbitt and Crane Lake.

Nice...and the airmass wasn’t even “extreme”. Just great radiational cooling. INL had lows of -38 and -35 on Saturday and Sunday mornings, respectively. Coldest I could find was -42 at Crane Lake and Babbitt.

Agree with your thoughts. I could see -10 around 2 or 3 AM, with steady or slowly rising temps after that due to incoming cloud cover. IMBY, I am thinking -5...and around 0 at ORD.

Glad you started the thread! At the moment, unfortunately, the only time period for which an arctic outbreak is fairly certain in Jan 25-26...and it looks to be short-lived. It's often hard to break daily records with such a short-duration outbreak, due to possibility of getting the high temp at midnight. Various runs of many different models have been occasionally showing the motherload coming down after that...but then it either disappears on subsequent runs, or gets pushed back in time. The 12z Euro from 1/18/19 was the craziest run of all, but it has since backed off significantly. Anyway...here are the upcoming daily records for Chicago. Even though Jan 25-26 seems to be the most certain, I'm including numbers for the rest of January in case the models bring back the arctic outbreak. At this distance, the record with the greatest chance of being broken (and it's still a fairly small chance imo) appears to be the low max of -3 on Jan 26. Daily records (low and low max): Jan 25: -20 (1897); -10 (1904) Jan 26: -16 (1897); -3 (1897) Jan 27: -10 (1955); -1 (1895) Jan 28: -13 (1977); -3 (1966) Jan 29: -16 (1966); -6 (1966) Jan 30: -15 (1966); 3 (2004) Jan 31: -12 (1985); 1 (1971)

LE snow headlines no longer exist. It would either be WWA or WSW.

Lost in the tracking of the current storm is the first significant arctic outbreak of the season in the upper Midwest. Ely MN hit -36 this morning. As has been seen sporadically on some models over the past 5 days, there could be a more widespread arctic outbreak towards the end of January. Would like to stop seeing it getting pushed back in time before jumping all in. We’ll see. I just saw a separate thread started for this; if it becomes more certain, I’ll post some stats in there for ORD and other areas.

Yeah the Euro is insane....worthy of the 21 bun salute. That bitter arctic air has been sitting there in southern Canada for awhile, waiting to be tapped. Maybe this is it.

Yeah, seems like the surface lows are generally similar in strength and location on the 12z GFS and 12z NAM...but for Chicago area, GFS shows about 0.4” of liquid and NAM is close to 1”. Splitting the difference is probably a reasonable approach for now. 0.7” of liquid at 13:1 ratios implies about 9” of snow. Admittedly it’s a very rough estimate, but we will see what other hi res guidance starts showing as it gets into better range. Either way, lake effect/enhancement will be an interesting wildcard.