{ "number": 809, "headline": "December 7, 2025 Sunday Evening Weather", "standfirst": "Extreme cold (again) next weekend in Midwest and Great Lakes", "desk": "winter", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-12-08", "published": "2025-12-08T02:30:10.245000Z", "updated": null, "access": "free", "body_html": "
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This is post number 807 \u2026 evening update to keep the ball rolling into next week. Author: Dr. Ryan Maue (X @RyanMaue X @weathertrader)

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Some active thunderstorms across central Florida this evening \u2014 a reminder of what \u201cwarm convection\u201d looks like as we move into mid-December

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HRRR 18z | Next 48-Hours into Tuesday Early Afternoon

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Precipitation Type | Weather Next 6-days | ECMWF 18z

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Headlines Sunday Evening

  1. Powerful Alberta Clipper system Tues-Wed across the Midwest and Great Lakes

  2. 72-hours of \u201catmospheric river\u201d event \u201cboatloads\u201d of moisture into the Pacific Northwest

  3. Strong Western U.S. ridge remains anchored \u2014 and firmly in charge for the next 10-14 days (at least)

  4. Blocking ridge out west \u2014> Arctic air continues to spill out of Canada and Alaska as lobes of the polar vortex are extended southward by passing shortwaves \u2014 vorticity / energy packets from the North Pacific riding down the polar front boundary.

  5. COLD \u2014 even for mid-December \u2014 peaking Sat/Sun across the Midwest/Great Lakes.

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ECMWF 18z Precipitable Water Next 6-days | My favorite parameter

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Atmospheric river systems into the Pacific Northwest \u2014 narrow at first, and then quite a wide swath by Tues/Wed \u2014 see how shortwave disturbances along the polar front (polar vortex edge) pick up the moisture = Alberta clipper systems

White colored precipitable water = absence of moisture = cold/polar air mass surges southeast out of Western Canada into the Midwest into next weekend.

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West coast atmospheric river (AR \u2014 Category 5) = pineapple express out of Hawaii

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Temperature Anomaly | Next 15-days

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Flagship European model ensemble solution for temperature anomaly next 15-days shows intense cold pool formation over Alaska and Western Canada while a very warm/persistent blocking ridge remains stuck across the Western U.S.

Main uncertainty is ability of this ridge to extend east across the Rockies \u2014 and perhaps transition to a much warmer pattern into the 3rd week of December, but it\u2019s not guaranteed (yet)

Note, there are fast moving disturbances or short-waves riding along the polar front from the Gulf of Alaska through the Pacific Northwest and then in the Midwest and Great Lakes. These features are spaced out in time \u2014 so the ensemble mean blends or smooths out 51 solutions that ALL have cold blasts but intermixed with warm periods. The end result is a rather smoothed continuous blob of cold connecting Alaska with the Northeast U.S.

Temperature Anomaly Days 3-6 | Into Saturday morning

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Exceptionally cold air spills into the Midwest and Great Lakes

RTMA | Current Temperature Analysis | 8:00 PM ET

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Temperature Anomaly | 8:00 PM ET

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Lower 48 Temperature Anomaly was -2.4\u00b0F below normal

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NWS Precipitation Next 72-hours

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NWS Snowfall Next 72-hours

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More snowfall for Midwest \u2014 Great Lakes but looks to mainly miss Minneapolis, Chicago, and Detroit \u2014 big bummer for large population if you like travel disruptions!

Blend of Models | 7 Days Precipitation Total

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Upwards of 10-20 inches of precipitation \u2014 including liquid equivalent of snowfall in the Cascades from AR event

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Blend of Models | Total Snowfall Next 10-Days

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Completely snow free \u2014 zip/zero/zilch across California and the Great Basin

Plenty of opportunity for Lake Effect snow showers to crank up as Arctic air flows over the still much, much warmer Great Lakes.

Monday Morning Low Temperatures

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175 million below freezing (Lower 48 average low is 26.1\u00b0F) \u2026 6 million below 0\u00b0F

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Single digits across Michigan \u2014- across the lake into Toronto, and interior New England.

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Subzero in the Midwest \u2014 but could worse \u2014 it will get colder into next weekend.

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Monday High Temperatures

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Around 10 million at/above 80\u00b0F in Florida! 118 million don\u2019t get above freezing!

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20s across the Great Lakes and Northeast \u2014 chilly!

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\u2026 still in the mid-80s in South Florida \u2014 escaping the Arctic air mass completely.

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Tuesday Morning Low Temperatures

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200 million below freezing (Lower 48 average low is 27.9\u00b0F)

Coldest compared to \u201cnormal\u201d in the Northeast more than 15\u00b0F to 20\u00b0F below average lows \u2014 in the single digits to below 0\u00b0F

Tuesday High Temperatures

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AI-GFS 18z | 500 mb Temperatures | Polar Vortex Watch Next 10-days

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ECMWF AIFS-Single 18z | Height Anomaly (500 hPa) Next 10-days

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Integrated Vapor Transport Next 10-days | North America

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Parameter used for monitoring \u201catmospheric rivers\u201d usually along the U.S. west coast, but the idea works well for many other areas \u2014 highlighting midlatitude storm systems with warm conveyor belts (moisture plumes)

Integrated Vapor Transport Next 4-days | South America

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Powerful storm system forms over Southern Brazil \u2014 a cut-off low with huge moisture flow coming in off Atlantic = major rainfall/flooding risk

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ECMWF 18z | Snowfall | Next 6-days

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ECMWF EPS 12z | Ensemble Median Snowfall Next 15-days

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ECMWF EPS 12z | Ensemble Snowfall Probability > 1\u201d | Next 15-days

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We\u2019ll be monitoring the 1\u201d chance of snowfall for a \u201cWhite Christmas\u201d in the coming weeks. This map is through late December 20th.

ECMWF EPS 12z | Ensemble Snowfall Probability > 6\u201d | Next 15-days

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6-inches is sufficient for a \u201cbig storm\u201d and Lake Effect machine diagnostic

Next 15-days Temperature Anomaly | Ensemble Mean to December 21

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The western ridge is STRONG \u2026 and should provide enough Pacific moisture and moderating mild air to temper the longevity and intensity of any Arctic blasts that sink from the massive cold pool over Western Canada.

Temperature Anomaly | Next 15-days | ECMWF EPS 12z

5-Day Chunk #1 | Temperature Anomaly | Dec 7 - Dec 11

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5-Day Chunk #2 | Temperature Anomaly | Dec 12 - Dec 16

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5-Day Chunk #3 | Temperature Anomaly | Dec 17 - Dec 21

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", "body_key": null, "teaser_html": "

Some active thunderstorms across central Florida this evening \u2014 a reminder of what \u201cwarm convection\u201d looks like as we move into mid-December

Another storm system for Virginia \u2014 not intense but decent snowfall accumulations

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