{ "number": 828, "headline": "December 27, 2025 Saturday Evening Winter Weather", "standfirst": "Great Lakes Blizzard of 2025 scheduled to end the year with heavy snow and damaging winds", "desk": "winter", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-12-28", "published": "2025-12-28T02:46:29.674000Z", "updated": null, "access": "free", "body_html": "
\"\"

This is post number 828: Good Evening \u2014 5-Days until New Year 2026. This is a quick/bonus update with maps to keep everyone apprised of the upcoming major storm system to bury and blow away the Great Lakes.

Author: Dr. Ryan Maue (X @RyanMaue X @weathertrader)

Major Blizzard \u2014> Bomb Cyclone forecast for Midwest and Great Lakes Sunday into Monday. The system maintains pressure in the 970s mb then intensifies again once it phases with the upper-level (Polar Vortex) lobe that arrives out of Arctic Canada. This whole \u201ctreble clef\u201d looking deal is representative of the \u201cbaroclinic\u201d or extratropical cyclone lifecycle. This is an impressive example with very low pressure over land almost entirely on its journey. Dynamic tropopause maps show the air masses and the movement of the cyclones + anticylones (ridges) as they migrate through North America. The atmosphere is a fluid and sometimes when we don\u2019t use high temporal frequency maps of every 1-2 hours, it looks like the storm systems jump, but that\u2019s not so.

Purple haze + white fuzzballs = cold polar vortex related air vs. red = subtropical (warmer) origin. Next 5-days from GFS 18z:

\"\"

Simulated Radar Next 48-hours into Monday 7 PM ET

\"\"

HRRR captures most of the storm development through 48-hours from the 00z cycle. IN addition to the heavy snowfall and wintery precipitation, MARGINAL chance of severe thunderstorms with a risk of tornadoes along the warm front in IL/IN and perhaps southern Michigan on Sunday. The main threat even outside of thunderstorms will be very gusty winds.

Severe Thunderstorm Outlook | Sunday morning to Monday morning

\"\"

Weather Trader is an entirely subscriber-supported publication [sweat equity] from Dr. Ryan Maue. To receive all new posts, consider becoming a free [1-2 updates per week] or paid subscriber [golden ticket] and please LIKE and SHARE posts.

Headlines Saturday Evening

Give a gift subscription

RRFS-A Extension from Sunday to Tuesday morning

\"\"

RRFS-A Zoom on Great Lakes | Precipitation Type

\"\"

RRFS-A Zoom on Great Lakes | Wind Gusts \u2014> Yikes (50-60 mph)

\"\"

Total Snowfall \u2014> System + Lake Effect

\"\"

Total Precipitation \u2014> intense bands of rainfall from Northern Illinois across I-80 into Detroit.

\"\"

ECMWF 18z Precipitable Water Next 6-days

\"\"

White/gray = Arctic air from Canada wraps around the \u201cbomb cyclone\u201d into middle of next week. The polar cold front sweeps through Florida.

A Subtropical Something System comes out of the Eastern Pacific northward into Southern California by Wednesday.

ECMWF 18Z MSLP Next 6-days

\"\"

Long track of \u201cbomb cyclone\u201d to 957 mb in Quebec retrograde into Hudson Bay \u2014 maintains the cyclonic / cold circulation out of Canada into the Great Lakes.

ECMWF 18z Precipitation Type and Intensity | Next 6-days

\"\"

NWS Precipitation Next 72-hours

\"\"

NWS Snowfall Next 72-hours

\"\"

RTMA | Current Temperature Analysis | 8:45 PM ET

\"\"

Average Lower 48 temperature was 42.4\u00b0F with 69 million below freezing.

Temperature Anomaly | 8:45 PM ET

\"\"

Lower 48 Temperature Anomaly whopping 8.2\u00b0F ABOVE normal

Sunday Morning Low Temperatures

\"\"

117 million below freezing and a small area of subzero in Maine

Sunday High Temperatures

\"\"

101 million at least 70\u00b0F \u2014> nationwide average of 47.0\u00b0F.

Monday High Temperatures

\"\"

Only 33 million at least 70\u00b0F \u2014> nationwide average of 38.3\u00b0F

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

\"\"

Alaska + Canadian Cold Pool drains ESE into the Midwest and Great Lakes next week and it seems the Lower 48 ridge will weaken \u2014 allowing a southward push of the \u201cpolar front\u201d \u2014 Canada finally warms up into 2nd week of January \u2014> pattern shifts to much warmer for North America

Blend of Models | 7 Days Precipitation Total

\"\"

Blend of Models v5.0 | Total Snowfall Next 7-Days

\"\"
\"\"
\"\"

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

\"\"

The bomb cyclone interacts with the \u201cPolar Vortex\u201d lobe over the Northeast and then violently retrogrades into Hudson Bay \u2014 also due to the Greenland blocking ridge

ECMWF AIFS-Single 18z | Temperature at 500 hPa Next 10-days

\"\"

ECMWF 18z | Snowfall | Next 6-days | Lower 48 and Europe

\"\"
\"\"

Europe Precipitation Type Next 6-days

\"\"

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

\"\"

Ensemble Maximum | Max Snowfall out of 51-members thru 15-days

\"\"

The actual chance of seeing accumulating snow somewhere in the Lower 48 is actually pretty small BUT not zero.

Probability of 1-inch or more Snowfall in the next 15-days

Probability of 6-inches or more Snowfall in the next 15-days

\"\"

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

\"\"

5-Day Chunk #1 | Temperature Anomaly | Dec 27 - Dec 31

\"\"

5-Day Chunk #2 | Temperature Anomaly | Jan 1 - Jan 5

\"\"

5-Day Chunk #3 | Temperature Anomaly | Jan 6 - Jan 10

\"\"

Maps sourced from weathermodels.com designed and innovated by yours truly! Please subscribe there for real-time access to the newest maps, charts from all of the weather models including ECMWF and AIFS, NOAA AI-GFS/AI-GEFS

Active coupon codes:

None. Please send a message or reply to this email for inquiries.

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

Major Blizzard \u2014> Bomb Cyclone forecast for Midwest and Great Lakes Sunday into Monday. The system maintains pressure in the 970s mb then intensifies again once it phases with the upper-level (Polar Vortex) lobe that arrives out of Arctic Canada. This whole \u201ctreble clef\u201d looking deal is representative of the \u201cbaroclinic\u201d or extratropical cyclone lifecycle. This is an impressive example with very low pressure over land almost entirely on its journey. Dynamic tropopause maps show the air masses and the movement of the cyclones + anticylones (ridges) as they migrate through North America. The atmosphere is a fluid and sometimes when we don\u2019t use high temporal frequency maps of every 1-2 hours, it looks like the storm systems jump, but that\u2019s not so.

", "claims": [], "assets": [], "provenance": { "built_at": "2026-09-10T14:46:14Z", "model": null, "cycle": null, "stores": [ "https://weather.substack.com/p/december-27-2025-saturday-evening" ], "mint_sha256": null, "pairing_rule": null, "detector": null, "detector_version": null, "inputs": { "substack_post_id": "182739762.december-27-2025-saturday-evening", "audience": "everyone", "type": "newsletter", "imported_from": "substack export" } }, "strength": 0.0, "tags": [ "archive", "everyone" ], "supersedes": null, "superseded_by": null, "source": "substack", "canonical": "https://weather.substack.com/p/december-27-2025-saturday-evening", "slug": "december-27-2025-saturday-evening-winter-weather", "path": "/mp/828/", "url": "https://forecastpost.com/mp/828/", "desk_label": "Winter", "digest": "34d888c1c1a24e0ca1dfd45f9ebb4a6a1757c58bdcd7e6fe1e8a2076d09664d0" }