{ "number": 822, "headline": "December 20, 2025 Saturday Weather After Dark", "standfirst": "Northeast will not participate in the exceptional warmth through end of year", "desk": "notebook", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-12-21", "published": "2025-12-21T03:12:59.504000Z", "updated": null, "access": "free", "body_html": "
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This is post number 822: Good Evening \u2014 less than 5-days until Christmas! Welcome to new subscribers, long-time supporters, and visitors! Author: Dr. Ryan Maue (X @RyanMaue X @weathertrader)

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White Christmas

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Snow on the ground Christmas morning mainly because there was so much that fell in recent weeks and lack of a major thaw.

ECMWF 18z | Next 6-days Temperature Anomaly

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The western Canada cool pool is looking to escape in any direction and sends a blast of cold air out in the Pacific with a \u201cPolar Vortex\u201d lobe and upper-level trough \u2014 all linked with a complex of powerful surface storm systems (low pressure) off the California coast.

Cold air is finally eroded in the Great Lakes \u2014 but the Northeast might not see much warmth in the coming week, and instead be on watch for snow squalls.

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

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Precipitation Type and Intensity | Next 6-days

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Powerful West Coast Storm Systems \u2014 Wednesday and Thursday

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Chance of snowfall accumulations Tues, Wed, and Friday across the Northeast

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HRRR 00z | Next 48-Hours Sim Radar through Monday 7 PM ET

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West coast moisture plume \u2014 centered on Northern California initially and then northward again into OR/WA by Monday.

RRFS-A Total Precipitation Through 84-hours \u2014> Wednesday 2 AM

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Northern and Central California precipitation through early Wednesday \u2026 northern Sierra capture upwards of 20\u201d of precipitation (!) while the NorCal coast could see 6\u201d to 10\u201d just in the next 3-days. Whoa.

NWS Precipitation Next 72-hours

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National Weather Service gridded forecasts similar to RRFS \u2026 also showing the huge max over northern Sierra.

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NWS Snowfall Next 72-hours

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Nice area of 2\u201d to 4\u201d of snowfall across the Northeast mainly into Tuesday \u2026 more off the Lakes.

RTMA | Current Temperature Analysis | 9:00 PM ET

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Average Lower 48 temperature was 39..3\u00b0F with 44 million below freezing.

Temperature Anomaly | 9:00 PM ET

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Lower 48 Temperature Anomaly was a 4.3\u00b0F ABOVE normal

Sunday Morning Low Temperatures

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128 million below freezing with extreme cold in the Midwest > 3 million subzero.

Sunday High Temperatures

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Warming trend underway from south to north \u2026 65 million at least 70\u00b0F

Christmas Eve Temperatures | High Temperatures

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Almost 100 million at least 70\u00b0F

Christmas Day Temperatures | Morning Lows

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Only 64 million below freezing for low temperatures

Christmas Day Temperatures | Daily Highs

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108 million now at/above 70\u00b0F on Christmas Day!

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

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The Lower 48 settles into a MUCH ABOVE NORMAL temperature pattern except for the Northeast \u2026 the ridge reforms (build a block 2.0) across the central U.S. in the New Year. Alaska goes into the Deep Deep Freeze.

Blend of Models | 10 Days Precipitation Total

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Enormous rainfall totals across California | Deluge

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Blend of Models | Total Snowfall Next 10-Days

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

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Upper-level pattern is blocked (Omega) across the central U.S. and seems to hit the repeat button into final days of 2025.

ECMWF AIFS-Single 186z | Temperature (500 hPa) Next 10-days

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Polar Vortex (tropospheric) monitor \u2014> the pink = coldest at 500 mb and we see the arrival of some cold air from Siberia over the pole into the New Year to reinforce the PV over Alaska and Canadian Arctic.

The ridge builds back into the New Year across the central Lower 48 (?)

ECMWF 12z | Integrated Vapor Transport Next 10-days

Look at the IVT source from the Tropical Pacific heading westward out of the Caribbean and then pulled northward into Southern California and the U.S. Southwest.

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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)

ECMWF 06z | Snowfall | Next 6-days

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Snowfall for New England \u2014> could be significant in a narrow band as winter is not taking a break.

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

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

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

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

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The Northeast will be below normal for the 15-day period \u2026 as the ridge is not strong enough to prevent the polar vortex related troughs from dipping through along with strong storm systems out in the Atlantic.

5-Day Chunk #1 | Temperature Anomaly | Dec 20 - Dec 24

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5-Day Chunk #2 | Temperature Anomaly | Dec 25 - Dec 29

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5-Day Chunk #3 | Temperature Anomaly | Dec 30 - Jan 3

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Canadian Cold Pool remains intense \u2014 and seems to be dumping out over the Pacific rather than escaping to the east across Manitoba into the Great Lakes.

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Snow on the ground Christmas morning mainly because there was so much that fell in recent weeks and lack of a major thaw.

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