{ "number": 817, "headline": "December 16, 2025 Tuesday Morning Winter Weather", "standfirst": "Boatloads of precipitation from powerful west coast atmospheric rivers", "desk": "winter", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-12-16", "published": "2025-12-16T14:39:25.262000Z", "updated": null, "access": "free", "body_html": "
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This is post number 817: Good Evening \u2014 only 9 days until Christmas! Hopefully the warmer weather will make travel easier especially in the Great Lakes and Northeast!

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

HRRR 06z | Next 48-Hours through Thursday 1 AM ET

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Atmospheric river crashes into Pacific Northwest \u2026 moisture crosses the Rockies within a parade of storm systems on the edge of the tropospheric polar vortex.

Storm System Parade Across Canada | Next 6-days | MSLP

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Sequence of 3 powerful storm systems measured by central pressure in the 970s in an unlikely location over land in southern Canada. These mobile cycles quickly track east over the next 6-days \u2026 each time providing a \u201cclash of air masses\u201d between warmer Pacific origin air to the south and the Alaska/Canadian cold pool to the north.

Next 6-days | 850 mb Winds

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Lower atmosphere level winds show plenty of energy with these storm systems sweeping across the Midwest, Great Lakes, and Northeast into next weekend. Thankfully, much warmer across the Lower 48 so we\u2019re NOT looking at a trio of crippling blizzards.

Precipitation Type | Weather Next 6-days | ECMWF 06z

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Headlines Tuesday Morning

  1. Significant warming trend into upcoming week with some interludes of Arctic air associated with parade of storm systems in Southern Canada.

  2. Powerful storm systems with pressure in the 970s mb track from the Pacific through British Columbia into the Prairie provinces. There isn\u2019t much moisture available to the south until the Gulf of Mexico can be accessed Friday.

  3. One of these storms intensifies in Quebec to perhaps the 950s mb and will usher in a polar vortex lobe and colder air behind it on Friday

  4. And, another quick blast of cold air from that replenished Western Canada \u201ccold pool\u201d for the Midwest and Great Lakes this weekend.

Next 6-days Temperature Anomaly

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Pattern looks more like early March than mid-December with these strong storm systems \u2026 thankfully not looking at severe weather. Instead, we\u2019ll see windy and wet conditions in the Great Lakes and Northeast, but unlikely to see much in the way of snow accumulations in the Lower 48. Canada will be further buried in snow.

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High Temperatures Next 8-days | Until Wednesday Dec 24th

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The temperature pattern sees some \u201camplification\u201d with the brief cold snaps on Friday and Sunday \u2026 but the cold retracts northward as strong, warm zonal flow dominates the Lower 48 with a strong/honking ridge.

Christmas Day Temperatures | Morning Lows

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86 million below freezing for low temperatures \u2014 but that\u2019s not too bad for December 25th.

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Christmas Day Temperatures | Daily Highs

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Almost 70 million at/above 70\u00b0F on Christmas Day! Only 9% of the Lower 48 by area will be freezing on Christmas Day \u2014 according to Blend of Models (v4.3)

ECMWF 06z Precipitable Water Next 6-days | My favorite parameter

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ECMWF 00z EPS | Temperature Anomaly | Next 15-days

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The Lower 48 settles into a MUCH ABOVE NORMAL temperature pattern \u2014 eventually \u2014 once we can finally block off the \u201cpolar vortex\u201d by the weekend.

Temperatures surge to well above normal for much/all of the Lower by Christmas \u2014 BUT the Northeast could see normal or colder air, especially with proximity to the \u201cPolar Vortex\u201d and any lobes that may be dragged south by passing storm systems.

The Alaska / Western Canada cold pool replenishes strongly into the New Year, but the Lower 48 blocking ridge remains firmly in charge \u2014 at least for now!

NOAA GFS 06z | Dynamic Tropopause (Polar Vortex monitor)

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Don\u2019t often show GFS \u2014 but I do like this parameter which shows the clash between the Arctic air mass (purple + white fuzzball) and subtropical warmth (red)

We can see the \u201clobes\u201d of the tropospheric polar vortex still rotating through the Midwest and Northeast into next week until the blocking ridge firmly takes hold.

RTMA | 24 Hour Temperature Change | 8:15 AM ET

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Lower 48 is 6.0\u00b0F warmer than 24-hours ago

RTMA | Current Temperature Analysis | 8:15 AM ET

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Average Lower 48 temperature was 33.0\u00b0F with about 143 million below freezing.

Temperature Anomaly | 8:15 AM ET

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Lower 48 Temperature Anomaly was 3.4\u00b0F ABOVE normal

Tuesday High Temperatures

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Lower 48 average high > 51\u00b0F \u2014 with 50 million at least 70\u00b0F and 40 million below freezing mainly in the great Lakes and Northeast

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Wednesday Low Temperatures

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159 million below freezing but not seeing any subzero readings.

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Wednesday High Temperatures

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Even warmer \u2014 we lose almost the entire freezing population \u2014 up to 56 million at least 70\u00b0F

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NWS Precipitation Next 72-hours

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NWS Snowfall Next 72-hours

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Blend of Models | 10 Days Precipitation Total

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Massive amount of rain into California over the next 10-days \u2014> 5 trillion gallons+

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Enormous rainfall totals across the Pacific Northwest continue

Blend of Models | Total Snowfall Next 10-Days

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Not much snowfall east of the Rockies \u2014 but we see cold enough air at higher elevation to dump major accumulations on higher elevations.

ECMWF AIFS-Single 06z | Height Anomaly (500 hPa) Next 10-days

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One more \u201cpolar vortex\u201d trough into this weekend \u2026 and then the ridge builds across the Rocky Mountains and forms a long-lasting block.

No doubt about the intensity of this Lower 48 Blocking Ridge \u2014 so we next must determine when this pattern \u201cbreaks down\u201d and we shake the bag, spin the wheel, or whatever to determine where the overall upper-level patterns goes into the weekend after Christmas

ECMWF 00z | Integrated Vapor Transport Next 10-days

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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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ECMWF EPS 00z | 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 00z

5-Day Chunk #1 | Temperature Anomaly | Dec 16 - Dec 20

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5-Day Chunk #2 | Temperature Anomaly | Dec 21 - Dec 25

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5-Day Chunk #3 | Temperature Anomaly | Dec 26 - Dec 30

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Atmospheric river crashes into Pacific Northwest \u2026 moisture crosses the Rockies within a parade of storm systems on the edge of the tropospheric polar vortex.

Sequence of 3 powerful storm systems measured by central pressure in the 970s in an unlikely location over land in southern Canada. These mobile cycles quickly track east over the next 6-days \u2026 each time providing a \u201cclash of air masses\u201d between warmer Pacific origin air to the south and the Alaska/Canadian cold pool to the north.

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