{ "number": 818, "headline": "December 16, 2025 Tuesday Evening Maps", "standfirst": "Enormous precipitation totals for California in coming week from atmospheric rivers", "desk": "notebook", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-12-17", "published": "2025-12-17T03:16:45.045000Z", "updated": null, "access": "free", "body_html": "
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This is post number 818: Good Evening \u2014 new weather maps and headlines to keep the ball rolling into mid-week.

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

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Enormous Rainfall Totals for the West Coast \u2014 20\u201d+ of precipitation

HRRR 00z | Next 48-Hours through Thursday 7 PM ET

Simulated Radar \u2014> Pacific Northwest storm system \u2014> Great Lakes over next 2-days

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Wind Gusts \u2014> hurricane force \u2014 upwards of 80-100 mph maximum gusts as powerful low pressure systems move eastward through Southern Canada

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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.

Next 6-days | Jet Stream Winds at 250 mb

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Very strong jet stream across the Western U.S. providing huge baroclinic energy resource for the mid-latitude storms + wind energy to power the near-surface gusts especially in the Rockies and then Plains.

Maximum Wind Gusts from NWS Next 72-hours \u2014> Holy Moly!

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

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Headlines Tuesday Evening

  1. Significant warming trend into next week for Christmas but we need to deal with the Canadian cold pool that gets pulled into the Midwest and Great Lakes behind these powerful storm systems tracking through Southern Canada.

  2. Powerful storm systems with pressure in the 970s mb track from the Pacific through British Columbia into the Prairie provinces. Very gusty winds!

  3. One of these storms intensifies in Quebec to 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.

  5. Christmas looks quite warm for almost the entire Lower 48 relative to normal for December 25th.

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 Thursday Dec 25th

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

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Christmas Day Temperatures | Daily Highs

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Almost 75 million at/above 70\u00b0F on Christmas Day! Only 8% of the Lower 48 by area will be freezing on Christmas Day \u2014 according to Blend of Models (v4.3)

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

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ECMWF 12z 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!

RTMA | Current Temperature Analysis | 9:30 PM ET

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Average Lower 48 temperature was 42\u00b0F with about 82 million below freezing.

Temperature Anomaly | 9:30 PM ET

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Lower 48 Temperature Anomaly was 7.4\u00b0F ABOVE normal

Wednesday Low Temperatures

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160 million below freezing but not seeing any subzero readings.

Wednesday High Temperatures

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54 million at least 70\u00b0F

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

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Enormous rainfall totals across the Pacific Northwest continue

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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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. However, we\u2019re seeing little disturbances riding the crest of the ridge and dipping through the Great Lakes in to the Northeast as part of the giant pinwheeling Polar Vortex anchored over Hudson Bay.

The ridge will break down eventually \u2014 and might need a strong digging trough over the West Coast coming out of the Gulf of Alaska to do it into the New Year.

ECMWF 12z | 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 18z | Snowfall | Next 6-days

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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

5-Day Chunk #1 | Temperature Anomaly | Dec 17 - Dec 21

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5-Day Chunk #2 | Temperature Anomaly | Dec 22 - Dec 26

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5-Day Chunk #3 | Temperature Anomaly | Dec 27 - Dec 31

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Enormous Rainfall Totals for the West Coast \u2014 20\u201d+ of precipitation

Simulated Radar \u2014> Pacific Northwest storm system \u2014> Great Lakes over next 2-days

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