{ "number": 465, "headline": "December 20, 2024 Friday Winter Weather", "standfirst": "Glancing blow from Nor'easter will dust New England with 1-3\" of snowfall", "desk": "winter", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2024-12-20", "published": "2024-12-20T14:20:01.975000Z", "updated": null, "access": "free", "body_html": "
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Friday Headlines

  1. Less exhaustive update this morning, and more details this afternoon after the 12z models complete [for paid subscribers].

  2. Alberta Clipper \u2014> offshore Gulf of Maine low pressure

    HRRR 11z showed an interesting solution with just enough precipitation on the back side of the developing Nor\u2019easter (heading into Canada) to provide a quick 1-3\u201d of snowfall in Boston late this evening. The potential is there for more \u2026 we\u2019ll watch the model trends this morning into the afternoon.

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    Current NWS Forecast for Snowfall Next 36-hours: 1\u201d-3\u201d for Boston.

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  3. Trough across Eastern U.S. = brief winter cold

    The storm system that forms off the east coast later tonight tracks across Newfoundland and deepens to 974 mb. Unfortunately for snow lovers across the Northeast, it misses the trough to \u201cbomb out\u201d in the Gulf of Maine by a few hundred miles. Instead, it will assist with cold air advection out of Quebec, so not completely wasted. The Canadian high pressure centered over the Great Lakes will slowly move eastward killing the winds = cold Sunday and Monday morning.

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Sunday Morning Low Temperatures

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Monday Morning Low Temperatures

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8:00 AM ET Temperatures across the Lower 48

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Almost 100 million at/below freezing at 8 AM ET. Coldest air by far in the Dakotas and now into Nebraska and Kansas.

Temperature Anomaly | 8:00 AM ET

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Overall the Lower 48 is still 0.6\u00b0F (above normal) with western warmth beating out the central U.S. cold.

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High Temperatures on Friday

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High temperatures this afternoon only in the 30s into Kansas City, St. Louis, and the Ohio River Valley. Sunshine will keep the southeast in the 50s and up to 80\u00b0F in South Florida. The Southwest including Phoenix also in the 80s.

High Temperature Anomaly on Friday

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The Western U.S. is very warm (relative to climatology) with temperatures 20\u00b0F above normal including Denver. The coldest air is only 10\u00b0 to 15\u00b0F below normal, so far.

Total Precipitation next 7-Days | NOAA WPC

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Trillions of gallons of Pacific atmospheric river rainfall (and mountain snow) to pile up across northern California, Oregon, and Washington.

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ECMWF AIFS 06z | Height Anomaly Next 15-days

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The North Pacific storm track through downstream Rossby wave trough thinning spawns many shortwaves that cruise through Southwest U.S. and then eastward across the Lower 48. However, ridging to the north (also built up by the powerful North Pacific storm systems) keeps these cut-offs from connecting to the tropospheric polar vortex well in Canada. The result is a fixed/stuck pattern of mild weather across the Lower 48 into the first week of January.

6-day Ensemble Median Snowfall

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Probability of 1\u201d+ Snowfall Next 6-days

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Could be light snowfall \u2014 stars align perfectly for a White Christmas morning across the Great Lakes into the Northeast. Outside chance (small) in D.C.

Next 15-days

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Still no weak (or strong) signal for a strong winter storm across the Eastern U.S. into January 2025.

ECMWF EPS 00z | 5-Day Chunk Temperature Anomaly

Days 1-5: December 20 - December 24

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Days 6-10: December 25 - December 29

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Days 11-15: December 30 - January 3

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Hard to see any cold signals in the Ensemble Mean from Days 7 to 15 into January 3, 2025.

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.

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Friday Headlines

Alberta Clipper \u2014> offshore Gulf of Maine low pressure

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