{ "number": 498, "headline": "January 16, 2025 Thursday Evening Update", "standfirst": "Yes, this is the Polar Vortex.", "desk": "notebook", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-01-17", "published": "2025-01-17T02:52:31.532000Z", "updated": null, "access": "free", "body_html": "
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Good Evening!

I\u2019m quoted in the AP News on the upcoming Polar Vortex episode.

Now more than 11-years since we helped popularize the \u201cpolar vortex\u201d term in the national discourse in January 2014. And, it looks like this next week will see a couple mornings very close to the coldest day then.

My goal is to be informational but also quotable meaning some unique tidbit or trivia that contextualizes the extreme event usually historically or something like \u201ctrillions of gallons\u201d of precipitation.

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Is this the Polar Vortex or Not?

Prior to January 2014 and the viral usage of polar vortex in the news and social media, the term would have most likely referred to the stratospheric PV only observed in the winter. It is usually very smooth and consists of long-wavelength features with minimal synoptic activity. This is opposite to the omnipresent year-round tropospheric circumpolar vortex, which consists of the wave patterns we see at mid-levels to the jet stream or tropopause.

The extrusions or lobes of the polar vortex winter ebb and flow to lower latitudes and bring extremely cold polar air to the middle or even subtropical latitudes. These synoptic waves are energized by baroclinic instability due to the temperature gradient between the equator and poles providing all the exciting weather we talk about everyday.

So are we being hit by the polar vortex? Yes \u2014 scientifically and now colloquially.

The PV in the troposphere is loosely defined as the 315K to 320K potential temperature level on the dynamic tropopause (2 PVU surface) with fine details quite apparent in this parameter: the little white fuzzballs that correspond to extreme thickness anomalies and coldest air near the surface.

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Or, in January, I\u2019d use the -25\u00b0C isotherm on the 500 hPa pressure level.

The Polar Vortex allows cold air to traverse the pole though the Great Circle route and transfer cold air formed in Siberia over the Arctic into Canada and then the U.S.

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Winter Precipitation Opportunities

A weak system could bring a couple inches of snowfall to the Mid-Atlantic including Washington D.C. on Sunday.

That low pressure develops more into a mini-Nor\u2019easter that would blanket New England with some snowfall.

Then, the focus shifts to the Gulf Coast with ECMWF 18z and other models now consistently showing a mess from Houston to New Orleans and Tallahassee with historical snowfall 3\u201d-6\u201d or more along with heavy freezing rain in North Florida.

This is probably going to shift north or south, but I\u2019d admit that it\u2019s amazing to even be talking about this only 4-5 days out.

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Snowfall next 6-days \u2014 Crazy!

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How realistic is this snowfall? Well, it\u2019s a 10% to 50% probability depending upon the snowfall threshold. We can get there with percentiles or probabilities.

\u2014> quite plausible

Extreme Cold Waves

Next 6-days temperature anomaly \u2014 the Arctic blast doesn\u2019t surge southward all at once but instead evolves behind a positively inverted trough.

I\u2019d note the corridor of extreme cold from Chicago to Pittsburgh that shows up in the HRES and EPS over the snow covered ground.

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Pittsburgh into the minus 20s Wednesday morning?

I\u2019m not sure how good the ECMWF model is with extreme cold over snow cover, but it\u2019s indicating dangerously cold numbers.

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EPS mean is at -14\u00b0F in Pittsburgh for Wednesday morning.

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Chicago goes down to -8\u00b0F on Tuesday morning.

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My Favorite Variable Precipitable Water

The surge of moisture out of the Gulf of Mexico is enormous, and if it is able to reach the Gulf Coast where the Arctic cold dome sits, then it mean heavy snowfall along Interstate 10 from Houston to New Orleans to Jacksonville, Florida.

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Temperature Anomaly over the Next 15-days

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The signal for another cold period ending January is settled into the Ensembles across the Northern Tier of states. Sigh.

Friday Morning Lows

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Friday Afternoon Highs

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Sunday Low Temperatures

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Lower 48 average of only 14\u00b0F

Next Monday Lows \u2014> LOWER 48 average of 7.9\u00b0F

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Next Tuesday Lows \u2014> Lower 48 average of 6.8\u00b0F

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ECMWF EPS 12z | 5-Day Chunk Temperature Anomaly

Days 1-5: January 16 - January 20

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Days 6-10: January 21 - January 25

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Entire Lower 48 is below normal except for perhaps Miami.

Days 11-15: January 26 - January 30

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Another very strong cold signal over the Western U.S. with -20\u00b0F below normal in Montana in the ensemble mean.

For new followers coming from Substack, X, or friends, you\u2019ll get daily updates of mainly Lower 48 weather including winter storms, heat waves, hurricanes, and now Arctic blast. The goal is to provide a \u201cheads up\u201d to impending extreme weather in the coming 1-2 weeks \u2014 medium range weather prediction. I use the best and most advanced Numerical Weather Prediction (NWP) systems including ECMWF ensembles, NOAA GFS, and the state-of-the-art A.I. systems.

Who writes and researchers this Newsletter? Dr. Ryan N. Maue [X https://x.com/ryanmaue] with 20-years experience of daily weather model production and analysis. You may have seen my weather maps! I live in Atlanta but was born and raised in Northern Michigan. I know snow, and southern heat and humidity.

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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I\u2019m quoted in the AP News on the upcoming Polar Vortex episode .

Now more than 11-years since we helped popularize the \u201cpolar vortex\u201d term in the national discourse in January 2014. And, it looks like this next week will see a couple mornings very close to the coldest day then.

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