North Pacific Atmospheric River next 6-days —> Pineapple Express from Hawaii

New: NOAA launched their AI-GFS, AI-GEFS, Hybrid GEFS into operations today at 12z. Press Release from NOAA

NOAA 18z AI-GFS | 500 mb Temperature to monitor the polar vortex in the troposphere

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

• Midwest —> Great Lakes to Northeast powerful storm system into Friday

• Another major storm system crashes into the Pacific Northwest

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

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

Sequence of 3 powerful storm systems measured by central pressure over land in southern Canada. These mobile cycles quickly track east over the next 6-days … each time providing a “clash of air masses” between warmer Pacific origin air to the south and the Alaska/Canadian cold pool to the north.

Maximum Wind Gusts from NWS Next 72-hours

Red is > 50 mph and the brown is hurricane force > 73 mph

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

Headlines Wednesday Evening

1. Storm track across Southern Canada north of the jet stream = blustery/gusty winds for the Lower 48 but not a lot of precipitation east of the Rockies

2. Couple more brief Arctic blasts of cold air from that replenished Western Canada “cold pool” for the Midwest and Great Lakes Friday and again this weekend.

3. Christmas looks quite warm for almost the entire Lower 48 relative to normal for December 25th. This is great for travelers and the economy.

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Next 6-days Temperature Anomaly

Chunks of the Western Canada cold pool break off with passing storm systems — and sweep eastward to be replaced by the warm front … roller coaster for the week across the Midwest and Great Lakes.

Christmas Day Temperatures | Morning Lows

Only 91 million below freezing for low temperatures

Christmas Day Temperatures | Daily Highs

Over 80 million at/above 70°F on Christmas Day! Only 9% of the Lower 48 by area will be freezing on Christmas Day — according to Blend of Models (v4.3)

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

• White/gray/black colored precipitable water = absence of moisture = cold/polar air masses rotate through the Midwest and Great Lakes around the “still potent” polar vortex anchored over Canada.

• Parade of “atmospheric rivers” continue for the West Coast — and sink a bit further south across Oregon then into Northern California by the weekend with major impacts likely.

• A mini-Arctic blast scheduled for Friday — not severe and brief as the warmer westerly flow from the Pacific wins the battle with the parade of southern Canada storm systems.

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

The Lower 48 settles into a MUCH ABOVE NORMAL temperature pattern — eventually — once we can finally block off the “polar vortex” by the weekend.

Temperatures surge to well above normal for much/all of the Lower 48 by Christmas

The Alaska / Western Canada cold pool replenishes strongly into the New Year, but the Lower 48 blocking ridge remains firmly in charge.

RTMA | Current Temperature Analysis | 9:00 PM ET

Average Lower 48 temperature was 44.5°F with only 17 million below freezing.

Temperature Anomaly | 9:00 PM ET

Lower 48 Temperature Anomaly was a whopping 9.0°F ABOVE normal

Thursday Low Temperatures

127 million below freezing and a handful (290k) below 0°F along Montana/North Dakota border with Canada.

Thursday High Temperatures

76 million at least 70°F as the Great Lakes warm up into the 40s … wow, that will feel wonderful

NWS Precipitation Next 72-hours

NWS Snowfall Next 72-hours

Blend of Models | 10 Days Precipitation Total

Enormous rainfall totals across the Pacific Northwest continue into California

Blend of Models | Total Snowfall Next 10-Days

Huge snowfall for Manitoba … colder air from Gulf of Alaska will lower snow levels across the entire Western U.S.

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

The blocking ridge centers over the Lower 48 — but it’s not big enough / honking to keep the troughs on its edges from dipping southward.

Western U.S. —> trough = pattern shift —> much colder and even more rain/snow

Northeast U.S. —> trough = repeated mini-blasts of colder air to stay wintry

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

Polar Vortex (tropospheric) monitor —> 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.

ECMWF 12z | Integrated Vapor Transport Next 10-days

Parameter used for monitoring “atmospheric rivers” usually along the U.S. west coast, but the idea works well for many other areas — highlighting midlatitude storm systems with warm conveyor belts (moisture plumes)

ECMWF 18z | Snowfall | Next 6-days

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

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

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

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

5-Day Chunk #1 | Temperature Anomaly | Dec 18 - Dec 22

5-Day Chunk #2 | Temperature Anomaly | Dec 23 - Dec 27

5-Day Chunk #3 | Temperature Anomaly | Dec 28 - Jan 1

Snowfall Analysis Season to Date

While the next 2-weeks won’t see much snow, as we head into 2026, hard to complain about what snow has fallen so far … need to keep it going into January and February!

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