Headlines this Thursday Evening:

• Major warming trend for much of the Eastern Lower 48 relative to the frigidity we saw over the past 2 weeks.

• Upper-level pattern change — more western moisture (and now colder) with the jet stream bending into the U.S. Southwest and connecting subtropical moisture and warmth for the southern U.S.

• Western U.S. (California) Major storm system — long lasting onshore moisture flow Sunday to Wednesday and enormous mountain snowfall.

• The main storm track next week sees northern tier with wintry weather from the upper-Midwest, Great Lakes, and Northeast — into next weekend.

• Major Canadian Arctic cold pool intensifies into late February waiting for an opportunity to plunge southward. Keep asking if we are done with the “Polar Vortex” for this winter or one more dance? And, nothing has changed with the Ensembles —> Still undetermined past Days 10-12!

Running late — so I will keep commentary to a minimum tonight, and let the maps run the show.

I wanted to show GFS 18z for a change of pace, just to give everyone an idea of what solutions are there for non-ECMWF based modeling. And, we see an active weather pattern for the next 10-days with moisture bombarding the Western U.S. and then a northern storm track into middle of next week.

GFS 18z does not intensify a Nor’easter for Presidents’ Day.

Jet Stream Next 6-days

Dip/kink off the West Coast —> wetter & colder (mountain snow) pattern for a while!

Much Warmer Temperatures into Next Week — Highs through next Saturday much above normal

Potential Presidents’ Day Nor’easter: out to sea & limited development! ECMWF 18z update does snow some brief snowfall on the very northern edge of the heavier precipitation envelope, but the track is quickly due east without phasing with the upper-level trough / Polar Vortex Anomaly over Quebec.

However, there are still a handful of ensemble members that are suggesting that northern edge of precipitation could be heavy snow > 6”

Ensemble probability of 6-inches + Snowfall (18Z EPS)

I see the maximum of 1 in 4 chance of significant snowfall in Philadelphia and 1 in 6 in NYC. Small chance, but still on the board as an option!

Indeed, the median snowfall outcome is almost a non-event: Median snowfall next 6-days

But, the interquartile spread (75% minus 25%) shows where the highest variance in member solutions resides — in southern PA including Philadelphia.

And, a quick look at all 51 members for Philadelphia — you interpret this as conditional — if it snows, then it could be a “big ticket” — however, that is a low probability outcome.

Integrated Vapor Transport — Atmospheric Rivers next 12-days

Subtropical moisture feeds out of the Pacific associated with areas of low pressure dipping southward along the U.S. West Coast from the Gulf of Alaska —. great for Rocky Mountain snowfall — and then downstream rain in Texas and the Southeast. Overall this a more active weather pattern with the main polar vortex northerly flow shut off for the next week.

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

Major warming trend for the next 7-12 days across the Lower 48 with only exception being the West Coast. You can see the major Alaska + Western Canada cold pool intensify but largely remain stuck through the end of February.

ECMWF IFS 18z | Precipitable Water Next 6-days

Storm system across Texas into the Southeast from Saturday - Monday unlikely to become a major Nor’easter. However, heavy rainfall (welcome) across the south.

Major atmospheric river into California + storm system!

Chicago 7-day Forecast — 50s to 60°F next Wednesday

New York City 7-Day Forecast: upper-40s next week

Washington D.C. 7-Day Forecast: 50s again on Saturday will feel like a heat wave, and then close to 60°F next week should melt most of the remaining snow piles

ECMWF 18z Precipitation Type + Intensity | Next 6-days

ECMWF 18z Snowfall | Next 6-days

West Coast USA Zoom | Next 6-days

Major storm system Sunday into Wednesday with multiple days of onshore moisture flow!

15-day Snowfall (Long Range) ECMWF AIFS 18z — repeat, this is long range

Winter is not over by any stretch of the imagination.

Total through 15-days — still seeing “big ticket” snowfalls showing up in the Northeast and Midwest and Great Lakes in the long-range.

15-day Precipitation (Long Range) ECMWF AIFS 18z

HRRR Simulated Radar Next 48-hours

Cut-off trough / storm system arrives in the Southwest — which will become the weather maker for Texas on Saturday and then push east.

NWS NDFD Snowfall next 3-days

NWS NDFD Precipitation (QPF) next 3-days through Sunday evening

RTMA | Temperature Analysis | 8:15 PM ET

Avg Lower 48 temperature was 44.3°F — but 106 million below freezing.

Temperature Anomaly | 8:15 PM ET

Lower 48 Temperature Anomaly above normal by 5.2°F

Low Temperatures on Friday

32.4°F average Lower 48 minimum - 165 M below freezing

High Temperatures Friday

82 million above 70°F

ECMWF AIFS-Single 18z | Temperature (500 hPa) Next 15-days

The temperature at 500 mb is the easiest way to highlight the “polar vortex” across North America with the coldest pool at -50°C (pink) with the -25°C contour usually associated with below freezing temperatures at 2-meters (surface).

Heading into the final week of February —> the main Polar Vortex cold pool reservoir remains largely locked up over Canada north of the Arctic Circle

Blend of Models | 7 Days Precipitation Total

Blend of Models | Total Snowfall Next 7-Days

Long Range | Ensemble Median next 15-days Total Snowfall (ECMWF EPS 12z)

Probability of 1-inch of snowfall from the Ensembles (12z)

Probability of 6-inches of snowfall from the Ensembles (12z)

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

5-Day Chunk #1 | Temperature Anomaly | Feb 12 - Feb 16

Over 20°F above normal for upper Midwest for a 5-day chunk — fabulous for mid-February.

5-Day Chunk #2 | Temperature Anomaly | Feb 17 - Feb 21

17°F + above normal anomaly in the Midwest centered upon Missouri

5-Day Chunk #3 | Temperature Anomaly | Feb 22 - Feb 26

Shrinking above normal warmth intensity (down to 6°F above normal) in the center of the Lower 48 — continue to see the looming / huge cold pool over Western Canada + cooler air across California … zooming out to see it (note the map projection is flat) for nearing the end of February.

Update on Global Temperatures next 2-weeks

Using the Ensemble Mean from the EPS 2-meter temperatures (ECMWF 12z) you can see the “global areal average” in the upper right corner start out from +0.97°F at the beginning compared to the 30-year climatology (1991-2020) and drop all the way to +0.04°F in two weeks — loss of almost 1°F globally compared to climatology. How is that possible?

Colder air over the continents = sensible heat loss = rapid radiational cooling due to albedo and reflection of the late February sun angle (in the NH) back to space —> Earth’s radiator.

This will skew the February global monthly mean temperature anomaly colder.

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