Not much change with our major ice/snow storm across the Southern U.S. although the recent northward elongation or adjustment of the trough has brought snowfall totals significantly upward in D.C. and NYC —> Boston.

Lots of maps — less text tonight, since this one is baked in the cake.

I’ll mention the extreme cold “Arctic Blasts” — perhaps 2 or even 3 of them in the next 12 days, which sent Natural Gas futures skyrocketing.

Precipitation Type and Intensity Next 6-days (ECMWF 18z)

Texas Zoom

Southeast Zoom | Atlanta will be battling the “wedge” of cold air damming against the higher terrain to the ENE

Mid-Atlantic and Great Lakes Zoom | Huge Snowfall Event

Northeast Zoom | Mainly All Snow for NYC into New England

Wind Chills Friday Morning Across the Lower 48 | -40s and -50s

Wind Chills Saturday Morning Across the Lower 48

Very dangerous wind chills

Integrated Vapor Transport (Atmospheric River) Next 6-days

A plume of moisture out of the subtropical Pacific crosses Mexico and combines with a very strong feed (atmospheric river) out of the Gulf of Mexico to fuel the overrunning precipitation into Texas and the South.

I calculated through 90-hours the “Dynamic Snowfall” which takes into account the near surface temperatures — which does not get us through the entire storm but definitely shows the enhancement from OKC into Arkansas.

Overall, the QPF that is p-typed as snowfall is a good way to eyeball the huge amounts. Purple is > 1” of QPF so you can expect anywhere from 10” to 18” depending upon the air temperatures, which will be very cold to the north to take the latter.

Washington D.C. only shows 0.43” snow QPF because of freezing rain mixed in but plenty to the west, so only a slight track adjustment will jackpot the Capitol.

Freezing Rainfall Next 6-days

Not good! This will not all “stick” or encrust trees and power lines, but if only a fraction did, then it’s major / catastrophic damage.

The wedge in Atlanta is usually underestimated in the models, but we’re still 3-4 days away, and we can monitor the situation —> NWS Atlanta does not yet have the metro in a “Winter Storm Watch”

The cold-air damming or “wedge” keeps Atlanta and NE Georgia much cooler than usual even with approaching storm systems. e.g. very early Sunday.

And, the major Freezing Rain problems now extending into North Carolina and Virginia.

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

The second Arctic blast is at Days 8-10 — and then hopefully we get a break. However, the 12z ECMWF HRES showed an even more powerful and colder Arctic Blast 3. The ensembles do not show that clearly, yet.

Tuesday, February 3 from HRES

ECMWF 18z | Temperature Anomaly Next 6-days

Larger scale view: Extremely cold air intensifies in southern Canada and then floods southward into Lower 48 — dumps into Texas by Saturday and stays there — with potential of a major ice storm as boatloads of subtropical moisture overruns the Arctic air — from Texas through the south into the Carolinas. Complete mess.

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

Thickness —> Showing the Polar Vortex spinning over Ontario and finally eroding by Day 10 — however, the process may repeat with a PV anomaly coming from the North Pole.

Multiple polar vortex (PV) anomalies drop out of Canada circulating around the main polar front or cold pool centered over southern Canada (Ontario)

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

The temperature at 500 mb is the easiest way to highlight the “polar vortex” across North America with the coldest pool at -40°C (pink) with the -25°C contour usually associated with below freezing temperatures at 2-meters (surface).

ECMWF 18z | Precipitable Water Next 6-days | My Favorite Parameter

The collision of the extremely cold and dry/dense Arctic air will undercut the very moist and warmer air coming from the Gulf of Mexico and Pacific subtropics. The result is a battleground of frozen precipitation from freezing rain, sleet, ice, and snow to whatever else you can think of —> massive frozen precipitation mess.

NWS Precipitation Next 72-hours | Doesn’t include whole event

Ice Accumulation from NWS through 66-hours (Saturday mid-day)

NWS Snowfall Next 72-hours until Saturday mid-day

RTMA | Temperature Analysis | 8:45 PM ET

Average Lower 48 temperature was 34.4°F with 76 million below freezing.

Temperature Anomaly | 8:45 PM ET

Lower 48 Temperature Anomaly below normal by -0.6°F

Thursday Morning Low Temperatures

157 million below freezing — nationwide average of only 25.0°F. 3 million below zero.

Thursday High Temperatures

Nationwide average of 41.7°F and about 58 million stay below freezing.

Lower 48 | Low Temperatures Next Several Days

The Blend of Models is rather smooth and was underestimating the intensity of the cold next weekend further north — now down to 11.2°F — for a Lower 48 minimum temperature, which is getting us into the range where record lows can be set.

Lows Friday | 19.9°F | 186 million freezing | 39 million subzero

Lows Saturday | 13.3°F | 222 million freezing | 62 million subzero

Lows Sunday | 11.8°F | 250 million freezing | 27 million subzero

Lows Monday | 11.2°F | 260 million freezing | 37 million subzero

Lows Tuesday | 14.8°F | 256 million freezing | 6 million subzero

In terms of real estate, 91% of the Lower 48 is below freezing.

Blend of Models | 5 Days Precipitation Total

That’s a lot of QPF from this atmospheric river / subtropical atmospheric river

Blend of Models | Total Snowfall Next 5-Days

The snow to liquid ratios (SLR) are incorporated directly into the Blend of Models snowfall forecasts —> quite amazing totals in Washington D.C. + Philly —> NYC and Boston. Wow!

ECMWF 18z | Snowfall next 10-days | 10:1 Ratio

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

This is a potentially HUGE underestimate: There is a very wide distribution of solutions with the Interquartile range (25% to 75%) the same amount as the median = boom or bust & the snow-to-liquid ratio will be upwards of 15:1 or higher in the cold air, so we could double the median snowfall amounts.

IQ (25-75%) range through 15-days

Ensemble Maximum through 15-days: Boom Potential Dialed up to 100%

—> this map is a “worst case scenario”

Probability of some Snowfall (0.1”) in next 15-days

A few ensembles showing snow into Florida again through 2-weeks, but don’t need to grab a shovel

Probability of 1-inch Snowfall in next 15-days

Probability of 6” and 12” of Snowfall next 15-days

Lower 48 Temperature Anomaly | Next 15-days | ECMWF EPS 12z

5-Day Chunk #1 | Temperature Anomaly | Jan 21 - Jan 25

5-Day Chunk #2 | Temperature Anomaly | Jan 26 - Jan 30

5-Day Chunk #3 | Temperature Anomaly | Jan 31 - Feb 4

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