Fig. 1: NOAA/NWS weather watch, warning and advisory areas currently in effect.
Discussion: Winter Storm Warning’s are in effect across 16 states this morning for snow/sleet/ice combination to all snow (Fig. 1). A major ice storm is forecast for the central Mississippi River area turning northeastward into Kentucky. A Winter Storm Watch has been posted for the northern 2/3 of New England. Causing the wintery weather is the next arctic cold air mass which produces Wind Chill Warnings across the northern Great plains/Upper Midwest today. Heavy rains are ahead in the Southeast U.S. A Flood Watch for 2-3 in. of rain is posted for Alabama and Tennessee. Meanwhile, a widespread high wind event has evolved in California, Nevada and Arizona.
ECMWF indicates potential for one foot (or more) of snow from eastern Oklahoma to New England over the next 2-3 days (Fig. 2). Initially, snow is wet and heavy but trends toward 10:1 rain-to-snow ratio after a few hours. Once arctic air works into the snow and 15:1 rain-to-snow ratio develops, the snowfall can pile-up fast. A major concern is the freezing rain/ice accretion event that develops today in the Mid-south states and shifts to the East-central U.S. tomorrow (Fig. 3-4). Freezing rain can accrete to 0.50 to 1.00 in. tomorrow centered on Kentucky and southern Ohio causing widespread power outages.
The snowfall across the southern Great Plains and northern Texas will lead to a long duration cold spell for ERCOT centered on the northern half of the state (Fig. 5-6). Minimum temperatures are arctic cold in this region for 4 consecutive mornings beginning with tomorrow morning and lasting into the middle of next week. The air mass modifies slightly into southern Texas with peak cold on Saturday morning.
The U.S. gas population weight forecast indicates a steady colder than normal national signature, slightly warmer next week but colder the following week (Fig. 7).
Fig. 2: ECM indicates potential for one foot (or more) of snow from Oklahoma to New England over the next 2-3 days.
Fig. 3: A moderate icing event unfolds later today and tonight in the Mid-south states. Dangerous driving and some power outages develop.
Fig. 4: A major icing event is forecast for Memphis toward Pittsburgh on Thursday. In this zone >0.50 in. of ice accretion is likely causing widespread power outages and impossible travel conditions.
Fig. 5: Friday morning low temperature forecast across Texas according to GFS.
Fig. 6: Saturday morning low temperature forecast across Texas according to GFS.
Fig. 7: U.S. gas population weight HDD forecast using all models, their consensus, comparison with 24 hours ago and the 30-year/10-year normal.