Severe Thunderstorms and Heavy Rainfall in the Ohio Valley and Great Lakes; Winter Weather in the Northern Tier

A slow moving front extending from the Great Lakes region into the Plains will bring snow, wintry mix, and ice accumulation north of the front from the Upper Midwest into New England, and severe weather and heavy rain south of the front. Scattered severe thunderstorms with damaging gusts, severe hail, and heavy rain are expected across parts of the Great Lakes/Midwest through tonight. Read More >

Here is a summary of the significant storm which impacted Central PA

on Christmas Eve and Christmas Day 2020

(as of 10AM 25 Dec 2020)

A significant storm brought 1" to 4" of rain to most of Pennsylvania on Christmas Eve and Christmas Day 2020 (Thursday and Friday, 24-25 December). The rain was followed immediately by a sharp drop in temperatures and several inches of snow over western PA.

The rain fell onto a deep snow pack over much of the state. The snow had fallen from a storm one week before, dropping up to 2 feet of snow over parts of northeastern PA. The snow held as much as 2 inches of water in it before it started to melt in the middle of the week.

The combination of the heavy rain and melting snow brought flooding to most of Central and Eastern PA, especially the Susquehanna and Delaware River basins. You will find below some of the specifics of the storm, including river gauge traces (hydrographs) for many points/cities.

Rainfall from the storm...

Water held in the snow pack before the rain fell...

Snow Water Equivalent (SWE)

River Gauge Traces (Hydrographs) = ROLL OVER TO ZOOM IN

Beech Creek Station	Loyalsockville	Danville	Bloomsburg

Spruce Creek	Milton	Sunbury	Penns Creek

Williamsburg	Lewisburg	Harrisburg	Harper Tavern

Camp Hill	Shermansdale	Marietta	Hershey

Shirleysburg	Hogestown	Lancaster	Middletown

Timeline of events...

Timeline

Earlier Forecast Information

current warning 10 am 25 Dec 2020

A storm system will bring multiple hazards to central PA beginning on Christmas Eve Day (12/24) of 2020 and continue into Christmas Day. See the graphic below (composed of 3 slides).

Highlights:

Heavy rain of 1.5-3.0 inches will bring the threat for flash flooding today and tonight.
Several inches of snow will fall west of I-99 later today and tonight with the heaviest snow expected over the northwest.
Plummeting temperatures across all of central PA can cause wet surfaces to become icy Friday as depicted by the Winter Storm Severity Index graphic above.
The heavy rain and melting snow will lead to a risk for river flooding through the weekend, especially along the Mainstem of the Susquehanna and tributaries, especially north of Sunbury, but the Juniata Basin and small tributaries around Harrisburg may also be affected.

Weather story leading up to the storm