Weather Outlook for the Week of December 10, 2019

Dec 13, 2019

A wave along an exiting cold front will bring a period of light snow to parts of southeastern Pennsylvania on Wednesday that will wind down after sunset. Most areas will see little to no accumulation (<2”) from this snow, but it will likely be the first measurable snow in that portion of the state. Temperatures will be a bit cooler than normal on Thursday with afternoon highs mostly in the 30s with a mix of sun and clouds. Friday will be slightly warmer with highs in the upper 30s to mid 40s. By Friday evening, a storm developing in the Gulf Coast will begin moving northward along the East Coast. Southern Pennsylvania will see precipitation first by sunset on Friday. Periods of rain will overspread the state overnight into Saturday morning. Parts of central Pennsylvania, where colder air may stubbornly remain for a longer period of time, may have a wintry mix at the onset of precipitation. The storm will exit the region by Saturday night as rainfall comes to an end. Behind the storm, cooler air will arrive and lake-effect snow showers in northwestern PA will ensue through Sunday afternoon. Monday will likely remain dry before another storm threatens the area later Monday into Tuesday. At the moment, precipitation type is difficult to determine but parts of the state are at risk for a prolonged period of wintry mix or accumulating snow. In the longer range, temperatures will likely be milder than average through the start of the new year while precipitation will be slightly above seasonal levels.

Source : psu.edu

Video: Spring 2026 weather outlook for Wisconsin; What an early-arriving El Niño could mean

Northeast Wisconsin is a small corner of the world, but our weather is still affected by what happens across the globe.

That includes in the equatorial Pacific, where changes between El Niño and La Niña play a role in the weather here -- and boy, have there been some abrupt changes as of late.

El Niño and La Niña are the two phases of what is collectively known as the El Niño Southern Oscillation, or ENSO for short. These are the swings back and forth from unusually warm to unusually cold sea surface temperatures in the Pacific Ocean along the equator.

Since this past September, we have been in a weak La Niña, which means water temperatures near the Eastern Pacific equator have been cooler than usual. That's where we're at right now.

Even last fall, the long-term outlook suggested a return to neutral conditions by spring and potentially El Niño conditions by summer.

But there are some signs this may be happening faster than usual, which could accelerate the onset of El Niño.

Over the last few weeks, unusually strong bursts of westerly winds farther west in the Pacific -- where sea surface temperatures are warmer than average -- have been observed. There is a chance that this could accelerate the warming of those eastern Pacific waters and potentially push us into El Niño sooner than usual.

If we do enter El Nino by spring -- which we'll define as the period of March, April and May -- there are some long-term correlations with our weather here in Northeast Wisconsin.

Looking at a map of anomalously warm weather, most of the upper Great Lakes doesn't show a strong correlation, but in general, the northern tiers of the United States do tend to lean to that direction.

The stronger correlation is with precipitation. El Niño conditions in spring have historically come with a higher risk of very dry weather over that time frame, so this will definitely be a transition we'll have to watch closely as we move out of winter.