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Long Range: First wintry threat possible for interior next week

Record breaking warmth occurred throughout the area today, with high temperatures in the lower 70’s shattering previous high temperature records by nearly 10 degrees. In fact, New York City reached their record high temperature at 12:01am, breaking the previous record for Christmas Eve set back in 1990. This is no small feat — temperatures averaged almost 30 degrees above normal throughout the day in our forecast area.

In the midst of an incredibly warm, snowless pattern, forecast models suggest the potential for a trend-breaker during the middle of next week. Within a fast, warm mid level atmospheric flow, models are indicating the potential for a slower moving, closed low in the mid levels of the atmosphere. As this low shifts eastward through the Mississippi Valley and eventually de-amplifies toward the Northeast US, the potential exists for significant amounts of moisture to be drawn northward toward the Northeast US. Waiting to our north, precariously timed — as models suggest — will be a strong and cold Canadian high pressure system.

These high pressure systems have generally been few and far between so far this cool season, but a changing pattern is expected to aid in them appearing more frequently. This high pressure system is forecast to settle in to Southeast Canada during the early to middle part of next week. As the closed low shifts northeastward, a low pressure system will develop into the Ohio Valley. Eventually, a secondary low pressure system will develop to our south.

GFS model showing an expansive high pressure developing over Southeast Canada and the Northeast next week.

GFS model showing an expansive high pressure developing over Southeast Canada and the Northeast next week.

Significant moisture moving northward creates some problems for precipitation type if this high pressure is modeled correctly. Precipitation could begin as frozen — i.e snow, sleet, or freezing rain — and stay that way for a few hours before changing over to liquid. As is typical in these events, the transition occurs first near the coast and eventually spreads northward. Interior and higher elevation areas stay frozen for the longest period of time, and often see the greatest impacts.

Fundamentally, the high pressure creates a problem and the potential for hazardous weather. Warm air in the mid levels of the atmosphere surges northward as the low pressure system develops. So although snow may fall for a while, it typically quickly changes to sleet or freezing rain. The high pressure system, however, creates a funnel of cold air near the surf

GFS model showing a large, significant closed low in the mid levels of the atmosphere over the Mississippi Valley during the middle part of next week.

GFS model showing a large, significant closed low in the mid levels of the atmosphere over the Mississippi Valley during the middle part of next week.

ace. Despite the fact that warm air has surged in aloft, the surface remains cold, which means sleet or freezing rain can create icing hazards.

At this current state, the event is too far away to speculate on the exact impacts or hazards. This is especially true in a situation like this, where intricate details can result in major changes in the forecast. As we approach the event, monitoring forecast models will be important — and it will show us with more confidence what to expect. Think of it this way: small nuances in the mid levels of the atmosphere can cause major changes in terms of forecast modeling.

 

Often times, with these events, the warming in the mid levels of the atmosphere is more intensive than expected. So forecast models trend warmer as the event draws near. Meanwhile, the surface cold air can often be under-estimated, resulting in more icing and less snowfall. These are just a few headaches caused by intricate meteorological occurrences within storm systems — and forecast models can sometimes have significant difficulty ironing them out at such long ranges.

Regardless, it appears that our first wintry weather event may be closer on the horizon than many thought, especially for the interior and higher elevations. Stay tuned for further updates.

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