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John Homenuk

Heavy rain, thunderstorms transition into crisp weekend

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Southwesterly winds have ushered in a warmer, more humid airmass this Friday morning. Temperatures are running in the mid 60’s throughout the area with low clouds and fog in the valleys and even some of the higher elevations of Northern NJ and Southeast NY. The southwesterly flow will continue to build into Friday afternoon, ahead of an approaching cold front. The warmer, more humid air will lead to increasing atmospheric instability by later this afternoon.

This instability, expanding from Southeast Pennsylvania into New York, will briefly align with favorable atmospheric shear parameters as a cold front approaches from the west this afternoon. In this area, a few strong to severe thunderstorms are likely moving from west to east through New Jersey, Southeast New York, Connecticut and potentially the NYC Metro Area.

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John Homenuk

Severe weather outbreak possible in the Midwest today

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Severe weather season is kicking up, and today could feature a dangerous outbreak of storms over the Midwest and North/Eastern Plains states toward parts of the Mississippi River Valley. The Storm Prediction Center has issued a large “Moderate Risk” for severe thunderstorms in those areas, the second highest risk category they use (only High Risk denotes a greater potential), with the potential for widespread damaging wind gusts and strong tornadoes.

A large high pressure ridge, currently situated over the Central United States, is slowly shifting eastward. But, more notably, the high pressure dome is serving as a highway for severe thunderstorm formation on its northern edge. Along the periphery of the ridge, atmospheric disturbances have been sliding east and then southeast from the Northern Plains into the Mississippi Valley. These disturbances are acting to force thunderstorm development within an incredibly unstable and supportive environment for severe thunderstorms.

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John Homenuk

Not-so-polar vortex will make disruptive return next week

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Wait! Don’t go digging into your closet to find your winter jacket in that bin of winter clothes just yet. The Polar Vortex may “technically” be returning next week — but it isn’t so “polar” in air quality, and it may not be by other definitions as well. So is it really a Polar Vortex at all? The meteorological community is up in arms today over the usage of the term — and the end result is, of course, leading to varying opinions and arguments. The cause of the argument itself is the modeled approach of a massive upper level troughing system, which will feature much below normal temperatures both aloft and at the surface. The track, size and orientation of the system bear many resemblances to the Polar Vortex which tracked through the Great Lakes this past January.

Still, the time of year makes the sensible weather results quite different. Temperatures which are 10-20 degrees below normal (or more in some locations) won’t quite drop the thermometer near the freezing mark. But, still, things could get quite cool over the Great Lakes and Ohio Valley. Some meteorologists prefer to call the incoming system a Polar Vortex, others don’t. But the bottom line has to do more with meteorology than terminology — and the sensible weather effects are becoming more clear as we move closer. Figure 1 shows temperature anomalies at 850mb as forecast by the GFS next week. Notice the broad area of well below normal temperatures as a result of the large upper level troughing system with cold air moving south from Canada.

Fig 1. (Atmos Albany)

Fig 1. (Atmos Albany)

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John Homenuk

Warm, unsettled weather continues Wednesday

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Strong thunderstorms powered through the area on Tuesday afternoon and evening, as an energetic trough moved through the Great Lakes and Ohio Valley. Thunderstorms maintained themselves through much of New Jersey on the leading edge of stronger forcing from the mid and upper level trough. As they shifted eastward, weakening occurred due to lesser instability in our area. Still, gust fronts on the edge of the pre-frontal trough mixed down stronger winds aloft, leading to branch and tree damage in many areas. Figure 1, below, shows the storm reports from Tuesday via the Storm Prediction Center. Needless to say — it was a significant severe weather event in the Northeast US.

Figure 1 (NWS/SPC)

Figure 1 (NWS/SPC)

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