BLOG: Severe Weather Threat Today; Quick Long-Range Peek

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Good morning everyone,Hope you enjoyed the warm weekend. Today will be the last balmy day for a while. The transition from the May Preview to more of a late-March pattern will be marked by some showers and thunderstorms today into tonight. Will the ingredients come together for some big storms and perhaps even severe weather?The setup: A cold front is marching east this morning and can easily be picked out on the surface map:nowAhead of the front, it is warm but not super humid. Dewpoints are in the 50s in most places.dewAs the front pushes east and some sunshine heats the air mass up, the atmosphere over the region will grow moderately unstable. Have a look at the CAPE, (Convective Available Potential Energy) which is a measure of how unstable the air mass is, at 2pm:CAPEA few/several hundred J/KG of CAPE is certainly enough for thunder and some "strong" storms but it's hard to get "severe" weather with CAPE values that low.Another thing we look at is something called "helicity", which measures the atmosphere's ability to produce rotating storms. It is not very high locally so the threat for a tornado is very very small.helicityThat said, there is a fair amount of wind energy above our heads and any stronger shower or storm could bring some of that down to the ground. Winds at 5,000 feet will be around 40-50 mph early this afternoon:850So we are looking at some showers and thunderstorms getting going during the midday and early afternoon. The 2pm simulated radar off our highest-resolution model shows this:2pmIf we are going to get some heavy storms today it looks like 1-4pm is our best window. By 5pm, the threat has shifted east, and the threat for severe weather is certainly higher in that direction.5pmThe Storm Prediction Center odds of large hail are low but not zero around the Valley today. Higher odds east.HAILODDSThreat for damaging winds is on the low end of the scale as well but overall is probably the more likely threat from any heavy storms today.WINDODDSAs always, we will keep you updated on TV and online as we navigate the day today. A quick reminder of the difference between watches/warnings/etc:severe-weather-awareness1OK, once we are done with today, it's not a very late-April like forecast for a while. Why? Well an area of low pressure in the upper levels is going to get bogged down for a while around the northern Great Lakes and SE Canada. This will prevent any sort of warmth from gaining a foothold and will steer chilly Canadian air south.jetthursjetsundayWe may start to emerge from that pattern by the middle of next week as the atmosphere gets "unclogged". jetwedsLong-range modeling shows a better pattern emerging by early May. The pattern may not produce temperatures as warm as we have seen recently, but it should be milder than the next 7-8 will be.16dayThanks for reading!Eric

BLOG: Severe Weather Potential Today

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The atmosphere has been busy over the eastern 2/3 of the country this week with lots of severe weather. Thankfully we have not had to deal with much more than April showers to this point. But that may change today.Our Thursday started with some rain as the same front that has been bobbing around all week continues to be a trigger for wet weather. It's easy to find that front this morning by looking at regional temperatures: nowsfcZooming out and taking a look at the country, we have a strong area of low pressure in the Plains and it is moving northeast. As it does so it will drag a warm front in our direction today and temperatures will have little trouble reaching the lower 70s this afternoon. It will even feel humid.nowbigsfcMeanwhile, the juicy air is being transported north by what we call a "low level jet", a fast-moving river of air that is a few thousand feet above our heads. This isn't the "jet stream" that we normally think of, which is up at around 30,000 feet. THat low level jet brings the warm, humid air north and can also aid in creating instability in the atmosphere. Here's the wind at 5,000 feet this afternoon:Notice the brighter colors (faster winds) just west of our region.850The ingredients are coming together for some big storms. But where? The Storm Prediction Center has the highest risk across the Mississippi and lower Ohio Valleys:1This makes sense, given that that region is closer to the low-level jet, there is more "wind shear" (changing of wind direction and/or speed as you go up through the atmosphere) and generally has a more unstable atmosphere overhead. One measure of instability is CAPE, or Convective Available Potential Energy.While we have a moderate amount of CAPE around the Valley later today, it's highest to the west.capeSo, what do we think will happen? There will be a break from the rain during the midday and early afternoon. IF we manage to get some sunshine during that period, it will help make the atmosphere more unstable. A line of showers and thunderstorms looks to push in late this afternoon and evening (roughly 4-7pm). 6pm simulated radar, based off HRRR model:6pmThe odds of severe weather (winds in excess of 58 mph and/or hail 1" or larger), while highest to the west, are not negligible here...generally in the 5-15% range.riskThe primary threat will be damaging winds.11149422_449257775227871_8950276984107845480_nWe will keep you updated all day on TV and social media. If the situation warrants, we will do live streaming coverage later today on wfmj.com.Thanks for reading!Eric