BLOG: Severe Weather Threat Tonight/Wednesday

in

Good morning all,We have a complicated situation unfolding over the next 36 hours. The timing and potential severity of thunderstorms is difficult to get a handle on this morning, but I will try my best to at least set the table for you.We still have a pretty dry air mass overhead, but moisture is building off to our west. Here's a look at this morning's weather map with the dewpoint temperatures: nowAlong the northern fringes of that juicy air mass across the Midwest, thunderstorms will likely get going late today and early tonight.As the warmer and more humid air pushes east, the air mass across the region will become much more unstable. CAPE (Convective Available Potential Energy), a measure of instability, will get quite high tonight. These values may be overdone, but even if you reduce them by 1/2, they are still quite high. This animation covers 8pm this evening through 8am Wednesday: output_9NrIkJWith the ingredients for big thunderstorms there, the Storm Prediction Center has placed parts of the region (but NOT the Mahoning Valley) under an enhanced risk (yellow) of severe weather through tonight: day1Here are the SPC odds of a tornado within 25 miles of any location: torLarge hail odds: hailDamaging wind odds: windSo, the threat appears to be south and west of Youngstown tonight, right?? PROBABLY, but all of this is subject to change. This is the type of setup that is notorious for producing surprises.What about Wednesday? Well the SPC DOES have our area under the enhanced risk: day2My gut feeling is that we will have TWO windows for heavy storms that could produce severe weather. 1) Very late tonight and early Wednesday. 2) Wednesday late afternoon/early evening. The main threat will be damaging winds. Large hail will be a secondary threat. The tornado threat should be very low.Check out this animation of the simulated radar product off of the latest hi-res NAM model (covering midnight Wednesday to 8pm Wednesday): output_FGI8FfThis model may have a pretty good idea, or it may be full of it! We should know much more this afternoon and evening. Check out "Weather For Weather Geeks" this afternoon for a full update.Eric  

BLOG: Thursday Rains=Flooding?

in

We are done with the threat for severe weather, but now we have a waterlogged Thursday to contend with. This should not be a MAJOR flooding event across the Valley, but some minor problems can be expected.First, an animation of the simulated radar for the rest of the day today, according to the HRRR (High Resolution Rapid Refresh Model): output_WzoWpNHow much rain are we talking about? I think the highest totals, with the highest risk for flooding will be east of I-79 in Pennsylvania. Here's the NOAA rain outlook for today and tonight....and this looks reasonable to me: qpfGenerally 1"-1.5" for extreme eastern Ohio, with amounts ramping up to 1.75"-2.0" around I-79. Amounts could approach 3" in central Pennsylvania.This has the support of the latest run of the SREF model. This is an "ensemble" model in which the initial weather conditions fed into the model are tweaked several times to see how much those small tweaks influence the model's solution. This is useful to forecasters as it can help us determine how much uncertainty there is in a forecast. Each line on the graph represents one of those "tweaks" and the average of all the runs is in the thick black line. In this case, the average rain forecasted is about 1.5": srefFlood Watches are up across the region: watchAs far as river flooding goes, here's a look at the expected level of the Mahoning River at Leavittsburg: leav A crest tonight just under minor flood stage (10 feet).The Mahoning River at Youngstown: yngAgain, just below minor flood stage late today, tonight and Friday morning.We will keep you updated on the latest all day! Thanks for reading.  

BLOG: Detailed Look at the Next Week

in

It's a beautiful, warm day today! What about the rest of the week, the weekend and beyond? I thought I would take a few minutes to break down what is heading our way as we get into mid May. While Ohio and western Pennsylvania enjoy a great Thursday, we will be watching the Midwest and Plains states for another round of severe weather this afternoon: day1As the system that will spark the severe weather today tracks east on Friday, the threat for a few thunderstorms will go up in the Mahoning and Shenango Valleys by afternoon. The Storm Prediction Center does not have us in any sort of enhanced risk though...just a "general" thunderstorm zone: day2The NAM model simulated radar at 2:00pm Friday shows spotty shower and thunderstorm activity: 2pmfridayA look at the expected structure of the atmosphere Friday afternoon (via a model "sounding") reveals a fair amount of instability. In the yellow area, air parcels will be "allowed" to continue rising because they will be warmer than their environment. With this much buoyancy in the atmosphere, thunderstorms can get going if there is enough of a "trigger" to force the air to start rising. bufkitprofile (2)Since the "trigger", the cold front, will still be well off to our west Friday afternoon, I expect activity to be very spotty. A lot of us will be able to avoid thunderstorms through the end of the daylight hours.Showers and thunderstorms are most likely with the arrival of that front Friday night and early Saturday. We should see a drying trend during the midday and afternoon Saturday. The chances for precipitation through midday Sunday are illustrated nicely on this graph (from the SREF model):  srefNotice, there is a small chance for a shower or thunderstorm on Mothers' Day. Will not be a washout.Next week will start warm with a couple of chances for showers and thunderstorms. The wettest day is likely to be Wednesday. April ended on a wet note and we have had a few rounds of rain so far this month. 10 day precipitation totals across the region (legend on right): rainlast10Over the next week, we will likely pick up another 1" or so: qpfHave we seen our last 32 degree temperature of the season? Is it safe to plant? Probably, but it's not a 100% certainty yet. This chart shows the minimum temperature over 6 hour increments over the next 10 days, based on the European model. It shows to sub-32 degree readings (32 is red line toward bottom). eurotempsWhat about temperatures in general? While next week starts warm, the end of the week is likely to turn cooler than average. Notice the change in the jet stream configuration from Sunday to next Thursday. Sunday: jetsundayThursday: jetnextthursThe pattern over the US basically reverses, with the big trough of low pressure in the West making its way east during the week.The cooler weather will probably be around for a few days. Temperature anomalies for next 16 days, according to the GFS model: gefsIn the meantime, have a great Thursday...enjoy the warmth!Eric