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Paul Sherman

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Posts posted by Paul Sherman

    Tornado threat 18th March onward

    in Storm Chase USA

    Posted

    Huge Uptick in Activity coming from Wednesday the 13th May Onwards - When we are out there chasing this is the timescale we watch when no more Moisture Scouring Cold Fronts are occuring and Moisture stays in Situ. This opens up more Mesoscale days in the High Plains with Marginal Dewpoints and multiple re-setting dryline days.

    Wednesday Looks like a really good Dryline Set-Up with High 60's Dewpoints, A surface Low and Warm Front Triple Point. Risk area along the dryline anywhere from NW Texas through Western Kansas upto SW Nebraska but better upper support resides further North. I would expect a Broad Enhanced Risk for this with 10% Hatched Tornado somewhere might even push out a Moderate Risk for this one although the flow is not classic still.

    Going forward the Period 20th Onwards for 2 weeks looks very nice amongst the Ensembles.

    • Like 8

    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    When In the USA I dont really overcook things as I find if you look at too many variables you can actually do more harm when picking a target. These are the things I will always look at which we can actually find on our Uk Storms in the next 5 months upto the end of September.

    First thing I look at is obviously shear and I am looking for at least 30-35knts of Deep Layer Shear. Ideally you want your 2m winds out of the east of South East, your 850mb winds out of the south and at least 25knts of speed on those. Your 500mb winds out of the South West or West and again around 40knts so storms are not moving at warp speeds. Once you look at your Hodograph that should yield winds turning with height (Shear) and then look at your T'Td Spreads. In the Uk a few years back we had those Supercells in the Midlands with temps of 75 and Dewpoints of 66. That is an amazing Spread even in the USA that would make you sit up and take notice. Notice I have not even mentioned Cape yet ? It is not the be all and end all of Supercell formation and I have seen Tornadoes with as little as 500jkg of Cape. One thing the USA has that is quite rare in the Uk is the LLJ (low Level Jet) and this really helps to get storms spinning and gives that extra spin to Mesocyclones in the early evening, although rare in the Uk we have seen the LLJ nosing up from France before.

    When we get a decent Set-Up in the Uk in the next few months it will be good for us to all look at the charts to see if any or all of these ingredients come into play.

    • Like 7
    • Thanks 2

    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    Yes we do get Supercells in the Uk and as another poster said how many low topped Supercells go unnoticed due to the lack of Doplar, remember Cold Core Supercells only really reach levels of 20-27k feet which is attainable by quite a few UK Storms in our Spring and Summer Months. 

    Most Uk Single Cell Storms hang out at around 15-18k feet but we have had Storms above 40,000 feet before

    • Like 6
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    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    Okay so this was a Risk in the Texas Panhandle last Season where we saw a Tornado at Sunset.

    Picture 1 is from the Baron System which does not have a great Resolution more like the Uk Radar - White Brick is my car/Position

    Picture 2 is from GRLevel3 which shows Dopplar Radar and better resolution again the white circle is my position

    Picture 3 is showing the Velocities 

    Picture 4 is showing what was in front of us

    As you can see we need much better radar to call Supercells from radar alone

    IMG_20190523_215338.jpg

    IMG_20190523_210557.jpg

    IMG_20190523_210555.jpg

    IMG_20190523_204741.jpg

    • Like 9

    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    2 minutes ago, Windblade said:

    Haha, I'm not even looking at the radar at the moment (although I know your comment was not direct at me). I think Thunder And Lightning was commenting more on the size of the storm image an comparing it to a supercell. Out of interest though, what are the telltale signs on a supercell radar signature? I'd like to know a bit more about this and be able to spot them more easily on radar on the rare occurrences they do show up in this country.

    Will attach a few from my chasing last season, sometimes I save the GRLevel3 data when I do a blog write up and include the signatures in there so give me a few mins

    • Like 3

    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    1 hour ago, Xanderp009 said:

    a spanish plume on Tuesday to Wednesday

    Cant see that myself, no plume of Theta air makes it further north than Central France - Cape is almost at zero (MU & SFC) 

    In fact I will apologise now to everyone, this is the first May I will be in the Uk since 2004 and I know you guys have had some humdingers over the past Mays, but going on the latest GFS alone it looks devoid of any sort of Plume outbreak for the Entire run upto the 15th May and Cape gets to 200jkg on 1 day at the end of the run.

    Sorry again 

    • Like 8

    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    Also following on from what Ben has put above, this all comes about due to the record heat being progged for Iberia this weekend and early next week. 36-38c are being forecasted for some parts of Spain and a push north of a Plume of sorts looks likely next Sunday to Tuesday for the Uk. So although we wont see the record heat the transport of High Theta towards the Uk with a trigger out west moving in are the perfect ingrediants.

    One to watch and nice and early in the season and one I would have missed had my flight to DFW to Tornado Alley was going ahead (Silver Linings and all that) Add into that the weather looks set fair over in the States on current model outlooks 

    You really couldnt make 2020 up really if you tried

    • Like 8

    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    47 minutes ago, East_England_Stormchaser91 said:

    I stand corrected. I’m not jealous much Paul! That place called tornado alley is on my top priority list over the coming years! 

    I bet seeing one of our wonderful Spanish plumes is simply just child’s play compared to what you have witnessed out there! 

    Yes you will defo have to do it one year, we only get 1 life after all. Since we have been running the tours 16 years ago I have pretty much detroyed nearly 500 people with UK Storms now lololol

    But it is what it is - And this year I will get hyped up for our Summer Plume events and you never know if we get get an engaging trough pulling up mid 60's dewpoints and favourable shear you never know that illusive beast the Supercell might make an appearance in the Uk - You of course would be best placed to see it 

    • Like 4

    Tornado threat 18th March onward

    in Storm Chase USA

    Posted

    Seeing as we wont be using the Storm Chase area this Season will put my thoughts on this thread for the 6-10 days ahead

    Tuesday sees NW Flow established over the Central Conus but with high 60's to low 70s dewpoints there are 2 risk areas currently. The first i from a crashing cold front moving from NW to SE and any convection will be linear in Nature, only real tors from these tend to be in LEWP structures and often are HP in Nature. The 2nd area is conditional at the moment along a dryline but the capping inverson looks very strong, if storms do fire they will quickly go severe with 3000jkg of Cape to work with. 

    The cold front clears into the Gulf of Mexico for Wedneday and Thursday but moisture works back to the west into the Southern Plains for the end of the week. West coast troughing looks to set up from around the 3rd May and am watching Monday 4th May at the moment which currently looks like the next possible strong system ejecting into the Central and Southern Plains.

    Lots to keep our eyes on

    • Like 4
    • Thanks 1

    Storms and Convective discussion - 10th April 2020 onwards

    in Storms & Severe Weather

    Posted

    1 hour ago, East_England_Stormchaser91 said:

    Hopefully so. However, temps of 25-30c are more than adequate to trigger severe events. In fact, you don’t necessarily need excessive CAPE and colourful charts for a decent outbreak. Dew points, a trigger mechanism and wind shear play a big part.

    You can have all the CAPE and LI in the world, but if the cap is too strong, or there is insufficient trigger mechanisms, the whole thing can end up being a bust. Oklahoma May 20th last year had a rare high risk warning, but it did not live up to expectations, due to a strong cap and a warm nose in the mid levels scuppering lapse rates somewhat. 

    I wouldnt say the Strong Cap killed that event, having chased that risk the Dryline fired further to the SW around the Southern Texas Panhandle south of Childress and that Supercell produced 2 Tornadoes, this Supercell crossed the Red River and we crossed North on Highway 6 north of Quanah, this Storm then tracked towards Mangum where it Cycled South West of There and produced that Tornado which had it hit the town square on would have aquired an EF5 Rating due to the 268mph winds that were measured by the DOW (Doppler on Wheels) what happened next was the lifting warm front actually got undercut from North winds making it a South moving Cold Front which supressed convection and kept the northern half of the 45% Hatched High Risk Area untouched, my friend at the SPC (Doug Spheger) did mention the warm nose at 700mb further North though on Norman Midday Soundings. Definately not a Bust though 

    • Like 4
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