Mallow Posted March 11, 2015 Share Posted March 11, 2015 I don't see any inversions to stop them from mixing if the sun comes out. How do boundary layer winds being weaker prevent mixing? Honest question. They don't. They can HELP with mixing in the absence of strong radiational heating, by adding a mechanical (non-convective) component to vertical motion, but if radiation is strong, your surface layer becomes super-adiabatic and you will mix efficiently. Link to comment Share on other sites More sharing options...
OHweather Posted March 11, 2015 Share Posted March 11, 2015 They don't. They can HELP with mixing in the absence of strong radiational heating, by adding a mechanical (non-convective) component to vertical motion, but if radiation is strong, your surface layer becomes super-adiabatic and you will mix efficiently. That's what I figured. So given the weaker BL winds I can see how it's much riskier to go warm tomorrow since sun is questionable, which is why I went 3 cooler than today. I'm still taking a risk...too big of one? We'll find out tomorrow afternoon Link to comment Share on other sites More sharing options...
H2Otown_WX Posted March 11, 2015 Share Posted March 11, 2015 83/64/10/0 Am taking a risk on the high and am a bit torn...however, large scale ascent doesn't look very strong for much of the day tomorrow so I'm thinking they may get away with a broken deck of mid clouds and get some solar insolation through them. It looks like they have decent potential to mix about as high as today if there's just a little more sun than models show, and temps at the top of the mixed layer look just about the same as today, so I think there's potential for the highs to bust warm again. If they are completely overcast that won't happen which is why it's a risk on my part. It's interesting, there looks to be some good surface convergence along the front tomorrow afternoon and with some sun NAM and Euro are forecasting > 1000 J/kg of SBCAPE. However, the upper air pattern doesn't support large scale ascent, as you said. P.S. I originally had 83 for the high but chickened out. Link to comment Share on other sites More sharing options...
OHweather Posted March 11, 2015 Share Posted March 11, 2015 It's interesting, there looks to be some good surface convergence along the front tomorrow afternoon and with some sun NAM and Euro are forecasting > 1000 J/kg of SBCAPE. However, the upper air pattern doesn't support large scale ascent, as you said. 95fwbgus_init_2015031012.gif P.S. I originally had 83 for the high but chickened out. I'm sure there will be isolated to scattered storms around during the afternoon. I really debated the precip. It came down to I wasn't confident enough to go over 0.10", and with isolated to scattered stuff I don't like putting in a token amount...it'll either be 0 or way more than a token amount with storms (IE putting in 0.03" or something won't help me much if they get a quarter inch or more), so I put 0 as if they get 0 which is definitely possible I won't get a point or so of precip error. I was still debating the high when the deadline passed...but will roll with it and see what happens. Link to comment Share on other sites More sharing options...
weatherMA Posted March 11, 2015 Share Posted March 11, 2015 already 64... Link to comment Share on other sites More sharing options...
ma blizzard Posted March 11, 2015 Share Posted March 11, 2015 already 64...yikes .. my 64 for a low is in trouble ..80/64/9/0 Link to comment Share on other sites More sharing options...
ma blizzard Posted March 11, 2015 Share Posted March 11, 2015 down to 62 .. Link to comment Share on other sites More sharing options...
WxBlue Posted March 11, 2015 Share Posted March 11, 2015 And precipitation is only 10 miles to west... Link to comment Share on other sites More sharing options...
Max Posted March 11, 2015 Share Posted March 11, 2015 And precipitation is only 10 miles to west... It's going to miss them. And by the looks of it, it is weakening and dissipating. Link to comment Share on other sites More sharing options...
WxBlue Posted March 11, 2015 Share Posted March 11, 2015 It's going to miss them. And by the looks of it, it is weakening and dissipating. Yeah, I didn't think it'll hit the airport but it can't hurt to have little hope Link to comment Share on other sites More sharing options...
AppsRunner Posted March 11, 2015 Share Posted March 11, 2015 Back to 64. Hopefully it stays that way Link to comment Share on other sites More sharing options...
OHweather Posted March 11, 2015 Share Posted March 11, 2015 Wasn't expecting a solid line of heavy rain already Link to comment Share on other sites More sharing options...
Mallow Posted March 11, 2015 Share Posted March 11, 2015 Argh, so much for clouds sticking around all night. Wasn't expecting a solid line of heavy rain already That's what the Euro showed... Link to comment Share on other sites More sharing options...
phil882 Posted March 11, 2015 Share Posted March 11, 2015 Lol it was 58 last night? I'm totally butchering the temperature today but if we can pick up some decent rain from this band it will totally save me. Link to comment Share on other sites More sharing options...
OHweather Posted March 11, 2015 Share Posted March 11, 2015 Argh, so much for clouds sticking around all night. That's what the Euro showed... I thought it showed most of the precip between 20-0z, but yeah it did show a squall line. Today will probably be a disaster on my end for every variable Link to comment Share on other sites More sharing options...
L.B. LaForce Posted March 11, 2015 Share Posted March 11, 2015 Dang you Euro! That could put down some decent rain too. Link to comment Share on other sites More sharing options...
Mallow Posted March 11, 2015 Share Posted March 11, 2015 I thought it showed most of the precip between 20-0z, but yeah it did show a squall line. Today will probably be a disaster on my end for every variable You're right, I don't think it had the band this early. Link to comment Share on other sites More sharing options...
OHweather Posted March 11, 2015 Share Posted March 11, 2015 You're right, I don't think it had the band this early.I would've taken the Euro's timing as it would've given the warmer highs a chance and bit the bullet on precip, but oh well. There will be plenty of oppertunity to make up points I'm sure. Link to comment Share on other sites More sharing options...
Mallow Posted March 11, 2015 Share Posted March 11, 2015 Up to 0.21" so far. Link to comment Share on other sites More sharing options...
phil882 Posted March 11, 2015 Share Posted March 11, 2015 Looks like the precip from this first band is wrapping up, so we got to 0.24" with the possibility for more with convection that is going up behind the main band. Temp is also back up to 70F. Its certainly possible they can get into the mid-70's with a few more hours of good daytime heating. Link to comment Share on other sites More sharing options...
Mallow Posted March 12, 2015 Share Posted March 12, 2015 Tomorrow is a crapshoot for me. 83/59/16/0.38 Link to comment Share on other sites More sharing options...
WxBlue Posted March 12, 2015 Share Posted March 12, 2015 82/63/17/0.45 It's a gamble on low and trusting GFS MOS but... c'mon clouds! Link to comment Share on other sites More sharing options...
phil882 Posted March 12, 2015 Share Posted March 12, 2015 Same here... another convective precip day. One thing that is worth watching is how quickly convection initiates tomorrow. Looks like we won't have a frontal forced precip until late in the day as a backdoor cold front moves through overnight. So I think we see more daytime heating than today. That combined with deeper mixing should lead to a high not quite as warm as Monday, but potentially into the low 80's. Again if convection fires faster than forecasted, this could very well bust. Hopefully the high cirrus keeps a lid on the significant convection until better synoptic forcing arrives. 83/60/20/0.50" Link to comment Share on other sites More sharing options...
AppsRunner Posted March 12, 2015 Share Posted March 12, 2015 80/61/18/0.53 Just trying to make up ground Link to comment Share on other sites More sharing options...
Max Posted March 12, 2015 Share Posted March 12, 2015 85/63/21/0.68". I felt like there were two camps on the low. 59-60 and 63. I think I may have chosen the wrong one. The high I felt has a chance to get up to 85 if convection and cloudier skies hold off until after 20z. Precipitation is all convection so good luck to us all lol. Winds obviously will be high tomorrow night as the pressure gradient tightens and an easterly llj develops. Obviously if a strong storm goes right over late at night before 6z tomorrow we could see winds overperform. Link to comment Share on other sites More sharing options...
H2Otown_WX Posted March 12, 2015 Share Posted March 12, 2015 78/60/18/0.65 Link to comment Share on other sites More sharing options...
OHweather Posted March 12, 2015 Share Posted March 12, 2015 Went 82/62/20/0.50" Another challenging forecast. First off for the low, I initially had upper 50's just because every night they've gotten some clearing and have fallen below 60. However, dews were running much higher at 23z when I had my last look before going back to work than recent days and they did get a good shot of rain today, so I figured that would be enough to keep them in the lower 60's tonight. If they do clear with calm winds then fog/low clouds could develop and cap lows as well, and they appear to be pretty foggy right now. They are at 62 now so we will see, they'll probably manage to get to like 59 just because. As for the high/precip, they're a bit intertwined. They can mix fairly deep and get warm if there's enough sun. There appear to be just mid to high clouds after any morning fog burns off, so I did feel leaning a little warmer was the way to go. The possible wrinkle in this would be storms firing early or moving in early like on Wednesday...however, there is no active convection down there unlike Tuesday night into Wednesday morning and there looks to be a bit of a cap to overcome. This will hopefully keep things at bay until mid afternoon. Once we hit mid afternoon, some large scale ascent should be enough when combined with daytime heating and any ascent along an apparent wind shift on most models near MGM to blow the cap off and fire scattered to numerous storms. I didn't expect the front to move through so early if at all on Wednesday which is why I went dry for day 2, however for day 3 there is good evidence the wind shift/stationary front will be near MGM and fairly active with storms mid afternoon through evening. PWATs are reasonably high and storms should be slow moving, so a good amount of rain seems possible. Even so, hi-res models didn't show a squall line of heavier cells as much as more scattered heavier cells so it's possible they don't truly cash in, so I felt like 0.50" was a good middle ground solution. The Euro had about 0.40" of QPF and the 9z and 15z SREF means were in the neighborhood of 0.40", with most members showing the best chances for higher QPF near MGM and a 30-40% probability of 0.50"+ of QPF falling by 6z Thursday night...given the slow storm motion and high PWATs felt it was better to go a little higher than the SREF mean and Euro output...both models showing the higher QPF near or over MGM also made me feel somewhat comfortable...but it's a crap chute still to an extent. Low level easterlies looked strong during the evening and any stronger cells could also contribute to higher winds, so leaned high on the winds. Link to comment Share on other sites More sharing options...
Max Posted March 12, 2015 Share Posted March 12, 2015 I'm starting to kick myself for not going 59-60 now. That was my low for most of the day before I switched it late. Link to comment Share on other sites More sharing options...
phil882 Posted March 12, 2015 Share Posted March 12, 2015 Well it's still early but I am very worried about my forecast today. All the models are atrociously handling the convection in the GoM and it looks like KMGM might have a much thicker cloud deck than previously forecasted. Not to mention the HRRR has widespread convection developing before 18z. Could be a disaster in the making. Link to comment Share on other sites More sharing options...
AppsRunner Posted March 12, 2015 Share Posted March 12, 2015 61F min so far. Who knows what's actually going to happen this afternoon Link to comment Share on other sites More sharing options...
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