AmericanWxFreak Posted June 20, 2016 Share Posted June 20, 2016 4km NAM has a DC special supercell Link to comment Share on other sites More sharing options...
Kmlwx Posted June 20, 2016 Share Posted June 20, 2016 SPC SREF maps for tomorrow's potential event look pretty good. I think I'm about ready to hop on board. Somebody stop me Thursday still has potential too - but we'll deal with that later. Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted June 20, 2016 Share Posted June 20, 2016 SPC SREF maps for tomorrow's potential event look pretty good. I think I'm about ready to hop on board. Somebody stop me Thursday still has potential too - but we'll deal with that later. For thursday, itseems like that low keeps trending a bit further N across PA lately, no? Link to comment Share on other sites More sharing options...
high risk Posted June 20, 2016 Share Posted June 20, 2016 yes, so the big early day MCS may now go well to our north, but we'll have a better shot at svr later in the day with the second short wave. 12z NAM suggests that a secondary sfc low may form over northern VA Thursday afternoon which would add to the potential. For thursday, itseems like that low keeps trending a bit further N across PA lately, no? Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted June 20, 2016 Share Posted June 20, 2016 yes, so the big early day MCS may now go well to our north, but we'll have a better shot at svr later in the day with the second short wave. 12z NAM suggests that a secondary sfc low may form over northern VA Thursday afternoon which would add to the potential. hmm, i like the sound of that Link to comment Share on other sites More sharing options...
yoda Posted June 20, 2016 Share Posted June 20, 2016 12z GFS SBCAPE at 18z tomorrow is the lulz at KEZF... > 6000 SBCAPE Also, are we advecting in the remnants of an EML tomorrow afternoon? Reason being is that I see a lot of mid-lapse rates from 7.0 C/KM to 7.5 C/KM at 18z and then around 7.0 C/KM at 21z Link to comment Share on other sites More sharing options...
yoda Posted June 20, 2016 Share Posted June 20, 2016 Impressive (IMO) sounding for KIAD at 18z THURS from the 12z GFS: Link to comment Share on other sites More sharing options...
Eskimo Joe Posted June 20, 2016 Share Posted June 20, 2016 When doesn't the NAM spit out insane numbers anymore? Link to comment Share on other sites More sharing options...
yoda Posted June 20, 2016 Share Posted June 20, 2016 When doesn't the NAM spit out insane numbers anymore? Its the GFS, not the NAM in teh sounding I posted above Link to comment Share on other sites More sharing options...
high risk Posted June 20, 2016 Share Posted June 20, 2016 The problem with this sounding is that the software is taking pressure level data and then sticking in the 2-m temperature and dew point and doing its own computation. The GFS has had a widespread problem this spring of pumping a lot of moisture back right into the lowest level during and just after peak heating, and it's really, really inflating 2-m dew point values. (The NAM has been doing it to a lesser extent; the soil got pretty wet in May.) The actual GFS forecast data for IAD at 18z Thursday has a dew point of 73 at the lowest model level. And that computation yields barely half of the amount of sfc-based cape that this plot shows. You can clearly get a sense looking at the plot that if you reduce the dew point at the ground by 2C, it's going to bring the sfc-based cape down quickly. It's not your fault for posting this, since the product is out there; I just want to caution people to beware of the artificially large values caused by the computation using 2-m values to represent the surface. If the forecast sounding has that kink in dew point right at the surface, big values of cape are likely not properly representing things. EDIT: to be clear, even without 6000+ cape, it's still a very nice severe wx sounding with a respectable wind profile Impressive (IMO) sounding for KIAD at 18z THURS from the 12z GFS: Link to comment Share on other sites More sharing options...
osfan24 Posted June 20, 2016 Share Posted June 20, 2016 When doesn't the NAM spit out insane numbers anymore? I'm still waiting for the 6-12 inches of rain from the last storm LOL. Link to comment Share on other sites More sharing options...
yoda Posted June 20, 2016 Share Posted June 20, 2016 LWX afternoon disco for Tuesday: Tuesday remains a bit of a question. Guidance has generally slowedthe progress of the front down and it appears to wait until latein the day or the early evening before clearing the area. Indicesare fairly robust but westerly flow would suggest that the modelsare overdoing convective coverage. Any storms that do manage tofire could go severe...but think coverage will be below 50percent.Front clears the area Tuesday evening and a drier and slightlycooler air mass arrives behind it. For Thursday: Wednesday will be a day between systems with high pressure nudgingsouth from Canada and another dry air mass. Temperatures won`tdrop that much however with readings well into the 80s. Warm frontpushes into the area from the southwest on Wednesday night withshowers and perhaps some embedded thunder. Some steady rain ispossible Wednesday morning as the front pushes through. Mostguidance now has the front lifting north of us and bringing a verymoist...warm and unstable atmosphere across our area for Thursdayafternoon. With good shear and instability and the approachingcold front to our northwest...would think we will have a severeweather episode during the afternoon and evening. With PW`s sohigh also would expect some heavy rain and if any training orrepeat storms occur...flash flooding might be a concern as well.Lows Wednesday night will be high 60s to low 70s with highsThursday in the high 80s to low 90s. Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted June 20, 2016 Share Posted June 20, 2016 18z NAM looks a bit more impressive for storms tomorrow IMO. Shear looks to be improved and coverage on simrad is much better Link to comment Share on other sites More sharing options...
Kmlwx Posted June 22, 2016 Share Posted June 22, 2016 @ the 12z GFS in the long range. If that somehow is right we might get a tropical related tornado outbreak in July...Has a tropical system coming up from the Gulf and heading in our general direction from the SW. That'd be fun... Link to comment Share on other sites More sharing options...
Kmlwx Posted June 23, 2016 Share Posted June 23, 2016 A cursory glance at the 12z GFS I'd say *maybe* something tries again next Wed/Thur timeframe. I've looked at 500mb and there's some shortwaves that come our way. Link to comment Share on other sites More sharing options...
Ian Posted June 23, 2016 Author Share Posted June 23, 2016 Euro seems to like Tuesdayish.. maybe Monday but not much shear. Then again maybe end of week. Pattern isn't changing whole lot for now. Link to comment Share on other sites More sharing options...
mappy Posted June 23, 2016 Share Posted June 23, 2016 Euro seems to like Tuesdayish.. maybe Monday but not much shear. Then again maybe end of week. Pattern isn't changing whole lot for now. Monday? Please? Link to comment Share on other sites More sharing options...
Kmlwx Posted June 23, 2016 Share Posted June 23, 2016 Euro seems to like Tuesdayish.. maybe Monday but not much shear. Then again maybe end of week. Pattern isn't changing whole lot for now. Yeah - Euro does seem to be pretty CAPEy on Tuesday. Link to comment Share on other sites More sharing options...
high risk Posted June 24, 2016 Share Posted June 24, 2016 so I guess this doesn't go into the June 21/23 thread, but SPC has some of the area in marginal threat for today. HRRR does show around 1500 src-based cape for a nice chunk of the area along with moderate deep layer shear, and it has a few modest cells around this afternoon. Tend to think that most activity will stay sub-severe, but the 5% probabilities are probably not a bad idea. Link to comment Share on other sites More sharing options...
eurojosh Posted June 27, 2016 Share Posted June 27, 2016 HRRR shows a very mild line coming through about 23z (12k NAM supports, 4k doesn't). Meh. Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted June 27, 2016 Share Posted June 27, 2016 HRRR shows a very mild line coming through about 23z (12k NAM supports, 4k doesn't). Meh. Today? Looks like tomorrow looks a bit better, but still meh Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted June 28, 2016 Share Posted June 28, 2016 HRRR looks pretty bullish for multiple rounds today Link to comment Share on other sites More sharing options...
Kmlwx Posted June 28, 2016 Share Posted June 28, 2016 Nice little jackpot of CAPE and DCAPE around Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted June 28, 2016 Share Posted June 28, 2016 Nice little jackpot of CAPE and DCAPE around Hrrr still likes multiple rounds in places Link to comment Share on other sites More sharing options...
Kmlwx Posted June 28, 2016 Share Posted June 28, 2016 We might see that line extend to the south a bit (hopefully). The SPC meso maps on the frontogenesis maps have some purple back near the I-81 corridor. Shear is probably passable as well - seems to have increased a touch in the last few hours. CAPE jackpot remains centered right around and just to the SW of DCA. SBCAPE running 2500-3000 it seems. DCAPE also still decent at 1100. Link to comment Share on other sites More sharing options...
Kmlwx Posted June 28, 2016 Share Posted June 28, 2016 Hrrr still likes multiple rounds in places Given tendency for HRRR to convect too much I'd lean away from the multiple rounds idea perhaps. I'd check the HRRRx but the site hasn't updated since yesterday Link to comment Share on other sites More sharing options...
Kmlwx Posted June 28, 2016 Share Posted June 28, 2016 Franklin Co, PA is warned for 70mph winds and quarter sized hail. Not too shabby if it's legit I haven't looked at velocity for it. Link to comment Share on other sites More sharing options...
Kmlwx Posted June 28, 2016 Share Posted June 28, 2016 New cell near Baker, WV. Question now becomes how strong this stuff gets as it comes out of the mountains. Looks pretty mundane for now unless you're up in PA. But it's entering better instability now. Shear is passable as mentioned above. Mid level lapse rates suck as usual Link to comment Share on other sites More sharing options...
Kmlwx Posted June 28, 2016 Share Posted June 28, 2016 Latest mesoanalysis is out - it is showing slightly increased effective shear, still 2500-3000 CAPE around - DCAPE mostly the same. Link to comment Share on other sites More sharing options...
biodhokie Posted June 28, 2016 Share Posted June 28, 2016 That's one small STW box. Feels like a pity box to me. Link to comment Share on other sites More sharing options...
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