yoda Posted February 26, 2020 Share Posted February 26, 2020 Per 833pm HWO from LWX for the region: Quote DAYS TWO THROUGH SEVEN...Wednesday through Monday A line of storms is expected to develop along a strong cold front late Wednesday into Wednesday evening. A few damaging wind gusts are possible, and an isolated tornado cannot be ruled out. Link to comment Share on other sites More sharing options...
high risk Posted February 26, 2020 Share Posted February 26, 2020 22 minutes ago, yoda said: @high risk pretty decent squall line comes roaring through the region between 02z and 05z THU on 00z 3km NAM For sure. The reflectivity looks so impressive! But it's not surfaced-based. That said, there is some elevated cape, so while there wouldn't be any severe threat with that (assuming that the NAM nest is correct with the stable sfc layer), there would definitely be some chance of lightning. I would call that a win! Link to comment Share on other sites More sharing options...
arlwx Posted February 26, 2020 Share Posted February 26, 2020 The latest from LWX: NEAR TERM /THROUGH TONIGHT/... Satellite and observational trends show that dense fog is expanding in areal coverage as high clouds shift to the east. NSSL-WRF ARW synthetic imagery shows low clouds persisting all day east of the Blue Ridge, the eastern panhandle of WV, and northern MD. Based on its output, areas south of Winchester to Staunton are the only ones that are expected to experience clear skies. It will likely remain quiet through about 21Z, then widespread showers and possible thunderstorms are expected as low pressure forms along the Appalachians and Blue Ridge and develops north northeastward. The most recent model guidance showed a trend toward less instability/CAPE available due low overcast expected to persist all day. Other parameters such as model flash rate and lifted indices also showed a downward trend in t-storm potential. The areas of greater risk for any severe wx seems to be east of the Appalachians to the I-81 corridor where the most sunshine is expected and generally west of where SPC placed the marginal risk. Cdfnt will sweep through the area between 03Z-06Z Thu with showers ending quickly with fropa. Colder air will follow in its wake with showers turning quickly into snow showers over the Appalachians where sub-advisory snow accumulations are expected. A strong pressure surge behind the front will cause strong winds at higher elevations and have issued a Wind Advisory for the highest elevs from midnight tonight to 15Z Thu. Link to comment Share on other sites More sharing options...
mappy Posted February 26, 2020 Share Posted February 26, 2020 shame its happening late night. my old ass can't stay up until 11 waiting for a 15-minute line of storms 2 Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 38 minutes ago, mappy said: shame its happening late night. my old ass can't stay up until 11 waiting for a 15-minute line of storms LWX did note yesterday that it might come in a bit faster than expected with how dynamic it is. I can barely make it past 9:30pm myself these days. Link to comment Share on other sites More sharing options...
high risk Posted February 26, 2020 Share Posted February 26, 2020 I still don't understand why SPC is now even considering an upgrade to SLGT, but there is no argument that if sfc-based parcels can find a way to be buoyant, the wind fields are amazing. A faster evolution of the event might allow the line to take advantage of daytime warming for the western part of the outlook, so I understand the outlook expanding west. I'm setting my goal for getting a torrential downpour and maybe hearing thunder. Seeing several consecutive HRRR cycles wanting to break up the line as it moves east is giving me some pause, though...... Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 Wish we could muster dynamics like today with sunny skies in May. 1 Link to comment Share on other sites More sharing options...
mappy Posted February 26, 2020 Share Posted February 26, 2020 2 hours ago, Kmlwx said: LWX did note yesterday that it might come in a bit faster than expected with how dynamic it is. I can barely make it past 9:30pm myself these days. i'm not that old lol but a rumble of thunder before the cold wind would be cool Link to comment Share on other sites More sharing options...
Eskimo Joe Posted February 26, 2020 Share Posted February 26, 2020 2 hours ago, high risk said: I still don't understand why SPC is now even considering an upgrade to SLGT, but there is no argument that if sfc-based parcels can find a way to be buoyant, the wind fields are amazing. A faster evolution of the event might allow the line to take advantage of daytime warming for the western part of the outlook, so I understand the outlook expanding west. I'm setting my goal for getting a torrential downpour and maybe hearing thunder. Seeing several consecutive HRRR cycles wanting to break up the line as it moves east is giving me some pause, though...... I wonder if they are a bit gun shy after missing one of the largest winter tornado events in the Mid Atlantic the other week. Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 HRRR continues to send the most continuous part of the line mostly to the north of Central Maryland. It's more broken in DC proper and very scattered south. Link to comment Share on other sites More sharing options...
George BM Posted February 26, 2020 Share Posted February 26, 2020 8 minutes ago, Eskimo Joe said: I wonder if they are a bit gun shy after missing one of the largest winter tornado events in the Mid Atlantic the other week. They made a reference to that event in the 1630z update. Link to comment Share on other sites More sharing options...
high risk Posted February 26, 2020 Share Posted February 26, 2020 11 minutes ago, Eskimo Joe said: I wonder if they are a bit gun shy after missing one of the largest winter tornado events in the Mid Atlantic the other week. This is a very good point! But that event had some actual sfc-based instability. Link to comment Share on other sites More sharing options...
high risk Posted February 26, 2020 Share Posted February 26, 2020 8 minutes ago, Kmlwx said: HRRR continues to send the most continuous part of the line mostly to the north of Central Maryland. It's more broken in DC proper and very scattered south. Several of the morning CAMs show the same thing now. Seems like some showers break out ahead of the line in those runs and ruin the convergence. Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 10 minutes ago, high risk said: Several of the morning CAMs show the same thing now. Seems like some showers break out ahead of the line in those runs and ruin the convergence. Then again - it's the HRRR and could be totally wrong - but with agreement maybe not. Link to comment Share on other sites More sharing options...
AdamHLG Posted February 26, 2020 Share Posted February 26, 2020 It's really gotten bad when the most we can hope for in the climatologically favored snowless February is a potential rumble of thunder and wind shift in the middle of the night with overcast skies and little surface instability. Maybe a special radio show is in order? Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 16z HRRR had a bit more of a consolidated line. Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 The latest HRRR looks a bit better. Nothing significant but just a more solid line and a bit more on the gusty wind side of things. The weenie in me also sees a tiny bit of that light green shade on the UH maps. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted February 26, 2020 Share Posted February 26, 2020 Just now, Kmlwx said: The latest HRRR looks a bit better. Nothing significant but just a more solid line and a bit more on the gusty wind side of things. The weenie in me also sees a tiny bit of that light green shade on the UH maps. $20 says we see a quick temp spike pre-front as the low level inversion mixes out and we get a few SVRs / damaging wind reports tonight. Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 Just now, Eskimo Joe said: $20 says we see a quick temp spike pre-front as the low level inversion mixes out and we get a few SVRs / damaging wind reports tonight. That's about the max potential on this one. Absolute max. My current thinking (not very bold) is for zero TOR reports in the LWX CWA this evening and fewer than 5 reports of wind damage. I'm sure LWX will throw up a few warnings. I'll go max measured gust of 53mph. Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 https://www.spc.noaa.gov/products/md/md0131.html Just posted to Twitter - but it's not up on SPC quite yet. 1 Link to comment Share on other sites More sharing options...
Eskimo Joe Posted February 26, 2020 Share Posted February 26, 2020 5 minutes ago, Kmlwx said: https://www.spc.noaa.gov/products/md/md0131.html Just posted to Twitter - but it's not up on SPC quite yet. We had a 5% pity meso last time, but the low was about 7mb stronger and we were in Larko's Triangle. Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 1 minute ago, Eskimo Joe said: We had a 5% pity meso last time, but the low was about 7mb stronger and we were in Larko's Triangle. Different timing too - though some might argue the timing was even worse for that one. Wasn't it during the morning rush? I remember I was stuck in it driving to work around 7:45 that morning. I guess timing doesn't really mean crap in these low CAPE cold season events. Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 19z HRRR at 04z this evening. Looks acceptable. 1 Link to comment Share on other sites More sharing options...
Eskimo Joe Posted February 26, 2020 Share Posted February 26, 2020 1 minute ago, Kmlwx said: Different timing too - though some might argue the timing was even worse for that one. Wasn't it during the morning rush? I remember I was stuck in it driving to work around 7:45 that morning. I guess timing doesn't really mean crap in these low CAPE cold season events. Correct, it was between 8am - 10am. That event is a great reminder that if you get the dyanmics/instability right, the time of day doesn't matter. Link to comment Share on other sites More sharing options...
yoda Posted February 26, 2020 Share Posted February 26, 2020 LWX seems a bit gungho this evening in their afternoon AFD: As the aforementioned trough takes on a negative tilt this evening, surface low pressure will develop on the triple point between this convergence axis and a warm front stalled over the region. Low level wind fields will strengthen, forcing this line of convection to accelerate eastward. The low will quickly begin to lift northeastward by late this evening as an upper jet streak strengthens and approaches from the southern Appalachians. A surface cold front attendant to the upper trough will also accelerate eastward. The line of showers (and possible isolated thunderstorms) will trek eastward reaching the Blue Ridge between 9 and 10 PM, I-95 between 10 PM and midnight, and the Chesapeake Bay between 11 PM and 1 AM. Residence time of the line over any one area probably won`t be more than 15 to 30 minutes, but brief downpours and gusty winds (possibly strong enough to cause isolated wind damage given the ambient low level wind field) may accompany the line. As mid/upper forcing and stronger surface convergence pivot northeastward toward southeastern Pennsylvania through the evening into the overnight, low CAPE will wane and retreat southeastward. The best juxtaposition of CAPE, increasing low level winds and a weaker near-surface stable layer appears to be over portions of central Virginia (from around Waynesboro to Charlottesville to Culpeper, generally up US-29 toward Manassas). Hi-res guidance (namely the HRRR/WRF-ARW) indicate the triple point/mesolow tracking through this corridor, enhancing low level shear and vorticity amid backed surface flow. This may ultimately be where the best chance for damaging winds or an isolated tornado winds up. Elsewhere, isolated strong to damaging surface gusts are possible, especially if the line of convection solidifies more significantly making downward momentum transfer more probable despite a near surface stable layer in the cool sector/wedge Link to comment Share on other sites More sharing options...
Kmlwx Posted February 26, 2020 Author Share Posted February 26, 2020 @yoda - don't know if I'd refer to that as "gungho" seems more like they are just saying IF there was an area that had a higher risk - it would be there. The background risk is pretty low still. They just do a great job it seems of fleshing out the discussion and describing the potential. 1 Link to comment Share on other sites More sharing options...
MN Transplant Posted February 26, 2020 Share Posted February 26, 2020 HRRR going with gusts in the mid-40s after the line passes. That might be more interesting than the showery line. Link to comment Share on other sites More sharing options...
high risk Posted February 26, 2020 Share Posted February 26, 2020 13 minutes ago, MN Transplant said: HRRR going with gusts in the mid-40s after the line passes. That might be more interesting than the showery line. Agreed. We'll have no problems mixing behind the front. Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 27, 2020 Share Posted February 27, 2020 Misting here ahead of the rain/potential line. I wouldn’t think that bolds well for strong/severe chances Link to comment Share on other sites More sharing options...
NorthArlington101 Posted February 27, 2020 Share Posted February 27, 2020 Not severe but nice and gusty with some loud T&L in Charlottesville. Fantastic storm for February 2 Link to comment Share on other sites More sharing options...
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