WxUSAF Posted October 30, 2019 Share Posted October 30, 2019 1 hour ago, losetoa6 said: For sure will feel like deep fall. Most guidance has Fri and Sunday 40s for highs imby. Probably frost Sat thru Mon morning here with a hard freeze Sunday night maybe. Euro had coldest temps Saturday morning and Monday morning. 1 1 Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 Seeing some SRH values approaching or exceeding 400 m2/s2 at the 1km level... hodographs are decently curved as well around 00z Link to comment Share on other sites More sharing options...
dailylurker Posted October 31, 2019 Share Posted October 31, 2019 13 minutes ago, yoda said: Seeing some SRH values approaching or exceeding 400 m2/s2 at the 1km level... hodographs are decently curved as well around 00z So, wedges followed by possible flurries in the mountains and cold temps in central MD. Got it. 1 Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 Ton of low level shear at 00z THUR at KDCA on the 00z NAM sounding... look at the winds turn, damn... also 60kts at 900mb is yikes Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 Just now, losetoa6 said: Also over 70 kts at 850mb . Both nam and Euro been advertising surface gusts to near 60 in spots . I'm guessing higher gusts could mix down in strongest cells with those parameters? I would believe so... is that correct @high risk? Link to comment Share on other sites More sharing options...
high risk Posted October 31, 2019 Share Posted October 31, 2019 41 minutes ago, yoda said: 42 minutes ago, losetoa6 said: Also over 70 kts at 850mb . Both nam and Euro been advertising surface gusts to near 60 in spots . I'm guessing higher gusts could mix down in strongest cells with those parameters? One thing for sure ...if the storms don't get ya on the trick or treat trail the winds will . Winds really pick up tomorrow afternoon I would believe so... is that correct @high risk? well, yes, there is potential to mix down significant momentum to the surface with those wind speeds just above the ground, IF you have some instability in the lower levels. I was talking up this event yesterday, but I feel the need to put the brakes on it a bit today. There is a little bit of instability in the soundings, but it's not much, and it's shallow. It might be enough to get SVR gusts down to the surface, but we fail in these setups a lot. To be clear, an intense line will cross the region tomorrow evening, but I can't help but feel that a SLGT would have been sufficient. I'm not even sure if we'll hear thunder. But the potential for a significant event across the area is certainly still on the table. 1 Link to comment Share on other sites More sharing options...
midatlanticweather Posted October 31, 2019 Share Posted October 31, 2019 Even Reed Timmer is a bit hyped about it. If you read the thread he mentions chasing along I81 when someone mentions it. Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 @high risk @Kmlwx @Eskimo Joe ENH risk on 0600 Day 1 OTLK... rather large 5% tor and 30% wind probs 1 Link to comment Share on other sites More sharing options...
southmdwatcher Posted October 31, 2019 Share Posted October 31, 2019 That is a very large 5% Tornado risk area Link to comment Share on other sites More sharing options...
Kmlwx Posted October 31, 2019 Share Posted October 31, 2019 2 hours ago, southmdwatcher said: That is a very large 5% Tornado risk area That's probably broadbrushed due to the general large area of risk. Maybe more of a CYA than anything. But large 5% TOR can sometimes be a prelude to a little 10% area being introduced later. I think Reed Timmer was a bit much last night... Link to comment Share on other sites More sharing options...
arlwx Posted October 31, 2019 Share Posted October 31, 2019 From the latest LWX advisory: (snip) All the ingredients remain in place for a potentially dangerous severe weather event tonight. MLCAPE values increase to 500-1000 j/kg due to daytime heating in spite of the clock and calendar; there is more than ample shear present as a 60-70 kt low level jet develops in advance of the sharpening/negatively tilting trough axis; the area will be situated in the right-rear quadrant of the upper jet; and the baroclinic zone across the frontal boundary will be dramatic. These factors suggest that a squall line/QLCS should develop near the front, with straight line winds as the primary concern. However, the intensity of the wind/shear also suggests that spin-up tornadoes cannot be ruled out, as highlighted by STP index (HREF ensemble mean ranging from 2-5). THere is general consensus on timing too, from 21-00Z in the mountains, to 03-06Z near the Bay. An Enhanced Risk of severe weather remains in place from SPC. Link to comment Share on other sites More sharing options...
nw baltimore wx Posted October 31, 2019 Share Posted October 31, 2019 .79" overnight here and 6.47" for October. About a week ago, I think @WxUSAF said the yearly deficit was over 6" at BWI, and now I think it's just over 2". And we might make a lot of that up tonight. 1 Link to comment Share on other sites More sharing options...
WxUSAF Posted October 31, 2019 Share Posted October 31, 2019 14 minutes ago, nw baltimore wx said: .79" overnight here and 6.47" for October. About a week ago, I think @WxUSAF said the yearly deficit was over 6" at BWI, and now I think it's just over 2". And we might make a lot of that up tonight. Yeah we’ve really closed that deficit in the last 2 weeks. Link to comment Share on other sites More sharing options...
EastCoast NPZ Posted October 31, 2019 Share Posted October 31, 2019 .28" Warm and humid this morning. Gross. Awful way to end October. 1 Link to comment Share on other sites More sharing options...
wxdude64 Posted October 31, 2019 Share Posted October 31, 2019 0.35 for the day, 6.10 for the month of October, almost 6 inches more than September....... Link to comment Share on other sites More sharing options...
H2O Posted October 31, 2019 Share Posted October 31, 2019 need the hype meter for today. Seeing ENH on halloween is def unusual Link to comment Share on other sites More sharing options...
H2O Posted October 31, 2019 Share Posted October 31, 2019 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Thu Oct 31 2019 Valid 311300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT FOR NORTHERN NC INTO SOUTHERN PA... ...SUMMARY... Severe thunderstorms capable of damaging winds and a few tornadoes are expected mainly this afternoon into early tonight from the Carolinas into the Mid-Atlantic. ...Mid-Atlantic to Carolinas this afternoon into early tonight... An intense midlevel shortwave trough now over MO will accelerate east-northeastward through tonight toward PA/NY, while taking on a more neutral-to-negative tilt and peak 500 mb wind speeds exceeding 120 kt. Strong surface cyclogenesis is expected in advance of the amplifying midlevel trough, with a cyclone moving from OH to the lower Great Lakes this evening, and continuing into southwestern QC by early Friday. South of the deepening cyclone, a strong cold front will move eastward from the OH/TN Valleys across the Appalachians this afternoon, reaching the Atlantic coast overnight. The cold front will be the primary focus for severe thunderstorms through this evening. Northward advection of low-level moisture is underway across the Carolinas/VA, where boundary-layer dewpoints range from mid 60s north to the lower 70s south. Dewpoints in the 60s should reach as far north as southern NY by late afternoon, though widespread clouds/rain will limit surface heating with northward extent from VA. Despite poor low-midlevel lapse rates, the moist low levels will promote at least weak buoyancy rooted near the surface into PA. Buoyancy will be a little greater to the south into VA and the Carolinas, where richer low-level moisture and some surface heating in cloud breaks will support MLCAPE of 1000-1500 J/kg. Within the warm sector, vertical shear will increase through the day in response to the approach and deepening of the midlevel trough/surface cyclone. Long hodographs with effective bulk shear of 50-60 kt are expected, and there will also be sufficient low-level shear/hodograph curvature for rotating storms (effective SRH of 300-500 m2/s2). Strong linear forcing for ascent along the cold front will be the primary focus for storm development, mainly east of the Appalachians this afternoon/evening. The strong linear ascent will favor upscale growth into a squall line, though strong deep-layer shear and enough east component to storm motions may allow some embedded supercell structures to persist. The weak buoyancy and very strong low-level shear will favor damaging winds as the primary threat, though a few tornadoes will also be possible with embedded supercell and mesovortex structures this afternoon/evening. Link to comment Share on other sites More sharing options...
Kmlwx Posted October 31, 2019 Share Posted October 31, 2019 EF-5 tracing the beltway during the end of rush hour. Mark my words. Link to comment Share on other sites More sharing options...
George BM Posted October 31, 2019 Author Share Posted October 31, 2019 Already up to 70/67 at IAD as of 9:44am edt. Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 12z NAM pushing a little harder on the potential TOR threat this evening... gets SBCAPE up to near 800 J/KG and MLCAPE near 1000 J/KG at KIAD at 00z with EHI at 3.0 and 1km SRH at 470 m2/s2. STP is 6.6 and LCLs are fairly low - under 400m Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 lol 12z NAM throwing out PDS TOR down by EZF and and just south of Warrenton on the soundings on pivotalweather for 00z in the possible hazard type Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 12z 3km NAM has a mean squall line/QLCS that comes roaring through the LWX CWA -- around 23z for I81 corridor... 01z along the BR... and 02z through I95 corridor Link to comment Share on other sites More sharing options...
high risk Posted October 31, 2019 Share Posted October 31, 2019 10 minutes ago, yoda said: lol 12z NAM throwing out PDS TOR down by EZF and and just south of Warrenton on the soundings on pivotalweather for 00z in the possible hazard type the PDS TOR stuff is fun and all, and I see why the soundings are spitting it out, but that would only be realized in a discrete supercell which will definitely not be the mode this evening. As you noted, all guidance is consistent with a strongly-forced QLCS feature. Any tornado threat would be limited to mesovortices within the line due to the intense low-level shear. 4 2 Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted October 31, 2019 Share Posted October 31, 2019 7 minutes ago, yoda said: 12z 3km NAM has a mean squall line/QLCS that comes roaring through the LWX CWA -- around 23z for I81 corridor... 01z along the BR... and 02z through I95 corridor Yuck, terrible timing. I'd rather have this come through in the afternoon then possibly have to wake the kids up and take them to the basement. (My house is surrounded by large, very old, oak trees). Link to comment Share on other sites More sharing options...
George BM Posted October 31, 2019 Author Share Posted October 31, 2019 Meanwhile we remain "King of the Fake Droughts". Link to comment Share on other sites More sharing options...
Kmlwx Posted October 31, 2019 Share Posted October 31, 2019 I pulled a sounding from the 12z 3km NAM and it had a 500 value for 0-1km SRH it was 800 for 0-3km I think. That's absurd. 40+kts of shear in the 0-1km range. Link to comment Share on other sites More sharing options...
WxUSAF Posted October 31, 2019 Share Posted October 31, 2019 20F temp drop with the front on the NAM. Says first freeze for IAD and BWI is Saturday morning. Link to comment Share on other sites More sharing options...
MN Transplant Posted October 31, 2019 Share Posted October 31, 2019 4 minutes ago, WxUSAF said: 20F temp drop with the front on the NAM. Says first freeze for IAD and BWI is Saturday morning. I've noticed that the NAM has been overly aggressive with the immediate temp drops. The HRRR has ~22° over two hours. We'll see who does better. 1 Link to comment Share on other sites More sharing options...
Kmlwx Posted October 31, 2019 Share Posted October 31, 2019 RAP (FWIW) has like 1000 CAPE. Instability has been trending upward more. A few days ago I thought we'd be lucky to get 500J/KG Link to comment Share on other sites More sharing options...
yoda Posted October 31, 2019 Share Posted October 31, 2019 Mesoscale Discussion 2128 NWS Storm Prediction Center Norman OK 1012 AM CDT Thu Oct 31 2019 Areas affected...Parts of eastern North Carolina...northeastern Tennessee...southwestern Virginia...far eastern Kentucky...West Virginia and southwestern Pennsylvania Concerning...Severe potential...Watch likely Valid 311512Z - 311715Z Probability of Watch Issuance...80 percent SUMMARY...A more substantial increase in potential for severe wind gusts, and perhaps isolated tornadoes, is expected with a developing line of storms during the 1-3 PM EDT time frame. One or more watches probably will be needed within the next couple of hours. DISCUSSION...Although mid/upper-level lapse rates across much of the region are more or less moist adiabatic, latest objective analysis suggests that boundary layer warming and moistening are contributing to at least weak destabilization along the western slopes of the Allegheny Mountains. Mixed-layer CAPE may not become much more than roughly 500 J/kg, but this is expected to occur in the presence of strengthening lower/mid tropospheric wind fields, as deepening of the surface cyclone (now centered near Columbus OH) proceeds more rapidly through early to mid afternoon. Model forecast soundings indicate south to southwesterly flow intensifying to 50-70+ kt, just off the surface through around 500 mb, as the strengthening surface cold front advances toward the Alleghenies. This is expected to coincide with increasing lift along/ahead of the cold front, aided by forcing for upward vertical motion ahead of a vigorous short wave trough gradually pivoting east of the the Mississippi Valley, to support an intensifying line of thunderstorms. It is possible that this may be gradually underway across parts of northeastern Tennessee through eastern Kentucky and southeastern Ohio, but a more notable increase/intensification seems more likely during the 17-19Z time frame, before gradually spreading eastward into/through the Appalachians. As convection intensifies, downward momentum transport in downdrafts will contribute to increasing potential for damaging convective surface gusts. Large low-level hodographs could also support supercell structures along and perhaps just ahead of the developing line of storms, with a risk for tornadoes. ..Kerr/Grams.. 10/31/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CTP...LWX...RNK...PBZ...RLX...GSP...MRX...JKL... Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now