Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 I am personally not sure the upgrade was warranted in our area. To our west and north sure...but the modeling just doesn't seem to support a robust threat for DC area locally. Robust wording in the SPC outlook though...they even mention the potential for strong tornadoes... A lot of the hi-res guidance has stuff weakening before it gets here or the dreaded DC split. I'm having trouble finding modeling that brings robust activity through DC. We'll see if the trend is for something more on the short range models...I'm out unless you're well west...for now. Link to comment Share on other sites More sharing options...
JoJo Posted May 1, 2017 Share Posted May 1, 2017 NW in Pennsylvania, if there would be an upgrade to moderate risk that's where it will be for either wind damage or tornado risk idk yet Link to comment Share on other sites More sharing options...
H2O Posted May 1, 2017 Share Posted May 1, 2017 Its funny to read the differences between SPC and LWX. Sterling is def more ho-hum about chances. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 1, 2017 Share Posted May 1, 2017 SPC likely included the cities as a cover-your-a$$ and they've been off recently. LWX is weenie as heck and if they're pretty 'meh' then it doesn't encourage me. Still, we're 72 in Gaithersburg at 8am and the cloud deck is racing NE. Probably good for a gusty thunderstorm or something today. Link to comment Share on other sites More sharing options...
mappy Posted May 1, 2017 Author Share Posted May 1, 2017 I don't want to knock SPC, but they haven't had the best record with this system as it moved across the country. With that said, today is worth keeping an eye on. Really going to depend on how fast the backdoor front can move north and out of the area and clearing. Much like yesterday, north of that boundary that was near DC, it was much too stable and anything that popped up was meet with a quick death. Today could be the same if clouds hang around. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 1 minute ago, mappy said: I don't want to knock SPC, but they haven't had the best record with this system as it moved across the country. With that said, today is worth keeping an eye on. Really going to depend on how fast the backdoor front can move north and out of the area and clearing. Much like yesterday, north of that boundary that was near DC, it was much too stable and anything that popped up was meet with a quick death. Today could be the same if clouds hang around. We love our clouds on severe days here in the DC area I'm out for now on today. Pending instability - a lot of the models are very meager with instability for our area. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 1, 2017 Share Posted May 1, 2017 One thing we have going for us is that large area of clearing from I-95 west. The broad SW flow should aid the eroding of any low level wedge. It was 51 in Reisterstown and overcast when I left, 63 in Lisbon and it's 72 with partly sunny skies in Gaithersburg. Impressive boundary. http://weather.cod.edu/satrad/exper/?parms=dcarea-02-48-0 Link to comment Share on other sites More sharing options...
JoJo Posted May 1, 2017 Share Posted May 1, 2017 2 minutes ago, Kmlwx said: We love our clouds on severe days here in the DC area I'm out for now on today. Pending instability - a lot of the models are very meager with instability for our area. Today looks like it could be a day where the shear takes advantage of any instability between 500 j/kg and 1000 j/kg. The enhanced risk large and somewhere in it will get an upgrade based one the trends Link to comment Share on other sites More sharing options...
mappy Posted May 1, 2017 Author Share Posted May 1, 2017 2 minutes ago, JoJo said: Today looks like it could be a day where the shear takes advantage of any instability between 500 j/kg and 1000 j/kg. The enhanced risk large and somewhere in it will get an upgrade based one the trends Agreed. Shear is about the only real good thing we have going for us, as of now. ETA: disregard HRRR comment, was from an earlier run. Link to comment Share on other sites More sharing options...
mappy Posted May 1, 2017 Author Share Posted May 1, 2017 10z HRRR showing >1000 CAPE north into PA 4pm Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 Odd CAPE distribution it seems. I'll be watching from work today but I'm glad I didn't get *too* invested in this one. Link to comment Share on other sites More sharing options...
H2O Posted May 1, 2017 Share Posted May 1, 2017 get ready for 100 sun obs posts. Blue sky already showing up here. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 1 minute ago, H2O said: get ready for 100 sun obs posts. Blue sky already showing up here. I'm heading west to work in Rockville and can see some blue to my west Link to comment Share on other sites More sharing options...
mappy Posted May 1, 2017 Author Share Posted May 1, 2017 Sun filtering in through clouds/fog in Hunt Valley. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 If we can hold the sun I'll get more on board with today Link to comment Share on other sites More sharing options...
mappy Posted May 1, 2017 Author Share Posted May 1, 2017 WW007 Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 1, 2017 Share Posted May 1, 2017 WW007 is money. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 He's my favorite Link to comment Share on other sites More sharing options...
mappy Posted May 1, 2017 Author Share Posted May 1, 2017 updated Day 1 -- ENH shifts west. Link to comment Share on other sites More sharing options...
high risk Posted May 1, 2017 Share Posted May 1, 2017 Cheers to WW007! This case is a great example of the evolution of severe weather forecasting from basing it off of forecasted parameters to forecasting it off of details in hi-res guidance. It has previously been the latter, and we're moving towards the former - kind of in the dreaded "in between" zone now, figuring out how much to trust when the models show "meh" when the parameters scream "woohoo!" (or vice versa). We saw this on the FL/GA high risk bust earlier this year: the parameters were insane, yet the models showed weak updraft helicity signatures. The models were correct. But it would be unwise to say that we can always trust the hi-res forecasts. So today, the parameters here look good, but the reflectivity forecasts are uninspiring until you go further north and northwest. It *may* be related to the models mixing out some of the low-level moisture. If you look at NAM nest or HRRR forecast soundings, the dew points drop from the upper 60s this morning to the lower 60s by the end of the day. If that's right, a big event here won't happen. If the mixing is overdone, then it could be game on. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 12z HRRR focuses best stuff north and west and kind of splits us again. Updraft helicities go right where SPC mentioned (W MD panhandle and then northeast into PA Link to comment Share on other sites More sharing options...
high risk Posted May 1, 2017 Share Posted May 1, 2017 To see why the HRRR (and other hi-res guidance) hates our area later today, here is a forecast sounding for 6PM in south-central Montgomery Co. The dew point was in the upper 60s earlier in the day (with cape in the 1250 range), but it mixes out the low-level moisture later in the day, dropping the sfc dew point and killing instability. If it's wrong about this mixing, then we'll be in business. Otherwise, meh. Link to comment Share on other sites More sharing options...
mappy Posted May 1, 2017 Author Share Posted May 1, 2017 Same hour, but IMBY. Not much better. Link to comment Share on other sites More sharing options...
yoda Posted May 1, 2017 Share Posted May 1, 2017 17 minutes ago, high risk said: To see why the HRRR (and other hi-res guidance) hates our area later today, here is a forecast sounding for 6PM in south-central Montgomery Co. The dew point was in the upper 60s earlier in the day (with cape in the 1250 range), but it mixes out the low-level moisture later in the day, dropping the sfc dew point and killing instability. If it's wrong about this mixing, then we'll be in business. Otherwise, meh. 12z NAM is intriguing... it takes DP's back to the lower 60s around 21z... but back to the mid to upper 60s by 03z and 06z as the storms move in Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 1, 2017 Share Posted May 1, 2017 Amazing to have this thick cloud deck race back in despite SW flow. This area really stinks for interesting weather. Seems like all we can do is hot and wind. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 It figures that only our area would mix out while other surrounding regions do just fine. Only fitting. Link to comment Share on other sites More sharing options...
yoda Posted May 1, 2017 Share Posted May 1, 2017 Near Winchester VA (NW VA) Link to comment Share on other sites More sharing options...
Kmlwx Posted May 1, 2017 Share Posted May 1, 2017 I have decent confidence that the western panhandle of Maryland NE up into PA will do decently. Models keep delivering decent storms to those areas and fizzle for us. We can hope they will be wrong. Will be interesting to watch dewpoints later today. And Yoda, never bank on nocturnal severe except in rare cases. Even if dews come back up at 3z or 6z - we won't perform at that hour. They'll naturally surge before cold frontal passage. Link to comment Share on other sites More sharing options...
yoda Posted May 1, 2017 Share Posted May 1, 2017 13z HRRR has a decent line moving in around 01z Link to comment Share on other sites More sharing options...
yoda Posted May 1, 2017 Share Posted May 1, 2017 Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 947 AM EDT Mon May 1 2017 .SYNOPSIS... A strong cold front will approach from the west today before passing through tonight. High pressure will bring cooler and drier weather during the middle of the week. Low pressure will move into the area late in the week. && .NEAR TERM /THROUGH TONIGHT/... Hazardous weather expected across the Mid-Atlantic region later this afternoon and evening. Strong to severe thunderstorms are likely. Interested parties should stay tuned into the changing weather through tonight. A strong cold front is located over the Ohio Valley this morning and a warm front is located across northeastern Maryland. The warm front will lift north late this morning into early this afternoon while the cold front approaches from the west. A strong pressure gradient between the cold front and high pressure over the Atlantic will allow for gusty southerly winds. Frequent gusts around 30 to 35 mph are expected. The southerly flow will usher in warm and humid conditions for today. Dewpoints will top off well into the 60s and max temps will be in the lower 80s across most locations. The warm and humid airmass will lead to some instability. The modified 12z KIAD sounding shows around 500-1000 j/kg of mlcape later this afternoon into this evening. This lines up with forecast soundings as well. Shear profiles will be quite impressive due to a strengthening jet associated with the cold front. The combination of forcing from the cold front...the instability and the strong shear profiles enhances the threat for severe thunderstorms later this afternoon and evening. Damaging winds will be the primary threat...but isolated tornadoes and large hail are also possible in thunderstorms that develop during this time. The first round of convection is likely to propagate in from the southwest well ahead of the cold front during the mid to late afternoon hours. Severe thunderstorms are possible during this time...but confidence is low since the strongest forcing from the mid and upper-level jet as well as the cold front should remain well off to the west. Those features will move into the area from the west by early this evening. This is when confidence for severe thunderstorms is highest. The highest instability...shear and forcing should line up for locations near and west of the Blue Ridge and Catoctin Mountains early this evening...best chance between 21 and 01z. Farther east...confidence is a bit lower for severe weather since peak heating will have passed and the outflow may outrun some of the stronger storms since the storm motion will be southwest to northeast. Having that been said...the wind fields will remain quite strong through this evening and there will still be some instability due to the unusually warm and humid airmass in place. Therefore...severe thunderstorms are still possible near and east of Interstate 95 this evening...best chance between 00z and 04z. Link to comment Share on other sites More sharing options...
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