weatherwiz Posted May 31, 2012 Share Posted May 31, 2012 Both ARW and NMM slow the front down, the line doesn't get here until 00z or later This could be a good thing. By this time the tornado potential will be rather low though as the main mode would be linear...have to watch out where any pre-frontal trough sets up and how much instability can develop out ahead of it...this will be the key for any tornado potential. Link to comment Share on other sites More sharing options...
mappy Posted May 31, 2012 Share Posted May 31, 2012 This could be a good thing. By this time the tornado potential will be rather low though as the main mode would be linear...have to watch out where any pre-frontal trough sets up and how much instability can develop out ahead of it...this will be the key for any tornado potential. Good if you don't want tornadoes Link to comment Share on other sites More sharing options...
weatherwiz Posted May 31, 2012 Share Posted May 31, 2012 Good if you don't want tornadoes That is true Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 Good if you don't want tornadoes TOR Watch or bust Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 This could be a good thing. By this time the tornado potential will be rather low though as the main mode would be linear...have to watch out where any pre-frontal trough sets up and how much instability can develop out ahead of it...this will be the key for any tornado potential. True, but wouldn't the atmosphere be losing instability as cooling takes effect? Link to comment Share on other sites More sharing options...
Derecho! Posted May 31, 2012 Share Posted May 31, 2012 For people more familiar with the mid-Atlantic. in similar situations or setups to this how does the area do for cloud cover? Do models tend to overdo cloud cover? About 100% of the severe and/or tornado busts in the Mid Atlantic seem to be from more cloud cover than was forecast, actually. Link to comment Share on other sites More sharing options...
weatherwiz Posted May 31, 2012 Share Posted May 31, 2012 True, but wouldn't the atmosphere be losing instability as cooling takes effect? I actually think the NAM had an instability spike late in the evening just ahead of the front. I think 500mb temps were slightly cooling which could act to slightly bump up instability. About 100% of the severe and/or tornado busts in the Mid Atlantic seem to be from more cloud cover than was forecast, actually. Good to know...thanks. Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 About 100% of the severe and/or tornado busts in the Mid Atlantic seem to be from more cloud cover than was forecast, actually. Either that or some type of garbage comes in early and messes it all up or nothing develops till really late and by that time everything is out of position re instability and shear Link to comment Share on other sites More sharing options...
wxsniss Posted May 31, 2012 Share Posted May 31, 2012 hey guys, any thoughts on the 5% over Indiana / Kentucky today? which regional forum would that be? i ask here because most people seem to be here and nothing going on in Central/Western or SE... Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 hey guys, any thoughts on the 5% over Indiana / Kentucky today? which regional forum would that be? i ask here because most people seem to be here and nothing going on in Central/Western or SE... Not much in thaat thread either but here -- http://www.americanwx.com/bb/index.php/topic/34606-may-24-severe-thread/page__pid__1571432__st__140#entry1571432 Link to comment Share on other sites More sharing options...
Scuddz Posted May 31, 2012 Share Posted May 31, 2012 Either that or some type of garbage comes in early and messes it all up or nothing develops till really late and by that time everything is out of position re instability and shear 4 km NAM had early am crap with the warm front going through edit: followed by a DC split Link to comment Share on other sites More sharing options...
mappy Posted May 31, 2012 Share Posted May 31, 2012 4 km NAM had early am crap with the warm front going through edit: followed by a DC split Not surprised, poor DC Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 4 km NAM had early am crap with the warm front going through edit: followed by a DC split Perhaps we need Howard's take on the corn fuel aspect? Link to comment Share on other sites More sharing options...
Disc Posted May 31, 2012 Share Posted May 31, 2012 For people more familiar with the mid-Atlantic. in similar situations or setups to this how does the area do for cloud cover? Do models tend to overdo cloud cover? I know in SNE models can often times overdo cloud cover, especially if winds in the BL and below are more from the SW...SW winds will usually tend to help mix the clouds out much faster and allow for more in the way of sunshine. I'm going to assume though SE winds down there (like here) aren't very good b/c it draws in more llvl moisture off the water. While you want SE winds for increased helicity unless you have a capping inversion (EML) aloft SE winds just draw in llvl clouds. Seems like down here in western Virginia (I'm in Roanoke), a SE/E wind likes to keep the clouds around the mountains longer and is sometimes harder to burn off. We get left out a lot of times on severe weather down here because of a cool-air wedge against the mountains caused by the E/SE winds. Maybe this will be different, though. Link to comment Share on other sites More sharing options...
wxsniss Posted May 31, 2012 Share Posted May 31, 2012 Not much in thaat thread either but here -- http://www.americanw...40#entry1571432 thanks! yeah only 2 posts since this morning lol... probably appropriate the way it's looking now, low DPs, not much CAPE etc. Link to comment Share on other sites More sharing options...
Bob Chill Posted May 31, 2012 Share Posted May 31, 2012 Either that or some type of garbage comes in early and messes it all up or nothing develops till really late and by that time everything is out of position re instability and shear You mean the infamous unforcasted mcs that runs through ohio and over the apps right around sunrise that gives us morning showers and cloudy skies until early afternoon? Then we all pray for sun and by the time it comes out convection out west is already firing and loses its punch as it moves in? Link to comment Share on other sites More sharing options...
weatherwiz Posted May 31, 2012 Share Posted May 31, 2012 I wonder if perhaps the models could be overdoing cloud cover...looking at the NAM RH values at 925/850/700mb are all relatively dry...even the GFS doesn't look too bad. Also, the sfc winds coming from the SE aren't particularly strong so perhaps areas further inland won't have as much as an effect from the ocean? I guess it wouldn't be a bad idea to watch to the SW/W at how much convection develops as these clouds are moving towards the area. Link to comment Share on other sites More sharing options...
mappy Posted May 31, 2012 Share Posted May 31, 2012 You mean the infamous unforcasted mcs that runs through ohio and over the apps right around sunrise that gives us morning showers and cloudy skies until early afternoon? Then we all pray for sun and by the time it comes out convection out west is already firing and loses its punch as it moves in? Winner winner chicken dinner Link to comment Share on other sites More sharing options...
Bob Chill Posted May 31, 2012 Share Posted May 31, 2012 Also, the sfc winds coming from the SE aren't particularly strong so perhaps areas further inland won't have as much as an effect from the ocean? Not saying it means much tomorrow but anytime we have an easterly component we run the risk of a ll deck from the piedmont westward. SFC flow tomorrow is prob too shallow to worry about though. Even without sun we have some nice ingredients in play. Squall lines can be fun sometimes. Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 You mean the infamous unforcasted mcs that runs through ohio and over the apps right around sunrise that gives us morning showers and cloudy skies until early afternoon? Then we all pray for sun and by the time it comes out convection out west is already firing and loses its punch as it moves in? Yup, that would be it Link to comment Share on other sites More sharing options...
mattie g Posted May 31, 2012 Share Posted May 31, 2012 You mean the infamous unforcasted mcs that runs through ohio and over the apps right around sunrise that gives us morning showers and cloudy skies until early afternoon? Then we all pray for sun and by the time it comes out convection out west is already firing and loses its punch as it moves in? This is a man with experience. Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 Will be interesting to see if LWX repeats their strong wording their afternoon AFD or tones it down some... I expect them to tone down some after yesterday's AFD Link to comment Share on other sites More sharing options...
Bob Chill Posted May 31, 2012 Share Posted May 31, 2012 Winner winner chicken dinner Yup, that would be it This is a man with experience. lol- just for the record.....if anything of the sort happens tomorrow i had nothing to do with it and please only throw tomatoes. Rocks hurt. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 31, 2012 Share Posted May 31, 2012 At the risk of sounding like a weenie, we are approaching the highest sun angle of the year. Provided the SE / E flow isn't too strong the sun *should* be able to overcome an low level cloudiness west of I-95. Link to comment Share on other sites More sharing options...
mattmfm Posted May 31, 2012 Share Posted May 31, 2012 Yikes, forgot the overwhelming pessimism present in AM threads Think we see a pretty solid convection line push through with fairly widespread wind-related severe. And with enough breaks in the clouds and heating think we can get a few discrete cells out ahead of the main line that should be fairly potent. Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 LWX still pounding the drum .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/... -- Changed Discussion -- ...FORECAST ON TRACK FOR POTENTIAL SEVERE WEATHER FRIDAY.... WARM FRONT SHOULD BE NEAR THE MASON-DIXON LINE EARLY FRIDAY MORNING. SHOWERS POSSIBLE WITH THE FRONT OVER NORTHERN PORTIONS OF THE FORECAST AREA...AND FURTHER WEST ON A POSSIBLE PRE-FRONTAL TROUGH AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. MORNING INSTABILITY IS NOT VERY IMPRESSIVE...BUT ELEVATED INSTABILITY LOOKS SUFFICIENT ENOUGH TO INCLUDE AT LEAST A LOW CHANCE OF THUNDER MIXED IN WITH SHOWERS. ONCE THE WARM FRONT IS THROUGH...CWA WILL BE WARM-SECTORED AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. 12Z NAM/GFS POSITION THE FRONT OVER WESTERN/CENTRAL OHIO AT 12Z FRIDAY WITH 999/1000 MB LOW PRESSURE JUST WEST OF CLEVELAND. TSTMS WILL DEVELOP ALONG THE FRONT AS IT PUSHES EASTWARD. FAVORABLE SEVERE PARAMETERS WILL BE IN PLACE OVER OUR CWA. FORECAST SBCAPE AROUND 1000-2000 J/KG WILL BE PLENTY TO TRIGGER STORMS...AND SHEAR WILL INCREASE AS A NEGATIVELY-TILTED UPPER TROUGH APPROACHES. HELICITY ON DULLES AIRPORT NAM SOUNDING APPROACHES 200 M2/S2 BY 21Z. SPC MAINTAINS SLIGHT RISK FOR SEVERE THUNDERSTORMS OVER THE REGION...WITH POTENTIAL FOR DAMAGING WINDS...LARGE HAIL AND TORNADOES. HIGHS GENERALLY IN THE UPPER 70S TO LOW 80S FRIDAY. FRIDAY EVENING...GUIDANCE HAS SLOWED THE PROGRESSION OF THE COLD FRONT AND LEADING THUNDERSTORM ACTIVITY TO MAINLY BE IN THE EVENING HOURS FOR AREAS EAST OF THE BLUE RIDGE BECAUSE THE PROGGED LOW TRACK HAS SHIFTED A LITTLE WEST. FRIDAY AFTERNOON ACTIVITY AND THE APPALACHIANS WILL MAKE FOR POTENTIALLY TWO WAVES OF PRECIPITATION /SCATTERED AFTERNOON ACTIVITY...THEN PRE-FRONTAL LINES OF THUNDERSTORMS/. BULK SHEAR IS STILL EXPECTED TO BE GREATER THE LATER IT GETS...SO THE MAIN THREAT SEEMS TO BE WITH THE PRE- FRONTAL LINES OF THUNDERSTORMS THAT ARE PROGGED TO IMPACT THE DC METRO STARTING AT THE END OF THE EVENING RUSH. TO PUT IT SIMPLY...THE FLASH FLOODING AND SEVERE THREAT LOOKS TO BE MAINLY 6PM TO MIDNIGHT FOR THE BALT- WASH METRO. Link to comment Share on other sites More sharing options...
weatherwiz Posted May 31, 2012 Share Posted May 31, 2012 Not saying it means much tomorrow but anytime we have an easterly component we run the risk of a ll deck from the piedmont westward. SFC flow tomorrow is prob too shallow to worry about though. Even without sun we have some nice ingredients in play. Squall lines can be fun sometimes. The shear certainly is fairly impressive, even 35-40 knots of bulk shear is more than adequate, especially if you can develop sufficient instability and as of now that is the biggest question for tomorrow. I forgot where it was mentioned...either an AFD or SPC discussion but one of them mentioned a forced line developing along the cold front...I certainly can see that happening as their will be vigorous lift associated with the front and you don't need a great deal of instability for this to happen...if you want svr though you would like to see it. Link to comment Share on other sites More sharing options...
mappy Posted May 31, 2012 Share Posted May 31, 2012 I don't mind a later start time, means I can get home and enjoy it rather than have to drive home during it Link to comment Share on other sites More sharing options...
ohleary Posted May 31, 2012 Share Posted May 31, 2012 You mean the infamous unforcasted mcs that runs through ohio and over the apps right around sunrise that gives us morning showers and cloudy skies until early afternoon? Then we all pray for sun and by the time it comes out convection out west is already firing and loses its punch as it moves in? Good news Debbie Downer, the synoptic setup isn't right for that scenario. Link to comment Share on other sites More sharing options...
yoda Posted May 31, 2012 Share Posted May 31, 2012 I don't mind a later start time, means I can get home and enjoy it rather than have to drive home during it Neither do I... I would like all our buses to get out back to DC before any come in. Link to comment Share on other sites More sharing options...
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