iceman56 Posted August 21, 2011 Share Posted August 21, 2011 Thunder to the west here in NW Chesco. Another crappy day on the weekend when there is stuff to do... Link to comment Share on other sites More sharing options...
MGorse Posted August 21, 2011 Share Posted August 21, 2011 The high res models, like the HRRR and SPC WRF, are not doing well at all with this convection thus far. Nothing like forecast updating just using radar trends and instability variables. Fun day at the office I sense. Will be interesting to see how this impacts convection this afternoon, but I still think it will be active given the large scale ascent that is forecast to arrive along with increasing shear and instability. NWS LWX's 12z sounding looks interesting especially once you erode the low-level inversion. Link to comment Share on other sites More sharing options...
chubbs Posted August 21, 2011 Share Posted August 21, 2011 Just caught the edge of first cluster of storms - 0.06" Link to comment Share on other sites More sharing options...
SmokeEater Posted August 21, 2011 Share Posted August 21, 2011 The high res models, like the HRRR and SPC WRF, are not doing well at all with this convection thus far. Nothing like forecast updating just using radar trends and instability variables. Fun day at the office I sense. Will be interesting to see how this impacts convection this afternoon, but I still think it will be active given the large scale ascent that is forecast to arrive along with increasing shear and instability. NWS LWX's 12z sounding looks interesting especially once you erode the low-level inversion. Mike, in reference to later on, SPC had talked about the tornado threat being conditional on mesoscale features/boundaries. I'm thinking these storms could set down boundaries for later on. Thoughts? Link to comment Share on other sites More sharing options...
SmokeEater Posted August 21, 2011 Share Posted August 21, 2011 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0745 AM CDT SUN AUG 21 2011 VALID 211300Z - 221200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NERN STATES AND MID-ATLANTIC REGION... ...NERN STATES TO MID-ATLANTIC REGION... BUSY WEATHER DAY ON TAP FOR THE REGION. WATER VAPOR SHOWS TWO-STREAM FLOW WITH PRIMARY WLYS AND STRONG UPR TROUGH DIGGING ACROSS THE CNTRL GREAT LAKES. SEPARATE UPR JET WAS MOVING THROUGH THE MIDWEST WITH A FORMIDABLE SHORTWAVE TROUGH MIGRATING ACROSS THE MID-OH VLY AND A WEAKER PERTURBATION MOVING INTO THE LWR GREAT LAKES REGION. ONGOING TSTM CLUSTERS TIED TO THE LWR GREAT LAKES DISTURBANCE WILL CONTINUE TO PROGRESS EWD...REACHING CNTRL/ERN NY BY 15-18Z. DOWNSTREAM AIR MASS HAS BEEN MOISTENING OVERNIGHT AND DAYBREAK SATL IMAGES SUGGEST MODEST DIABATIC HEATING WILL OCCUR THIS MORNING WITH MLCAPES 1000-1500 J/KG BY AFTN. EXPECT EXISTING TSTMS TO GROW STRONGER THIS MORNING WITH ADDITIONAL STORMS DEVELOPING WITHIN THE INSTABILITY AXIS. THIS WILL RESULT IN BKN-BANDS OF STG-SVR STORMS THAT TRANSLATE ENE INTO WRN NEW ENGLAND/ERN NY BY MID/LATE AFTN. LOWER-AMPLITUDE WAVE MIGRATING EWD FROM THE MID-OH VLY WILL BE INSTRUMENTAL IN INSTIGATING MORE STORMS FROM ERN PA SWD INTO NRN/CNTRL VA. STRONGER THERMAL BUOYANCY WILL EXIST HERE AS SATL SHOWS POTENTIAL FOR STRONG HEATING AMID COMPARATIVELY MORE MOIST BOUNDARY LAYER. VERTICAL SHEAR...WHILE SOMEWHAT WEAK THIS MORNING...WILL BE INCREASING AS 40-60 KT WNW MID-LVL FLOW/STEEPER MID-LVL LAPSE RATES ARRIVE THIS AFTN PER UPSTREAM RAOBS. THIS WILL RESULT IN MULTICELLS AND A FEW SUPERCELLS CAPABLE OF DMGG WINDS AND LARGE HAIL. ISOLD TORNADOES CANNOT BE RULED OUT...ESPECIALLY FROM NRN VA/MD NWD WHERE FCST HODOGRAPHS SHOW STRONGEST 0-1KM SHEAR VCNTY LEE TROUGH/WEAK SFC LOW. Link to comment Share on other sites More sharing options...
MGorse Posted August 21, 2011 Share Posted August 21, 2011 Mike, in reference to later on, SPC had talked about the tornado threat being conditional on mesoscale features/boundaries. I'm thinking these storms could set down boundaries for later on. Thoughts? I agree. As the low-level flow increases some through the day, that could help with the damaging wind threat plus some backing of the low-level flow could occur (especially if a lee side trough becomes better defined). Any boundary will enhance the low-level shear. One of the storms in eastern Maryland earlier had some weak rotation in the lower velocity scan. There is an inversion in place near the surface, although signs of this weakening now as surface temperatures warm. Link to comment Share on other sites More sharing options...
SouthernNJ Posted August 21, 2011 Share Posted August 21, 2011 Nasty storm went right over Dover. In the bay now with some circulation. Would not want to be out on the water in that one. Link to comment Share on other sites More sharing options...
mcwx Posted August 21, 2011 Share Posted August 21, 2011 Picked up a quick .26" in 15 minutes with the cell that popped up along the delaware river between southern hunterdon and northern mercer counties... some closer-in lightning strikes as well Link to comment Share on other sites More sharing options...
Thunder Road Posted August 21, 2011 Share Posted August 21, 2011 wow this is about as good as it gets for your part of the country SPC Mesoanalysis for 15z had a little nub of >200 0-3km helicity over extreme NE MD and >150 over all of EPA (east of I-81 anyway). Suffice to say...I'm jealous Watch out for anywhere that surface winds start backing just a little bit more for decent tornado potential. Although, imo, I would take the 30% hail out if I were SPC. Lapse rates are somewhat unimpressive, despite the large and deep area of instability. (I mean yeah, its August, so what do you expect?) Link to comment Share on other sites More sharing options...
phlwx Posted August 21, 2011 Share Posted August 21, 2011 The high res models, like the HRRR and SPC WRF, are not doing well at all with this convection thus far. Nothing like forecast updating just using radar trends and instability variables. Fun day at the office I sense. Will be interesting to see how this impacts convection this afternoon, but I still think it will be active given the large scale ascent that is forecast to arrive along with increasing shear and instability. NWS LWX's 12z sounding looks interesting especially once you erode the low-level inversion. The SPC WRF sucked on placement but had the idea of crap firing ahead of the front...missed the placement and coverage by a good deal though. hhttp://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/00/nmmwrf.refd1000_animate_1h.html#picture Link to comment Share on other sites More sharing options...
Boch23 Posted August 21, 2011 Share Posted August 21, 2011 Already a 77 mph wind gust recorded at Dover AFB with damage reported . Link to comment Share on other sites More sharing options...
PennMan Posted August 21, 2011 Share Posted August 21, 2011 86/73 here in eastern Lebanon County. Sun peeking through occasionally. A bit warmer than I was expecting. Link to comment Share on other sites More sharing options...
yoda Posted August 21, 2011 Share Posted August 21, 2011 802 WWUS30 KWNS 211649 SAW4 SPC AWW 211649 WW 794 SEVERE TSTM CT DC DE MD NJ NY PA VA WV CW 211655Z - 220100Z AXIS..90 STATUTE MILES EAST AND WEST OF LINE.. 45NNE ABE/ALLENTOWN PA/ - 55SSW DCA/WASHINGTON DC/ ..AVIATION COORDS.. 80NM E/W /27WNW SAX - 37N RIC/ HAIL SURFACE AND ALOFT..2 INCHES. WIND GUSTS..60 KNOTS. MAX TOPS TO 500. MEAN STORM MOTION VECTOR 27035. LAT...LON 41247337 38097576 38097906 41247683 THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS FOR WOU4. Link to comment Share on other sites More sharing options...
dryslotted Posted August 21, 2011 Share Posted August 21, 2011 Full sun and thunder here right now... Link to comment Share on other sites More sharing options...
summerbreeze Posted August 21, 2011 Share Posted August 21, 2011 Statement as of 12:55 PM EDT on August 21, 2011 The NWS Storm Prediction Center has issued a Severe Thunderstorm Watch for portions of western Connecticut District of Columbia Delaware Maryland New Jersey extreme southeast New York central and eastern Pennsylvania northern Virginia the eastern West Virginia Panhandle coastal waters Effective this Sunday afternoon and evening from 1255 PM until 900 PM EDT. Hail to 2 inches in diameter... thunderstorm wind gusts to 70 mph... and dangerous lightning are possible in these areas. The Severe Thunderstorm Watch area is approximately along and 90 statute miles east and west of a line from 45 miles north northeast of Allentown Pennsylvania to 55 miles south southwest of Washington district of colum. For a complete depiction of the watch see the associated watch outline update (wous64 kwns wou4). Remember... a Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. Discussion... thunderstorms will increase in coverage/intensity this afternoon in conjunction with continued daytime heating... and as a midlevel trough and cold front move ewd/sewd across the region. Additionally... a surface Lee trough from nrn VA to ern PA/se NY will help focus thunderstorm development. Moderate-strong instability /MLCAPE aoa 2000 j per kg/ and increasing vertical shear through the afternoon will be favorable for storms to produce damaging winds and large hail. A couple of supercells may also develop this afternoon near the Lee trough... and an isolated tornado will be possible where low-level shear will be somewhat stronger. Aviation... a few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27035. ... Thompson Link to comment Share on other sites More sharing options...
phlwx Posted August 21, 2011 Share Posted August 21, 2011 congrats to the NAM for getting the early timing right on the 6z run. http://www.meteo.psu.edu/~gadomski/ETAPA_6z/etaloop.html Link to comment Share on other sites More sharing options...
ChescoWx Posted August 21, 2011 Share Posted August 21, 2011 Heavy T-storm here in NW Chesco Rain so far this hour 0.51" Temp down to 70.2 Link to comment Share on other sites More sharing options...
phlwx Posted August 21, 2011 Share Posted August 21, 2011 getting pummeled in RoFo at this point. Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted August 21, 2011 Author Share Posted August 21, 2011 lot of activity Link to comment Share on other sites More sharing options...
Grothar Posted August 21, 2011 Share Posted August 21, 2011 Statement as of 12:55 PM EDT on August 21, 2011 The NWS Storm Prediction Center has issued a Severe Thunderstorm Watch for portions of western Connecticut District of Columbia Delaware Maryland New Jersey extreme southeast New York central and eastern Pennsylvania northern Virginia the eastern West Virginia Panhandle coastal waters Effective this Sunday afternoon and evening from 1255 PM until 900 PM EDT. Hail to 2 inches in diameter... thunderstorm wind gusts to 70 mph... and dangerous lightning are possible in these areas. The Severe Thunderstorm Watch area is approximately along and 90 statute miles east and west of a line from 45 miles north northeast of Allentown Pennsylvania to 55 miles south southwest of Washington district of colum. For a complete depiction of the watch see the associated watch outline update (wous64 kwns wou4). Remember... a Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. Discussion... thunderstorms will increase in coverage/intensity this afternoon in conjunction with continued daytime heating... and as a midlevel trough and cold front move ewd/sewd across the region. Additionally... a surface Lee trough from nrn VA to ern PA/se NY will help focus thunderstorm development. Moderate-strong instability /MLCAPE aoa 2000 j per kg/ and increasing vertical shear through the afternoon will be favorable for storms to produce damaging winds and large hail. A couple of supercells may also develop this afternoon near the Lee trough... and an isolated tornado will be possible where low-level shear will be somewhat stronger. Aviation... a few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27035. ... Thompson why was a tornado watch not posted for these areas? Tornado development is a real possibility this afternoon Link to comment Share on other sites More sharing options...
hazwoper Posted August 21, 2011 Share Posted August 21, 2011 About to get our 2nd storm in 30 mins here. Was at the Grange Fair when the skys opened up with that first small storm. Link to comment Share on other sites More sharing options...
chrisNJ Posted August 21, 2011 Share Posted August 21, 2011 Rather breezy here and rather sunny..not sure what this portends for later in the day Link to comment Share on other sites More sharing options...
ChescoWx Posted August 21, 2011 Share Posted August 21, 2011 1.04" from this first storm...MTD rain now at 5.99" - still 2.04" below normal YTD Link to comment Share on other sites More sharing options...
MGorse Posted August 21, 2011 Share Posted August 21, 2011 why was a tornado watch not posted for these areas? Tornado development is a real possibility this afternoon The potential is there, however during the SPC conference call it was decided to go with a severe thunderstorm watch as confidence was not all that high tornadoes would actually occur. It was felt the larger threat at that time would be damaging straight line winds. Link to comment Share on other sites More sharing options...
chrisNJ Posted August 21, 2011 Share Posted August 21, 2011 Looks to be a 'Nado warning in the State College area now. Will be interesting to see how that areas forms or expands once it gets closer to the LV. The potential is there, however during the SPC conference call it was decided to go with a severe thunderstorm watch as confidence was not all that high tornadoes would actually occur. It was felt the larger threat at that time would be damaging straight line winds. Link to comment Share on other sites More sharing options...
mike2010 Posted August 21, 2011 Share Posted August 21, 2011 Looks like Philly's about to get slammed. close to 70 DBZ Link to comment Share on other sites More sharing options...
lman Posted August 21, 2011 Share Posted August 21, 2011 Looks like Philly's about to get slammed. close to 70 DBZ I'm in Jenkintown. The skies are green and lots of close CTG lightning. Is this storm rotating? Link to comment Share on other sites More sharing options...
hazwoper Posted August 21, 2011 Share Posted August 21, 2011 Yeah I am just north of that storm and even here constant lightning and thunder right now off to my south Link to comment Share on other sites More sharing options...
phlwx Posted August 21, 2011 Share Posted August 21, 2011 I'm in Jenkintown. The skies are green and lots of close CTG lightning. Is this storm rotating? wind/hail...a couple of radar runs show possible rotation but nothing steady yet Link to comment Share on other sites More sharing options...
mike2010 Posted August 21, 2011 Share Posted August 21, 2011 oops, make that close to 60 DBZ. (was lookin at wrong radar) Link to comment Share on other sites More sharing options...
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