user13 Posted September 20, 2012 Share Posted September 20, 2012 Interesting setup for Saturday night... Link to comment Share on other sites More sharing options...
user13 Posted September 20, 2012 Author Share Posted September 20, 2012 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0231 AM CDT THU SEP 20 2012 VALID 221200Z - 231200Z ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NY/WRN NEW ENGLAND TO INLAND MID-ATLC...... ...SYNOPSIS... LARGE-SCALE TROUGHING WILL PERSIST FROM GREAT LAKES DOWN MS VALLEY TO NRN GULF. PRIMARY/EMBEDDED SHORTWAVE PERTURBATION DESCRIBED IN DAY-2 OUTLOOK SHOULD PIVOT EWD THROUGH MEAN TROUGH POSITION...FROM IL/LM ACROSS LOWER MI...INDIANA...OH...AND LE. PROGS DO VARY SOME IN LATITUDINAL EXTENT REGARDING TRACK OF THIS SYSTEM. NONETHELESS...WHAT AMOUNTS TO JUST MESOSCALE DISCREPANCIES ALOFT THIS FAR IN ADVANCE NOW OFFERS REASONABLE CONFIDENCE IN TIMING/PLACEMENT OF ASSOCIATED FRONTAL ZONE AND ACCOMPANYING BELT OF STG LOW-LEVEL FORCING. SFC COLD FRONT SHOULD MOVE EWD ACROSS MID-ATLC AND CENTRAL APPALACHIANS REGIONS EARLY-MIDDLE PERIOD...REACHING ERN NY...ERN PA...WRN VA...ERN TN...AND NRN/CENTRAL AL BY 23/00Z. FRONT SHOULD PROCEED EWD TO NEAR WRN MAINE...CAPE COD...ERN NC AND FL PANHANDLE BY END OF PERIOD. PASSAGE OF FRONT ACROSS OUTLOOK AREA SHOULD BE TIMED WELL WITH RESPECT TO PEAK WARM-SECTOR THETAE. ...NERN CONUS...MID-ATLC... AS FRONT AND PERHAPS PREFRONTAL CONFLUENCE LINE PROCEED EWD...RELATED CORRIDOR OF ENHANCED LIFT WILL IMPINGE ON PROGRESSIVELY GREATER ATLC-BASED RETURN-FLOW MOISTURE WITH EWD EXTENT. SFC DEW POINTS MID-50S TO MID-60S F SHOULD BE ENOUGH TO SUPPORT SFC-BASED CONVECTIVE DEVELOPMENT IN PRESENCE OF SUCH LIFT...EVEN IF PREFRONTAL DIABATIC SFC HEATING IS MUTED CONSIDERABLY BY CLOUD COVER. LAPSE RATES ALOFT WILL BE RELATIVELY WEAK...AND NEITHER BUOYANCY NOR DEEP-LAYER FORCING APPEAR TO BE QUITE AS STG AS MOST RECENT EVENT IN THIS REGION. STILL...PRESENCE OF AT LEAST MRGL CAPE JUXTAPOSED WITH STG DEEP-LAYER WIND FIELDS INDICATES DAMAGING-WIND POTENTIAL. AS SUCH...15% THRESHOLD UNCONDITIONAL PROBABILITIES ARE IS BEING INTRODUCED ATTM...SUBJECT TO INCREASE IN FUTURE OUTLOOKS IF INSTABILITY/KINEMATIC TRENDS WARRANT. OVERALL SVR THREAT GENERALLY WILL LESSEN AND BECOME MORE CONDITIONAL WITH SWD EXTENT THROUGH CAROLINAS/SERN CONUS...WITH INCREASING DISTANCE FROM STRONGEST ISALLOBARIC FORCING...MID-UPPER WINDS...AND FRONTAL LIFT. ..EDWARDS.. 09/20/2012 Link to comment Share on other sites More sharing options...
earthlight Posted September 20, 2012 Share Posted September 20, 2012 This threat actually has some decent wind fields and kinematic support over Eastern NY, Northeast PA, and the northern half of Western New Jersey. There is certainly the potential for a band of strong to severe storms in that area ahead of the front -- in fact I think the potential for damaging winds in that corridor could eventually be highlighted by 30 pct probabilities from SPC. However, the timing and the dropoff in height falls to the east suggest this threat could come to an abrupt halt just west of NYC -- I think the threat for strong/severe storms is low over Long Island and more than 50-75 miles east of the NY and CT/MA border in New England. Interestingly the SPC SREF has been showing some enhanced low level shear over Eastern NY/Northeast PA and Northern NJ which could harbor a potential localized threat for isolated tornadoes. The timing of the event has a sped up a bit on the last few model cycles, too, I think we'll have to wait this one out a few more cycles before we make any definitive statements other than the general ideas I touched on and a few others around the forums have touched on as well. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted September 21, 2012 Share Posted September 21, 2012 Lapse rates near the surface are much better this time around and the ML CAPE isn't nearly as awful as it has been in the past. Timing might be the biggest question. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted September 21, 2012 Share Posted September 21, 2012 This KSMQ sounding at 21z actually looks really good. Those 0-1.5 km lapse rates being nearly dry-adiabatic combined with the dewpoint line going "straight up" to 900mb...almost through the entire mixed layer...meaning we get both good SB CAPE and good ML CAPE. This would greatly help to maintain a squall line. Also I'm hoping this sounding would allow a cloud top to around 700mb...hopefully that would be good enough for strong winds to get accelerated to the surface. The lapse rates above 700mb are absolutely awful, though. Link to comment Share on other sites More sharing options...
Dark Energy Posted September 21, 2012 Share Posted September 21, 2012 The NAM and GFS are worlds apart with CAPE/LI. The nam is bullish, the GFS is meh. ML lapse rates are crap....and we've seen how that has worked so far this year. I'm not sold on this yet. I did put in my forecast on the NY metro weather page for likely tsras for SAT eve, but idk about svr. Link to comment Share on other sites More sharing options...
phlwx Posted September 21, 2012 Share Posted September 21, 2012 The NAM and GFS are worlds apart with CAPE/LI. The nam is bullish, the GFS is meh. ML lapse rates are crap....and we've seen how that has worked so far this year. I'm not sold on this yet. I did put in my forecast on the NY metro weather page for likely tsras for SAT eve, but idk about svr. ...same with 850 jet. GFS doesn't even have 40 kts at 850 in the immediate region. The "best" wind energy is up in Northern New England and Canada, or behind the front. I'm not sold at all on this. Link to comment Share on other sites More sharing options...
Quincy Posted September 21, 2012 Share Posted September 21, 2012 Very intriguing output from the latest SPC SREF run, as tornado ingredient probabilities are impressive across portions of SE NY: Link to comment Share on other sites More sharing options...
earthlight Posted September 21, 2012 Share Posted September 21, 2012 The NAM and GFS are worlds apart with CAPE/LI. The nam is bullish, the GFS is meh. ML lapse rates are crap....and we've seen how that has worked so far this year. I'm not sold on this yet. I did put in my forecast on the NY metro weather page for likely tsras for SAT eve, but idk about svr. I also think the timing is a big issue. So essentially, I agree. The SPC SREF shows the cutoff in potential severe thunderstorm probabilities over NYC Link to comment Share on other sites More sharing options...
bluewave Posted September 22, 2012 Share Posted September 22, 2012 The NAM hits the interior zones the hardest later on. The models also are indicating that the Northeast will be in a coupled jet region with a STJ streak working up from the south. Link to comment Share on other sites More sharing options...
Weathergun Posted September 22, 2012 Share Posted September 22, 2012 I think we see a line of showers and t-storms. But I'm not enthused for much severe wx. The best shortwave forcing is to the NW or arriving too late. And mid-level lapse rates are poor. Link to comment Share on other sites More sharing options...
Quincy Posted September 22, 2012 Share Posted September 22, 2012 Doesn't look too impressive. The K-index is still fairly low. Could see an area of storms pop up in southeast New York, but only isolated severe weather would be expected, at worst. Link to comment Share on other sites More sharing options...
Analog96 Posted September 22, 2012 Share Posted September 22, 2012 http://www.spc.noaa.gov/products/md/md1981.html Severe watch going up? Link to comment Share on other sites More sharing options...
Quincy Posted September 22, 2012 Share Posted September 22, 2012 There is a narrow area of combined wind shear/CAPE values that could marginally support some severe weather. Looks to be across NE PA, N NJ and SE NY. Link to comment Share on other sites More sharing options...
earthlight Posted September 22, 2012 Share Posted September 22, 2012 1500 J/kg of surface based Cape over Northern/West-Central New Jersey with 40 kts of effective shear. Low level lapse rates are decent for the time being..if we can get some lift in here before it gets too late there is a narrow window for severe storms. But as it stands now, the few hours in delay from good timing will likely support the storms weakening as they move from W to E through NJ. Link to comment Share on other sites More sharing options...
Snow_Miser Posted September 22, 2012 Share Posted September 22, 2012 T Storms are starting to firing up in South Central Pennsylvania and over Northern New Jersey. Link to comment Share on other sites More sharing options...
Quincy Posted September 22, 2012 Share Posted September 22, 2012 The line looks strong, but not really severe at the moment. I'm beginning to wonder if SPC is going to pull the trigger or not... Link to comment Share on other sites More sharing options...
Snow_Miser Posted September 22, 2012 Share Posted September 22, 2012 The line looks strong, but not really severe at the moment. I'm beginning to wonder if SPC is going to pull the trigger or not... Northward toward NY State, there is a pretty decent line shaping up. Further south, the radar is lighting up in the form of individual cells popping up. Link to comment Share on other sites More sharing options...
LongBeachSurfFreak Posted September 22, 2012 Share Posted September 22, 2012 Big shocker it looks the break in the line will head right for the meat of our area! Link to comment Share on other sites More sharing options...
Allsnow Posted September 23, 2012 Share Posted September 23, 2012 At bruce concert telling us to sheek shelter Link to comment Share on other sites More sharing options...
LongBeachSurfFreak Posted September 23, 2012 Share Posted September 23, 2012 To bad that bowing section near philly is headed due east. That looks like the most legit severe storm i have seen on radar in a while! Link to comment Share on other sites More sharing options...
Stormlover74 Posted September 23, 2012 Share Posted September 23, 2012 Hearing some loud thunder from my south/west Storm in somerset county appears to be intensifying and heading to the northeast Link to comment Share on other sites More sharing options...
Stormlover74 Posted September 23, 2012 Share Posted September 23, 2012 Pretty good storm in progress Link to comment Share on other sites More sharing options...
earthlight Posted September 23, 2012 Share Posted September 23, 2012 Incredible rains here right now. We already have some street flooding and the power is out. Link to comment Share on other sites More sharing options...
BxEngine Posted September 23, 2012 Share Posted September 23, 2012 pretty impressive light show up here. Link to comment Share on other sites More sharing options...
Stormlover74 Posted September 23, 2012 Share Posted September 23, 2012 Cell intensified right over us..this ones headed right for Manhattan Link to comment Share on other sites More sharing options...
earthlight Posted September 23, 2012 Share Posted September 23, 2012 Wind was almost dead calm...not close to a severe storm but that was some impressive rain , not sure what caused us to lose power. Link to comment Share on other sites More sharing options...
winterwx21 Posted September 23, 2012 Share Posted September 23, 2012 Wind was almost dead calm...not close to a severe storm but that was some impressive rain , not sure what caused us to lose power. I'd say it was one of the 3 heaviest downpours of the summer here. It was nice, but not much wind like you said. Not a lot of lightning either, but I did have a couple nice close strikes. Link to comment Share on other sites More sharing options...
Weathergun Posted September 23, 2012 Share Posted September 23, 2012 0830 PM TSTM WND DMG ESSEX FELLS 40.83N 74.29W 09/22/2012 ESSEX NJ EMERGENCY MNGR TREE LIMBS AND WIRES DOWN ON ROSELAND AVENUE. TIME ESTIMATED BY RADAR. Link to comment Share on other sites More sharing options...
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