andyhb Posted September 7, 2012 Share Posted September 7, 2012 Decided to start a specific thread, given the SPC has issued a 30% hatched risk area for Saturday. DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1225 AM CDT FRI SEP 07 2012 VALID 081200Z - 091200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID ATLANTIC AREA THROUGH THE NERN STATES... ..SYNOPSIS QUASI-ZONAL SYNOPTIC PATTERN WILL TRANSITION TO A MORE AMPLIFIED REGIME BY SATURDAY. THE POSITIVE TILT UPPER TROUGH NOW EXTENDING FROM ONTARIO WSWWD THROUGH MT WILL AMPLIFY SEWD THROUGH THE GREAT LAKES AND INTO THE OH VALLEY LATER FRIDAY. THIS FEATURE WILL THEN BECOME NEGATIVELY TILTED AS AN EMBEDDED SHORTWAVE TROUGH EJECTS NEWD THROUGH THE REMAINDER OF THE OH VALLEY INTO THE NERN STATES SATURDAY AFTERNOON. SFC LOW WILL DEEPEN IN ASSOCIATION WITH THIS PROCESS AND LIFT NEWD INTO SRN QUEBEC...WHILE TRAILING COLD FRONT SWEEPS EWD/SEWD AND OFF THE ATLANTIC SEABOARD AND GULF COAST SATURDAY NIGHT. ..ERN PORTIONS OF OH VALLEY...MID ATLANTIC THROUGH NERN STATES A PRE-FRONTAL SQUALL LINE WILL LIKELY BE IN PROGRESS SATURDAY MORNING FROM THE OH VALLEY SWWD INTO THE TN VALLEY. RICH GULF MOISTURE /UPPER 60S TO 70F DEWPOINTS/ NOW RESIDING OVER THE MID ATLANTIC AND SRN PORTIONS OF NERN STATES WILL ADVECT THROUGH REMAINDER OF THE WARM SECTOR SATURDAY AS SLY LLJ STRENGTHENS IN ASSOCIATION WITH EJECTING SHORTWAVE TROUGH AND DEEPENING SFC LOW. WEAK MID LEVEL LAPSE RATES AND AREAS OF CLOUDS WILL MITIGATE INSTABILITY SOMEWHAT. HOWEVER...BREAKS IN CLOUDS SHOULD ALLOW FOR SOME DIABATIC WARMING OF THE MOIST BOUNDARY LAYER...CONTRIBUTING TO MLCAPE FROM 500-1000 J/KG. STORMS ARE EXPECTED TO INTENSIFY ALONG AND AHEAD OF PRE-EXISTING PROGRESSIVE OUTFLOW BOUNDARY AS WARM SECTOR DESTABILIZES. DEEP LAYER WINDS WILL INCREASE IN ASSOCIATION WITH THE SHORTWAVE TROUGH AND ITS ATTENDANT SFC LOW WITH LARGE HODOGRAPHS AND 40+ KT 0-6 KM SHEAR. ORGANIZED STORMS INCLUDING LEWP/BOWING STRUCTURES AND EMBEDDED SUPERCELLS WILL BE POSSIBLE AS ACTIVITY DEVELOPS EWD. DAMAGING WIND AND MAYBE A FEW TORNADOES WILL BE THE PRIMARY THREATS. VERTICAL SHEAR PROFILES SHOULD BE WEAKER WITH SWD EXTENT INTO NC SUGGESTING DOMINANT MULTICELL MODES. HOWEVER...INSTABILITY WILL PROBABLY BE GREATER IN THIS AREA...AND THESE STORMS MAY BECOME CAPABLE OF PRODUCING ISOLATED DAMAGING WIND AS THE BOUNDARY LAYER DESTABILIZES DURING THE AFTERNOON. Link to comment Share on other sites More sharing options...
tmagan Posted September 7, 2012 Share Posted September 7, 2012 Can see an eventual upgrade to a moderate risk. Link to comment Share on other sites More sharing options...
andyhb Posted September 7, 2012 Author Share Posted September 7, 2012 Can see an eventual upgrade to a moderate risk. Based on the strength of this incoming trough, I could see it, especially as the thermodynamics involved become more clear. Link to comment Share on other sites More sharing options...
tmagan Posted September 7, 2012 Share Posted September 7, 2012 NAM KLGA BUFKIT forecast sounding for 00Z Sunday September 9th. Look at the wind profile just above the inversion. Link to comment Share on other sites More sharing options...
Dsnowx53 Posted September 7, 2012 Share Posted September 7, 2012 Glad we started a new thread. My thoughts are here: http://www.nymetroweather.com/2012/09/07/severe-weather-potential-for-saturday/ I'm loving this potent trough, but I'm still a bit concerned about maybe too much large-scale ascent just because such a potent trough can generate so much lift on a very large scale. Link to comment Share on other sites More sharing options...
supermeh Posted September 7, 2012 Share Posted September 7, 2012 Link to comment Share on other sites More sharing options...
Brian5671 Posted September 7, 2012 Share Posted September 7, 2012 Looks like the NAM is even slower now? Link to comment Share on other sites More sharing options...
Jefflaw77 Posted September 7, 2012 Share Posted September 7, 2012 Looks like the NAM is even slower now? When does this look to be pretty bad? Time wise? Link to comment Share on other sites More sharing options...
Brian5671 Posted September 7, 2012 Share Posted September 7, 2012 When does this look to be pretty bad? Time wise? From what I can glean from the SNE board, looks to be at the NY-CT border around 7-8 pm with perhaps some cells ahead of the main line a bit earlier (As a possibility) Anyone got the NAM sim radar? Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 7, 2012 Share Posted September 7, 2012 From what I can glean from the SNE board, looks to be at the NY-CT border around 7-8 pm with perhaps some cells ahead of the main line a bit earlier (As a possibility) Anyone got the NAM sim radar? Looks like the squall line moves through between 00z and 02z, but I wouldn't take a 36hr NAM simulated radar verbatim. Link to comment Share on other sites More sharing options...
bluewave Posted September 7, 2012 Share Posted September 7, 2012 The NAM is showing the potential for a MESO developing in the line over Eastern PA then tracking ENE across NNJ-SENY and SW CT tomorrow evening. This may end up being the focus for most of the high wind potential along with an embedded TOR threat. Link to comment Share on other sites More sharing options...
NorEaster27 Posted September 7, 2012 Share Posted September 7, 2012 Either way a shot of very heavy rain and gusts winds looks possible...I expect winds to gust over 25-35mph esp along the south coast of long island tomorrow afternoon. Any sun will help mix the winds down. Link to comment Share on other sites More sharing options...
NEG NAO Posted September 7, 2012 Share Posted September 7, 2012 12Z Nam is showing heavy rain with the frontal passage but for folks interested in the max severe potential looks like the timing is going to possibly be off if you look at the cape on the NAM the best numbers are in the late afternoon evening but here is the rainfall heaviest rain as mentioned earlier is going to be around midnight give or take an hour or 2 http://raleighwx.ame...amp24_NE048.gif Link to comment Share on other sites More sharing options...
IsentropicLift Posted September 7, 2012 Share Posted September 7, 2012 The line on the 12z NAM more or less "explodes" right over the area and stays strong as it pushes through NNJ and eastward into LI Link to comment Share on other sites More sharing options...
Weathergun Posted September 7, 2012 Share Posted September 7, 2012 I'm concerned tomorrow how much the models show LLJ cranking up, just before the main squall line comes in. We could see too much low-topped junk form in just ahead of squall line tomorrow. If that happens, threat for damaging winds or tornadoes would become more isolated. Link to comment Share on other sites More sharing options...
Allsnow Posted September 7, 2012 Share Posted September 7, 2012 Either way a shot of very heavy rain and gusts winds looks possible...I expect winds to gust over 25-35mph esp along the south coast of long island tomorrow afternoon. Any sun will help mix the winds down. Never seen u so bullish before Link to comment Share on other sites More sharing options...
Stormlover74 Posted September 7, 2012 Share Posted September 7, 2012 Maybe but it is September and we seem to do well this month severe wise. Also its a potent cold front with a fall like air mass behind it. I'm concerned tomorrow how much the models show LLJ cranking up, just before the main squall line comes in. We could see too much low-topped junk form in just ahead of squall line tomorrow. If that happens, threat for damaging winds or tornadoes would become more isolated. Link to comment Share on other sites More sharing options...
earthlight Posted September 7, 2012 Share Posted September 7, 2012 I'm concerned tomorrow how much the models show LLJ cranking up, just before the main squall line comes in. We could see too much low-topped junk form in just ahead of squall line tomorrow. If that happens, threat for damaging winds or tornadoes would become more isolated. Agreed Link to comment Share on other sites More sharing options...
Superstorm93 Posted September 7, 2012 Share Posted September 7, 2012 Day 2 MDT Risk for the NE ...THERE IS A MDT RISK OF SVR TSTMS FROM NERN MD/NRN DE...NWD INTO UPSTATE NY/VT/NH... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM THE CAROLINAS INTO WRN ME... ...DAMAGING SEVERE THUNDERSTORMS ARE EXPECTED ACROSS THE NORTHEASTERN U.S. SATURDAY... Link to comment Share on other sites More sharing options...
CooL Posted September 7, 2012 Share Posted September 7, 2012 SPC still likes our chances. Moderate risk for the area Link to comment Share on other sites More sharing options...
CooL Posted September 7, 2012 Share Posted September 7, 2012 Strong Wording. WHILE A DAMAGING SQUALL LINE IS EXPECTED ALONG THE ADVANCING COLD FRONT...ENVIRONMENTAL SHEAR WILL BECOME QUITE FAVORABLE FOR PRE-FRONTAL SUPERCELLS AND EMBEDDED SUPERCELLS WITHIN THE MAIN SQUALL LINE. Link to comment Share on other sites More sharing options...
blizzardof09 Posted September 7, 2012 Share Posted September 7, 2012 Like during the winter with snowstorms/blizzards, these severe threats area wide especially close to the coast are difficult to get to materialize especially this year. Case inpoint the derecho threat a couple months ago, severe parameters were maxed out but lapse rates were too meager. Tommorow like weather gun pointed out the LLJ jet ramping up before the main show may cause too much debris/junk could hurt our chances for a more sustained severe line of storms tommorow evening as the trough moves through our area. SPC did the right thing by issueing this kind of forecast, but im still a little weiry about this tommorow as far as too much stuff going on before the main line gets here Link to comment Share on other sites More sharing options...
tmagan Posted September 7, 2012 Share Posted September 7, 2012 KEWR BUFKIT forecast sounding for 00Z Sunday September 9th. Link to comment Share on other sites More sharing options...
Sock Puppet Posted September 7, 2012 Share Posted September 7, 2012 Maybe it's just a fluke but I recall the best storms occurring end of summer. http://blogs.wsj.com/metropolis/2010/09/16/possible-tornado-rocks-brooklyn-queens-and-staten-island/ Maybe but it is September and we seem to do well this month severe wise. Also its a potent cold front with a fall like air mass behind it. Link to comment Share on other sites More sharing options...
uncle W Posted September 7, 2012 Share Posted September 7, 2012 Maybe it's just a fluke but I recall the best storms occurring end of summer. http://blogs.wsj.com...-staten-island/ yea labor day 1998 was a biggie...when the Ocean gets warmer it has less effect one severe storms near us... Link to comment Share on other sites More sharing options...
bluewave Posted September 7, 2012 Share Posted September 7, 2012 yea labor day 1998 was a biggie...when the Ocean gets warmer it has less effect one severe storms near us... Yeah, the ocean temperature south of Long Island is 77 degrees this afternoon which is just about the warmest that I have seen on September 7th. 9/16/10 was also a big day in September. September 1973 was an active severe month after a very warm start. Link to comment Share on other sites More sharing options...
earthlight Posted September 7, 2012 Share Posted September 7, 2012 Given the enhanced low level shear on most forecast soundings I would think SPC will issue a 10% tornado probability area over parts of Northern New Jersey and Eastern New York including Western CT and MA. The SREF mean is also hitting this potential hard with some high numbers on the significant tornado ingredients graphic. Link to comment Share on other sites More sharing options...
rcad1 Posted September 7, 2012 Share Posted September 7, 2012 Looks like Upton thinks the coast won't get many storms due to the marine layer... Are you guys thinking the squall line weakens alot as it approaches the coast.... Link to comment Share on other sites More sharing options...
NorEaster27 Posted September 7, 2012 Share Posted September 7, 2012 I've never seen 45 percent hatched for nyc by spc and yet no mention of severe weather in the grids out of upton. Link to comment Share on other sites More sharing options...
andyhb Posted September 7, 2012 Author Share Posted September 7, 2012 I think it might be a bit of a bad idea to rest everything on the marine layer. Link to comment Share on other sites More sharing options...
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