weatherwiz Posted October 17, 2012 Share Posted October 17, 2012 As we move through the middle of the week computer models show a rather broad and deep mid/upper level trough working through the country towards the east coast along with a closed off mid/upper level circulation. East of this trough a rather strong south/southwesterly flow will develop advecting in some unseasonably high dewpoints all the way up through New England as several computer models are showing dewpoints increasing to the low to mid 60's. Not only will we see an increase in moisture/higher dewpoints but warmer low-level air will also be working into the region as computer models indicate 925mb temperatures increasing to as much as +15C across southern New England with 850mb temps increasing to as much as +10C to +11C. While full sunshine and strong mixing would promote high temperatures in the mid to upper 70's substantial cloud cover is expected to hold temps back towards the mid and upper 60's. As the trough begins to approach New England swinging a cold front eastward we will begin to see an increase in the winds aloft; 1) With the approaching trough winds in the middle and upper levels of the atmosphere will increase and 2) With an area of high pressure located just east of New England out in the Atlantic the pressure gradient will also allow for the development of a secondary low-level jet max right over the region. Computer models are showing a 60-80 knot mid-level jet max working into the region by early Friday afternoon with much of the region entering the right front quadrant of a 100-125 knot upper-level jet max. The resultant mid-level jet should yield to vertical shear values of 45-55 knots across the entire region. Computer models also show as 30-35 knot secondary low-level jet max over southern New England during the day on Friday. While surface temperatures will not be that warm thanks in part to a lack of appreciable sunshine, increasing moisture both at the surface and in the lower levels of the atmosphere should be enough to generate some weak instability values across the region, even with fairly poor mid-level lapse rates. Computer models are developing as much as 500 J/KG of SBcape and MLcape as far north as MA along with LI values of around -2C. The combination of very strong winds aloft, forcing along a strong cold front/trough and weak surface-based instability could result in the development of t'storms, likely into a fine low-topped squall line. In fact, this line should already be ongoing very early Friday as it moves northeastward from the mid-Atlantic states and the question will be does the line maintain itself or perhaps slightly intensify? The main threats with any convection would be some gusty winds along with torrential downpours potentially leading to localized areas of flash flooding. Some meso models, however, also have a decent amount of helicity as winds from the surface up through the lower-levels of the atmosphere have a directional component to them. While we're still a few days from Friday it is interesting to see the SPC SREF designate a SIG TOR over the region this far out. Not saying this is a threat but something to keep an eye on. Link to comment Share on other sites More sharing options...
CoastalWx Posted October 17, 2012 Share Posted October 17, 2012 Probably a few rumbles around....models do destabilize a bit, but as usual for October..it may be mostly +RA. Link to comment Share on other sites More sharing options...
Quincy Posted October 17, 2012 Share Posted October 17, 2012 Just checked the data. Marginal setup for some CT thunderstorms, but severe weather looks unlikely at this point. Link to comment Share on other sites More sharing options...
Cold Miser Posted October 17, 2012 Share Posted October 17, 2012 What happened to beginning to end washout for the weekend? Link to comment Share on other sites More sharing options...
CoastalWx Posted October 17, 2012 Share Posted October 17, 2012 What happened to beginning to end washout for the weekend? It's a meh. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 17, 2012 Author Share Posted October 17, 2012 The SPC SREF has some decent probs for Friday. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 17, 2012 Author Share Posted October 17, 2012 I was just told that the SPC changed the algorithm for the SIG TOR parameter and that's why it's showing some pretty high numbers here for Friday. Link to comment Share on other sites More sharing options...
Quincy Posted October 17, 2012 Share Posted October 17, 2012 I was just told that the SPC changed thealgorithm for the SIG TOR parameter and that's why it's showing some pretty high numbers here for Friday. Not only that, but the Significant Tornado Ingredients forecast is showing some >20% values: Link to comment Share on other sites More sharing options...
weatherwiz Posted October 17, 2012 Author Share Posted October 17, 2012 Friday's setup is rather decent for this time of year provided we can generate some instability which the NAM/SREF's actually aren't too bad in that disregard. low to mid 60's dewpoints this time of year is a bit unusual and should help with the advection of some higher low-level instability. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 17, 2012 Author Share Posted October 17, 2012 Not only that, but the Significant Tornado Ingredients forecast is showing some >20% values: Yes, this is what I was referring too. I guess though they changed their thresholds for Cape and MLLCL...the Cape threshold went from 1000 to 500 and raised MLLCL from 1000 to 1500 Link to comment Share on other sites More sharing options...
weatherwiz Posted October 17, 2012 Author Share Posted October 17, 2012 Latest SPC SREF cut back on instability for Friday. Link to comment Share on other sites More sharing options...
Quincy Posted October 18, 2012 Share Posted October 18, 2012 Still getting a See Text from SPC...haven't checked the latest data, but SPC says an upgrade to Slight is possible. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 19, 2012 Author Share Posted October 19, 2012 Still think some svr could be possible, especially across SW areas...may be more down by NJ and such though Link to comment Share on other sites More sharing options...
TalcottWx Posted October 19, 2012 Share Posted October 19, 2012 Really wasn't all that impressive here don't get your hopes up Link to comment Share on other sites More sharing options...
weatherwiz Posted October 20, 2012 Author Share Posted October 20, 2012 MESOSCALE DISCUSSION 2080 NWS STORM PREDICTION CENTER NORMAN OK 1050 PM CDT FRI OCT 19 2012 AREAS AFFECTED...ERN CT...RI...ERN MA...ERN LONG ISLAND CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 200350Z - 200545Z PROBABILITY OF WATCH ISSUANCE...5 PERCENT SUMMARY...WEAK TSTMS HAVE DEVELOPED WITHIN A STRONGLY SHEARED ENVIRONMENT OFF THE NE COAST. WEAK SUPERCELLS WITH TRANSIENT ROTATION WILL RESULT IN A LOW PROBABILITY OF A TORNADO. THERE IS ALSO A LOW PROBABILITY OF A STRONG WIND GUST. DISCUSSION...TSTMS JUST OFF THE CT/RI/MA COAST HAVE INCREASED OVER THE PAST HOUR. THIS ACTIVITY IS LIKELY ASSOCIATED WITH WEAK SHORTWAVE TROUGH NEAR THE NY/PA BORDER...EMBEDDED WITHIN THE STRONG SLY FLOW ALOFT AROUND THE DEEP UPPER LEVEL LOW. SOME ADDITIONAL LIFT IS ALSO BEING PROVIDED BY UPPER LEVEL DIVERGENCE WITHIN THE ENTRANCE REGION OF A JET STREAK. THESE FAVORABLE LARGE SCALE FIELDS ARE COUNTERED BY A SURFACE INVERSION DEPICTED BY 00Z RAOBS AND VERY WEAK INSTABILITY. RECENT RADAR/LIGHTNING TRENDS INDICATE THE TSTMS HAVE BECOME STRONGER OVER THE PAST HOUR. GIVEN THE STRONG SHEAR AND AT LEAST MODEST LOW-LEVEL MOISTURE...THESE STORM POSE A LOW PROBABILITY TORNADO THREAT. THERE IS A LOW PROBABILITY OF SOME STRONG WINDS AS WELL. LOW COVERAGE AND PROBABILITY PRECLUDE THE NEED FOR A WW. Link to comment Share on other sites More sharing options...
CoastalWx Posted October 20, 2012 Share Posted October 20, 2012 Good amount of lightning too. Bob is gonna get nailed. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 20, 2012 Author Share Posted October 20, 2012 Good amount of lightning too. Bob is gonna get nailed. A nice pocket of 500 J/KG MLcape across the region...lapse rates are quite nice as well along with shear...the highest and more intense helicity is a bit offshore but if we had higher helicity values in place some of these cells would be more interesting. Link to comment Share on other sites More sharing options...
CoastalWx Posted October 20, 2012 Share Posted October 20, 2012 Actually can hear thunder hear thanks to anvil crawlers. Link to comment Share on other sites More sharing options...
Cyclone-68 Posted October 20, 2012 Share Posted October 20, 2012 What an awesome little bonus to this thunderstorm season in eastern MA..What a nice little surprise! Link to comment Share on other sites More sharing options...
CoastalWx Posted October 20, 2012 Share Posted October 20, 2012 South shore getting hit good, but the lightning is actually C-C close by. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 20, 2012 Author Share Posted October 20, 2012 Activity really starting to fire up across the region with much healthier looking action south of Long Island. Link to comment Share on other sites More sharing options...
CoastalWx Posted October 20, 2012 Share Posted October 20, 2012 This line has some good lightning with it to my se. Link to comment Share on other sites More sharing options...
CoastalWx Posted October 20, 2012 Share Posted October 20, 2012 Those guys are gonna get a second round in PYM county. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 20, 2012 Author Share Posted October 20, 2012 Should be some areas of flash flooding. I have a scanner feed from Bristol county up but not hearing anything. Gathering flooding reports this time of night is quite difficult...hell, gathering any type of reports this time of night is quite difficult. Link to comment Share on other sites More sharing options...
Kevin W Posted October 20, 2012 Share Posted October 20, 2012 Woke up to a lot of thunder about an hour ago but calm right now. Looks like I'll be up for a bit as it looks like more is on the way. I'll take it! Link to comment Share on other sites More sharing options...
Roger Posted October 20, 2012 Share Posted October 20, 2012 Saw a few flashes of lightning last evening and that was it. Link to comment Share on other sites More sharing options...
Baroclinic Zone Posted October 20, 2012 Share Posted October 20, 2012 Good amount of lightning too. Bob is gonna get nailed. Great show overnight Pretty vivid lightning Link to comment Share on other sites More sharing options...
TheBudMan Posted October 20, 2012 Share Posted October 20, 2012 tremendous storm here at 3 AM. Great Call Wiz !!!! Link to comment Share on other sites More sharing options...
Quincy Posted October 22, 2012 Share Posted October 22, 2012 Not New England, but an EF-1 tornado was confirmed in Pennsylvania from this system. http://kamala.cod.edu/pa/latest.nous41.KCTP.html Link to comment Share on other sites More sharing options...
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