weatherwiz Posted October 7, 2015 Share Posted October 7, 2015 When it comes to convection, fall means one thing and one thing only here...low topped convection. While these events (setups) don't pan out most of the time, they provide a great deal of interest b/c that one time they do produce something, it can pack a punch. On Friday a warm front is expected to push into and through southern New England out ahead of an advancing cold front and a strengthening trough associated with a vigorous piece of energy at 500mb. Within the warm sector, surface dewpoints are expected to climb into the lower 60's and surface temperatures in the upper 60's to lower 70's (dependent on degree of sun of course). As evident by PWAT values increasing to 1.5'' to 1.8'' the low-level airmass will be quite moist. The combination of a moist low-level airmass, temps around 70F (maybe a few ticks higher) and increasing (steepening mid-level lapse rates) may be enough to yield as much as several hundred J/KG of SBcape and moreso of elevated instability. While instability values aren't screaming high when juxtaposed with strong shear, that can be enough. Forecast models develop a fairly decent 500mb jet streak (50-65 knots) crossing the region between 18z and 0z. Low-level shear is expected to increase as well, anywhere from 25-40 knots from 925mb up through 700mb. If we can muster up enough instability Friday might be worth watching for a few strong storms! Link to comment Share on other sites More sharing options...
Quincy Posted October 7, 2015 Share Posted October 7, 2015 The NAM is showing decent hodographs in the lowest 1-1.5km. While the trend has been for more veering winds, the NAM still maintains an environment that could support a few severe thunderstorms. The most realistic scenario is probably a line or broken line with a few stronger wind gusts mixing down. There is some room for the setup to improve though. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 7, 2015 Author Share Posted October 7, 2015 The NAM is showing decent hodographs in the lowest 1-1.5km. While the trend has been for more veering winds, the NAM still maintains an environment that could support a few severe thunderstorms. The most realistic scenario is probably a line or broken line with a few stronger wind gusts mixing down. There is some room for the setup to improve though. the one thing that annoys me about these setups is the strongest winds typically occur out ahead of the approaching line (or cell). So you get all amped up seeing the winds before everything starts and then once the precip occurs and the outflow chokes of the inflow its just rain with maybe a gust or two. I'm actually a little intrigued with the lapse rates here b/c they don't look awful...often times they blow with these setups but you have a vigorous s/w associated with very cold air and pretty decent height falls. Link to comment Share on other sites More sharing options...
OceanStWx Posted October 8, 2015 Share Posted October 8, 2015 Sneaky severe threat Friday afternoon. Worth watching! From Ryan in the October thread, to which I say Link to comment Share on other sites More sharing options...
weatherwiz Posted October 8, 2015 Author Share Posted October 8, 2015 From Ryan in the October thread, to which I say SREF_prob_combined_sigtor__f054.gif So I'm assuming you have an interest in this setup? Link to comment Share on other sites More sharing options...
OceanStWx Posted October 8, 2015 Share Posted October 8, 2015 So I'm assuming you have an interest in this setup? At any rate it will make my short term midnight shifts interesting. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 8, 2015 Author Share Posted October 8, 2015 At any rate it will make my short term midnight shifts interesting. These setups are really a big pain in the ass. 9/10 times they ate nothing but b/c of the parameters in place, you have to watch extremely closely at anything that develops. When it comes to these setups I always try and think back about previous setups...either that produced something or didn't and try to find a distinguishable difference...and often times it isn't easy b/c it usually comes down to the mesoscale level. There are two features though that I'm really interested in 1) the 500mb MLJ streak modeled to almost arrive at a perfect time 2) advection of steeper lapse rates #1 really draws my interest b/c one factor that typically always lacks here (maybe moreso than lapse rates...or at least equal) is the lack of a good solid jet streak moving in as convection is occurring or initiating...too many times the shear lags the front. I can even add a #3 here and that is height falls...the height falls modeled are quite impressive actually, especially in the potential environment we may have. Substantial height falls can really compensate for other parameters that may be lacking, especially in the cool season. Link to comment Share on other sites More sharing options...
OceanStWx Posted October 8, 2015 Share Posted October 8, 2015 These setups are really a big pain in the ass. 9/10 times they ate nothing but b/c of the parameters in place, you have to watch extremely closely at anything that develops. When it comes to these setups I always try and think back about previous setups...either that produced something or didn't and try to find a distinguishable difference...and often times it isn't easy b/c it usually comes down to the mesoscale level. There are two features though that I'm really interested in 1) the 500mb MLJ streak modeled to almost arrive at a perfect time 2) advection of steeper lapse rates #1 really draws my interest b/c one factor that typically always lacks here (maybe moreso than lapse rates...or at least equal) is the lack of a good solid jet streak moving in as convection is occurring or initiating...too many times the shear lags the front. I can even add a #3 here and that is height falls...the height falls modeled are quite impressive actually, especially in the potential environment we may have. Substantial height falls can really compensate for other parameters that may be lacking, especially in the cool season. New England will be sitting in a pretty favorable location for the amplifying right entrance region of the upper level jet too. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 8, 2015 Author Share Posted October 8, 2015 New England will be sitting in a pretty favorable location for the amplifying right entrance region of the upper level jet too. and forecasted to be 100-110 knots...pretty freaking awesome. Actually it's not often at all we are in a favorable ULJ quadrant...while in the warm sector. That seems much more of a difficult feat around here than getting a MLJ streak to slide through during favorable timing. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted October 8, 2015 Share Posted October 8, 2015 All systems still appear to be on go this morning . Would be funny if we see more severe on a day in mid Oct. than we saw combined all summer Link to comment Share on other sites More sharing options...
CT Rain Posted October 8, 2015 Share Posted October 8, 2015 We shall see. I was talking to Hayden at BOX about this on Tuesday. Just need to get enough CAPE. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted October 8, 2015 Share Posted October 8, 2015 We shall see. I was talking to Hayden at BOX about this on Tuesday. Just need to get enough CAPE. I wish he was on the desk overnight. Other than 40-45 mph synoptic gusty winds BOX doesn't mention anything. If it happens , certainly will take folks by surprise Link to comment Share on other sites More sharing options...
weatherwiz Posted October 8, 2015 Author Share Posted October 8, 2015 Not too bad for October lol Link to comment Share on other sites More sharing options...
Brian5671 Posted October 8, 2015 Share Posted October 8, 2015 12z nam brings in a line around 5pm to western sections Link to comment Share on other sites More sharing options...
weatherwiz Posted October 8, 2015 Author Share Posted October 8, 2015 the SPC SREF isn't too bad with CAPE probabilities either across western CT and has some pretty solid shear Link to comment Share on other sites More sharing options...
CT Rain Posted October 8, 2015 Share Posted October 8, 2015 12z nam brings in a line around 5pm to western sections I'm by myself at work tomorrow. Count on something. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 8, 2015 Author Share Posted October 8, 2015 I'm by myself at work tomorrow. Count on something. I'll be in Clinton...wish I was in Danbury :thunbsdown: Link to comment Share on other sites More sharing options...
Damage In Tolland Posted October 8, 2015 Share Posted October 8, 2015 Big big day Link to comment Share on other sites More sharing options...
Quincy Posted October 8, 2015 Share Posted October 8, 2015 Looks like a subtle trough moves through around midday across SNE (warm front is earlier in the day) and while the 4km NAM shows a marked increase in 0-3km SRH, on the order of 400-600 mss-1, low-level helicities are not particularly impressive and there is little to no instability forecast at the time. Edit to note that low level shear is pretty solid, as 12km NAM forecast soundings show 30-40kts of 0-1km shear. Link to comment Share on other sites More sharing options...
CT Valley Snowman Posted October 9, 2015 Share Posted October 9, 2015 Not even a marginal risk here from SPC. Isolated wind damage is about as far as I would go. Instability stinks. Why couldn't we have this type of setup a couple months ago. ? Link to comment Share on other sites More sharing options...
Quincy Posted October 9, 2015 Share Posted October 9, 2015 Not even a marginal risk here from SPC. Isolated wind damage is about as far as I would go. Instability stinks. Why couldn't we have this type of setup a couple months ago. ?You'll probably see an expansion of the MRGL risk tonight on both the southern and northern edge. (I could see them bringing it up into NYC/CT and further SW across the Middle Appalachians) Link to comment Share on other sites More sharing options...
Quincy Posted October 9, 2015 Share Posted October 9, 2015 SPC says an upgrade to SLGT may be necessary later today. #damagingtimes Link to comment Share on other sites More sharing options...
Damage In Tolland Posted October 9, 2015 Share Posted October 9, 2015 BOX finally seeing what folks on here saw 2 days ago HIS SYNOPTIC SETUP YIELDS A HIGH SHEAR/LOW CAPE ENVIRONMENT WITH 0- 1 KM SHEAR OF 20-30 KT THIS AFTERNOON. TYPICALLY THE CASE IN THESEEVENTS - WILL THERE BE SUFFICIENT LOW LEVEL INSTABILITY FOR ANISOLATED T-STORM WITH STRONG WINDS. WHILE MID LEVEL LAPSE RATES ARENOT IMPRESSIVE...0-3KM AND 925MB-700 LAPSE RATES ARE MARGINAL 6-6.5C/KM WITH A FOCUS ACROSS CT/RI AND SOUTH OF THE MASS PIKE INWESTERN-CENTRAL MA. THIS IS A RESULT OF STRONG LOW LEVEL WARM AIRADVECTION WITH SFC DEW PTS CLIMBING INTO THE L60S TODAY ACROSS THEAREA ALONG WITH SURFACE TEMPS RISING INTO THE L70S. BOTH ANOMALOUSFOR EARLY OCT.WHAT COULD BE THE WILD CARD TO POTENTIAL STORMS IS ADDITIONAL JETENERGY DIVING INTO THE BASE OF THE TROUGH LATER TODAY YIELDING A 100KT UPPER LEVEL JET STREAK MOVING ACROSS THE AREA. THIS WILL ENHANCETHE FORCING FOR ASCENT AS WELL INCREASE WIND FIELDS. THE HI RES GUIDSUCH AS THE ARW AND NMM HINT AT THIS WITH A SHARP INCREASE IN QPFAND MODEL SIMULATED REFLECTIVITY AFTER 18Z ACROSS THE REGION AHEADOF THE COLD FRONT.SO WHILE MOST OF THE AREA WILL JUST SEE HEAVY SHOWERS AND GUSTYWINDS THERE IS A LOW RISK OF AN ISOLATED STRONG T-STORM. IF LOWLEVEL LAPSE RATES/INSTABILITY IS GREATER THAN MODELS SIMULATE THEREIS A VERY LOW RISK THAT A STRONG STORM COULD YIELD A BRIEF ISOLATEDTORNADO. Link to comment Share on other sites More sharing options...
OceanStWx Posted October 9, 2015 Share Posted October 9, 2015 BOX finally seeing what folks on here saw 2 days ago HIS SYNOPTIC SETUP YIELDS A HIGH SHEAR/LOW CAPE ENVIRONMENT WITH 0- 1 KM SHEAR OF 20-30 KT THIS AFTERNOON. TYPICALLY THE CASE IN THESE EVENTS - WILL THERE BE SUFFICIENT LOW LEVEL INSTABILITY FOR AN ISOLATED T-STORM WITH STRONG WINDS. WHILE MID LEVEL LAPSE RATES ARE NOT IMPRESSIVE...0-3KM AND 925MB-700 LAPSE RATES ARE MARGINAL 6- 6.5C/KM WITH A FOCUS ACROSS CT/RI AND SOUTH OF THE MASS PIKE IN WESTERN-CENTRAL MA. THIS IS A RESULT OF STRONG LOW LEVEL WARM AIR ADVECTION WITH SFC DEW PTS CLIMBING INTO THE L60S TODAY ACROSS THE AREA ALONG WITH SURFACE TEMPS RISING INTO THE L70S. BOTH ANOMALOUS FOR EARLY OCT. WHAT COULD BE THE WILD CARD TO POTENTIAL STORMS IS ADDITIONAL JET ENERGY DIVING INTO THE BASE OF THE TROUGH LATER TODAY YIELDING A 100 KT UPPER LEVEL JET STREAK MOVING ACROSS THE AREA. THIS WILL ENHANCE THE FORCING FOR ASCENT AS WELL INCREASE WIND FIELDS. THE HI RES GUID SUCH AS THE ARW AND NMM HINT AT THIS WITH A SHARP INCREASE IN QPF AND MODEL SIMULATED REFLECTIVITY AFTER 18Z ACROSS THE REGION AHEAD OF THE COLD FRONT. SO WHILE MOST OF THE AREA WILL JUST SEE HEAVY SHOWERS AND GUSTY WINDS THERE IS A LOW RISK OF AN ISOLATED STRONG T-STORM. IF LOW LEVEL LAPSE RATES/INSTABILITY IS GREATER THAN MODELS SIMULATE THERE IS A VERY LOW RISK THAT A STRONG STORM COULD YIELD A BRIEF ISOLATED TORNADO. Enjoy your damage! Link to comment Share on other sites More sharing options...
JC-CT Posted October 9, 2015 Share Posted October 9, 2015 Enjoy your damage! mxuphl_ne_f24.gif Is that an EF-5? Link to comment Share on other sites More sharing options...
weatherwiz Posted October 9, 2015 Author Share Posted October 9, 2015 The 11z RAP bufkit profile for HFD isn't terrible later on. Would like to see some more cape in the 0-3km level but cape in the 0-4 to 0-6km levels aren't horrid. Maybe a bit stronger shear too...its right around 23-26 m/s...26-30 would be a little better Link to comment Share on other sites More sharing options...
weatherwiz Posted October 9, 2015 Author Share Posted October 9, 2015 The profile at Waterbury, CT is actually more impressive than Hartford...higher cape values which makes sense. The higher cape values will probably just push into western CT. Link to comment Share on other sites More sharing options...
IsentropicLift Posted October 9, 2015 Share Posted October 9, 2015 The 11z RAP bufkit profile for HFD isn't terrible later on. Would like to see some more cape in the 0-3km level but cape in the 0-4 to 0-6km levels aren't horrid. Maybe a bit stronger shear too...its right around 23-26 m/s...26-30 would be a little better Tennis balls and wedges or bust. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted October 9, 2015 Share Posted October 9, 2015 HRRR rips a nice line thru later including what looks like a massive supercell thru Waterbury then SE twds HVN area Link to comment Share on other sites More sharing options...
IsentropicLift Posted October 9, 2015 Share Posted October 9, 2015 HRRR rips a nice line thru later including what looks like a massive supercell thru Waterbury then SE twds HVN area How much damage can I expect? Should I bring in the lawn furniture? Link to comment Share on other sites More sharing options...
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