Damage In Tolland Posted August 23, 2011 Share Posted August 23, 2011 Thursday afternoon and evening looks like another shot at some severe wx in SNE. Models have ramped up shear and instability the last 24 hours or so. It looks again like maybe Western and Central areas have the best shot..but maybe eastern areas could see some nocturnal stuff. Also qpf is modelled in the 1 inch range..that on top of a wet August and possible monumental rains from Irene should have Ginx scrambling for his waders and sandbags Link to comment Share on other sites More sharing options...
Cold Miser Posted August 23, 2011 Share Posted August 23, 2011 Got my pump ready. Water pump that is. Might as well add to my basement woes. Why not go for broke and give me a few feet of water down there. Link to comment Share on other sites More sharing options...
free_man Posted August 23, 2011 Share Posted August 23, 2011 The damage before the damage. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 23, 2011 Share Posted August 23, 2011 Thursday's potential once again seems to favor more of eastern NY and extreme western MA and CT (you can also include portions of VT/NH in here as well). Obviously the major question right now is how much will the atmosphere destabilize out ahead of the front? As always this we really won't know until Thursday AM. With the timing of the front being late afternoon/evening you would think this means a better chance for us to destabilize, however, as we usually see with cold fronts a pre-frontal trough may develop out across eastern NY. Given how there will be no capping in place that could spark off some showers/t'storms and keep us from getting much, if any sun. One thing impressive is the forecast shear values, low-level shear and mid-level shear values are both fairly impressive with a decent amount of directional shear in the lowest 1-2km of the atmosphere. Above here though winds are more unidirectional. Vertical shear values through the afternoon increase to 30-40 knots from the SW, meaning the front will become parallel to the mid-level flow. This will also act to slow the front down even more. Despite the fact there is a good deal of directional shear in place in the lowest 1-2km the unidirectional flow aloft running parallel to the front suggests storm mode will likely be more on the linear side of things. However, with the 30-40 knots of vertical shear combined with the low-level directional shear early on in storm mode we could see some supercells; even out ahead of any line there could be a few. ML lapse rates really suck so this will work against getting solid updrafts to develop and sustain themselves. We'd have to hope for a good deal of sun to get those temps up...enough to get a good 1500-2000 J/KG of MLcape. What may be the most impressive are the PWAT values. Models have PWAT values nearing 2.00''! This is suggestive of some extremely rainfall potential so flash flooding could be possible. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 24, 2011 Share Posted August 24, 2011 Wrote this just a few minutes ago... Yet another cold front will be pushing eastward across the region on Thursday. Out ahead of the cold front the airmass is expected to be warm/humid leading to a weakly unstable airmass. At this time there are major questions with how much sun/heating we will receive, which is usually always a question/concern in this part of the country when dealing with convective potential. Ongoing convection may spread cloud cover into the region which would help to inhibit much sun from occurring, however, given how the winds will be from the SW this may yield to some of these clouds mixing out, similar to what we saw occur this past Sunday. Depending on how much sun we see temperatures should at least get into the mid 70's; however, with sun temps could get into the upper 70's to even mid 80's if we see enough sun. This combined with dewpoints in the mid to near upper 60's will yield a weakly unstable airmass. One factor which will lead to weaker instability will be weak mid-level lapse rates. Forecast models are only showing mid-level lapse rates between 5.5-6 C/KM. Forecast model guidance at this current time is indicating between 1000-1500 J/KG of SBCape and 500-1000 J/KG of MLcape with LI values around the -2C to -4C range. Associated with the cold front will also be a fairly potent piece of s/w energy. This s/w energy will yield to some strong winds aloft. Low-level winds are expected to increase to 20-30 knots with mid-level winds increasing to 35-45 knots. With the increase in low-level winds and stronger atmospheric mixing developing as the day goes on winds at the surface will also increase as well, possibly in excess of 10-20 mph. Winds at the surface are forecasted to be from the south whilke winds in the lower-levels are expected to be more from the southwest. This will yield to a great deal of low-level directional shear. With winds in the mid and upper levels more from the SW as well this will yield to more in the way of unidirectional shear here. With winds in the mid-levels increasing to 35-45 knots from the southwest this means the front will run parallel to the wind flow, this will not only work to slow the eastward progression of the front but it means any convection that does develop will likely remain more linear rather than discrete meaning strong winds would be the main severe threat. However, due to the enhanced low-level directional shear a few supercells would be possible, especially early on in storm mode and potentially out ahead of any squall line that develops. Mid-level temperatures aren't relatively cold and freezing levels are rather high, this should limit the hail threat and would take some pretty hefty storms to generate hail. Since the atmosphere will be rather juicy and a pretty strong southerly/southwesterly flow in place ahead of the front PWAT values will be very high, up in the order of 2.00''. This means any storms will produce some extremely heavy rainfall and this could lead to isolated pockets of flash flooding. The best chance for stronger storms, like Sunday will be across eastern NY and western MA/CT where models show the strongest instability along with the strongest shear. The severe potential as usual will be determined by how much sun can occur in the morning and early afternoon hours. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 24, 2011 Share Posted August 24, 2011 Upgraded to a slight risk tomorrow. ML lapse rates really suck so that will help to keep instability numbers down and prevent potential for a more substantial event. Still could see a few marginally severe storms though with damaging winds the main threat. Have to watch any discrete storms though. Link to comment Share on other sites More sharing options...
ChrisM Posted August 25, 2011 Share Posted August 25, 2011 I realize Irene is coming but this is a very interesting threat without much fanfare. That line in wny is beautiful right now Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 I know with the Hurricane potential nobody probably cares but whatever... Pretty interesting situation ongoing just to our west currently, not sure what it means for our region tomorrow. First off, currently mesoanalysis is showing an area of incredibly steep ML lapse rates on the order of 7-7.5 C/KM across OH/western PA/western NY. I haven't paid attention to model forecasts of the lapse rates in that area but I looked at the 12z NAM and for this timeframe and they had them under 7 C/KM. Perhaps latent heat release from the very potent line will weaken them as the 0z NAM is showing them around 6 C/KM in our region with the EML weakening as it progresses eastward throughout the morning and early afternoon. Models are weakening the trough as it approaches New England which is allowing for heights to rise a bit throughout the morning and early afternoon and 500mb temps actually warm a bit as the -10C line at 500mb retreats northward towards northern New England and Canada where the 21z SPC SREF has the EML slowly weakening and advecting in. Models are also beefing up instability probs as well with the 21z SPC SREF indicating a 10% chance of SBcape values reaching 2000 J/KG, MLcape values reaching 2000 J/KG and 30-50% chance of MUcape values reaching 2000 J/KG...note though these probs are across eastern NY/western CT where the threat for strongest storms will be the highest. Shear tomorrow is expected to be strong at all levels, however shear may gradually weaken throughout the day if the trough does indeed weaken. Regardless models are indicating a 25-35 kt LLJ crossing through the area from the SW with a 30-40 knot MLJ punching into the region and portions of the region being in the RRQ of a 60-80 kt ULJ which would make for some enhanced upper-level divergence. Given the 30-40 knots in the mid levels this would yield to about 25-35 knots of vertical shear. While models are indicating a decent amount of low-level directional shear as winds at the surface are forecasted to be from the south turning to the southwest going up several thousand feet shear aloft in the mid/upper levels will be unidirectional as the flow will mainly be from the southwest. With the high levels of low-level directional shear 0-1km helicity values are forecasted to be between 100-200 m2s2. Despite the lack of mid-level directional shear due to strong wind fields from the surface up through the entire atmospheric column 0-3km helicity values are forecasted to be between 150-200 m2s2. Given the unidirectional flow aloft this means the front will run parallel to the mid/upper level flow, halting the eastward progression, this means any storm threat should be later in the afternoon, however, can't rule out development early on in the afternoon, especially if a pre-frontal trough sets up over eastern NY, a situation we saw occur this past Sunday and one that is fairly common around these parts. Currently there is a very potent line of thunderstorms well off to our west entering western NY/PA where a tornado watch is up until 5:00 AM EDT. Going back to the above mentioned unidirectional flow in the mid-upper levels this indicates any activity tomorrow will be more linear, this line, which will weaken tonight will re-intensify tomorrow afternoon if we receive enough heating to get the atmosphere destabilized. Given the level of helicity being forecasted there could be embedded cells within this line that do acquire rotation and we could see embedded supercells. It's also possible we see discrete development out ahead of the line. Depending on how much the atmosphere is able to destabilize tomorrow (if we can get Capes up near 1500-2000 J/KG) the threat for damaging winds would exist. The threat for large hail would also be enhanced especially in any supercells that develop. With a strong flow from the south/southwest tons of moisture will also be advected into the region and this is shown by the near 2.00'' PWAT values which are forecasted to work into the region. This is suggestive of the potential for extremely heavy rainfall with any storms and could lead to areas of localized flash flooding. An isolated tornado could also be possible too given the level of helicity in play...the more likely areas for this may be eastern NY extending northward into portions of northwestern MA and VT. The major question for tomorrow is how much instability will develop. With a warm front lifting northward through the region in the AM this will be accompanied by lots of clouds. However, as the front progresses northward the clouds should slowly burn off, especially with a SW flow in the lower-levels as a downsloping component to the wind helps to mix out some of that moisture and the sun helps to burn the clouds off. Link to comment Share on other sites More sharing options...
ChrisM Posted August 25, 2011 Share Posted August 25, 2011 Well done Paul Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Well done Paul Thanks man! Personally I think that may be one of my best writeups...too bad nobody will be in here Link to comment Share on other sites More sharing options...
ChrisM Posted August 25, 2011 Share Posted August 25, 2011 Haha maybe we can chase tomorrow and see something if it looks ok Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Haha maybe we can chase tomorrow and see something if it looks ok Maybe! Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Really intrigued by this EML b/c now ML lapse rates are increasing to 7.5-8 C/KM!!! Even tonight's 0z NAM doesn't have that...wonder if this does indeed weaken. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 New Day 1 is out...slight risk (2% TOR/15% Wind/15% Hail) Does say weak ML lapse rates will be an issue so SPC must be expecting the EML to weaken to nil as well. ...NORTHEAST... DESPITE WEAK MID-LEVEL LAPSE RATES...AN AXIS OF STRONGER HEATING FROM THE LEE OF THE NORTH CENTRAL APPALACHIANS NORTHEASTWARD INTO WESTERN NEW ENGLAND...COUPLED WITH PRECIPITABLE WATER INCREASES /1.75 INCHES TO NEAR 2 INCHES/...LIKELY WILL YIELD MODERATELY LARGE CAPE BY THIS AFTERNOON. AS STRONGER MID-LEVEL FORCING OVERSPREADS THE REGION...VIGOROUS CONVECTIVE DEVELOPMENT APPEARS PROBABLE. ALTHOUGH SOUTHWESTERLY FLOW FIELDS AHEAD OF THE UPPER TROUGH AXIS ARE PROGGED TO GENERALLY WEAKEN THROUGH THE PERIOD ...DEEP LAYER MEAN MAGNITUDES ON THE ORDER OF 20-30+ KT...WHEN COUPLED WITH HEAVY PRECIPITATION LOADING...MAY BE SUFFICIENT TO ENHANCE THE RISK FOR POTENTIALLY DAMAGING WIND GUSTS. VERTICAL SHEAR MAY EVEN BECOME MARGINALLY FAVORABLE FOR SUPERCELL STRUCTURES IN STRONGEST STORMS ACROSS PARTS OF THE HUDSON/ CHAMPLAIN VALLEYS INTO WESTERN NEW ENGLAND. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 ML lapse rates still 7-7.5 C/KM off to our west. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Opened up bufkit for BDL and NAM has ML lapse rates between 6-6.5 C/KM and GFS has a little closer to 6 C/KM. Better than what data on earl's page showed. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 ML lapse rates again at 8 C/KM across much of NYS...WOW Link to comment Share on other sites More sharing options...
free_man Posted August 25, 2011 Share Posted August 25, 2011 Thanks man! Personally I think that may be one of my best writeups...too bad nobody will be in here Today looks interesting for some severe. Hopefully things organize so it's more widespread than the very discrete storm year we have had. Not that discrete isn't good Irene is the ultimate redemption for you missing that tornado outbreak, btw. Even if you maybe prefer the severe versus the tropical. If it landfalls far enough west we'll see some more tors and even get into the sustained TS force stuff inland, no way around it. lol Link to comment Share on other sites More sharing options...
Damage In Tolland Posted August 25, 2011 Author Share Posted August 25, 2011 Today will all depend on clouds..Thankfully those storms over NY are dissipating, but we may be left with alot of cloud debris. Some of the models do bring several damaging lines of stoems thru later today and tonight Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 The EML has actually made it into the area. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 EVen behind the EML which has weakened a bit lapse rates are still decent. If we can get sunshine with this we could see a much more potent event than thought. Link to comment Share on other sites More sharing options...
free_man Posted August 25, 2011 Share Posted August 25, 2011 lol Link to comment Share on other sites More sharing options...
HoarfrostHubb Posted August 25, 2011 Share Posted August 25, 2011 Like we need this (and good analysis Paul) Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Like we need this (and good analysis Paul) Thanks, Dave. Today could certainly be interesting, especially if we burn these clouds off and get some good solar heating. Going to watch these lapse rates as the day progresses as well. Link to comment Share on other sites More sharing options...
HIPPYVALLEY Posted August 25, 2011 Share Posted August 25, 2011 Heavy overcast here currently. That won't help with the severe threat. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Heavy overcast here currently. That won't help with the severe threat. We have some breaks of sun here, however, mostly cloud filled. Lots of clouds off to the west as well, but some indications with some drying out aloft that the clouds could break up...sort of like Sunday so have to watch. Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Wow...the EML went away pretty damn quickly. Mesoanalysis page updated and ML lapse rates went from 7-7.5 C/KM to 6-6.5 C/KM...even 5.5 C/KM across eastern sections. Link to comment Share on other sites More sharing options...
free_man Posted August 25, 2011 Share Posted August 25, 2011 Wow...the EML went away pretty damn quickly. Mesoanalysis page updated and ML lapse rates went from 7-7.5 C/KM to 6-6.5 C/KM...even 5.5 C/KM across eastern sections. Judging by latest vis and obs, what areas do you think will recieve the most heating? Link to comment Share on other sites More sharing options...
weatherwiz Posted August 25, 2011 Share Posted August 25, 2011 Judging by latest vis and obs, what areas do you think will recieve the most heating? That's actually a very good question. By how it looks now looks like central/eastern areas would stand the greatest potential. I'm kind of thinking like areas similar to Sunday. Have to watch for some mid-level drying which could also try and help to mix out or break up some of the clouds as well. Link to comment Share on other sites More sharing options...
HoarfrostHubb Posted August 25, 2011 Share Posted August 25, 2011 Decent shear? Very windy here this morning and the lower level clouds are scooting along pretty well. Upper level seems to be buring off My son was wondering if this was the start of Irene...lol Link to comment Share on other sites More sharing options...
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