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wdrag

Sub 1000MB sfc low and associated significant hazards Nov 30-Dec 1, 2020

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Caution: VERYYYYYYY early and this could end up much less robust than outlined below, if the northern and southern streams don't phase, or phase early enough into a closed LOW somewhere over NYS/PA/OHIO.  (something always changes from what we see 7 days away but it's posted since there may be some discussion about the potential).

Modeling has been trending to a large sub-1000MB sfc low early next week, with it's maximum strength in the mid Atlantic states. Ensembles to start, offer a solid 1" of rain and wind gusts 40 MPH.  12z/24 EPS/GEFS 850MB wind at 06z/1 is around 45KT, not the operational magnitude of the southerly GFS 65KT, GGEM 70KT, ECMWF 75KT, found over LI.

Added the baseline D7 graphics from WPC and view these as a start. 

Added 12z/24 GFS lower wind field for LGA. The Richardson # preliminarily in this single 12z/24 member cycle allows downward from roughly 925MB. (50 KT).  

Also added the EC PWAT (tropical connection briefly 1.6"+). The 12z/24 operational EC has KI mid 30s generating lightning s of LI suggesting a High Shear Low Cape wind event.  Strongest wind threat this early in the modeling is LI/CT. (did not say 50 KT gusts will occur but based only on the modeling, it's possible). 

A very small chance of some backside snow cover higher terrain western-northern suburbs....

To avoid disappointment on a big wet wind storm not happening, prepare for the more routine WPC scenario, BUT monitor.

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Good Wednesday morning all, No significant change to this outlook.  ICON is out to sea (east and a miss),  00z/25 GEFS and EPS are similar to yesterday..EPS now a little heavier on QPF as is WPC heavier on QPF...  but still a range of possibilities including tracking Appalachians or maybe closer to e PA? NAEFS is going for phasing and while it's surface response lags, it's also getting stronger.

Probably not good to hang our hats on the strongest EC solution but some of the op runs are interestingly strong(not sure it will be quite as strong as Nov 15, but weakened ground due to Thursday=Thanksgiving mornings rain may compensate for less leafed trees)

I've included below this mornings D4-8 discussion from SPC...note this southern system may carry severe from the Gulf states to there mid-Atlantic. Probs so far too low, in part do to model differences. (i underlined). 

 

Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0354 AM CST Wed Nov 25 2020

   Valid 281200Z - 031200Z

   ...DISCUSSION...
   Medium-range guidance has come into better agreement regarding the
   eastward advance of an upper low over the southern Plains on Day
   4/Saturday. Any severe potential Saturday appears to be confined
   along/south of a surface boundary which should be located across
   parts of coastal/south TX and perhaps southern LA. Some phasing of
   this upper low with a northern-stream upper trough over the Midwest
   seems probable on Day 5/Sunday. A northward advance of a partially
   modified Gulf airmass may occur over parts of the Southeast Sunday,
   with an associated isolated/marginal severe risk. Differences in the
   evolution of a highly amplified upper trough/low over the eastern
   states become apparent in medium-range guidance by Day 6/Monday.
   Regardless, a continued isolated/marginal severe threat may exist
   Monday across the warm sector of a deepening surface cyclone from
   parts of FL and the Southeast along the East Coast and potentially
   extending into the Mid-Atlantic. For Day 4/Saturday through Day
   6/Monday, too much uncertainty currently exists regarding inland
   destabilization to include 15% severe probabilities for any day.

 

634A/25

 

 

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Good Wednesday afternoon,  No change in the oriented topic.  

12z /25 modeling: ICON now back on board. It and the op EC-UK-GGEM all have 70-80 kt 850 MB southerly inflow to LI late Monday.  GFS now up to 50kt but in two waves of se inflow. 

Ec OP rudimentary gust predictor has increased a bit, showing near 65MPH gust potential.

WPC qpf has increased each of the past two forecast cycles since yesterdays origination...now with widespread 2-4".   WPC also has a 996MB or lower sfc low nw PA 12z/Tue. 

We're still 5-6 days away. Phasing no guarantee but looking likely. If the energy is split,  like the 12z/25 GFS, then inflow and big qpf continues but less chance to exceed 50MPH gusts (reducing risk for more than isolated power outages) 

12z/25 GEFS ens checked but this discussion has not yet seen NAEFS and EPS from the 12z cycle. I don't anticipate much difference through Dec 2.  May not comment again til Thanksgiving morning. 

Plan for a fairly high impact event.  

Later,  

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The 12 GFS at 138hrs.       We are at bottom center.      We'll see it this holds up or gets worse.     Courtesy AccuWeather.

graphic.aspx?mt=12&hr=138&gs=crosssect&m

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Happy Thanksgiving everyone! Grateful to participate here in good health! Hopefully all who view this feel good as well.

No change in the topic outlined.  A decent HSLC severe weather event appears to coming with the storm maximizing its potential as it goes to our west Monday night-Tuesday morning.  EC continues very consistent and other modeling is gradually joining.

I think there is a pretty good chance of a widespread severe weather event into the Delmarva s NJ and probably reaching us Monday night, then on the wane to our northeast Tuesday morning as the primary storm weakens. In our forum, scattered uproots and power outage damage seems to be continually focused on NJ-LI-CT but no one is out of the picture. This morning's rains helps soften the ground a bit, especially I95 corridor eastward. Added this mornings SPC outlook. 

Weaker GFS 06z/26 lower wind profile graphic added for LGA plus the R#. Solid red near 00z/1 (7P MON) should be able to grab the seflow of 50-55 KT near 975MB in turbulent turnover-transfer. 

Pressure over our area will be less than 1000MB so the FOUS BL wind should be good for sustained. 

Model soundings offer shower-storm movement of about 200 degrees near 50 kt Monday evening. Not quite as intense on the GFS as the 11/15 event.  EC is stronger. Just have to wait and see if the EC lessens its impact.  For now its' still 50-60 MPH Gusts for an 
hour or two Monday evening with 850 winds around 80KT... slightly stronger than the GFS. 


Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 AM CST Thu Nov 26 2020

   Valid 291200Z - 041200Z

   ...DISCUSSION...
   It appears increasingly probable that a closed upper low over the
   southern Plains will merge with a northern-stream upper trough over
   the eastern CONUS on Day 4/Sunday, likely forming a highly amplified
   upper trough/low by Day 5/Monday. Medium-range guidance is in
   reasonably good agreement in depicting a deepening surface low
   developing from coastal LA Sunday morning northeastward to the
   Mid-Atlantic vicinity by Day 5/Monday.

   As greater low-level Gulf moisture advances inland across parts of
   the Southeast and Mid-Atlantic in tandem with the deepening surface
   low, weak instability may develop across the warm sector of this
   cyclone. Rapidly strengthening low and mid-level wind fields suggest
   that organized severe storms capable of producing at least isolated
   damaging winds may occur over parts of the Deep South into the
   Carolinas on Day 4/Sunday, and from the Carolinas into eastern
   portions of the Mid-Atlantic on Day 5/Monday.

   At this point, it remains very uncertain how much surface-based
   instability will ultimately develop across these regions, which will
   have a large impact on overall severe potential. This uncertainty
   precludes the introduction of 15% severe probabilities for now.
   However, the severe potential for this system will be reevaluated in
   later outlook updates. Once the cold front associated with this
   cyclone clears the East Coast, severe thunderstorm potential appears
   minimal across the CONUS on Day 6/Tuesday and Day 7/Wednesday.

   ..Gleason.. 11/26/2020

 

 

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Just too early for me... but I think just a wee bit less for us on LI but I see widespread minor or worse power outages Monday Ohio Valley-east coast... provided the EC continues with it's closing scenario and 80kt 850 MB inflow Delmarva northward to LI. That would occupy lots of utilities.  W

 

Reality check... I always worry talking so much confidence so far in advance...  something can always go very wrong.  My confidence stems from large scale ensembles, and recent modeling track record 6-10 days in advance. 

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We shall see what happens....   so far this fall  longer range modeling considerations in the 6-10 day period (per topics) have been pretty good.

For the storm early next week... see the measure of predictability. Notice the high prob reds on 500 MB trough axis etc.  Quite impressive. 

Doesn't look as confidently stated at 72 hours (before) not after the storm mid week., 

 

 

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651PM Thanksgiving eve update: No change to topic except I think the system is running 6 hours faster than when originally posted... seemingly favoring worst of the wind Noon-9PM Monday.  Will reevalute Friday morning. fwiw... the GEFS now has 75% chance of 50+ MPH gusts Montauk.  That's larger than I saw in the GEFS for the 15th.   Have a good night. 

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Good Friday morning everyone with interest for Monday-Tuesday,  No change in topic as originally outlined. This event will probably be a little less wind impact than that of Nov 15 (a little ess speed shear-less wind 850 MB) but still be significant for some of us. 

HSLC continues to be my concern with 45-50kt of wind at 950MB, 70-80 kt at 850MB during Monday afternoon, sfc dew points probably rising to ~60. Models already grabbing about 45-50kt of wind at LGA via NAM/GFS R# at 18z Monday with maximum wind poised for LI/CT for 3P-9P, a little sooner NJ coast.  Interior can still get a burst of damaging wind but that is less confidently outlooked due to a possible isothermal-inversion in the boundary layer sounding n of I80??  GFS has no sfc cape, EC minimal Sfc Cape. EC KI mid 30s and lightning still advertised. Wind gusts 45-55MPH with isolated G60-65 MPH possible. 

Rainfall: see WPC.  Since this is mainly an 8-16 hour event, doubt if we can reach 5" unless the front slows it's eastward progress Monday evening, which is possible, since the sfc low will probably have reached it's max intensity in PA (992MB?) by that time and a lot of energy is driving north instead of east.  If the front were to slow, then the extreme east portion of the area would be vulnerable to approaching the 5"- but not likely right now. 

Power outages:  While not expected to be generally as much as Nov 15... still expecting power outages. On the grid Minor or moderate event.  

Snow: slightest chance western high terrain suburbs later Tuesday as the trough axis slides eastward?  Power outage snow possible for a few parts of central Indiana into northern-western OH Monday afternoon if GFS/EC and ensembled modeled snow at 32F turns out correct. I didn't spend much time on the Ohio valley.

As we get to Saturday--- monitoring 3K NAM winds/R# as well as the FOUS BL winds at LGA will be helpful and of course local NWS offices statements... and SPC/WPC guidance.  For me, the main focus is HSLC convective wind event Monday afternoon -evening. Wish you a super day! 651A/27

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Good Saturday morning everyone,  Soon we'll be coming into guidance that should more accurate gauge the chances of the upcoming reality. I'll be looking for FOUS BL winds of 28 KT at PHL and 30 KT at LGA for a likelihood of wind event occurrence (damaging wind).  If the NAM is less than that, it may be a typical wind advisory event-except for thunderstorms that could easily cause damage. 

OKX early Saturday HWO now has 50-70 MPH wind gust mentioned for LI.  SPC D3 appended below... marginal risk into NJ but not LI  IF a line of thunderstorms does materialize, I think we're going to have a substantial event. Modeling continues to favor some thunder... marginal instability-sbcape and high shear with 70-75 KT modeled at 850 MB for LI, forenoon Monday through the afternoon by all models, except the weaker GFS. 

The Nov 15 event looked stronger to me... i worry about transfer of 50kt+ winds down from 925 MB. Richardson # says it will happen, the sounding to me looks a little isothermal, so no guarantee.  I'd prepare for scattered power outages NJ coast-LI-CT Monday afternoon-evening.

We'll have more tools to use by late tonight to help ascertain to confidence.  

This following statement could be overdone, especially if 00z-06z GFS verifies, but my guess is grid displayed "minor" power outages Monday into Tuesday from NC to our forum area and even back to Ohio/nw PA where wet snow acscums of 6+" occurs in a few areas. 

Note also: a chance of flurries or a slight covering of snow Tuesday in the distant nw suburbs (ne PA, extreme nw NJ, se NYS, nw CT hills) as the trough axis moves east over us Tuesday afternoon...and I'm suspicious of a dry Tuesday. I could see minor widespread 0.1-0.3" QPF in our forum Tuesday, in addition to the WPC Monday forecast now available (WPC has us in marginal risk excessive Monday)

Added this mornings D3 SPC discussion, and 00z/28 GEFS wind probabilities for gusts over 50 MPH..and this I think is conservative.  The NAM is stronger. 

  ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   FLORIDA/COASTAL GEORGIA INTO THE CAROLINAS AND MID-ATLANTIC...

   ...SUMMARY...
   Isolated strong to severe thunderstorms capable of producing
   damaging winds and perhaps a couple of tornadoes appear possible on
   Monday from parts of Florida and coastal Georgia into the Carolinas
   and Mid-Atlantic.

   ...Florida/Coastal Georgia into the Carolinas and Mid-Atlantic...
   A large-scale upper trough should evolve into a closed low over the
   Midwest/OH Valley and central Appalachians on Monday. A mid-level
   vorticity maximum embedded within this upper trough is forecast to
   move quickly northeastward from the central Appalachians into the
   Mid-Atlantic through Monday afternoon. A deep surface low should
   likewise develop northeastward in tandem with this vorticity
   maximum. A cold front trailing from this surface low will likely
   sweep eastward across much of the FL Peninsula and the East Coast
   through the day. A warm front extending northeastward from the
   surface low will probably make some northward progress across parts
   of the Mid-Atlantic through Monday afternoon as well.

   A line of low-topped showers/storms along or just ahead of the cold
   front should be ongoing at the start of the period from near the
   surface low in WV/western VA southward to northern FL. Although
   instability may remain modest across most of the warm sector ahead
   of this line, generally low to mid 60s surface dewpoints should be
   enough to support weak surface-based instability through the day. A
   very strong (50-60+ kt) south-southwesterly low-level jet should be
   present over the central/eastern Carolinas and southern VA Monday
   morning, and this feature is forecast to shift northward across the
   Mid-Atlantic through the day. 

   Given the strength of the low-level flow and sufficient, albeit
   weak, forecast instability, strong to damaging winds may occur with
   storms that either persist along the cold front or develop ahead of
   it over the open warm sector. A couple tornadoes also appear
   possible, mainly across parts of eastern SC/NC/VA to the Delmarva
   Peninsula and perhaps NJ in associated with the low-level jet and
   potentially greater low-level moisture and instability. Even so,
   there is too much uncertainty regarding sufficient destabilization
   to include higher severe probabilities for now.

   Farther south, low-level convergence along the cold front and
   deep-layer shear are both forecast to be somewhat weaker across
   coastal GA and the FL Peninsula. Still, there may be isolated
   strong/gusty winds with any storms through Monday afternoon.

 

Screen_Shot_2020-11-28_at_5_55.19_AM.png

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49 minutes ago, wdrag said:

Good Saturday morning everyone,  Soon we'll be coming into guidance that should more accurate gauge the chances of the upcoming reality. I'll be looking for FOUS BL winds of 28 KT at PHL and 30 KT at LGA for a likelihood of wind event occurrence (damaging wind).  If the NAM is less than that, it may be a typical wind advisory event-except for thunderstorms that could easily cause damage. 

OKX early Saturday HWO now has 50-70 MPH wind gust mentioned for LI.  SPC D3 appended below... marginal risk into NJ but not LI  IF a line of thunderstorms does materialize, I think we're going to have a substantial event. Modeling continues to favor some thunder... marginal instability-sbcape and high shear with 70-75 KT modeled at 850 MB for LI, forenoon Monday through the afternoon by all models, except the weaker GFS. 

The Nov 15 event looked stronger to me... i worry about transfer of 50kt+ winds down from 925 MB. Richardson # says it will happen, the sounding to me looks a little isothermal, so no guarantee.  I'd prepare for scattered power outages NJ coast-LI-CT Monday afternoon-evening.

We'll have more tools to use by late tonight to help ascertain to confidence.  

This following statement could be overdone, especially if 00z-06z GFS verifies, but my guess is grid displayed "minor" power outages Monday into Tuesday from NC to our forum area and even back to Ohio/nw PA where wet snow acscums of 6+" occurs in a few areas. 

Note also: a chance of flurries or a slight covering of snow Tuesday in the distant nw suburbs (ne PA, extreme nw NJ, se NYS, nw CT hills) as the trough axis moves east over us Tuesday afternoon...and I'm suspicious of a dry Tuesday. I could see minor widespread 0.1-0.3" QPF in our forum Tuesday, in addition to the WPC Monday forecast now available (WPC has us in marginal risk excessive Monday)

Added this mornings D3 SPC discussion, and 00z/28 GEFS wind probabilities for gusts over 50 MPH..and this I think is conservative.  The NAM is stronger. 

  ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   FLORIDA/COASTAL GEORGIA INTO THE CAROLINAS AND MID-ATLANTIC...

   ...SUMMARY...
   Isolated strong to severe thunderstorms capable of producing
   damaging winds and perhaps a couple of tornadoes appear possible on
   Monday from parts of Florida and coastal Georgia into the Carolinas
   and Mid-Atlantic.

   ...Florida/Coastal Georgia into the Carolinas and Mid-Atlantic...
   A large-scale upper trough should evolve into a closed low over the
   Midwest/OH Valley and central Appalachians on Monday. A mid-level
   vorticity maximum embedded within this upper trough is forecast to
   move quickly northeastward from the central Appalachians into the
   Mid-Atlantic through Monday afternoon. A deep surface low should
   likewise develop northeastward in tandem with this vorticity
   maximum. A cold front trailing from this surface low will likely
   sweep eastward across much of the FL Peninsula and the East Coast
   through the day. A warm front extending northeastward from the
   surface low will probably make some northward progress across parts
   of the Mid-Atlantic through Monday afternoon as well.

   A line of low-topped showers/storms along or just ahead of the cold
   front should be ongoing at the start of the period from near the
   surface low in WV/western VA southward to northern FL. Although
   instability may remain modest across most of the warm sector ahead
   of this line, generally low to mid 60s surface dewpoints should be
   enough to support weak surface-based instability through the day. A
   very strong (50-60+ kt) south-southwesterly low-level jet should be
   present over the central/eastern Carolinas and southern VA Monday
   morning, and this feature is forecast to shift northward across the
   Mid-Atlantic through the day. 

   Given the strength of the low-level flow and sufficient, albeit
   weak, forecast instability, strong to damaging winds may occur with
   storms that either persist along the cold front or develop ahead of
   it over the open warm sector. A couple tornadoes also appear
   possible, mainly across parts of eastern SC/NC/VA to the Delmarva
   Peninsula and perhaps NJ in associated with the low-level jet and
   potentially greater low-level moisture and instability. Even so,
   there is too much uncertainty regarding sufficient destabilization
   to include higher severe probabilities for now.

   Farther south, low-level convergence along the cold front and
   deep-layer shear are both forecast to be somewhat weaker across
   coastal GA and the FL Peninsula. Still, there may be isolated
   strong/gusty winds with any storms through Monday afternoon.

 

Screen_Shot_2020-11-28_at_5_55.19_AM.png

Walt, 

Any idea on why western areas aren't exactly looking to get in on these big winds? I assume inversions in the soundings? 

 

This is the latest GIS gust map.

NE_WGust.png

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10 minutes ago, crossbowftw3 said:

Walt, 

Any idea on why western areas aren't exactly looking to get in on these big winds? I assume inversions in the soundings? 

 

This is the latest GIS gust map.

NE_WGust.png

Good morning.  The lower level jet is strongest along the coast (often the case) and transfer may be diminished by the the isothermal or even inverted sounding in the lowest 2000 feet.  HOWEVER, if there is a meso low on this front as it crosses PA/NJ... that will induce 50+ gusts northward into NYS.  The EC transfer is a little less the past several cycles than previous but still says 45-50 MPH gusts for NYS ne PA.  So,  the collaborated max gusts as offered are a good start for a conservative message.

I see PHI raised the Poconos in comparison to nearby offices and that should be a good move.  

Spreaking for myself only, I'm a high ender preparer.... I look for the big problem.  Doesn't always work out. I factor in SVR gust potential and raising the guidance so EM's etc knew my-our thinking of potential and imo, I think this is better preparation visually.  I just don't like being caught flatfooted. Preparation imo, is very important for poise, provided those advance messages are reliably correct-no 50 50 chance of being right every time issued. 

Thanks for your post. I may be away from the forum at times today-decorating but will try to update forenoon or late this afternoon. 

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1135A post: FOUS is down, favoring e CT/se New England with best bashing of wind gusts... however, R# at LGA to about 930 MB all afternoon and NAM 3k 50KT down to about 960MB suggests to me, that if we get short lines of convection as modeled by the 12z/28 3K NAM ripping ne along I95 at 45-50 kt from Philly area,  that we will have wind damage in and near NYC, eastward and northeastward.  Again... if modeling weakens then this will have been a brief windy dousing.  As of now, I continue to expect everything outlined in the topic and previously.  Tomorrow morning we should have more guidance that I'm looking for but is only short term.  May post again around 5P...otherwise for sure tomorrow morning 7A. 

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Should know more tomorrow morning... guidance continues to punch us up Monday as the system just about reaches max intensity in its passage through our area.

Some of the  SPC short range guidance now has mean gusts ORF area 12z Monday 40-45 MPH really seeped rapidly northeast and intensify. 

Not much else to add for now, except the EC is going for quite a substantial snow event (8+") north and west OHIO, then eventually on Tuesday to a lesser extent, spreading in its dying embers, across northeast OHIO into nw PA. 

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GALE Watch for Monday AM to midnight in the coastal areas.

As indicated on models, wind gusts inhibited on the land areas.       But I will get some gusts by being near ocean.

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Good Sunday morning all, 

Preparing for a wind event near or just a little under November 15, I think is worthwhile.

Model consensus still lacking... but from what I can gather,  I'd prepare for two bursts of 45-55 knot gusts along the NJ coast, LI snd CT, with 40-50 kt gusts in the interior of NJ/se NYS where ridges seem a best fit for strongest gusts there.  IF a narrow line of showers/tstms moves east late in the across the forum... damage  will be accentuated. The low level sounding will be critical for transfer...even so I think there will be 50 Knots of wind ~500 feet above us, available for transfer with a 70-80kt 850 jet over LI Monday afternoon. I expect peak gust ~ 45 kt for many of the NYC/LI ASOS  airports in the window of Noon-6PM.  Thunder should occur in parts of our forum. 

Here is some of the graphical guidance...

What we need to look for to avoid damaging wind Monday, is a DECREASE in this guidance and NO shallow convective line in later modeling.

Right now the 06z/29 FOUS has BL winds of 34kt and 27 kt for LGA and PHL respectively Monday (36 kt at BOS).  This is very similar to that of November 15. 

I'm adding the last PGH of this mornings SPC D2 outlook for our area.  Then some graphics:  a couple from the SPC HREF (MINIMUM) wind gust potential in MPH, for 3PM Monday. 

The 00z/29 GEFS gust greater than 50 MPH is added for Monday afternoon--impressive!

Then some experimental HRRRX 80 meter wind guidance and 10 meter max wind gust potential in knots, at various times Monday afternoon. The HRRRX seems a little strong but it's possible and worth keeping in mind. 

Farther north (from the Delmarva into coastal southern New England),
   the primary severe threat will be later into the afternoon as the
   triple point moves across the region. Low probability potential
   exists for the development of a narrow and shallow line of
   convective along the cold front extending southward from the triple
   point. Even less instability is anticipated here than farther south
   and any convection will likely become elevated above a low-level
   stable layer, but the very strong wind fields suggest than even a
   shallow, elevated storm may be able to produce a strong gust at the
   surface.

 

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Pretty interesting to see. Accordingly BOX did hoist high wind watches. I would suspect advisories by Upton by later today.

 

Here inland from the city I still expect only 20-30 gusts with maybe 30-40 in elevations. Current point and click has winds sustained 10-15 with gusts to 25 at my house at 750' which seems reasonable. Still have the fairly obvious inversion in soundings.

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Yes... good for BOX.  IF svr occurs Carolinas overnight or tomorrow morning, then redevelops VA/MD midday... going to be widespread minor or greater power outages Monday-Tuesday inclusive of what I think is probably coming for parts of OH, w PA with wet snow. Still tbd the intensities but I saw the GFS has been getting closer to the EC on pressure in recent cycles. 

 

Yes on soundings as you note.. lets see how good the guidance is. Suspect the presentations posted MAY be 5MPH too high, but not much more than that and they could verify.  I don't know how your house behaves, but I'm also at about 750' in Wantage NJ and I'm thinking gust 32 possibly 45 MPH if convection rolls thru to enhance 3P-6P. 

 

Probably offline til 10AM ish. 

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Walt, great thread as usual. The 12z NAM has 70kt down to 950 mb on Long Island Monday afternoon. The 6z run indicated that this would be a 5 SD LLJ event. The NAM also has an elevated convection sounding which could enhance severe or damaging wind gust potential in excess of 60 mph on Long Island.

3C042C67-3EB4-4385-A1DE-D52C1B8A6C3C.thumb.png.c5e492b69847131a246b522e265ada41.png
AD9ECE28-A438-49D2-A800-E2E4D18803D3.thumb.gif.dae167c6147115f517cacb55dc21196f.gif

 

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Eek. Being fully exposed to the ESE and being 400 feet off the general valley floors in the area I worry about lows getting into the NY Bight and sending the winds accelerating up the gradual southern slope below me. Every time we get winds out of that direction it takes out trees, thankfully the leaves are down already. I think I'll fire up the generator this afternoon just to be sure I don't get caught short.

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26 minutes ago, bluewave said:

Walt, great thread as usual. The 12z NAM has 70kt down to 950 mb on Long Island Monday afternoon. The 6z run indicated that this would be a 5 SD LLJ event. The NAM also has an elevated convection sounding which could enhance severe or damaging wind gust potential in excess of 60 mph on Long Island.

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Excellent supporting model guidance Bluewave!  Still can be complications and lots of AMWX folks saying, what wind? .  SSE or se wind for the first burst.  The late afternoon burst might be bigger.   Need more guidance from the 12z cycle but I ado think we're on track for a fairly substantial event. 

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28 minutes ago, wdrag said:

Excellent supporting model guidance Bluewave!  Still can be complications and lots of AMWX folks saying, what wind? .  SSE or se wind for the first burst.  The late afternoon burst might be bigger.   Need more guidance from the 12z cycle but I ado think we're on track for a fairly substantial event. 

The wind will be enhanced by the N/S running Ct and Hudson River canyons. Especially near the West Point area where the mountains right along the River shoot up from sea level to 1,200’. It will be a tough afternoon for the Hudson River bridge crossings especially for those high profile vehicles.

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Nog much change in the D2  SPC update... the reasoning  below. 

...Chesapeake Bay vicinity to Coastal Southern New England...

   Instability will quickly diminish with northward extent as deeper
   boundary layer moisture lessens and cooler surface temperatures are
   forecast. Nevertheless, a couple hundred J/kg MLCAPE is evident in
   forecast soundings in conjunction with strong southerly shear.
   Forcing for ascent will also be maximized across the area, and
   low-topped bowing line segments will be possible in the high-shear,
   low-CAPE environment. Locally damaging gusts will be the main
   concern with this activity. A shallow low level inversion will
   likely limit tornado activity, however, this limitation could be
   overcome near the surface low and along the warm front, and a
   tornado or two can not be ruled out. 

 

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EC gusts 'roughly' as depicted... by the 12z/29 EC... these numbers are in knots..too small for my aging eyes to clearly read but it looks like lots of 50s coastal NJ into New England. Continues to look to me like LI CT hit hardest but if a low top line of storms develops in the wake of the warm frontal 2 hr torrents during midday,  then the  mid-late afternoon convective gusts could be damaging in e PA/NJ/and possibly se NYS.Not a lock but but worthy of monitoring. 

Also fwiw...to maintain self discipline... i use these at MPH instead of knots, trying to be conservative.  The potential is there for these in knots but sounding's isothermal lapse rate is always a concern for suppressing potential. 

Also..fwiw... and probably too high, but I see the EC has 15-20" of snow near CLE by Wednesday morning and quite a large area of 6+ snow DEPTH in OH. Interesting. We'll see what happens. Off line til 530PM ish. 

Screen Shot 2020-11-29 at 1.17.51 PM.png

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40 minutes ago, Intensewind002 said:

I'm somewhat surprised there is no high wind watch issued for NE and SE Suffolk

From the look of it this should be an advisory wind event. High wind criteria is 57mph or over I believe. 

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