may 10-16 convection

[HailMan06]

Wow SPC mentioning the D-word as a possibility.

[NJwx85]

[hudsonvalley21]

Keep an eye out for the descrete cells out in front of the advancing lines later. That's where most spin ups occur. 

[NJwx85]

 ...Northeast...
   Thunderstorms are expected to develop and grow upscale from midday
   through afternoon, sweeping eastward across the region with the main
   risk being severe wind.  The potential for a well-organized swath of
   damaging wind -- including a few gusts around hurricane force --
   appears greatest over the enhanced-risk area.  Large hail also is
   possible, especially in the first few hours of the convective cycle
   when storm modes can be more favorably discrete or semi-discrete.  A
   few tornadoes also may occur, whether from supercells or
   QLCS-embedded vortices.

   A nonsevere area of convection now moving across western NY and
   northern PA should reinforce the baroclinic zone across parts of
   south-central and eastern NY, which should act as a fairly sharp
   northern delimiter for substantial severe potential, given strongly
   stable air to its north.  The UVV field related to the MCV appears
   well-timed to encounter the destabilizing warm sector across
   northern PA today, along and south of the frontal zone, in support
   of initial development, which then should expand/intensify to severe
   levels as it moves rapidly eastward toward parts of southern NY, NJ
   and New England.  Whether the resulting convective wind event
   qualifies as a derecho may be a semantic exercise; impacts could be
   of that caliber in the area affected.

   One source of uncertainty in this scenario is an area of outflow to
   the south, across parts of VA/MD/Delmarva and eastern PA,
   originating from yesterday's MCS, and sampled peripherally by the
   12Z IAD sounding.  Airmass recovery is expected from the southwest,
   around the northwest rim of that outflow pool and south of the
   morning convective/frontal baroclinic zone.  Expect midday to
   afternoon preconvective destabilization arising from both theta-e
   advection and diabatic surface heating.  68-70 F surface dew points,
   such as forecast by the NAM, may be overdone considering the
   available recovery trajectories, and the nearest dew points that
   large are 300-400 nm away over NC, on the other side of the outflow
   pool.

   Regardless, a plume of EML air advecting over this region will
   foster steep midlevel lapse rates, overlying strengthening
   boundary-layer lapse rates and low/mid-60s F surface dew points. 
   That combination still supports peak MLCAPE in the 1500-2500 J/kg
   range, amidst strong west-southwesterly mean-wind and deep-shear
   vectors.  Forecast soundings suggest that, despite a nearly
   unidirectional vertical wind profile, effective-shear magnitudes of
   45-55 kt may be realized.  Downward momentum transfer from strong
   flow above 700 mb, into a well-mixed preconvective boundary layer,
   should offer favorable conditions for severe thunderstorm winds. 
   Given the strong westerly component of the near-surface flow,
   more-unstable inland air may be shunted eastward to very near the
   coast across much of the region, extending the severe threat
   accordingly, before the MCS encounters too much stable marine-layer
   air and weakens.

[NJwx85]

06z 3k NAM

 

[MJO812]

Partly sunny here

 

64 degrees

 

Looking forward to the severe threat later on unless it falls apart before reaching the coast .

[Rjay]

Fog burned off more quickly than expected here

[MJO812]

ABC 7

[NJwx85]

4 minutes ago, Snow88 said:

Partly sunny here

 

64 degrees

 

Looking forward to the severe threat later on unless it falls apart before reaching the coast .

SPC discussion indicated that the Westerly flow would help some of the more unstable air reach the coast which is why they extended the enhanced risk further Southeast.

[SnoSki14]

Very interested to see what happens later on, we've been very active overall since February. 

[TriPol]

2-5% chance of tornadoes! Yeah baby!

[LongBeachSurfFreak]

23 minutes ago, NJwx85 said:

SPC discussion indicated that the Westerly flow would help some of the more unstable air reach the coast which is why they extended the enhanced risk further Southeast.

That’s what I’m thinking. There isn’t your typical blasting onshore flow. One of the best setups I have seen for western LI. Obviously as you get far enough east there will be overwhelming marine influence. 

If we can get an organized MCS or ecpecially a derecho damaging winds are likely pretty much area wide. 

[Stormlover74]

12 minutes ago, SnoSki14 said:

Very interested to see what happens later on, we've been very active overall since February. 

Like with most severe weather events most people will consider it a bust if they don't get a tornado or golf ball sized hail in their backyard

[bluewave]

The MCS is in the early stages of development now with the warmed storms in NE Ohio. Racing east at 60 mph.

http://mp1.met.psu.edu/~fxg1/GOES_PA/loop60.html

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Cleveland OH
1027 AM EDT TUE MAY 15 2018

The National Weather Service in Cleveland has issued a

* Severe Thunderstorm Warning for...
  Southeastern Portage County in northeastern Ohio...
  Mahoning County in northeastern Ohio...
  Northeastern Stark County in northeastern Ohio...

* Until 1115 AM EDT

* At 1027 AM EDT, severe thunderstorms were located along a line
  extending from near Alliance to near Louisville to Canton, moving
  east at 60 mph.

  HAZARD...60 mph wind gusts and nickel size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to trees and power lines.

[NJwx85]

Pretty good low level wind shear on the soundings. Can't post pics, but a 21z sounding over NNJ on the 3k NAM indicates 15-30kts out of the Southwest below 900mb veering to 40-45kts out of the West between 700 and 900mb and then 50-60kts out of the WNW above 700mb. The hodograph shows the EML nicely.

[forkyfork]

the eml is here and there's no debris or crapvection. all systems go

[NJwx85]

[NJwx85]

 

[Rtd208]

Current temp 82/DP 67/RH 56%

Looking good so far.

[psv88]

temp rebounded nicely here, 76/66, clear skies

[NJwx85]

Mesoscale Discussion 423

< Previous MD

Mesoscale Discussion 0423 NWS Storm Prediction Center Norman OK 1043 AM CDT Tue May 15 2018 Areas affected...Central and northern Pennsylvania into southern New York and southwest New England Concerning...Severe potential...Watch likely Valid 151543Z - 151815Z Probability of Watch Issuance...95 percent SUMMARY...Severe storms are likely to develop over the next several hours from central and northern Pennsylvania into southern New York, continuing into southern New England by late afternoon. Severe wind and hail are likely across all areas, with a few tornadoes possible mainly from northeast Pennsylvania into southern New England. As such, one or more severe and/or tornado watches will be needed today. DISCUSSION...Surface analysis shows a cold front across northwest PA into OH, with a pre-frontal trough across central NY into central PA. A progressive area of early-day thunderstorms has produced outflow across much of southern NY to near the northern PA border. Satellite imagery shows strong heating is occurring across the warm sector, with a plume of mid to upper 60s F dewpoints spreading north across PA and NJ, and likely into southern NY later today. In addition, the aforementioned outflow will continue to modify, while likely maintaining some degree of enhanced low-level wind shear this afternoon. Thunderstorms currently exist along the cold front from western PA into western NY, and should continue a gradual increase in intensity as the air mass destabilizes to the east. In addition to these storms, other storms are expected to form near the surface trough, and perhaps atop the old outflow boundary. Deep-layer shear will favor cellular activity away from the cold front, while a mixed storm mode including bows or embedded supercells are possible along the front. Strong heating and steep lapse rates aloft will favor large hail, with an increasing damaging wind by the time storms organize into a line. Any cellular activity will be capable of large hail, perhaps very large, along with a few tornadoes where low-level shear is maximized. ..Jewell/Grams.. 05/15/2018 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOX...BTV...OKX...ALY...PHI...BGM...BUF...CTP... PBZ... LAT...LON 41207956 41757860 42017778 42427653 43007519 43357429 43487323 43337286 43047268 42567254 42027277 40857517 40327672 40177764 40197865 40467927 40797963 41207956

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[NJwx85]

I think the area in red has a chance at getting an upgrade to moderate risk and also a possible tornado watch

[purduewx80]

last few runs of the HRRR showing 60-80KT just above the surface with the line coming thru NYC. makes sense given where convection is developing now for a bow/qlcs to take direct aim. i do think there will be a few tornadoes, but as SPC says the most favored is along the boundary in the northern part of where you've circled, just N of NJ.

[Drz1111]

This is as good a setup as I can remember for NYC severe.   Yum.

[bluewave]

40 minutes ago, forkyfork said:

the eml is here and there's no debris or crapvection. all systems go

Some of the best midlevel lapse rates that our region has seen on May 15th. We finally have the big missing ingredient from warm season convection in recent years.

 

 

[Rtd208]

Just now, Drz1111 said:

This is as good a setup as I can remember for NYC severe.   Yum.

I am hoping this is the start of many good severe weather/heavy rain events for our area this warm season.

[Drz1111]

4 minutes ago, Rtd208 said:

I am hoping this is the start of many good severe weather/heavy rain events for our area this warm season.

well as long as you have that Hudson bay low and the ridging over the plains, we've got a shot.  Basically like an atmospheric river of barely-modified EML from the High Plains.

 

I can't stop gazing longingly at the 7.7 degree 700-500 lapse rate showing up on the model soundings. Swoooooooon

[purduewx80]

good call NJWX....about to upgrade to MDT almost exactly where you have it.

[NJwx85]

One of the most complete setups I can recall for this area. Only limiting factor I can think of is the marine influince close to the coast.

[TriPol]

10 minutes ago, Drz1111 said:

This is as good a setup as I can remember for NYC severe.   Yum.

Similiar to July 2011?