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SVR (iso FF) potential 4P-mid Sat and Mon, then during the day Tue


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Uncertainty as always but SPC has expanded their D1 into our area, and the attached 12z HRRR suggests iso 50-55KT gusts into PA/NJ/LI, mirroring the 00z/19 EC OP. 

Looks to me like 90-95F today (non marine), decent CAPE.  The severe risk suppresses south tomorrow, but WAA begins late Sunday and then both Monday and Tuesday look steamy 90-95F inland, depending on sunshine which also implies cirrus from Claudette  possibly tempering heat/cape.

This should result in pockets of heavy convection, and where training,  could see a ISOLATED max of 4" by 6PM Tuesday.  Otherwise, the necessarily more conservative early Saturday WPC outlook works.


So while not a big deal (yet) for heavy rain,  the convection later today, later Monday and Tuesday could provide some news (damage) footage, including lightning related.




Screen Shot 2021-06-19 at 10.26.53 AM.png

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Looks to me like the HRRR is the way to go, with some south extension blend of the EC/GFS etc.  Models have generally missed Nw PA and sw NYS, even CT.  I have no answer except the 19z HRRR cons spewing near 50KT gust ne NJ across n LI this eve.  Whether that occurs, per SPC and my gut, am not confident but this is a developing situation into this eve.  Should be decent qpf I78 to I80 and maybe LI. 


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n/c from the overall expectations the next 3 days.  timing will mean a lot for Tuesday.  

WAA isolated or a couple of clusters of showers/storms late today this eve for NJ/NYS/PA;

Dying line of SVR appears likely into se NYS/w NJ Mon eve;  then the timing of convection and potential svr for Tue. Right now, SPC doesn't like our chances for Tue.

Have a wonderful Fathers Day!

Attached RFC produced real for yesterday.  Seems a little low in the axis, as per previous post of weather station data.  Also low per pure radar estimates. 



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So you saw the spotty thunderstorms Sunday afternoon NNJ and extreme as NYS I think dying in sw CT last eve.  

Haven’t looked real close but believe big storms die out NYC li in the 10ptomidnight time frame today w SPC severe just w of NYC.   Tuesday may. Or be severe if this eve is, but have to thiink band of beavy showers and storms Tuesday I95 corridor east. Gotta go

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Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1114 AM CDT Mon Jun 21 2021

   Valid 211630Z - 221200Z


   Scattered severe thunderstorms are expected from the upper Ohio
   Valley and Mid-Atlantic into northern New England, capable of
   damaging gusts, sporadic severe hail, and perhaps a couple of

   ...Northeast States...
   Water vapor imagery shows a broad upper trough digging across the
   Great Lakes region, with the associated cold front sweeping across
   southeast Ontario and OH.  Mostly clear skies and dewpoints in the
   60s to lower 70s ahead of the front, coupled with steep midlevel
   lapse rates shown on 12z raobs and model forecast soundings will
   yield a moderately unstable air mass by early afternoon (MLCAPE over
   2000 J/kg).  It appears thunderstorms will develop by early
   afternoon along the front - and in the free warm sector to the east.
    Vertical shear will be sufficient for a mix of multicell and
   occasional supercell structures, capable of damaging winds and large
   hail.  Low level shear is strongest over Quebec, but may be
   sufficient over parts of VT/NY for an isolated tornado or two as
   well.  Activity will sweep eastward across the ENH risk area through
   the early evening, before weakening as it approaches cooler
   marine-influenced air mass over eastern New England and NJ.



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I've got a few minutes to add some impressions... Watch likely MCD is out.  


NJ expectations later in the day/eve.  


Will check CoCoRAHS for two days and revisit tomorrow.  WPC is rather paltry on qpf the next 24 hours, so i could be misreading. 

Screen Shot 2021-06-21 at 2.08.29 PM.png

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Warnings OH/PA at 1, probably to NJ by ~7PM ish.  Should be pretty fast moving. Max rainfalls so far past two days ~1.5" sw Ct and N Central NJ.

Unsure whether 12z/21 EC is a tease overdone, but if not... plenty of rain coming with high KI,  PWAT, and some decent Cape NYC eastward tomorrow + decent flow aloft.

Clusters heavy rain and weak sfc CAA Tuesday may limit the svr threat Tuesday, but eastern LI might be interesting?  For now, though would monitor this evening in our subforum.

I probably won't be able to contribute after 430P-10P.

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Mesoscale Discussion 1056
   NWS Storm Prediction Center Norman OK
   0550 PM CDT Mon Jun 21 2021

   Areas affected...central and eastern New York  into northeast
   Pennsylvania and far northern New Jersey

   Concerning...Severe Thunderstorm Watch 300...303...

   Valid 212250Z - 212345Z

   The severe weather threat for Severe Thunderstorm Watch 300, 303

   SUMMARY...A line of severe thunderstorms with a history of severe
   gusts and wind damage will likely continue to pose a risk for
   damaging gusts and perhaps a tornado or two this evening. Additional
   storm development/consolidation across southern New York and
   northeast Pennsylvania will pose a risk for damaging winds.

   DISCUSSION...Ahead of the cold front moving across western New York,
   a line of thunderstorms near Syracuse has produced a measured severe
   gust and numerous reports of wind damage over the last hour. Radar
   data shows a well developed comma head/bowing segment developing
   east of the KTYX radar. Damaging winds will be likely with this
   cluster of thunderstorms as they track to the east northeast over
   the next couple of hours. Regional VWP data also suggests some
   mesovortex tornado threat may evolve with 0-1km SRH around 100 ms/s2
   and 0-3km line normal shear around 30 kts. Some weakening of this
   portions of the line may occur closer to the border with Vermont as
   downstream convection has resulted in some airmass modification.
   Until then, a corridor of greater severe potential will likely

   To the south across portions of northeastern Pennsylvania and
   southern New York, several clusters of developing thunderstorms were
   noted along a line from Binghamton to Allentown. Additional storm
   development should consolidate into a linear mode with the potential
   for increasing damaging wind threat as storms track through northern
   New Jersey and southern New York this evening.
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