Is the threat for SVR in the northeast WED increasing?

[USAwx1]

Latest 0z ETA says so.

Convective instability will be strong w/ soundings at AVP indicating Boundary Layer CAPE above 5000 J/kg at 18z, w/ a wide area of LIs of -6 to -7 over PA and SRN NY.

Only real limiting factors would be weak deep layer shear in the lowest 6 KM, (which should remain post-frontal) and mid level (700-500H) lapse rates of less than 5.5 DEG C/km. Low level shear (using 1 KM SR-Helicity) is also marginal, which should limit the tornado threat, however i should have a look at hodographs before counting it out completely. Which is what i will do after this post.

However, with VERY strong instability in place -- as forced ascent/UVM increases across much of New York state and New england (which is where the PRIMARY threat will be at least early on ie...before 21z) thunderstorms will develop and become severe w/ the PRIMARY convective mode being multi-cells and bow segments.

Wind Damage will be the favored threat, however very intense convective updrafts associated w/ stronger storms MAY lead to a marginal threat for severe hail. this is also supported by SWEAT indices between 300-400, which similarly suggests a SVR threat, however are not within the range (usually 400+) which is associated w/ tornados.

Be careful of convective interactions which may increase localized shear, and thus tornado potential, something which the SWEAT index cannot resolve or account for.

the Boundary layer will slower to stabilize after dark, so strong to SVR storms will likely be ongoing well into the evening and overnight hours, w/ SFC dewpoints still at or above 70F over much of the region South of the cold front. Some temperature inversion was noted at 03z on the sounding at ABE, however, SB CAPE is still above 1000 J/kg, TTs 50, and LIs of -4.3. If lift is strong enough to overcome the Cap, and no Tw (wetbulb temp) inversion is present, then Strong and SVR thunderstorms w/ isolated wind damage may still be possible. as the cold front pushes SWD through the region.

As far as temperatures are concerned, the 0z ETA has 850H temps across the major cities of between 18-19 C south of the cold front w/ the exception of DCA at 21z (upper 60s to lower 70s dewpoints to compound that). So, w/ other variables considered, it should translate to Highs of 95-97 (35-36 C) Heat Indices will also be a problem, with some locations seeing Hi's > 100F.

In summary -- a HOT day (and there wont be ANY escaping it down at the shore either given westerly and SW flow in the lower levels, whch will prevent the sea breeze from making it inland until MUCH later in the day), w/ the primary severe threat running north of a line (keep in mind were talking about PRIOR to 18z here), from PIT to BDL, and out to the Cape.

[Brent]

How does the weather in DC look tomorrow and Thursday? The funeral procession for Reagan goes through the city tomorrow evening and then the people will be waiting to see him after that.

[USAwx1]

Tomorrow will be fine but the 3 H rule is in effect here --- HAZY, HOT and HUMID, thursday is into the crapper as the front approaches the region from the north. Lots of clouds and precip.

[USAwx1]

Already an active day in the Northeast and lakes -- As forecasted.

[Stormsfury]

Looking for the segments of thunderstorms to probably organize into a large squall line in the next couple of hours across NY/MA ... shear profiles aren't very impressive, however, the associated cool pool behind the convection should be able to give life to decent winds with the intensifying squall line.

Also, VIL's aren't running very impressive ... (highest DBZ that I saw was arond 45-50, so hail will probably not be much of a concern.)

SF

[USAwx1]

FRZ/WBZ heights are up there, which in concert w/ the weak shear (suggesting many unsteady updrafts driven by diurnal instabilty) should preclude hail threat, although some time ago, there were some impressive CAPEs in the -20 to -40 C layer.

High PW's, high 850H dewpoints and small Corfidi vectors suggest heavy rainfall and flash flooding may become a concern later.

the belt of strongest shear is mostly POST-FRONTAL beneath the mid and upper jet over SE CAN.

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