KOKX AFD Updated at 8:33pm:
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Severe thunderstorm watch 691 is in effect until 1 am for NE NJ and
the Lower Hudson Valley. A low topped line of convection is
approaching along the strong cold front across upstate NY and
eastern PA. The line of convection should enter northern NJ and the
Lower Hudson Valley 02-04z and then quickly move east towards the
Hudson River Corridor. Instability is marginal, but strong low-level
flow and shear may help bring down severe wind gusts in the low
topped convection. It is entirely possible that no lightning is
observed when this line moves through.
High resolution models indicate the line weakens as it approaches
the NYC metro and then the remnants of the line race across Long
Island and southern Connecticut. The strong low level jet, 65-75 kt
at 925 mb will cross eastern portions of the area this evening and
into the overnight. Despite the weakening of the convection, these
strong winds just above the surface may come down with turbulent
mixing with the frontal passage 06 to 08z east of the city. It may
be difficult to mix some of the higher winds above the surface down
initially with inversion observed on the 00z OKX sounding. However,
gusts gradually increase this evening as winds at the top of the
mixed layer are around 50 kt. Could still see gusts over 45 mph
before the actual front and stronger momentum arrives. Wind
headlines have not changed since previous forecast. Strongest winds
still appear likely across eastern Long Island and southeast
Connecticut where the high wind warning remains in effect.
Locally heavy rainfall is possible, but the best chance of seeing
this is likely across the Lower Hudson Valley and NE NJ, with
weakening of the line of showers thereafter. Rainfall amounts are
likely to drop off significantly across Long Island and southern
Connecticut.
Temperatures in the mid to upper 60s with some low 70s possible
ahead of the front. Temperatures will drop rapidly behind the front
and could be in the 40s west of NYC and low 50s east by
daybreak.