ACUS02 KWNS 311746
SWODY2
SPC AC 311744

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1244 PM CDT Fri Mar 31 2023

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
NORTHEAST...AND OVER PARTS OF THE SOUTHEAST....

...SUMMARY...
Damaging winds are expected across parts of the Northeast Saturday
during the day and through early evening. Other severe storms will
be possible over parts of the Southeast.

...Synopsis...
A large shortwave-trough will move across the Upper Great Lakes and
OH Valley to the Mid Atlantic by 00Z, with substantial height
falls/cooling aloft overspread the entire region. An intense leading
midlevel jet streak will approach the Appalachians by midday, with a
secondary cold pocket and vort max aloft affecting the I-95 corridor
late in the day. To the south, moderate westerlies aloft will exist
over the Southeast, as the influence of the upper trough grazes the
area.

At the surface, low pressure should gradually deepen as it moves
east/northeast from southwest Ontario toward northern ME. Extending
east of the low track will be a developing warm front which will
bring 50s F dewpoints into southern VT/NH and perhaps ME. 

Although the primary surface low will move toward more stable areas
to the north, a prominent surface trough will develop southward
coincident with the secondary vort max moving rapidly east. While
various regimes of severe weather may occur with these features,
this secondary wave will affect the Mid Atlantic late in the day and
into early evening, and is expected to result in wind damage from
western MA and CT into far eastern PA, all of NJ, and parts of the
Delmarva. A few tornadoes may occur over southern parts of this
region.

Farther south, a front/dryline will slow as it moves into southern
AL and across GA during the day, with a more substantial cold front
pushing east across VA and the Carolinas. Scattered severe storms
are possible across these areas during the day.

...From eastern OH into New England...
The initial severe risk on Saturday will likely be tied to the
leading vort max associated with left-front quadrant of the midlevel
jet. Cold temperatures aloft will result in 250-500 J/kg SBCAPE in
the corridor from eastern OH/western PA across much of NY and into
New England by late afternoon. The combination of very steep,
deep-layer lapse rates along with increasing boundary-layer wind
speeds suggest any convection at all will have the potential to
enhance downward mixing. This seems likely given expected sufficient
instability. The northward extent of this damaging wind regime will
be limited by the warm front, and it is possible that this boundary
eventually makes it into extreme southern ME.

...From the Delmarva across NJ and into southern New England...
Southerly surface winds for most of the day will help deepen the
moist boundary layer, with a plume of upper 50s F to near 60 F
dewpoints from eastern VA northward across Philadelphia and into far
southeast NY. Strong heating will occur along and west of this moist
plume, priming the air mass for the arrival of an intense cold front
arrive very late in the day and into early evening for eastern
areas. Forecast soundings reveal supercell wind profiles with
effective SRH over 300 m2/s2, and long hodographs as well. The
forecast is for storms to form in the moist axis as the front
rapidly intercepts the moist air mass, with rapid changes taking
place aloft. Some of these storms could develop along coastal
counties as well, and at least isolated supercells are expected. A
conditional tornado risk will exist where SBCAPE remains favorable,
centered over NJ and DE. Damaging winds will be quite likely with
any strong convection given 50+ kt winds out of the northwest just
off the surface. Clearly, these will be able to mix to the surface.
Various models appear to be struggling with this area, thus there is
uncertainty in the magnitude of the severe risk. 

...Southern GA into the eastern Carolinas...
Scattered showers and a few thunderstorms may be ongoing ahead of
the surface boundary early in the day, beneath southwesterly 50 kt
850 mb flow and within a theta-e plume. Strong heating is expected
near the synoptic boundary and deepening surface trough, and the
presence of mid 60s F dewpoints will lead to ample instability to
support daytime storms despite lack of upper support. With time,
storms along the boundary may develop into supercells as deep-layer
shear will be strong and effective SRH averages 150-200 m2/s2. Any
supercell/tornado threat is expected to be limited as midlevel
subsidence occurs, but sporadic hail, a brief tornado, and damaging
gusts will all be possible through the afternoon. Rapid drying from
the west should push the severe threat quickly eastward across the
region and to the eastern Carolinas before 00Z.

..Jewell.. 03/31/2023

$$