SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Thu Apr 14 2022
Valid 142000Z - 151200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A SMALL PART
OF THE MID ATLANTIC...
...SUMMARY...
Thunderstorms capable of strong wind gusts and marginal hail remain
possible across parts of the Mid Atlantic.
Little change was made to the outlook other than sharpening
probabilities along the advancing cold front.
...Discussion...
Storms are increasing in coverage along the cold front, primarily
from MD into southern NY. Deep-layer shear appears favorable for
primarily cellular storm mode, in which case marginal hail will be
possible given MLCAPE values of 200-500 J/kg. A few strong to severe
gusts may occur as well given timing of the storms with peak heating
and steep boundary-layer lapse rates.
Farther south into VA and NC, slightly stronger instability, though
also weaker shear, may also favor a few marginally severe storms
capable of hail or wind prior through early evening. For more
information, see mesoscale discussion 494.
..Jewell.. 04/14/2022
.PREV DISCUSSION... /ISSUED 1121 AM CDT Thu Apr 14 2022/
...Mid-Atlantic to Hudson Valley this afternoon/evening...
A deep occluded low over northern MN will move slowly
east-northeastward into ON as an embedded shortwave trough rotates
northeastward over the lower Great Lakes and Northeast. The
shortwave trough is accompanied by a surface cold front that will
cross the Appalachian crest early this afternoon and reach the
Mid-Atlantic coast this evening. Surface heating to the east of a
cloud band along the front will result in afternoon temperatures of
75-80 F inland from the coast, with boundary-layer dewpoints in the
55-60 F range across eastern PA/NJ to the Hudson Valley (west of the
cool air wedge across eastern New England).
Midlevel lapse rates will be poor, but the surface heating/mixing
will drive steep low-level lapse rates and MLCAPE of 500-1000 J/kg
in the pre-frontal warm sector. Relatively straight hodographs with
35-45 kt effective bulk shear will support a mix of multicell
clusters/line segments, and perhaps some low-end supercell
structures this afternoon, with a primary threat of damaging outflow
gusts. The severe threat should be limited to a roughly four-hour
window from about 19-23z, after which convection will move offshore
or weaken while encountering the cool air wedge lingering across
VT/MA/CT.
...VA to GA this afternoon/evening...
A remnant MCV from convection yesterday across MS/AL is now moving
northeastward into VA from NC, and will likely approach Chesapeake
Bay by mid afternoon. A few storms with strong outflow gusts may
form along or just ahead of the cold front from NC into VA this
afternoon where temperatures warm to near 80 F with dewpoints near
or above 60 F. However, the potential for organized storms will
diminish from southwest-to-northeast as midlevel flow weakens in the
wake of the remnant MCV. Farther south toward GA, severe storms are
not expected as a result of high-level cloud debris slowing surface
heating, in combination with weak vertical shear and only minimal
forcing for ascent.
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