SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Tue Sep 13 2022
Valid 131200Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN NEW
YORK INTO PARTS OF NEW ENGLAND...
...SUMMARY...
Thunderstorms capable of damaging wind gusts, isolated hail, and a
brief tornado or two are possible today from eastern New York into
parts of New England, with the greatest threat expected during the
afternoon into the early evening.
...Eastern New York into parts of New England...
A midlevel cyclone is expected to traverse the lower Great Lakes
region during the day today, before evolving into an open wave and
moving across northern New England this evening. As this occurs, a
surface cyclone is forecast to gradually deepen over northern New
England into southern Quebec, as an attendant cold front moves
across New York into southern New England by this evening.
Multiple rounds of convection are possible from eastern New York
into parts of New England today, as ascent associated with the
approaching midlevel cyclone spreads across a relatively moist
environment. Morning convection/cloudiness may tend to limit diurnal
destabilization, but some modest heating will be possible in the
wake of early-day activity, prior to the arrival of the cold front.
MLCAPE of 500-1000 J/kg is expected by early afternoon, with locally
higher values possible wherever temperatures can warm into the
mid/upper 70s F. Renewed storm development will be possible
along/ahead of the front by early afternoon, with increasing
deep-layer shear supporting the potential for a few organized storm
clusters and/or marginal supercells.
Even if organized storms develop, some uncertainty remains regarding
the severe potential, with the environment not expected to be overly
favorable for any particular hazard. Wind damage appears to be the
most likely threat, given the potential for a few longer-lived
clusters to move through the region. A 15% wind area has been added
where confidence is highest in the development of organized
convection during the afternoon. Generally weak midlevel lapse rates
will limit the overall hail threat, though some hail cannot be ruled
out with any sustained supercell. Low-level flow/shear will not be
particularly strong, but a brief tornado or two will also be
possible, especially where surface winds become backed in the
vicinity of any boundaries generated by early convection and/or
differential-heating zones.
...Arizona...
A midlevel trough (associated with the remnants of T.C. Kay) is
expected to gradually weaken and shift northeastward through the
day. Some drying and reduction in storm coverage is expected across
southwest/south-central AZ, but scattered thunderstorms are again
expected from northern into southeast AZ during the
afternoon/evening. At this time, deep-layer shear is expected to
remain rather weak, which should tend to limit any organized
severe-thunderstorm risk.
..Dean/Weinman.. 09/13/2022
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