Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS01 KWNS 251956
SPC AC 251955
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0155 PM CST Sat Feb 25 2017
Valid 252000Z - 261200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM A PORTION OF
THE MIDDLE ATLANTIC INTO EASTERN NEW YORK AND WESTERN NEW ENGLAND...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN
NORTH CAROLINA THROUGH A PORTION OF NEW ENGLAND...
Thunderstorms capable of producing isolated damaging wind and large
hail will persist through early evening from North Carolina through
Virginia and Maryland. Threat for mainly isolated damaging wind,
hail and a brief tornado or two exists farther north from eastern
Pennsylvania through eastern New York and western New England.
...Eastern North Carolina through Virginia and the Northeastern
Primary change to current outlook has been to trim from the west and
introduce a 15% hail category over eastern VA, MD and southeast PA
where discrete supercells have developed within zone of stronger
boundary-layer destabilization. These storms will continue to pose a
risk for isolated damaging wind as well as large hail. Farther north
across eastern New York into western New england, a dominant linear
mode will promote a risk for mainly isolated damaging wind into
early evening, but a brief tornado cannot be ruled out.
.PREV DISCUSSION... /ISSUED 1013 AM CST Sat Feb 25 2017/
...NY/VT into NC...
A strong upper trough is rotating across the mid MS and OH valleys
today, with the associated surface cold front extending from western
NY/PA southward into western NC. A band of showers and isolated
thunderstorms is present ahead of the front. This activity is
moving into an area where breaks in the clouds and dewpoints in the
50s will yield marginal CAPE values and the potential for
intensification. Strong winds aloft and focused forcing along the
front, coupled with model consensus of a broken squall line later
today, suggest a risk of a few storms intensifying to severe levels
this afternoon. Fast-moving bowing structures capable of locally
damaging winds would be the main threat, although hail may also
occur in the strongest cores.