SPC AC 020551
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Sat Jul 02 2022
Valid 021200Z - 031200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN HIGH PLAINS AND FROM THE MIDDLE ATLANTIC INTO SOUTHERN NEW
Isolated to scattered severe thunderstorms capable of producing
damaging winds and hail are expected Saturday across parts of the
Northeast and Mid-Atlantic, as well as across parts of the northern
Plains. Isolated severe thunderstorms may also develop across parts
of the interior Pacific Northwest.
Large-scale pattern will not change appreciably over the next 36hr
as upper ridging holds across lower latitudes into the northern High
Plains, with broad troughing expected over the northeastern states.
This flow regime will ensure seasonally strong flow aloft will
extend from the Pacific Northwest-northern High Plains-northern
Middle Atlantic. Several weak disturbances will traverse this flow
field, though height changes will prove negligible through the
period, especially where buoyancy is expected to support robust
updrafts. Even so, several areas will likely experience
isolated-scattered severe thunderstorm activity, namely: 1) interior
Pacific Northwest, 2) northern/central High Plains, 3) middle
Atlantic into southern New England, and 4) along a trailing boundary
draped from KY into KS. The most concentrated corridors for severe
will likely be across the northern High Plains and from northern VA
into southern New England. In both cases severe wind gusts should be
the primary severe threat, though hail can not be ruled out.
...Northern/Central High Plains...
Latest satellite imagery and 00z model guidance suggest a weak
short-wave trough over ID will top the ridge over eastern MT around
peak heating. This feature is expected to aid convection across the
northern High Plains where easterly low-level component maintains
buoyancy within a very steep lapse-rate environment. Scattered
strong/severe thunderstorms should develop then propagate southeast
during the late afternoon/evening hours, as weak LLJ develops across
western NE into southeast MT after sunset. Supercells are possible
in this regime, but wind/hail are the primary risks as convection
spreads downstream ahead of the weak short wave.
...Middle Atlantic to Southern New England...
Modest westerly mid-level flow will extend as far south as the PA/MD
border during the day as upper trough shifts east into QC. The
trough will encourage a surface boundary to advance into southern
New England, arcing southwest into the central Appalachians by 18z.
This boundary should be the primary focus for potentially robust
updrafts, within a sheared environment that favors organized
multicell updrafts, and perhaps a few supercells. Strong surface
heating ahead of the wind shift will contribute to steep low-level
lapse rates, and this should aid potentially severe downdrafts with
the strongest activity.
Latest radar imagery depicts a small cluster of convection migrating
across the central High Plains into southwest KS. A weak mid-level
disturbance should progress downstream and likely aid convection
along a front draped across KS/MO. Strong daytime heating in the
wake of this feature should contribute to additional convective
development later in the afternoon, possibly focused along
aforementioned early-day convective outflow. Other isolated storms
should also develop along the slow-moving front into the lower OH
Strong 500mb speed max is forecast to translate through the base of
an offshore trough into southeast OR during the late evening. This
feature will likely contribute to robust convection across interior
OR, which will spread northeast as the exit region of this jet
translates into the northern Rockies.
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