SPC May 16, 2022 0600 UTC Day 1 Convective Outlook
[html]SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon May 16 2022
Valid 161200Z - 171200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE MID-ATLANTIC AND NORTHEAST...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE SOUTHERN HIGH PLAINS...
...SUMMARY...
Scattered to numerous severe storms are expected Monday from central
New York/western New England southward into the Carolinas. Damaging
winds, hail, and a few tornadoes will be possible through about 00Z.
In addition, scattered severe storms are expected to move from
eastern New Mexico into the Texas Panhandle with a threat for large
hail and severe wind gusts.
...Synopsis...
A mid-level trough will move from the Great Lakes to the
Mid-Atlantic during the day today. A 55 to 60 knot mid-level jet
will round the base of this trough and overspread portions of the
Mid-Atlantic during the afternoon/evening hours as the trough
beco*es negatively tilted. A surface low will develop along the
frontal boundary and deepen through the day as it lifts northeast
from western Pennsylvania into central New York.
Farther west, a ridge centered over the Rockies will deamplify
through the day as several weak shortwave impulses eject from the
broad trough over the eastern Pacific. The strongest of these
mid-level impulses will move from southern California at 12Z this
morning to the central Rockies by late this evening.
...Mid-Atlantic into the Northeast...
Storms should be ongoing at the beginning of the period along and
ahead of the surface front from eastern Ohio into eastern Kentucky.
Initially, instability will be limited due to the cool temperatures
and meager moisture (mid-upper 50s dewpoints). However, expect storm
intensity to increase by late morning as the boundary layer warms.
The greatest instability is expected across eastern New York, and
east of the Appalachian crests across the Mid-Atlantic where low 60s
dewpoints are already in place this morning and are expected to
increase further by early afternoon as the surface low deepens and
brings a higher theta-e airmass poleward.
The line of storms will likely be fractured across western
Pennsylvania and western New York during the morning, but it is
expected to congeal into a squall line by mid-day as storms reach
this reservoir of greater instability. In addition,
lower-tropospheric flow is forecast to strengthen gradually through
the day which should also aid in storm organization.
Strong instability and moderate lower tropospheric flow co*bined
with the strong forcing should support widespread damaging winds
along this squall line. However, modest lapse rates (6 to 6.5 in the
low and mid levels) and DCAPE (300-500 J/kg) may preclude the
potential for significant (65 kt) winds.
Moderately strong ascent atop an uncapped warm sector will likely be
sufficient for some warm sector storm development ahead of the
squall line. Moderate effective shear would support supercell storm
mode from this activity with primary threats of large hail and
damaging winds.
...Carolinas to the Gulf Coast....
A relative minima in low-level instability is forecast across the
Carolinas into Georgia this afternoon as dewpoints mix into the low
60s ahead of the cold front. Some isolated storms remain possible
with a marginal threat for large hail and damaging wind. The greater
storm coverage is expected along the Gulf Coast where dewpoints
should remain in the upper 60s to near 70, yielding moderate to
strong instability. Mid-level flow will remain quite weak across
this region, but may be sufficient for some multicell clusters. The
weak shear and inconsistent storm coverage from 00Z CAM guidance
precludes the need for a slight risk across this region.
...Central and Southern High Plains...
Low-level moist advection is occurring across the southern High
Plains this morning with 50 degree dewpoints to the TX/New Mexico
border. This will continue as lee cyclogenesis strengthens through
the day. As a result, low to mid 50s dewpoints are expected near the
dryline in eastern New Mexico by mid day. Mid-level height falls
will overspread the southern and central High Plains by mid day and
scattered storms are expected to develop along the dryline from
eastern Colorado into eastern New Mexico by early to mid-afternoon.
Shear will be sufficient for at least some storm organization and
potentially supercells early. However, forecast soundings are very
supportive for strong downburst winds and relatively quick cold pool
development, with upscale growth anticipated. This is supported by
the majority of 00Z CAM guidance which shows at least a broken line
of storms moving out of eastern New Mexico and into the Texas
Panhandle. Instability will increase with eastward extent which
could allow the threat to persist into the early overnight hours.
Have ended the marginal delineation in western Oklahoma where storms
are expected to be around 05-06Z which is approximately when storms
are expected to weaken.
...Portions of the Northern Rockies...
Storms are expected to form over the Continental Divide this
afternoon as a weak shortwave traverses the region. A few sustained
storms are possible given the weak instability and moderate
effective shear. Marginally large hail and a damaging wind gust or
two will be the primary threats from this activity.
..Bentley/Dean.. 05/16/2022
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Source: SPC May 16, 2022 0600 UTC Day 1 Convective Outlook (http://ht**://www.spc.noaa.gov/products/outlook/day1otlk_1200.html)