SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Wed Jun 05 2024
Valid 051300Z - 061200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FOR MN/WI...LOWER MI/IN/OH...NORTHERN
VA/MD...SOUTHERN AND EASTERN ME...AND FROM SOUTH CENTRAL TX TO
SOUTHERN MS...
...SUMMARY...
Strong storms are possible across portions of the Upper Midwest,
Great Lakes, Northeast, Mid-Atlantic, and Texas Coastal Plain to the
southern Mississippi.
...MN/WI to the Mid-Atlantic this afternoon/evening...
Gradual pattern amplification is underway, with rising heights over
the Rockies and a deepening, downstream trough from MB to the upper
Great Lakes. A primary shortwave trough will dig southeastward from
ND to WI by tonight, accompanied by cool midlevel temperatures and
steep lapse rates below the 500 mb pressure level. Surface heating
and lingering boundary-layer moisture will contribute to
weak-moderate buoyancy in an environment with sufficient westerly
deep-layer shear/hodograph length for scattered, low-topped cells to
produce isolated wind damage and marginally severe hail this
afternoon across MN/WI.
Farther east, a lead shortwave trough will move generally eastward
from IA/WI toward Lower MI and northwest OH by this afternoon. An
associated, weak surface trough/cold front will accompany the
midlevel trough into the OH Valley, which will help focus
thunderstorm development this afternoon. Pockets of surface heating
will boost afternoon temperatures to near 80 F with boundary-layer
dewpoints in the mid-upper 60s, which will support MLCAPE up to 1000
J/kg. However, deep-layer vertical shear will remain rather modest
(effective bulk shear 20-30 kt) along with poor midlevel lapse rates
around 6 C/km, which suggests that isolated wind damage with
multicell clusters will be the main threat.
Remnant, convectively enhanced midlevel troughs will move
east-northeastward from WV and AL, coincident with the diurnal
heating cycle near and east of the Appalachians. Widely scattered
storm clusters will be possible this afternoon from GA into the
western Carolinas, but poor lapse rates and weak vertical shear will
limit any severe threat. Though lapse rates will be similarly poor
into the Mid-Atlantic, there will be a zone of stronger low-level
shear/hodograph curvature across northern VA/MD in advance of the
MCV approaching from WV. Here, a few weakly rotating storms could
produce isolated wind damage and a brief/weak tornado.
...TX/LA today...
An overnight MCS continues to move southeastward into east TX and
LA, though weak vertical shear has led to a cold pool dominated
system with the deeper convection trailing well north of gust front.
This MCS will likely continue to the northwest Gulf coast by late
morning and offshore by early afternoon. There will be some
potential for isolated strong/damaging outflow gusts, especially if
there is any temporary/diurnal strengthening of the storms.
However, the overall environment and convective structure suggest
that any wind threat should remain marginal. A few storms may
develop farther west this afternoon/evening along the trailing
outflow boundary in the area around DRT. Large CAPE/steep lapse
rates will support both strong updrafts and downdrafts, though weak
vertical shear will generally limit storm longevity and the
magnitude of any hail/wind threat.
...ME/NH this afternoon...
Downstream of shortwave ridging in the midlevels, a weak northwest
flow regime will persist today over northern New England. Lingering
low-level moisture, surface heating in cloud breaks southeast of the
higher terrain, and very subtle midlevel vorticity maxima will
support a few thunderstorms this afternoon across southern/eastern
ME and part of NH. MLCAPE of 1000-1500 J/kg and effective bulk
shear near 25 kt (with longer hodographs aloft) will be sufficient
for semi-organized storms capable of producing isolated wind damage
and marginally severe hail for a few hours this afternoon.
..Thompson/Grams.. 06/05/2024
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