SPC AC 080609
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0109 AM CDT Tue Jul 08 2025
Valid 081200Z - 091200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE
ATLANTIC...
CORRECTED FOR REGIONAL HEADER
...SUMMARY...
Scattered severe thunderstorms are expected across the Mid Atlantic.
More isolated activity is expected across portions of the Plains
into the Mid Mississippi Valley.
...Middle Atlantic...
Early-morning water-vapor imagery depicts a notable short-wave
trough over the upper MS Valley, shifting east in line with latest
model guidance. This feature is forecast to advance into the central
Great Lakes region by the end of the period. As the short wave
advances east, a corridor of higher PW (currently extending from AR
into the upper OH Valley) will be shunted downstream as a
low-amplitude disturbance ejects toward the Mid Atlantic. While some
suppression of the height field can be expected late, it appears the
weak disturbance should be the primary mechanism for encouraging
somewhat stronger southwesterly flow which would extend as far south
as central VA. Even so, 0-6km bulk shear is only expected to be on
the order of 20-25kt, but favorably oriented for clusters and short
line segments. Forecast soundings exhibit poor lapse rates, but
high-water content suggests damaging downbursts are likely,
especially with any organized clusters. Convective temperatures will
be breached by 17-18z as readings climb into the mid 80s, and
scattered thunderstorms should readily develop from central PA into
central VA. This activity will then propagate toward the Mid
Atlantic Coast with an attendant risk for damaging winds.
...Plains...
Upper ridge is forecast to hold across the southwestern U.S. through
the day1 period; although, northwesterly flow is expected to
increase a bit along the eastern periphery of this feature over the
High Plains. As a result, high-level diffluent flow will be noted
across the southern Plains into southern MO. At the surface,
low-level boundaries/convergence will prove weak, and left-over
convective debris will likely prove influential in late-afternoon
development. Early this morning, an MCS was propagating south across
eastern NE/southwest IA. This complex will likely advance into
southeast KS/southwest MO by sunrise. It's not entirely clear how
organized this cluster will be at the start of the period, but
convective outflow will likely contribute to additional development
later in the day. Strong boundary-layer heating will also aid
isolated thunderstorm development across the High Plains of eastern
WY/CO/NM. This activity will spread southeast during the evening
with a risk for hail/wind.
..Darrow/Weinman.. 07/08/2025
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
SPC AC 080556
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Tue Jul 08 2025
Valid 091200Z - 101200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS AS WELL AS PORTIONS OF THE SOUTHEAST INTO SOUTHERN
NEW ENGLAND...
...SUMMARY...
At least isolated severe storms are possible in the northern Plains
on Wednesday, with locally large hail and areas of severe gusts.
Isolated damaging gusts are also possible across parts of the
eastern U.S.
... Synopsis ...
A midlevel ridge centered over the four corners will begin to break
down on Wednesday as a low-amplitude shortwave trough quickly moves
from off the northern California coast into the Great Basin.
Additionally, a larger amplitude trough will move across southern
Canada. Elsewhere, broad mid-level troughing will persist across the
eastern US.
Surface lee toughing will exist across the northern Plains in
response to westerly downslope flow. This westerly flow will help
maintain steep mid-level lapse rates into the northern Plains atop a
moist boundary layer supported by southerly surface winds on the
east side of the northern Plains lee trough.
... Northern Plains ...
Strong diurnal heating should allow temperatures to warm into the
mid-to-perhaps-upper 90Fs across much of the Dakotas by mid
afternoon. This heating, coupled with surface dewpoint temperatures
in the 60Fs, will support surface-based CAPE in excess of 2500-3000
J/kg with little to no convective inhibition. Additionally, modest
northwest mid-to-upper-level flow on the northeast periphery of the
four corners ridge will support somewhat elongated hodographs and
effective-layer shear around 30 knots.
Despite the region being displaced from the stronger large-scale
ascent associated with the aforementioned shortwave troughs,
isolated thunderstorms are still expected to develop by late
afternoon. The overall thermodynamic and kinematic environment
should support multicell clusters to transient supercell structures
capable of producing large hail -- perhaps in excess of 2 inches in
diameter. By early evening any thunderstorm clusters persisting will
pose an increasing damaging wind threat.
A categorical upgrade to Level 2/Slight Risk was considered with
this forecast. However, given the nebulous forcing mechanisms for
initiating thunderstorms, uncertainty remains as to the coverage of
severe thunderstorms. As such a Level 1/Marginal Risk was
maintained, even though a potential for significant hail exists.
... Southeast US to Southern New England ...
Scattered to widespread thunderstorms will develop during the late
morning into the afternoon within a moist, unstable, and weakly
capped airmass. Precipitable water values around 2" will support
water loading of updrafts and a resulting potential for strong
thunderstorm winds capable of scattered wind damage.
..Marsh.. 07/08/2025
WUUS02 PTSDY2
SPC AC 080726
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0226 AM CDT Tue Jul 08 2025
Valid 101200Z - 111200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST SOUTH
DAKOTA...EASTERN NEBRASKA...NORTH-CENTRAL KANSAS...FAR NORTHWEST
MISSOURI AND WESTERN IOWA...
...SUMMARY...
Severe thunderstorms capable of producing large hail, damaging
winds, and perhaps tornadoes will be possible across portions of the
Central Plains. Elsewhere, strong to locally severe thunderstorms
may occur across the High Plains, northern Plains, and portions of
the Southeast US into the Mid-Atlantic.
... Synopsis ...
A low-amplitude shortwave trough will eject into the central Plains
during the late afternoon and evening ahead of a larger shortwave
trough that will impinge upon the northern Plains. At the surface, a
broad area of lower pressure associated with an initially diffuse
front will extend from northeast Colorado northeast to northwest
Minnesota.
... Central Plains ...
By mid afternoon surface temperatures will warm into the upper 80Fs
with dewpoints in the 70Fs beneath an area of steep mid-level lapse
rates. This combination will support most-unstable CAPE values in
excess of 3000 J/kg across portions of the region. At the same time,
the northern Plains trough will begin to interact with the central
Plains trough resulting in the central Plains trough taking on a
neutral to negative tilt as it is absorbed into the larger scale
flow. As this transition unfolds, strong forcing for ascent will
develop/overspread much of the central Plains. The expectation is
that thunderstorms will rapidly develop across portions of the area
-- currently anticipated across eastern Nebraska where a Level
1/Slight Risk is found. The degree of instability and effective
layer shear will support all modes of severe initially, with a
tendency toward large hail and damaging winds with time.
... Northern Plains ...
Here more uncertainty exists in the forecast evolution. Despite the
presence of extreme instability and a diffuse surface boundary by
midday, most guidance fails to develop robust convection. That said,
given the degree of instability will maintain a Level 1/Marginal
Risk to note the conditional threat for severe thunderstorms should
convection initiate.
... Southeast US into the Mid-Atlantic ...
Once again thunderstorms will develop within a very warm, moist, and
weakly capped atmosphere. Precipitable water values should be near 2
inches across a large portion of the area leading to water laden
downbursts capable of sporadic wind damage.
..Marsh.. 07/08/2025
WUUS03 PTSDY3
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1930Z
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