RSS Mesoscale Discussions from Storm Prediction Center
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0152 PM CST Wed Nov 05 2025
Valid 052000Z - 061200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
PACIFIC NORTHWEST COAST AND ACROSS THE LOWER GREAT LAKES INTO PARTS
OF NEW ENGLAND...
...SUMMARY...
Isolated severe thunderstorms are possible through the day along the
western Oregon and far northern California coastal region. Strong to
locally severe gusts may accompany shallow convection that develops
over parts of the Northeast.
...20z Update...
The only adjustment was a northward expansion of the 2% tornado and
5% wind risk probabilities across the far southwest WA coast. Recent
imagery from KLGX shows a cluster of semi-discrete cells off the far
southwest WA coast with weak, but discernible, mid-level rotation.
Regional VWPs continue to show ample low-level shear, and surface
temperatures are warming to near/slightly above the upper-end of the
ensemble envelope. These kinematic/thermodynamic conditions may
support at least a low-end wind and brief tornado threat along the
coast.
Across the Lower Great Lakes/New England, regional VWPs are sampling
40-50 knot winds at around 2 km AGL. Forecast soundings suggests
that winds at this level should reside well within the shallow CAPE
profile along/just ahead of the front. This lends confidence in the
potential for sporadic damaging winds, even though lightning
production may be very limited. For additional details see the
previous discussion below.
..Moore.. 11/05/2025
.PREV DISCUSSION... /ISSUED 1027 AM CST Wed Nov 05 2025/
...Northeast/southern New England...
A mid-level trough initially analyzed over the Great Lakes will
steadily amplify southeastward and reach coastal New England
tonight. A deepening cyclone will quickly move east across the
Lower Great Lakes toward coastal New England tonight in tandem with
a cold front.
Model guidance continues to show near neutral/scant buoyancy
profiles developing immediately ahead of the front. Despite this
limited thermodynamic setup, strong large-scale forcing for ascent
will act to augment the development of shallow convection later
today through this evening. Around 40-60 kt of west-southwesterly
flow within the lowest 1-2 km AGL will support a risk for downward
momentum transport for a few strong, potentially damaging wind gusts
(55-65 mph) during the afternoon and evening.
...Northern California and Oregon Coasts...
Water-vapor imagery this morning shows a mid-level shortwave trough
moving northeast across northern CA into southern OR as a
larger-scale troughing is maintained along the Pacific Northwest
coast. The mid-level cold pocket accompanying the trough will
result in -22 to -24 deg C 500-mb temperatures atop a moist maritime
airmass. Forecast soundings show upwards of a couple hundred J/kg
MLCAPE with the greatest buoyancy near the coast. Widely scattered
thunderstorms will episodically move inland. Very strong flow in
the lowest 1-2 km will support the possibility for isolated strong
to severe wind gusts. Forecast soundings do show some low-level
curvature closer to the coast, with 150-250 m2/s2 effective SRH. As
such, if a sustained, land-falling low-topped supercell can develop,
a brief tornado could occur.
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0130 PM CST Wed Nov 05 2025
Valid 071200Z - 081200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE TN
VALLEY...
...SUMMARY...
Isolated to scattered severe thunderstorms are possible, mainly
Friday afternoon to evening, from parts of the Deep South to the
Ohio Valley.
...Synopsis...
A broad mid-level trough which will dominate the eastern two-thirds
of the CONUS on Friday will have several embedded shortwave troughs.
The most notable of these will be a mid-level trough across the Ohio
Valley with an associated cold front extending from the southern
Great Lakes to the Lower Mississippi Valley on Friday afternoon.
...TN/KY into far southern Ohio...
Weak instability may develop on the northern periphery of the
advancing warm sector across TN/KY and southern Ohio during the day.
NAM forecast soundings show at least marginal surface based
instability to the Ohio River with at least some potential that it
extends farther north. While instability will not be great in this
region, strong lower tropospheric flow will support some damaging
wind threat with any organized storms.
The greatest coverage and intensity of severe storms is anticipated
across Middle Tennessee and vicinity where pockets of moderate
instability may develop within a supercell wind profile. As height
falls overspread the cold front/warm sector, expect storms,
including some supercells, to develop. Long, straight hodographs
will primarily support hail and wind, but some localized areas of
low-level backed flow could support an isolated tornado threat.
Greater instability (moderate to potentially strong) is forecast to
develop across central MS/AL during the afternoon. Forcing will be
more subtle that far south, but weak height falls may be sufficient
for a few storms to develop within an uncapped airmass Friday
afternoon. Moderate (35 to 40 knots) effective shear will support
supercell storm mode with anything that develops across this region.
A conditional threat for mainly large hail may exist with this
activity. However, a Level 1/MRGL threat appears sufficient given
storm coverage uncertainties farther from the upper-level forcing.
..Bentley.. 11/05/2025
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