RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Wed Nov 5 16:45:01 UTC 2025.
No Mesoscale Discussions are in effect as of Wed Nov 5 16:45:01 UTC 2025.
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0643 AM CST Wed Nov 05 2025
Valid 051300Z - 061200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHEAST AND OREGON/NORTHERN CALIFORNIA COASTS...
...SUMMARY...
Isolated severe thunderstorms are possible through the day along the
western Oregon and far northern California coastal region. Strong,
potentially damaging wind gusts may accompany the stronger showers
or low-topped thunderstorms that develop over parts of the
Northeast.
...Northeast/southern New England...
A trough will steadily amplify southeastward today over the Great
Lakes and Ontario/Quebec, reaching coastal New England tonight. A
considerably strengthening deep-layer wind field will accompany this
trough, accentuated by 80+ kt mid-level winds late today. A surface
low will steady deepen (approaching 1 mb/hr tonight) as it races
eastward across the lower Great Lakes toward coastal New England
tonight in tandem with a cold front.
Near-frontal/warm sector moisture will be meager, and surface-based
buoyancy will also be limited. Even so, modest diurnal
heating/destabilization could influence somewhat more stout
low-topped convection into late afternoon, and sustain into the
evening given the magnitude of the forcing for ascent/large-scale
mass response. Around 40-60 kt of west-southwesterly flow within the
lowest 1-2 km AGL will be present from roughly central Pennsylvania
to southern New England. As such, any stronger showers (or perhaps
short-lived low-topped thunderstorms) that can develop may encourage
sufficient downward momentum transport for a few strong, potentially
damaging wind gusts during the afternoon and evening.
...Northern California and Oregon Coasts...
As the mid-level trough overspreads the northern California/Oregon
coast this morning and a cold front moves inland, cooler
temperatures aloft will foster steep mid-level lapse rates atop a
maritime airmass, resulting in a couple hundred J/kg MLCAPE. Through
the afternoon, rapidly strengthening winds with height will be in
place, resulting in enlarged but mostly straight/elongated
hodographs. Any thunderstorms that manage to develop will be capable
of 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.
..Guyer/Kerr.. 11/05/2025
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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1027 AM CST Wed Nov 05 2025
Valid 051630Z - 061200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHEAST AND OREGON/NORTHERN CALIFORNIA COASTS...
...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.
...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.
..Smith/Thornton.. 11/05/2025
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1042 AM CST Wed Nov 05 2025
Valid 051700Z - 061200Z
...Southern Sierra Nevada and Owens Valley...
An upper-level trough and associated 70-80 knot mid-level jet over
northern CA/northwestern NV will bring gusty pre-frontal winds from
the south and southwest to portions of the Sierra Nevada today.
Strong downsloping in the lee of the southern Sierra Nevada is
currently supporting single digit relative humidity values in the
Owens Valley vicinity. South-southwest winds of 30-40 mph with gusts
to 60 mph are possible in wind prone areas. These strong winds
combined with 10-15% (below 10% locally) will promote a brief
elevated fire weather threat to the area, although generally cooler
temperatures and marginally dry fuels should limit a more
significant wildfire potential.
...Piedmont/Mid-Atlantic...
A strengthening surface low across southwest Ontario and approaching
cold front will promote increasing pre-frontal winds across portions
of the Mid-Atlantic today. Southwest winds of around 15 mph near and
east of the Blue Ridge along with relative humidity falling to
20-25% in localized areas will result in a period of elevated fire
weather conditions amid dry fuels. Similarly dry and breezy
conditions across eastern PA and NY Catskills are expected today but
recent rainfall and less receptive fuels should mitigate a broader
fire weather concern. The previous forecast remains on track with no
changes to existing Elevated highlights.
..Williams.. 11/05/2025
.PREV DISCUSSION... /ISSUED 1136 PM CST Tue Nov 04 2025/
...Synopsis...
The upper trough in the Great Lakes will intensify as it moves
eastward into the Northeast today. A surface low will simultaneously
deepen as it follows a similar track to its parent upper trough. A
cold front will make fairly rapid progress through the Ohio Valley
and Mid-Atlantic.
...Piedmont/Mid-Atlantic...
The deepening surface low moving into the Northeast will increase
the surface pressure gradient into the Mid-Atlantic. Ahead of the
cold front, winds of around 15 mph are possible near and east of the
Blue Ridge. There still remains some spread in guidance as to how
low RH will fall given at least some impact from upper-level clouds.
However, downslope warming should be sufficient to reduce RH to
25-35%. Elevated fire weather is possible within areas of modestly
dry fuels.
...Please see www.spc.noaa.gov/fire for graphic product...
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