RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Tue Jul 14 2026
Valid 141300Z - 151200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN NEW YORK AND NEW ENGLAND...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
MONTANA...
...SUMMARY...
Severe thunderstorms capable of producing damaging winds (isolated
75+ mph), large to very large hail, and tornadoes (some strong) are
expected today across parts of northern New York and New England.
Thunderstorms with scattered severe winds and isolated hail will
also be possible across portions of Montana.
...Northeast...
An active and potentially impactful severe weather event remains
apparent today across parts of the Northeast/northern New England.
Ongoing convection this morning now moving over the St. Lawrence
River in Quebec may tend to weaken as it approaches the
international border in the next couple of hours, as MUCAPE remains
quite weak at the moment with eastward extent into ME (reference the
12Z observed sounding from CAR). But if it persists, then an
isolated hail threat would be possible. In the wake of this
activity, an EML and strong mid/upper-level jet will overspread much
of the Northeast. Steepening lapse rates aloft combined with
filtered daytime heating and gradually increasing low-level moisture
advecting northeastward across the St. Lawrence River Valley will
all aid in the development of moderate to locally strong
instability. MLCAPE may peak in the 2000-3000 J/kg range by mid to
late afternoon across northern NY/VT/NH into western ME, generally
along/south of outflow from the morning convection. Strong mid-level
flow (around 50-60 kt) associated with a west-northwesterly
mid-level jet will foster similar values of effective bulk shear and
easily support organized updrafts, including the potential for
intense supercells.
Current expectations are for organized severe thunderstorms,
including a mix of clusters and supercells, to move southeastward
across southern Quebec by 19-22Z. The rather favorable thermodynamic
and kinematic environment across northern New England suggests a
significant threat for severe/damaging winds (some 75+ mph possible)
and large to very large hail (isolated 2+ inches) will exist with
this activity. While low-level flow will tend to remain from the
west-southwest, it is forecast to strengthen through the day, and
also veer strongly to north-northwesterly with height through
mid/upper levels. The resulting effective SRH appears more than
sufficient for updraft rotation, and multiple tornadoes may occur. A
narrow corridor of greater tornado potential (including strong
tornadoes) may exist this afternoon and evening across parts of
western into central ME if supercells can be maintained. Otherwise,
one or more intense clusters will likely spread east-southeastward
towards the coast through the evening while continuing to pose a
threat for scattered to numerous damaging winds and line-embedded
tornadoes.
...Montana...
A subtle mid-level shortwave trough on the western periphery of
upper ridging over the north-central CONUS will translate
northeastward through the period across the northern Rockies and
adjacent High Plains. Low-level moisture should continue to
gradually spread westward from eastern into central MT through the
day to the north of a weak surface low. The airmass from southwest
to central MT will destabilize by mid afternoon as daytime heating
occurs, and the boundary layer is forecast to become rather
well-mixed.
Large-scale ascent associated with the mid-level shortwave trough
and attendant 40-50 kt mid-level jet will support convective
development across the higher terrain of southwest MT by late
afternoon. This initial activity may pose both an isolated hail and
severe wind threat given weak instability and moderate to strong
deep-layer shear. With time, this activity should tend to cluster as
it spreads into central/eastern MT through the evening and
encounters greater low-level moisture and related instability. With
steepened low to mid-level lapse rates expected, scattered
severe/damaging winds and isolated hail appear possible with this
cluster. A Slight Risk has been included for parts of central of MT
where greater confidence exists in severe gusts occurring.
...Florida Peninsula...
Even though shear will remain weak, occasional gusty winds may occur
with the stronger thunderstorms that develop this afternoon across
parts of the FL Peninsula as low-level lapse rates gradually steepen
with daytime heating.
..Gleason/Thornton.. 07/14/2026
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0401 AM CDT Tue Jul 14 2026
Valid 171200Z - 221200Z
...DISCUSSION...
Ensemble guidance remains in good agreement that the US mid-level
pattern will transition from a CONUS-wide ridge centered over the
north-central US to a western US ridge and eastern US trough.
However the details of how this transition evolves are still
uncertain.
The general pattern through the forecast period will favor northwest
flow from the Upper Midwest southeast into the Mid-Atlantic and
areas north and east from there. Individual members of the ensemble
suite, including the control members, show several small
vorticity/speed maxima moving through the flow this weekend in quick
succession, with significant variability in the strength of these
waves. Ensemble guidance does have support for a more substantial
shortwave trough moving through the area, but differ on when this
will occur. For example, both the control runs of the ECMWF and GFS
have a stronger wave moving across the Great Lakes, but the GFS does
so on Saturday and Sunday, whereas the ECMWF does so on Monday and
Tuesday.
Thus, while the overall pattern will favor thunderstorm development,
perhaps in relatively quick succession, uncertainty is too high to
highlight any severe areas with confidence at current lead times.
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