RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1141 PM CST Sat Dec 06 2025
Valid 071200Z - 081200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE FL
PENINSULA...
...SUMMARY...
Isolated damaging winds and a brief tornado or two are possible,
mainly across central Florida during the late afternoon and evening.
...FL Peninsula...
Abundant convective development is expected later this morning
across the north-central to northeast Gulf along a largely
west/east-oriented quasi-stationary front. Downstream
cloudiness/rain along/north of the front will support pronounced
differential boundary-layer heating across it, from central to north
FL. With most guidance indicating potential for an MCV to evolve
from the morning convection, within the broadly cyclonic mid-level
flow regime across the Southeast, it is plausible that convection
may strengthen along the baroclinic zone towards peak heating. Weak
mid-level lapse rates will remain a key limiting factor to
convective intensity. But adequate deep-layer shear will exist for
transient mid-level rotation. With a warm boundary layer anticipated
across central to south FL, a few strong gusts capable of localized
damaging winds are possible. While the 00Z NAM appears to be an
aggressive outlier with stronger low-level mass response, expected
modest low-level SRH may be sufficient for a brief tornado or two.
..Grams/Thornton.. 12/07/2025
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SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1100 PM CST Sat Dec 06 2025
Valid 081200Z - 091200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Aside from the possibility of a couple weak thunderstorms near and,
perhaps, inland of southern Florida coastal areas, the risk for
thunderstorms will remain negligible across much of the U.S. Monday
through Monday night.
...Synopsis...
The center of a fairly prominent, but relatively compact mid-level
vortex is likely to continue redeveloping east-southeast of southern
Hudson/James Bay, into and across the Newfoundland and Labrador
vicinity during this period. However, models indicate that
large-scale mid-level troughing will be maintained east of the
Rockies through the western Atlantic, downstream of persistent broad
ridging across the eastern mid-latitude Pacific into U.S
Intermountain West.
One notable short wave perturbation embedded within the troughing is
forecast to accelerate east-northeast of the southern Appalachians,
across and offshore of the southern Mid Atlantic, but this may
contribute to suppression of subtropical ridging as far south as the
Caribbean and Bahamas. In lower levels, an associated reinforcing
intrusion of cooler/drier air appears likely to contribute to the
southward advancement of the primary cold front through much of the
remainder of the Florida Peninsula and Gulf Basin.
At the same time, it appears that another notable short wave
perturbation, progressing through the crest of upstream ridge, will
provide support for surface cyclogenesis to the lee of the Canadian
and northern U.S. Rockies by late Monday night. This likely will be
accompanied by downslope aided warming across much of the high
plains, but dry, stable conditions will be maintained there and
across much of the remainder of the U.S.
...Southern Florida/Keys...
Latest model output remains varied concerning potential for
thunderstorm development along/ahead of the southward advancing
front. Mid/upper support appears weak, with potential for
appreciable destabilization, particularly inland of coastal areas,
limited as well.
..Kerr.. 12/07/2025
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SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0114 AM CST Sun Dec 07 2025
Valid 091200Z - 101200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
The risk for thunderstorms appears negligible across the U.S.
Tuesday through Tuesday night.
...Discussion...
Models continue to indicate little substantive change to the
large-scale mid/upper flow impacting the U.S. through this period.
Broad ridging is likely to persist across the eastern mid-latitude
Pacific into the U.S. Intermountain West and Rockies, with
downstream troughing east of the Rockies through the Atlantic
Seaboard and western Atlantic. The troughing is likely to be
reinforced by another significant short wave perturbation, digging
within northwesterly flow to the lee of the crest of the ridge.
It appears that this will be accompanied by a rapidly migrating
cyclone across the northern Great Plains through much of the upper
Great Lakes region by late tonight. In the wake of this feature,
models indicate an increasingly significant intrusion of cold air
will begin to surge southward into parts of the northern Great
Plains and upper Mississippi Valley, preceded by strengthening flow
veering to an increasing westerly component as far south as the Gulf
coast vicinity.
Even as the Gulf boundary layer begins to modify to the north of a
stalling and weakening front, south of the Florida Peninsula through
the southern Gulf Basin, appreciable inland moisture is unlikely
through this period and beyond.
..Kerr.. 12/07/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0248 AM CST Sun Dec 07 2025
Valid 101200Z - 151200Z
...DISCUSSION...
After becoming suppressed a bit, medium-range guidance indicates
that a blocking high may become more prominent again, near/north of
the Aleutians late this coming work week into next weekend.
Surrounding developments across the mid- and higher latitudes of the
Pacific do become characterized by increasing spread. However, it is
not yet clear how much impact this will have on downstream flow
across North America. It still appears that an increasingly
confluent northwesterly mid-level regime, between persistent ridging
across the eastern Pacific into western North America and downstream
troughing, may support the development of another expansive surface
ridge east of the Rockies into the Gulf Basin and Atlantic Seaboard
late this week through next weekend. This is likely to further
impede deep boundary-layer moistening over the northwestern Gulf.
Coupled with the lack of a developing southerly return flow from
the Gulf Basin until at least early next week, it appears that
generally stable conditions will be maintained through this period.
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