Mesoscale Discussion 2250
NWS Storm Prediction Center Norman OK
1225 PM CST Sat Dec 06 2025

Areas affected...Far southeast South Dakota and northwestern Iowa

Concerning...Heavy snow 

Valid 061825Z - 070030Z

SUMMARY...Periods of heavy snowfall are developing across portions
of far southeastern SD, and will continue to expand into
northwestern IA within an hour or two. Snowfall rates of 1 to 1.5"
per hour can be expected.

DISCUSSION...An area of moderate to heavy snow is expected to
broaden this afternoon through this evening across northwestern IA,
as a mid-level shortwave trough approaches. Increasing DPVA will
accompany this feature, in addition to strong isentropic ascent.
Most NWP models and forecast soundings suggest omega will peak
within the dendritic growth zone through ~22Z over northwestern IA.
HREF probabilities of QPF greater than 0.10" per hour, combined with
snow to liquid ratios around 15-20 to 1, also support this time
frame for the heaviest snowfall.

..Barnes.. 12/06/2025

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DMX...FSD...OAX...

LAT...LON   43709693 43699633 43629615 43589590 43509545 43439511
            43249476 43069448 42829426 42399452 42339494 42149520
            42109535 42119548 42159557 42189572 42229581 42269592
            42269606 42339633 42429642 42559654 42699686 42849722
            42999725 43449725 43709693 

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1013 AM CST Sat Dec 06 2025

Valid 061630Z - 071200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Synopsis...
A progressive flow pattern will remain over the Lower 48 states
today.  In the low levels, a front will reside over the Gulf and
extend east-northeastward across the northern half of the FL
Peninsula and east of the Carolina coast.  The 12 UTC Tampa, FL raob
showed poor lapse rates.  Limited buoyancy coupled with
weak/negligible low-level convergence/large-scale ascent will act to
limit convective coverage and intensity across the central FL
Peninsula today.

..Smith/Barnes.. 12/06/2025

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1049 AM CST Sat Dec 06 2025

Valid 071200Z - 081200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible on Sunday across portions of
Florida. Severe potential appears low at this time.

...Florida...

An upper trough will develop east from the Plains toward the eastern
U.S. on Sunday. As this occurs, a belt of 30-40 kt 850-700 mb
west/southwest flow will overspread portions of the FL Peninsula
atop a quasi-stationary surface boundary extending across
north-central FL. Forecast soundings depict elongated hodographs
with modestly curved low-level hodographs in the vicinity of the
surface boundary during the afternoon into early evening. 

Surface heating will be somewhat muted by cloud cover, and
persistent showers/isolated thunderstorms in the warm advection
regime to the cool side of the boundary. Furthermore, midlevel
temperatures are forecast to be rather warm, limiting lapse rates,
and instability will remain weak (generally less than 500 J/kg
MLCAPE). This should largely limit severe potential. However, a
stronger, rotating storm offshore from west-central FL could
approach the coast during the afternoon/early evening. While a
strong gust or waterspout could occur with this activity, over all
risk appears too low/conditional, and limited in spatial extent, to
include probabilities.

..Leitman.. 12/06/2025

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
1233 PM CST Sat Dec 06 2025

Valid 081200Z - 091200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible across South Florida on Monday.
Severe storms are not expected.

...South Florida...

Broad upper troughing will persist across the eastern U.S. on
Monday, through deep-layer west/southwesterly flow will weaken as an
embedded jet streak moves off the East Coast. At the surface, a cold
front will extend across central FL Monday morning, and develop
southward through afternoon. Isolated showers and thunderstorms may
be ongoing early in the day and persist southward ahead of the
front. Poor lapse rates/weak instability and generally modest
surface to 700 mb westerly flow will preclude severe thunderstorm
potential.

..Leitman.. 12/06/2025