RSS Mesoscale Discussions from Storm Prediction Center
WW 643 TORNADO IL IN KY MO 282045Z - 290200Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 643
NWS Storm Prediction Center Norman OK
345 PM EST Sun Dec 28 2025
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Southern and Central Illinois
Western and Central Indiana
Western Kentucky
Far Southeast Missouri
* Effective this Sunday afternoon and evening from 345 PM until
900 PM EST.
* Primary threats include...
A couple tornadoes possible
Scattered damaging winds likely with isolated significant gusts
to 75 mph possible
SUMMARY...A broken line of thunderstorms will move quickly
east-northeastward this afternoon and evening while posing a threat
for scattered severe/damaging winds up to 65-75 mph and a couple of
tornadoes.
The tornado watch area is approximately along and 80 statute miles
east and west of a line from 40 miles north northwest of Lafayette
IN to 5 miles southeast of Paducah KY. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU3).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.
&&
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1 inch. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 400. Mean
storm motion vector 26045.
...Gleason
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WW 0643 Status Updates
STATUS REPORT ON WW 643
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 SE FAM TO
20 WSW MVN TO 30 S MTO TO 20 S DNV TO 30 N LAF TO 5 WSW SBN.
..JEWELL..12/28/25
ATTN...WFO...PAH...LSX...ILX...LOT...IND...IWX...LMK...
STATUS REPORT FOR WT 643
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ILC003-023-025-033-035-045-047-055-059-065-069-077-079-081-087-
101-121-127-145-151-153-159-165-181-185-191-193-199-290040-
IL
. ILLINOIS COUNTIES INCLUDED ARE
ALEXANDER CLARK CLAY
CRAWFORD CUMBERLAND EDGAR
EDWARDS FRANKLIN GALLATIN
HAMILTON HARDIN JACKSON
JASPER JEFFERSON JOHNSON
LAWRENCE MARION MASSAC
PERRY POPE PULASKI
RICHLAND SALINE UNION
WABASH WAYNE WHITE
WILLIAMSON
INC005-011-013-015-017-021-023-027-031-035-037-045-049-051-053-
055-057-059-063-065-067-069-071-079-081-083-085-093-095-097-099-
101-103-105-107-109-117-119-121-125-129-131-133-135-139-145-147-
149-153-157-159-163-165-167-169-173-181-183-290040-
IN
. INDIANA COUNTIES INCLUDED ARE
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MD 2280 CONCERNING HEAVY SNOW FOR SOUTHEAST MINNESOTA INTO NORTHWEST/NORTHERN WISCONSIN
Mesoscale Discussion 2280
NWS Storm Prediction Center Norman OK
1240 PM CST Sun Dec 28 2025
Areas affected...Southeast Minnesota into northwest/northern
Wisconsin
Concerning...Heavy snow
Valid 281840Z - 290045Z
SUMMARY...Conditions will initially be marginal for heavier snowfall
rates, but cooling temperatures at the surface and aloft will
increase potential for snowfall rates to around 1 inch per hour.
DISCUSSION...As the mid-level jet intensifies in the central Plains,
a surface low continues to deepen in northern Illinois. Cold air
advection is increasing within the upper Mississippi Valley in
response. Furthermore, deep-layer lift is also increasing as
evidenced by a broad area of precipitation moving into parts of
northwest/northern Wisconsin. While temperatures in some areas have
been just above freezing for most of the morning, recent surface
observations have shown decreasing temperatures/dewpoints. Dynamic
cooling within the heavier precipitation bands has also been
evident. That said, snowfall should increase through the afternoon.
Observations from Eau Claire and Hayward already show moderate
snowfall occurring. As the atmospheric profile continues to cool,
the environment should become more favorable for snowfall rates up
to around 1 inch per hour through late afternoon/early evening.
..Wendt.. 12/28/2025
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MQT...GRB...DLH...ARX...MPX...
LAT...LON 46479079 46509029 46298948 46128922 45778928 44679108
44269186 44049236 43999277 44059292 44669282 45029257
45429221 46059139 46479079
Read more
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0146 PM CST Sun Dec 28 2025
Valid 282000Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
ILLINOIS...WESTERN KENTUCKY AND INDIANA...
...SUMMARY...
Scattered severe thunderstorms are possible over parts of the
Midwest and lower Ohio Valley this afternoon through the evening.
Severe/damaging wind gusts and a couple of tornadoes are the primary
threats.
...20Z Update...
The only change to the outlook for this issuance is to trim the
Marginal Risk area across parts of north-central Illinois behind a
cold front that is moving southeastward across the region.
..Broyles.. 12/28/2025
.PREV DISCUSSION... /ISSUED 1040 AM CST Sun Dec 28 2025/
...Mid Mississippi Valley into the Midwest/Ohio Valley...
An upper trough/low over the northern Plains this morning will
further intensify today as it develops towards the Upper
Midwest/Great Lakes through the period. Pronounced large-scale
ascent associated with a strengthening mid/upper jet (100-120 kt at
500 mb) over the mid MS Valley into IL/IN will encourage rapid
deepening of a surface low as it develops from central/northern IL
into Lower MI by this evening. A rather moist low-level airmass with
generally upper 50s to low 60s surface dewpoints will continue to
spread northward across the mid MS Valley into parts of the
Midwest/OH Valley and southern Great Lakes regions in tandem with a
northward-shifting surface warm front. A cold front is also expected
to sweep east-southeastward across these regions this
afternoon/evening as the surface low tracks northeastward. This cold
front should serve as a focus for strong to severe convection later
today.
The 12Z ILX sounding showed a moist but saturated profile through
much of the troposphere, with strong west-southwesterly
mid/upper-level winds already present over the warm sector. Current
expectations are for ongoing, mostly elevated convection across
central IL to pose a threat for isolated hail and strong to locally
severe gusts given the strength of the mid-level flow. This activity
may linger along/just north the warm front through the afternoon as
it spreads quickly east-northeastward into IN. Additional
thunderstorms are expected to form along/near the cold front across
IL and vicinity by 20-22Z as modest/filtered daytime heating occurs,
with come cloud breaks already noted in visible satellite imagery
across east-central MO/south-central IL. It does appear that surface
temperatures are warming faster/more than forecast by some guidance
across the warm sector in IL, with 16Z observations at some stations
already reaching into the upper 60s/low 70s.
The more aggressive 12Z guidance and recent RAP runs suggest that
around 500-1000 J/kg of MLCAPE may ultimately develop in a narrow
corridor across eastern IL and western IN/KY ahead of the front,
even though modest lapse rates aloft will likely inhibit more robust
destabilization. This weak instability should be sufficient to
support organized updrafts, as both low-level and deep-layer shear
will be quite strong owing to the strengthening wind profiles across
the warm sector this afternoon/evening with the approaching
mid/upper-jet. There is still some uncertainty regarding the
potential for pre-frontal convection. But, any low-topped supercells
that can form and be sustained should pose a threat for a couple of
tornadoes with upwards of 200-250 m2/s2 of effective SRH present.
Eventual development of a thin/forced line of convection along the
cold front appears likely, with a threat for scattered
severe/damaging winds and perhaps a couple of embedded tornadoes. At
least an isolated severe threat may persist this evening/tonight
across the OH Valley and parts of western PA, where low-level flow
is forecast to remain quite strong even with minimal instability.
Read more
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
1244 PM CST Sun Dec 28 2025
Valid 301200Z - 311200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorm probabilities appear less than 10 percent across the
U.S. for Tuesday through Tuesday night.
...Discussion...
Models indicate that the center of a broad and still deepening
cyclone will migrate north-northwest of the St. Lawrence Valley,
toward the southern Hudson Bay vicinity through this period. At
mid-levels, it appears that the broadening circulation will be
reinforced by a vigorous short wave perturbation digging from the
higher latitudes. Surrounding this low, cyclonic flow will likely
encompass most areas east of the Rockies through the offshore
western Atlantic, with some further amplification across the Gulf
Basin into the Caribbean and Bahamas. Beneath this regime, cool
surface ridging entrenched across much of the southern Great Plains,
Gulf Coast and Gulf Basin is forecast to only slowly begin to
weaken.
Upstream, a cyclonic circulation over the subtropical eastern
Pacific may gradually begin to consolidate in advance of more
notable short wave troughing digging across the mid-latitude eastern
Pacific. However, a substantive northeastward acceleration of the
low toward the California coast appears unlikely through at least
early Wednesday, and mid-level ridging will generally be maintained
across much of the interior West. While lower/mid-tropospheric
moisture return emanating from the lower latitude eastern Pacific
may overspread portions of the Southwest into Great Basin, it is
still not clear that this will yield sufficient destabilization to
support convection capable of producing lightning (although NAM
forecast soundings around the Las Vegas, NV vicinity late Tuesday
evening/overnight suggest that this might not be completely out of
the question).
..Kerr.. 12/28/2025
Read more
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1246 PM CST Sun Dec 28 2025
Valid 291200Z - 301200Z
An elevated area was added across portions of the Southeast,
southern Appalachians, and North Carolina. In the wake of a strong
surface-cold front, a drier and windier airmass will overspread the
Southeast. Although meteorologically elevated fire weather
conditions will take hold across much of the area, the recent influx
of Gulf moisture ahead the strong cold front has tempered the
seasonally adjusted ERC percentiles, especially farther west across
Mississippi and Alabama. As such, for this forecast period,
highlights will focus on regions where seasonally adjusted ERC
percentiles are the highest. The totality of the Southeast will need
to be monitored for an increase in fire weather concerns through
much of the upcoming week.
Elsewhere, across the Southern Plains the very dry low-level airmass
will remain firmly entrenched beneath northwest flow aloft. The
result will be minimum afternoon relative humidity percentages
falling into the teens with maximum surface winds between 10-15 mph
(and locally higher gusts). This will support a continued elevated
risk of fire weather conditions.
..Marsh.. 12/28/2025
.PREV DISCUSSION... /ISSUED 0142 AM CST Sun Dec 28 2025/
...Synopsis...
A mid-level trough will impinge on the East Coast tomorrow (Monday),
resulting in northwesterly upper flow overspreading the Plains
states through the Day 2 period. Northwesterly flow will also
prevail at the surface over the Plains as surface high pressure
settles over the region. Sustained surface north-northwesterly winds
should peak around 15 mph by afternoon, amid 40 F surface
temperatures and 15-25 percent RH. Given drying fuels, the
aforementioned meteorological conditions should support low-end
Elevated conditions. The best chance for these conditions will be
across the eastern Texas Panhandle into northwest Texas and western
Oklahoma, where Elevated highlights have been introduced.
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0334 PM CST Sun Dec 28 2025
Valid 301200Z - 051200Z
The large-scale mid-level pattern for this forecast period will be
characterized by northwest flow across much of the eastern United
States, resulting from a western ridge and eastern trough. Global
guidance continues to suggest a short-wave trough will undercut the
ridge mid-to-late week, although timing of this trough varies from
run-to-run.
... Southern Plains ...
A low-end fire threat may develop on Tuesday (D3) associated with a
modest dry-return flow pattern. Afternoon minimum relative humidity
will fall below critical criteria (15-20%) across the region, with
temperatures beginning to warm in response to the surface ridge
moving east of the area. The limiting factor for a fire environment
supportive of critical fire weather conditions appears to be the
surface winds. As the center of the surface ridge moves slowly east,
winds will turn southwesterly and weaken on Tuesday as compared to
previous days. This forecast maintains the inherited 40% area given
model guidance tendency to under-forecast winds. Further refinements
will be needed in subsequent forecasts.
Later in the week may see an uptick in large-scale fire weather
concerns as westerly surface winds increase in response to the
approaching aforementioned short-wave trough undercutting the
western ridge. There will likely be a period of at least elevated
fire weather concerns associated with this feature before surface
winds across portions of the area back to northerly in response to a
developing surface low across the ArkLaTex region. The timing and
details of this scenario are such that forecast probabilities on any
day are too low to warrant highlights.
... Southeast US ...
A very dry continental polar airmass will be entrenched across the
region in the wake of the strong cold frontal passage on Monday.
Most areas across the region will achieve minimum relative humidity
below critical thresholds (25-30%) for multiple consecutive days. On
Tuesday (D3), winds will remain somewhat gusty before the
surface-pressure gradient further relaxes on Wednesday. A mitigating
factor on Tuesday for fire occurrence will be the cold temperatures,
with high temperatures across the Appalachians struggling to get out
of the 30s.
On Wednesday (D4), the continental polar airmass will moderate
slightly, allowing for warmer afternoon temperatures. However,
northerly winds will hold any moisture return at bay, resulting in
even lower relative humidity than the previous day. The mitigating
factor on Wednesday will be that surface winds should decrease as
compared to Tuesday as the surface pressure gradient continues to
relax.
This forecast will introduce an expansive 40% area on both Tuesday
and Wednesday. Further refinements will be necessary in subsequent
forecasts.
The dry airmass will persist beyond Wednesday for at least some
areas of the Southeast. However, at this time range some uncertainty
exists in the magnitude and timing of potential moisture return
associated with a surface low tied to the aforementioned short-wave
trough.
..Marsh.. 12/28/2025
...Please see www.spc.noaa.gov/fire for graphic product...
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