WW 646 SEVERE TSTM OH PA WV 022055Z - 030400Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 646
NWS Storm Prediction Center Norman OK
455 PM EDT Wed Sep 2 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Eastern Ohio
Western and Central Pennsylvania
The Far Northern West Virginia Panhandle
* Effective this Wednesday afternoon from 455 PM until Midnight
EDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
A tornado or two possible
SUMMARY...Robust thunderstorms have developed across eastern Ohio
into northwest Pennsylvania in a favorable environment for severe
hail and damaging winds. Current expectations are for this
convection to spread generally east-southeastward through the late
afternoon and into the evening. A tornado or two may also occur with
any sustained supercell.
The severe thunderstorm watch area is approximately along and 50
statute miles north and south of a line from 25 miles west southwest
of Youngstown OH to 45 miles northeast of State College PA. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU6).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 643...WW 644...WW 645...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
27030.
...Gleason
WW 645 TORNADO NY LE LO 022040Z - 030300Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 645
NWS Storm Prediction Center Norman OK
440 PM EDT Wed Sep 2 2026
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Western and Central New York
Lake Erie
Lake Ontario
* Effective this Wednesday afternoon and evening from 440 PM
until 1100 PM EDT.
* Primary threats include...
A few tornadoes and a couple intense tornadoes possible
Scattered damaging wind gusts to 70 mph likely
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
SUMMARY...Supercell thunderstorms should pose some threat for large
hail and perhaps a few tornadoes as they move eastward late this
afternoon and evening across parts of western and central NY. A
strong tornado appears possible if thunderstorms can remain at least
semi-discrete this evening. Thunderstorms will likely grow upscale
into a bowing cluster later this evening, with a greater threat for
scattered to numerous severe/damaging winds up to 60-70 mph.
The tornado watch area is approximately along and 85 statute miles
east and west of a line from 35 miles west northwest of Watertown NY
to 60 miles east of Jamestown NY. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU5).
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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 643...WW 644...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean
storm motion vector 27035.
...Gleason
WW 0646 Status Updates
STATUS FOR WATCH 0646 HAS NOT BEEN ISSUED YET
WW 0645 Status Updates
STATUS FOR WATCH 0645 HAS NOT BEEN ISSUED YET
WW 0644 Status Updates
STATUS REPORT ON WW 644
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 E LWT TO
50 NNW LWT TO 35 WSW HVR TO 20 ESE CTB TO 40 W CTB.
..WENDT..09/02/26
ATTN...WFO...TFX...MSO...
STATUS REPORT FOR WS 644
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MTC005-027-035-041-051-101-030040-
MT
. MONTANA COUNTIES INCLUDED ARE
BLAINE FERGUS GLACIER
HILL LIBERTY TOOLE
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
MD 2209 CONCERNING SEVERE THUNDERSTORM WATCH 646... FOR NORTHERN PA VICINITY
Mesoscale Discussion 2209
NWS Storm Prediction Center Norman OK
0748 PM CDT Wed Sep 02 2026
Areas affected...northern PA vicinity
Concerning...Severe Thunderstorm Watch 646...
Valid 030048Z - 030215Z
The severe weather threat for Severe Thunderstorm Watch 646
continues.
SUMMARY...Severe potential will continue over the next few hours
across northern PA.
DISCUSSION...The main severe hazard will continue to be damaging
wind gusts and hail with more discrete convection across
north-central PA in the short term. VWP data from KCCX indicates
somewhat small but favorably curved low-level hodographs and 0-1 km
SRH greater than 150 m2/s2. Given the very moist and unstable
airmass in place, a tornado can not be ruled out, but damaging wind
and hail are expected to be the primary hazards, especially as loss
of daytime heating results in gradual low-level stabilization. The
southern extent of a line moving across western NY will spread into
portions of northern PA over the next 30-60 minutes. This activity
could pose a greater risk for damaging gusts given the
well-organized line and storm motion around 40 kt.
Downstream across eastern PA, the thermodynamic environment quickly
becomes more hostile for sustained severe potential. A sharp
instability gradient and rapidly increasing inhibition should limit
the eastward extent of severe potential, and a downstream watch is
not expected.
..Leitman.. 09/03/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BGM...BUF...CTP...PBZ...CLE...
LAT...LON 41817586 41627584 41237594 40907625 40667709 40857928
41368089 41548096 42108091 42328033 41977893 42027717
41957605 41817586
MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
MD 2208 CONCERNING TORNADO WATCH 645... FOR WESTERN NY
Mesoscale Discussion 2208
NWS Storm Prediction Center Norman OK
0651 PM CDT Wed Sep 02 2026
Areas affected...western NY
Concerning...Tornado Watch 645...
Valid 022351Z - 030115Z
The severe weather threat for Tornado Watch 645 continues.
SUMMARY...As storm mode has become more linear with time this
evening, the damaging wind risk may increase over the next 1-2 hours
across western NY. The tornado risk also will continue, particularly
with line-embedded circulations.
DISCUSSION...Earlier supercell storms have consolidated into a more
linear storm structure across western NY this evening. Vertical
shear remains favorable for storm organization, and the KBUF VWP
indicates rear-inflow around 50-60 kt between 1-2 km AGL. The
downstream airmass remains very moist and unstable toward the Finger
Lakes region before approaching a sharper decrease in instability
further east. This thermodynamic and kinematic parameter space
should continue to support organized severe convection capable of
damaging wind swaths. Furthermore, low-level shear remains favorable
for storm rotation and effective STP is around 1 to 2. As such, a
tornado risk will also continue, with line-embedded circulations
already noted over the past 30 minutes or so.
..Leitman.. 09/02/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BGM...BUF...CTP...
LAT...LON 41957846 42067938 42167957 42377944 42567901 42817858
43167802 43497748 43527713 43477684 43017644 42317636
42097645 41987659 41987712 41957846
MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Wed Sep 02 2026
Valid 030100Z - 031200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING
ACROSS PARTS OF THE SOUTHERN TIER OF NEW YORK INTO NORTHERN AND
CENTRAL PENNSYLVANIA...
...SUMMARY...
Thunderstorms posing a risk for potentially damaging wind gusts may
continue into late evening across parts of the Southern Tier of New
York into northern and central Pennsylvania.
...01Z Update...
...Great Lakes into Mid Atlantic...
To the south of a modest lower/mid-tropospheric cyclone, now
migrating to the east of James Bay, the leading edge of broad
mid-level troughing is in the process of gradually shifting
east-southeast of the lower Great Lakes region. Forcing for ascent
associated with this feature has contributed to the evolution of an
organizing cluster of storms now spreading across western New York
state, ahead of a southward advancing segment of the surface frontal
zone trailing the cyclone. However, in the wake of an early day
convective cluster, appreciable warm sector boundary-layer
instability is becoming confined to a narrowing corridor across the
Allegheny Plateau. As the ongoing convective system continues
east-southeastward, and the onset of boundary-layer cooling
progresses, more stable southeasterly near-surface updraft inflow
seems likely to weaken convection and reduce the associated risk for
severe weather as it spreads toward northern Mid Atlantic coastal
areas tonight.
Upstream, convection-allowing guidance suggests that forcing for
ascent associated with lower/mid-tropospheric warm advection may
support renewed widely scattered thunderstorm development overnight.
This is mostly likely to focus near/to the cool side of the
stalling trailing frontal zone on the southern fringe of the
westerlies, across southern portions of the Great Lakes into Upper
Midwest. Aided by modest strengthening of westerly flow in excess
of 30 kt around 850 mb, and steep lapse rates of
lower/mid-tropospheric temperature and potential wet-bulb
temperature, there appears potential for one or two upscale growing
clusters which may pose a risk for severe hail and wind.
...Northern Rockies and adjacent Great Plains...
The risk for severe weather has diminished considerably in the wake
of weakening convection now overspreading the Montana international
border. As the supporting vigorous short wave impulse continues to
pivot north of the border into the Canadian Prairies this evening,
this appears unlikely to change. An isolated strong storm to the
east-southeast of Miles City MT does appear supported by updraft
inflow of relatively moist boundary-layer air characterized by
sizable CAPE in excess of 2000 J/kg. However, it is not clear how
long this will be maintained, as inhibition increases with
boundary-layer cooling and perhaps some further warming aloft.
..Kerr.. 09/03/2026
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0431 PM CDT Wed Sep 02 2026
Valid 041200Z - 101200Z
...Synopsis...
Upper-level troughing will linger across the northwestern U.S.
through early next week while ridging will hold firm over the
central U.S. This pattern will likely suppress overall fire weather
concerns and fuel receptivity across much of the West under an
extended period of cloud cover, cooler temperatures and
precipitation. A lingering fire weather threat will persist into Day
3/Friday for portions of WY and northern High Plains under dry
southwest flow ahead of the broader upper trough. Additional
mid/upper moisture from tropical cyclone activity in the eastern
Pacific has the potential to advect into southern CA and the
southwestern CONUS but forecast rainfall amounts and distribution
remain uncertain. Nonetheless, fire weather concerns will generally
decline over the weekend into next week across the West.
...Day 3/Friday...
A corridor of dry, southwesterly flow ahead of the broader trough
across the Northwest will promote fire weather concerns across
portions of WY and the northern High Plains Day 3/Friday. Minimal
rainfall and persistently dry fuels combined with southwest winds of
10-20 mph and RH as low as 10% Friday afternoon supports the
continuation and slight expansion of a 40% critical area for
northeastern WY, southeastern MT and adjacent SD/ND border areas.
Farther southwest, a similarly dry and breezy environment sets up
over southern NV into western UT. However, marginal fuels after
prior rainfall preclude introduction of critical probabilities.
..Williams.. 09/02/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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