WW 686 SEVERE TSTM DC MD NY PA VA WV CW 161725Z - 170000Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 686
NWS Storm Prediction Center Norman OK
125 PM EDT Fri Oct 16 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
District Of Columbia
Maryland
Southern New York
Central and Eastern Pennsylvania
Northern Virginia
Eastern West Virginia
Coastal Waters
* Effective this Friday afternoon and evening from 125 PM until
800 PM EDT.
* Primary threats include...
Widespread damaging wind gusts to 70 mph likely
A tornado or two possible
SUMMARY...Clusters of storms will continue to develop and intensify
this afternoon, with the expectation that fast-moving bands/lines of
storms will evolve with the potential for wind damage.
The severe thunderstorm watch area is approximately along and 70
statute miles east and west of a line from 45 miles north of
Wilkesbarre PA to 80 miles south southwest of Martinsburg WV. 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.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 450. Mean storm motion vector
25030.
...Guyer
WW 0686 Status Updates
STATUS FOR WATCH 0686 HAS NOT BEEN ISSUED YET
No Mesoscale Discussions are in effect as of Fri Oct 16 19:10:41 UTC 2026.SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Fri Oct 16 2026
Valid 161630Z - 171200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC INTO SOUTHERN NEW ENGLAND...
...SUMMARY...
Thunderstorms capable of producing damaging winds and perhaps a
tornado or two are expected across parts of the Mid-Atlantic into
southern New England, mainly this afternoon and early evening.
...Mid-Atlantic States/southern New England...
A large-scale positive-tilt upper-level trough will approach the
region, with a modest buoyancy/high-vertical shear scenario expected
to be favorable for low-topped/fast-moving storms capable of wind
damage near/ahead of a cold front. Such severe potential is expected
to maximize across the Delmarva and eastern Pennsylvania into New
Jersey and southern New York.
Stratus remains very prevalent across much of the region late this
morning, although visible satellite imagery reflects a rather quick
erosion south to north across southern Virginia, and this same trend
should continue for east of the Blue Ridge/Appalachians spine
especially across Virginia into eastern Pennsylvania and perhaps
nearby parts of New Jersey/Delmarva.
A related surface low over southern Ontario will develop
east-northeastward today into southern Quebec, as a trailing cold
front sweeps east-southeastward across the eastern states. Low-level
moisture is forecast to gradually increase ahead of the front
through the afternoon, and MLCAPE should gradually increase into the
500-1000 J/kg range, particularly where more cloud breaks occur.
But, lapse rates through low/mid levels are likely to remain quite
poor (reference BUF/PIT/IAD 12Z observed soundings). This should
temper overall updraft strength to some extent, and low-topped
convection which develops along/near the front may produce little
lightning, especially with northward extent into southern New
England.
Even with the potential thermodynamic limitations, favorable
deep-layer shear will support some updraft organization. Given the
strength of the low/mid-level flow, isolated strong/gusty winds may
occur. A low-topped convective line will further develop across
central into eastern Pennsylvania and southern New York this
afternoon. Convectively augmented wind gusts capable of producing
scattered damaging winds will likely be the main severe risk as this
activity spreads quickly eastward across the northern Mid-Atlantic
and southern New England through early evening. A few line-embedded
mesocirculations could also occur, which could yield a brief
tornado.
..Guyer/Karstens.. 10/16/2026
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 PM CDT Fri Oct 16 2026
Valid 171200Z - 181200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not expected Saturday.
...Synopsis...
The majority of the CONUS will be dominated by a cool/dry air mass
with no potential for deep convection in the wake of a cold frontal
passage off the southeast Atlantic coast. One exception will be
across central/south FL where moist profiles (PW greater than 2
inches) and ascent along the cold front will support scattered
thunderstorms. A second possible exception will be across the
Desert Southwest as midlevel moisture and ascent increase gradually
near and east of a weak closed low over northern Baja. Buoyancy
rooted in the midlevels will be weak but could become sufficiently
deep for charge separation and isolated lightning flashes the latter
half of the period.
..Thompson.. 10/16/2026
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1135 AM CDT Fri Oct 16 2026
Valid 161700Z - 171200Z
...CRITICAL FIRE WEATHER AREA FOR WESTERN L.A. COUNTY...VENTURA
COUNTY...AND SOUTHEASTERN SANTA BARBARA COUNTY IN SOUTHERN
CALIFORNIA...
The forecast remains on track for an Elevated fire weather threat
across portions of CA, and critical conditions for a localized
region of southern CA. Wind gusts of 35-55 mph are being measured in
the wind-prone areas of L.A./Ventura/Santa Barbara counties amid RH
values of 15-20% this morning. As the offshore gradient relaxes
throughout the day, winds will gradually ease; however, a 700 mb
30-40 kt easterly jet will remain over the region into Day
2/Saturday morning, potentially allowing some stronger gusts to
reach the surface.
Farther east, a cold front will continue to traverse the lower MS
Valley/ArkLaTex today. Behind the front, northerly sustained winds
of 15-20 mph (gusts up to 30 mph) are depicted by 16z observations.
RH values will decline to 25-40% this afternoon where receptive
fuels exist, maintaining an Elevated fire weather threat.
..Elizalde-Garcia.. 10/16/2026
.PREV DISCUSSION... /ISSUED 0204 AM CDT Fri Oct 16 2026/
...Synopsis...
A mid/upper low will remain positioned just west of the northern
Baja Peninsula within a broader upper-level ridge over the western
U.S. In conjunction with a strong surface high pressure system (1044
mb per the 03 UTC WPC surface analysis) moving into the central
Great Plains, this upper low will continue to support dry, offshore
flow and elevated to critical fire weather conditions across
portions of California today. To the east, a robust upper-level
trough will pivot eastward across the eastern U.S., with an
attendant surface low deepening as it progresses northeastward
across the St. Lawrence River Valley and a strong cold front
advancing across the East/Southeast. Strong post-frontal flow in the
wake of this cold front will bring elevated fire weather concerns to
portions of the lower Mississippi River Valley and ArkLaTex today.
...Southern California...
A closed mid/upper low will aid in the maintenance of deep-layer
east-northeasterly flow across much of southern California, which
will continue to support an offshore wind event and elevated to
critical fire weather conditions today. A corridor of sustained
east-northeasterly 20-30 mph surface winds with gusts up to 50-60
mph (occasionally higher in terrain-favored and exposed elevated
areas) is forecast across western L.A, Ventura, and southeastern
Santa Barbara counties, with a peak during the late morning/early
afternoon hours before gradually diminishing beginning later this
afternoon. With minimum RH values likely dropping to near 15%
(locally lower), this will favor a critical fire weather threat.
Elevated to locally critical conditions are also expected farther
west towards the central CA coast where RH reductions to 15% and
sustained easterly winds of 15-20 mph are expected.
...Sierra Nevada, Sacramento Valley into the North Bay area...
Residual easterly/northeasterly downslope winds of 10-15 mph
(locally up to 20 mph) are expected today across the western slopes
of the Sierra Nevada. Poor overnight humidity recoveries are
observed as of 0600 UTC, with RH values noted to range from 15-25%
across portions of the western slopes. RH values should further
decrease to near 10% today. Coupled with receptive fuels and the
breezy east-northeast winds, this will help maintain an elevated
fire weather threat across this region today. North-northeast winds
of 10-15 mph and minimum RH values of 10-15% will also bring
elevated fire weather concerns to portions of the Sacramento Valley,
Napa Valley, and North Bay areas today.
...Lower Mississippi River Valley and ArkLaTex Region...
A strong surface high pressure system will build into the central
Plains today in the wake of the passage of a substantial surface
cold front advancing across the East/Southeast. The resultant
surface pressure gradient between these two features will favor
sustained northerly winds of 10-15 mph (with occasional gusts up to
around 30-35 mph possible) across portions of the lower Mississippi
River Valley and ArkLaTex within the dry, post-frontal air mass.
With RH reductions as low as ~25% over receptive fuels (ERCs up to
the 80-90th percentiles), elevated fire weather conditions are
expected for at least a few hours this afternoon. While RH will
improve into the overnight hours, gusty surface winds are expected
to continue into Saturday morning. Only a minor southward expansion
to the existing elevated area was made with this update.
...Please see www.spc.noaa.gov/fire for graphic product...
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0208 PM CDT Fri Oct 16 2026
Valid 171200Z - 181200Z
The Elevated fire weather threat over the lower MS River Valley was
expanded slightly eastward to cover a broader region of coinciding
north-northeast winds of 10-15 mph and minimum RH values of 25-35%.
These meteorological conditions are expected to overlap increasingly
receptive fuels (and ERCs approaching the 90th percentile),
supporting Elevated fire weather conditions in east-central to
southeastern MS on Day 2/Saturday. The rest of the forecast remains
on track; see the previous discussion for more information.
..Elizalde-Garcia.. 10/16/2026
.PREV DISCUSSION... /ISSUED 0204 AM CDT Fri Oct 16 2026/
...Synopsis...
A closed mid-level low will remain positioned to the southwest of
Southern California on D2/Saturday as upper-level ridging begins to
shift eastward into the Plains. This will foster residual offshore
flow and lingering elevated fire weather conditions across portions
of Southern California Sunday morning. Meanwhile, a strong cold
front will continue to progress offshore of the East Coast as
surface high pressure shifts into the Ohio Valley, helping to
maintain dry and breezy post-frontal conditions and elevated fire
weather concerns across portions of the lower MS Valley.
...Southern California...
A closed mid-level low will remained positioned west of the northern
Baja Peninsula, which will help maintain residual easterly offshore
flow into D2/Saturday. Generally easterly surface winds of 10-20 mph
(locally greater) are forecast Saturday morning before magnitudes
begin to weaken Saturday afternoon. With RH values likely to remain
around 15-20% during the morning hours, this will continue to
support elevated fire weather conditions Sunday morning across the
Simi Valley and Sierra Madre/San Rafael ranges.
...Lower Mississippi River Valley...
A dry and breezy post-frontal pattern will continue across portions
of the lower Mississippi River Valley and Southeast on Saturday as
surface high pressure shifts into the Ohio River Valley to the
north. North-northeast winds of 10-15 mph and minimum daytime RH
values around 25% are expected atop dry, receptive fuels (ERCs
commonly above the 80-90th percentiles) across portions of the lower
Mississippi River Valley, fostering elevated fire weather conditions
from southern LA into southeastern AR and much of western/central
MS.
...Please see www.spc.noaa.gov/fire for graphic product...
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