SPC Severe Thunderstorm Watch 105
WW 105 SEVERE TSTM NY OH PA WV LE 011555Z - 012200Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 105
NWS Storm Prediction Center Norman OK
1155 AM EDT Sat Apr 1 2023
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Western New York
Eastern Ohio
Western and Central Pennsylvania
Far Northern West Virginia
Lake Erie
* Effective this Saturday morning and evening from 1155 AM until
600 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
Isolated large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...Bands of storms will continue to organize and intensify
and rapidly move east-northeastward across the region through the
afternoon, with corridors of damaging wind gusts aside from some
hail.
The severe thunderstorm watch area is approximately along and 80
statute miles north and south of a line from 30 miles west of Akron
OH to 30 miles east northeast of Bradford PA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU5).
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
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 400. Mean storm motion vector
25045.
...Guyer
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SPC Severe Thunderstorm Watch 105 Status Reports
WW 0105 Status Updates
STATUS FOR WATCH 0105 HAS NOT BEEN ISSUED YET
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SPC MD 429
MD 0429 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF SOUTHEASTERN ALABAMA...SOUTHERN GEORGIA AND SOUTHWESTERN SOUTH CAROLINA
Mesoscale Discussion 0429
NWS Storm Prediction Center Norman OK
1155 AM CDT Sat Apr 01 2023
Areas affected...portions of southeastern Alabama...southern Georgia
and southwestern South Carolina
Concerning...Severe potential...Watch possible
Valid 011655Z - 011900Z
Probability of Watch Issuance...40 percent
SUMMARY...Severe thunderstorm potential may increase early this
afternoon across southern GA/AL into western SC. Damaging winds will
remain the primary threat but a tornado or two cannot be ruled out.
Storm coverage and the need for a watch is somewhat uncertain.
DISCUSSION...Midday visible imagery showed mostly clear skies ahead
of a band of developing pre-frontal convection from southeastern AL,
southern GA and into western SC. Ample daytime heating of a
relatively moist airmass (63-66 F surface dewpoints) was
contributing to gradual destabilization across the region. Area
model soundings show around 1000 J/kg of MLCAPE through the
afternoon which should support current thunderstorms as they move
east. Elongated, hodographs with moderate speed shear (40+ kt)
should allow for organized short line segments and perhaps some
supercell structures. However, low-level flow is strongly veered
suggesting the primary severe risk will be damaging winds though a
tornado or two cannot be ruled out.
Hi-res guidance and observation trends suggest storms may take some
time to organize given the modest lapse rates and weak overall
forcing for ascent. It remains unclear if a weather watch is
warranted given the uncertainty with storm coverage and overall
severe risk. However, the greatest confidence some risk is across
portions of southern GA where buoyancy and shear are best
overlapped.
..Lyons/Guyer.. 04/01/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...CAE...JAX...FFC...TAE...BMX...
LAT...LON 31878112 31348145 31038200 30808425 30928532 31028557
31208566 31508568 31758559 32158477 32628347 33178152
33148108 32868081 32468069 32058088 31878112
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SPC MD 428
MD 0428 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR EASTERN OHIO INTO WESTERN PENNSYLVANIA AND NEW YORK
Mesoscale Discussion 0428
NWS Storm Prediction Center Norman OK
1015 AM CDT Sat Apr 01 2023
Areas affected...eastern Ohio into western Pennsylvania and New York
Concerning...Severe potential...Watch likely
Valid 011515Z - 011745Z
Probability of Watch Issuance...95 percent
SUMMARY...Storms producing damaging winds appear increasingly likely
today, beginning over eastern Ohio and moving quickly into parts of
New York and Pennsylvania.
DISCUSSION...Satellite imagery shows strong heating occurring over
the region, with storms beginning to form ahead of the cold
front/vort max. Despite low dewpoints, very steep deep-layer lapse
rates, strong shear and substantial mixing of high winds aloft will
likely yield wind gusts in excess of 50 kt over much of the area. As
such, a watch is likely, and the outlook will feature a 30% severe
wind probability.
..Jewell/Guyer.. 04/01/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BGM...BUF...CTP...PBZ...CLE...
LAT...LON 43167875 43167804 43067780 42597752 41447750 40697783
39917843 39738036 39688131 39858173 40088179 40698195
41388197 42038161 43127903 43167875
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SPC Apr 1, 2023 1300 UTC Day 1 Convective Outlook
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0744 AM CDT Sat Apr 01 2023
Valid 011300Z - 021200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
EAST...
...SUMMARY...
Scattered damaging winds and a couple tornadoes will be possible
across parts of the Northeast this afternoon and evening. Isolated
to scattered damaging winds and a tornado or two remain possible
across parts of the Southeast through this afternoon.
...Northeast...
A vigorous shortwave trough centered over southern Lake MI will
rapidly progress off the Northeast/southern New England coast by
this evening. Strong forcing for ascent will overspread the Lower
Great Lakes towards midday, with initial thunderstorm development
expected across north-central/northeast OH. While 12Z observed
soundings sampled negligible buoyancy, with upper 40s to low 50s
surface dew points over the Upper OH Valley and full insolation
ahead of the wave, weak MLCAPE to around 500 J/kg is anticipated
within a rather steep low to mid-level lapse rate environment. Very
strong deep-layer shear and enlarged low-level hodographs will
support a broken linear band with embedded supercells into
western/northern PA and southern NY. Relative paucity of buoyancy
across central PA should tend towards storms producing damaging
winds as the primary hazard, with potential for any organized
clustering to temporarily weaken.
Richer boundary-layer moisture should remain present closer to the
coastal plain across the DE and Lower Hudson Valleys. Pervasive
cloud coverage should decrease somewhat by late afternoon, which
would support a conditional supercell environment. A few CAMs
indicate one to two leading discrete supercells across portions of
the DE Valley. Should they be sustained, tornadoes, hail, and
damaging winds would all be possible. The more probable scenario is
for the fast-moving convection along the front spreading east and
impinging on the relatively greater moisture. This may yield an
uptick in severe wind potential until storms shift off the coast.
...Southeast...
Deep-layer flow will gradually become more westerly with time as the
strong upper low advances east across the OH Valley. This evolution
will encourage pre-frontal convection that currently extends from
north GA to central AL to advance east-southeast through the
period. While the primary large-scale forcing will spread well north
of this region, deep-layer flow will be strong and organized
clusters/short-line segments are expected. Damaging winds should be
the primary concern, though some risk for a tornado or two is also
evident.
..Grams/Goss.. 04/01/2023
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SPC Apr 1, 2023 1630 UTC Day 1 Convective Outlook
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1134 AM CDT Sat Apr 01 2023
Valid 011630Z - 021200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHEAST STATES INCLUDING PARTS OF PA/NY/OH/NJ...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST
STATES...
...SUMMARY...
Damaging winds and a couple tornadoes will be possible across parts
of the Northeast this afternoon and evening. Isolated to scattered
damaging winds and a tornado or two remain possible across parts of
the Southeast through the afternoon.
...Northeast States...
Parts of the region have been upgraded to a categorical Enhanced
Risk. This is related to an initial concern for increasingly
organized/fast-moving linear low-topped convection moving from
eastern Ohio into western portions of Pennsylvania/New York early
this afternoon. Although the immediately preceding air mass is not
overly moist, ample insolation/heating via cloud-free skies in
conjunction with a strong wind field and regionally observed steep
lapse rates will support scenario for potentially widespread
damaging winds aside from some hail.
Farther east, richer boundary-layer moisture will persist closer to
the coastal plain across the Delaware/Lower Hudson Valleys. While
pervasive cloud cover persists at midday (roughly within 75-100
miles of the Atlantic Coast at 16z), steady clearing is expected
this afternoon based on radar/satellite trends. Environment will
support both a conditional supercell environment as well as
persistence/potential rejuvenation of the upstream fast-moving
convective line. If a few supercells materialize, tornadoes, hail,
and damaging winds would all be possible, and damaging winds are
otherwise probable with the inbound convective line roughly centered
in the 21z-01z time frame for eastern Pennsylvania, New Jersey,
southern New York/NYC Metro vicinity.
...Southeast States...
Deep-layer flow will gradually trend more westerly with time as the
strong upper low advances east across the Ohio Valley. Pre-frontal
convection currently extends from central Georgia to southern
Alabama at midday, and this will continue to advance east-southeast
through the day. While the primary large-scale forcing will spread
well north of this region, deep-layer flow will be strong and
organized clusters/short-line segments are expected. Damaging winds
should be the primary concern, though some risk for a tornado or two
exists as well.
..Guyer/Lyons.. 04/01/2023
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SPC Apr 1, 2023 1730 UTC Day 2 Convective Outlook
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1223 PM CDT Sat Apr 01 2023
Valid 021200Z - 031200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS DURING THE DAY
ACROSS NORTH TX...
...SUMMARY...
Occasional large hail, isolated damaging winds, and a couple of
tornadoes will be possible during the day tomorrow, mainly across
north Texas.
...North TX and vicinity through the day...
In the wake of a pronounced midlevel trough now moving over the OH
Valley/lower Great Lakes, a front will stall along the Gulf coast.
Upstream, a shortwave trough now near northern Baja will progress
eastward to the southern Plains tomorrow afternoon. In response to
the approach of this trough and increasing westerly flow across the
Rockies, lee cyclogenesis across the southern High Plains will
result in strengthening southerly low-level flow and northward
moisture advection during the day across TX. The increasing
low-level moisture beneath the eastward extent of a elevated mixed
layer plume will support substantial destabilization during the day
across north TX.
Clusters of mainly elevated storms are probable during the day in
the zone of stronger low-level warm advection across northwest TX
into southern OK, with sufficient MUCAPE/lapse rates for occasional
large hail. Farther south, there will be a few hour window of
opportunity for supercells rooted near or at the surface within the
southern fringe of the stronger forcing for ascent, close to the
surface warm front around mid afternoon. Mid-upper 60s
boundary-layer dewpoints and surface heating in cloud breaks and
midlevel lapse rates of 7-8 C/km will drive MLCAPE up to 1500 J/kg
along the warm front, with sufficient deep-layer shear/hodograph
length and low-level shear/hodograph curvature for supercells with
all hazards. These threats will be focused along the warm front
from about 20-00z, with the threat for surface-based supercells
diminishing during the evening with passage of the midlevel trough.
Otherwise, clusters of slightly elevated storms will spread eastward
toward northwest LA/southwest AR and slowly weaken early tomorrow
night.
..Thompson.. 04/01/2023
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SPC Day 1 Fire Weather Outlook
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1137 AM CDT Sat Apr 01 2023
Valid 011700Z - 021200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN/CENTRAL
HIGH PLAINS...
The forecast remains on track and no changes were necessary. Some
elevated conditions are already present across southeast Colorado
and vicinity. Sunny skies will allow additional warming and deep
mixing through the afternoon with critical conditions likely
developing by 19-20Z.
..Bentley.. 04/01/2023
.PREV DISCUSSION... /ISSUED 1248 AM CDT Sat Apr 01 2023/
...Synopsis...
A belt of strong westerly flow aloft will overspread the Pacific
Northwest and Northern Rockies on Saturday as an embedded shortwave
moves eastward across Arizona and into New Mexico. East of the
Rockies, lee troughing will develop in response with increased south
to southwesterly flow across the Central and Southern High Plains
across a very dry post-frontal air mass. Elevated to Critical fire
weather will be possible. Dry conditions will extend further south
and east but lighter winds will preclude the need for expansion of
any areas.
...Eastern CO, Northeastern NM, northwest TX, western OK
Panhandle...
The Critical area was maintained with this update. HREF guidance
still shows the highest conditional probability of Critical
conditions across far southeastern Colorado, northeastern New
Mexico, west Texas, and the Oklahoma Panhandle. Confidence in
relative humidity reductions to around 10-15 percent within this
region is high. Some question remains in the extent of the stronger
winds. As such, ensemble guidance was leveraged to narrow down the
most likely region of dry/windy overlap with the driest fuels. It is
possible that locally Critical fire weather conditions may occur
within the broader Elevated region. Minor adjustments were made to
expand the Elevated area across the eastern edge further into
Oklahoma and Texas.
...Far West Texas near Stockton Plateau and Edwards Plateau...
Localized Elevated to Critical fire weather conditions will be
possible across the Stockton and Edwards Plateau Saturday afternoon.
Given the localized and largely terrain driven nature of any
Critical conditions, no area was included with this update. However
areas of Elevated to Critical fire weather conditions will be
possible. Drying fuels in this region will likely support fire
spread.
...Please see www.spc.noaa.gov/fire for graphic product...
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