SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Sat May 21 2022
Valid 212000Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NEW ENGLAND
TO SOUTHERN TEXAS...
...SUMMARY...
Scattered severe thunderstorms capable of producing both damaging
winds and large hail should continue through evening from parts of
the southern Plains into the lower Ohio Valley, lower Great Lakes
and Northeast.
...20Z Update...
The primary change made to the Day 1 Outlook was to trim higher
severe probabilities behind the convective line across the Mid
Mississippi Valley, as convective overturning has reduced
surface-based buoyancy. Otherwise, the previous forecast remains on
track, with scattered to numerous wind/hail producing thunderstorms
developing ahead of the cold front, from New England to the lower
Mississippi Valley. Please refer to MCDs 0852-0854 for more
information. Likewise, damaging gusts/occasionally large hail may
still accompany ongoing storms across the southeast CONUS (more
details available via MCDs 0855-0856).
..Squitieri.. 05/21/2022
.PREV DISCUSSION... /ISSUED 1046 AM CDT Sat May 21 2022/
...Southern Plains to Northeast...
A complex and active convective day is anticipated for much of the
central and eastern US. Several lines/clusters of strong to severe
thunderstorms are expected to intensify by mid-afternoon along a
cold front and associated outflow boundaries from southeast Ontario
into the Great Lakes region, OH Valley, middle MS Valley and
southern Plains. The air mass ahead of the boundaries is quite
moist with areas of strong daytime heating already occurring. While
large scale forcing mechanisms are generally weak along this broad
corridor, numerous thunderstorms are expected. Strong instability
combined with sufficient flow aloft and steep low-level lapse rates
will result in a risk of locally damaging wind gusts and some hail
along the entire frontal zone. Most areas will see multicell storm
clusters and lines. However, sufficient low and deep layer shear
will likely result in a few supercells moving into northern New
England later today with a slightly higher risk of a tornado or two.
Please reference recent MCDs #848 and #849 for further short-term
details.
...Gulf Coast states into the Carolinas...
There is also a broad area of potential for at least isolated strong
to severe storms over much of the southern and southeastern US
today. Wind fields aloft are relatively weak in most places.
However, strong heating, rich low-level moisture, and relatively
cool temperatures aloft will promote robust up/downdrafts capable of
locally damaging wind gusts and some hail.
Read more CHECK UPDATE ZOOM GRAPHIC
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Weather conditions on bar directly above are near Lakefront. Tabs under Moon Phases refer to O'Hare (official).
Archives for SPC Convective outlook are updated daily with a live map a the beginning of the article. Touch or click map to get possible update, and follow link at end of article for referral to NOAA/NWS Storm Prediction Center. Archives for Chicago's hourly weather data were updated 24-48 hours after end of each day prior to Dec. 2020.
CONVECTIVE | TORNADO | WIND | HAIL
Saturday, May 21, 2022
SPC May 21, 2022 2000 UTC Day 1 Convective Outlook
SPC May 21, 2022 Day 4-8 Severe Weather Outlook
Day 4-8 Outlook
Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0359 AM CDT Sat May 21 2022
Valid 241200Z - 291200Z
...DISCUSSION...
...Tuesday/Day 4 to Thursday/Day 6...
An upper-level trough is forecast to move into the southern High
Plains on Tuesday. Ahead of the trough, a moist airmass will be
located across parts of central and east Texas, where moderate
instability is expected to develop by afternoon. Thunderstorm
formation will be possible over a large part of the southern Plains
eastward into the lower Mississippi Valley. An MCS may organize
along the northern edge of the stronger instability and pose a
severe threat during the afternoon and evening. At this time, there
is a large spread in the model solutions concerning where this MCS
could potentially form. This combined with the fact that mesoscale
influences will be a strong contributor to any severe threat, makes
for a lot of uncertainty. There will likely be need for a severe
threat area once the model solutions key in on a specific area with
greater potential.
On Wednesday, the upper-level trough is forecast to move slowly
eastward across the southern Plains. A moist and unstable airmass
should be in place from the Texas Coastal Plains eastward into the
central Gulf Coast states. Moisture advection will also take place
across the Ohio and Tennessee Valleys. A potential for strong
thunderstorm development will be possible along the northern edge of
the stronger instability, somewhere from east Texas eastward into
lower Mississippi Valley. Other strong thunderstorms could form
ahead of a cold front from the mid Mississippi Valley northeastward
into the Ohio Valley. Mesoscale influences and the distribution of
instability will again have a strong impact any severe threat that
develops Wednesday afternoon.
The upper-level trough is forecast to move into the lower to mid
Mississippi Valley on Thursday, as a moist airmass remains to the
east of the system. Thunderstorm development will be possible over a
large area from the central Gulf Coast states northward into the
Ohio Valley. Isolated strong thunderstorms will again be possible
along this corridor in areas that heat up the most, and in areas
where mesoscale factors are favorable.
From Tuesday to Thursday, predictability is too low to add a threat
area, due to the uncertainties previously mentioned.
...Friday/Day 7 and Saturday/Day 8...
On Friday and Saturday, the upper-level system is forecast to move
slowly eastward toward the East Coast. Thunderstorms will again be
possible each day across a broad area ahead of the system. Although
strong thunderstorms will be possible in some areas of the eastern
U.S. each afternoon and evening, the range in the forecast is too
far out to make any solid conclusions concerning specific threat
areas.
Read more CHECK UPDATE ZOOM GRAPHIC
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SPC May 21, 2022 0730 UTC Day 3 Severe Thunderstorm Outlook
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0222 AM CDT Sat May 21 2022
Valid 231200Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS...
...SUMMARY...
Isolated wind damage and large hail will be possible across parts of
central Texas Monday afternoon and evening. Marginally severe storms
with strong wind gusts and hail could also occur across parts of
north and east Texas.
...Texas...
An upper-level trough is forecast to move eastward into the southern
and central High Plains on Monday. At the surface, a trough is
forecast to develop across central Texas. Ahead of the surface
trough, a moist and unstable airmass will be in place with surface
dewpoints from the upper 60s to the mid 70s F. In response, moderate
instability is expected across much of the moist sector by
afternoon. Although thunderstorm development will be possible across
a large portion of the southern Plains, the strongest convection is
expected along the western edge of the moderately unstable airmass.
Thunderstorms are forecast to increase in coverage during the
afternoon and move eastward into the stronger instability across the
Texas Hill country and north Texas.
Forecast soundings Monday afternoon, near the axis of strongest
instability, have MLCAPE peaking in the 2500 to 3500 J/kg range. 0-6
km shear is forecast to range from about 30 knots in north Texas to
around 40 knots in the Texas Hill Country. This combined with steep
low to mid-level lapse rates should be sufficient for an isolated
severe threat. Wind damage would be the greatest of the threats if
an organized line segment can develop. If cells remain more
discrete, then supercell development will be possible. At this time,
the models show the best severe-weather parameters over southwest
and central Texas, where there could be a slightly greater potential
for wind damage and isolated large hail than further to the north.
If tomorrow's model runs continue to show more potential for severe
storms in central and southwest Texas on Monday, then a slight could
be added in an upcoming outlook.
..Broyles.. 05/21/2022
Read more CHECK UPDATE ZOOM GRAPHIC
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Friday, May 20, 2022
SPC May 20, 2022 2000 UTC Day 1 Convective Outlook
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Fri May 20 2022
Valid 202000Z - 211200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR A SMALL
PART OF EASTERN PENNSYLVANIA INTO NEW JERSEY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
LOWER MICHIGAN...AND OKLAHOMA INTO NORTH TEXAS...
...SUMMARY...
Severe thunderstorms are expected to be most concentrated over
portions of the northern Mid-Atlantic states, Lower Michigan, and a
small part of the southern Plains this afternoon and evening.
...20Z Update...
Have trimmed severe probabilities behind a small cluster of
thunderstorms over eastern PA. Damaging winds should continue to be
the main threat with this activity as it spreads into NJ over the
next couple of hours, but a tornado or two also remain possible. See
Mesoscale Discussion 842 and 843 for more information on the
near-term severe threat across this area.
An intense supercell producing a tornado is ongoing at 1958Z over
northern Lower MI. The 19Z sounding from APX shows a favorable
environment for continued thunderstorm organization, and it appears
plausible that this supercell will persist across the rest of
northern Lower MI over the next hour or so. A threat for tornadoes,
large to very large hail, and damaging winds should persist with
this supercell in the short term, and with any other intense
thunderstorms that can develop. Still, weak large-scale ascent will
probably tend to limit overall coverage through the rest of the
afternoon, with the overall severe threat probably remaining fairly
isolated. See Mesoscale Discussion 844 for additional details on the
near-term severe threat across northern Lower MI.
Elsewhere, little to no changes were made to the outlook.
..Gleason.. 05/20/2022
.PREV DISCUSSION... /ISSUED 1126 AM CDT Fri May 20 2022/
...Mid Atlantic Region...
A well-defined MCV is noted on satellite imagery over southwest PA.
This feature will track eastward today across PA, northern MD, and
into NJ, fostering the development of severe thunderstorms.
Destabilization ahead of the MCV, combined with strong low and
mid-level wind fields near the circulation will promote the
development of supercell and bowing structures capable of damaging
winds, large hail, and a few tornadoes. Given the rapid eastward
motion of the activity, it should move off the NJ coast well before
dark, ending the severe threat.
...MI...
A strong surface cold front currently extends from southern WI
northward into upper MI. This front will cross Lake Michigan this
afternoon and move into lower MI by early evening. Thunderstorms
are expected to form in vicinity of the front and move across parts
of the northern Lower MI. Forecast soundings suggest favorable
parameters for large hail in the stronger storms, along with the
possibility of isolated tornadoes.
...OK/TX...
A cold front is sagging southward across OK today, and should stall
for awhile this evening before progressing into TX overnight. A
strengthening southerly low-level jet atop the boundary will lead to
scattered thunderstorms in a very unstable air mass. Storms may be
supercellular with large hail and damaging winds. A tornado or two
cannot be ruled out before activity becomes more linear after dark.
...FL...
A moist boundary layer is present today across the FL peninsula,
along with pockets of strong heating. Scattered thunderstorms have
begun to form over south FL, and this activity is expected to build
northward through the day. Relatively cool temperatures and modest
westerly flow aloft will promote a few organized multicell storm
clusters capable of gusty/damaging winds or perhaps hail.
Read more CHECK UPDATE ZOOM GRAPHIC
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