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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

ARLINGTON HEIGHTS WEATHER

Thursday, May 23, 2024

SPC May 23, 2024 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 PM CDT Wed May 22 2024

Valid 230100Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN CENTRAL TX TO
THE ARK-LA-MISS AND NORTHEAST OH TO WESTERN PA...

...SUMMARY...
Scattered severe thunderstorms remain possible this evening from
central Texas to the Ark-La-Miss, and in northeast Ohio to western
Pennsylvania. Isolated severe thunderstorms may persist overnight
from the Mid-South to the Northeast.

...01Z Update...
Primary severe threat will exist immediately ahead of multiple
clusters with embedded supercells from east-central TX to the
Ark-La-Tex. Over the next few hours, a threat for significant severe
wind/hail along with a couple tornadoes will continue. Recent HRRR
and WoFS runs along with 18Z guidance suggests this activity will
diminish during the late evening as MLCIN increases from south to
north ahead of the clusters. Still, have expanded level
1-2/MRGL-SLGT risks farther southeast in southeast TX to central LA.

Elsewhere, thunderstorms from eastern TN to NY have largely
subsided. Renewed development has occurred ahead of a surface cold
front from the central OH Valley to southwest ON. This activity has
held in a narrow convective line with marginally severe hail as the
primary initial threat. Despite the unfavorable time of day, as the
front fully overtakes this band, an increase in strong gusts may
occur with some linear clustering, mainly across northeast OH into
western PA.

Finally, additional low-level warm theta-e advection storms should
persist through the overnight from north TX across parts of the
Ozarks and Mid-South. Isolated severe hail will be possible in the
more sustained updrafts.

..Grams.. 05/23/2024


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/T7GpD4

Wednesday, May 22, 2024

SPC May 22, 2024 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Wed May 22 2024

Valid 222000Z - 231200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS CENTRAL TEXAS
INTO ARKANSAS...

...SUMMARY...
Within a long swath of severe-thunderstorm potential from central
Texas to the Lower Great Lakes, the greatest concentration of severe
weather (mainly large hail and damaging wind) should be across parts
of central Texas to central Arkansas. A few tornadoes are also
possible.

The existing day 1 outlook remains on track and little change was
needed at 20Z.

Large supercells are currently forming along the front across
central Texas, with giant hail possible in this extremely unstable
and deep-sheared environment.

To the east corridors of damaging wind and hail may develop with
storms extending from northeast TX into TN. For more information see
mesoscale discussions 893 and 894.

..Jewell.. 05/22/2024

.PREV DISCUSSION... /ISSUED 1109 AM CDT Wed May 22 2024/

...Southeast OK/AR/TN...
A band of strong/severe thunderstorms currently extends from
southeast OK into northwest AR, ahead of a surface cold front.
These storms will track eastward today across AR, with new storms
forming in the moist and moderately unstable air mass farther east.
Activity will spread into west/middle TN this afternoon, with a
continued risk of hail and damaging wind gusts.

...Central/East TX...
The ongoing forecast remains valid, with few changes made this
update cycle. A very moist surface air mass is present today over
central TX, with widespread dewpoints in the 70s. Multiple subtle
southern-stream shortwave troughs may affect this region this
afternoon, leading to intense thunderstorm development from
northwest into west-central TX. Strong deep-layer shear and fast
westerly flow aloft will promote supercells capable of very large
hail, damaging winds, and a few tornadoes. As this activity tracks
southeastward, congealing outflow will increase the risk of
corridors of damaging wind gusts.

...Upper OH Valley into MD/PA/NY...
Relatively fast southwesterly mid/upper level flow is present today
over much of the northeast quadrant of the US, with a cold front
moving across the OH Valley. Dewpoints in the 60s, strong daytime
heating, and moderately steep mid-level lapse rates will yield
afternoon MLCAPE values of around 1500 J/kg. Model guidance is in
agreement that scattered clusters of thunderstorms will form across
the region later today, with parameters favoring a risk of damaging
winds and some hail in the strongest cells.


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/T7GMk2

SPC May 22, 2024 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1109 AM CDT Wed May 22 2024

Valid 221630Z - 231200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING FROM CENTRAL TEXAS INTO SOUTHERN ARKANSAS AND NORTHWEST
LOUISIANA...

...SUMMARY...
Within a long swath of severe-thunderstorm potential from central
Texas to the Lower Great Lakes, the greatest concentration of severe
weather (mainly large hail and damaging wind) should be across parts
of central Texas to central Arkansas. A few tornadoes are also
possible.

...Southeast OK/AR/TN...
A band of strong/severe thunderstorms currently extends from
southeast OK into northwest AR, ahead of a surface cold front.
These storms will track eastward today across AR, with new storms
forming in the moist and moderately unstable air mass farther east.
Activity will spread into west/middle TN this afternoon, with a
continued risk of hail and damaging wind gusts.

...Central/East TX...
The ongoing forecast remains valid, with few changes made this
update cycle. A very moist surface air mass is present today over
central TX, with widespread dewpoints in the 70s. Multiple subtle
southern-stream shortwave troughs may affect this region this
afternoon, leading to intense thunderstorm development from
northwest into west-central TX. Strong deep-layer shear and fast
westerly flow aloft will promote supercells capable of very large
hail, damaging winds, and a few tornadoes. As this activity tracks
southeastward, congealing outflow will increase the risk of
corridors of damaging wind gusts.

...Upper OH Valley into MD/PA/NY...
Relatively fast southwesterly mid/upper level flow is present today
over much of the northeast quadrant of the US, with a cold front
moving across the OH Valley. Dewpoints in the 60s, strong daytime
heating, and moderately steep mid-level lapse rates will yield
afternoon MLCAPE values of around 1500 J/kg. Model guidance is in
agreement that scattered clusters of thunderstorms will form across
the region later today, with parameters favoring a risk of damaging
winds and some hail in the strongest cells.

..Hart/Wendt.. 05/22/2024


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/T7FmhL

SPC May 22, 2024 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Wed May 22 2024

Valid 221300Z - 231200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL TEXAS TO CENTRAL ARKANSAS...

...SUMMARY...
Within a long swath of severe-thunderstorm potential from central
Texas to the Lower Great Lakes, the greatest concentration of severe
weather (mainly large hail and damaging wind) should be across parts
of central Texas to central Arkansas. A few tornadoes are also
possible.

...Synopsis...
An active mid/upper-level pattern persists southeast through
southwest of a longstanding cyclone over southern SK and paths of
southern MB. That circulation will continue to meander erratically
near its present location through the period. Meanwhile, a train of
shortwaves will cross the northwestern and central CONUS and Great
Lakes regions. A strong shortwave trough -- with embedded 500-mb
low now over ON near the MN border -- should become stacked with its
deep surface cyclone this morning and drift erratically over ON
northwest of Lake Superior today. The stacked low then should eject
toward James Bay tonight.

The associated cold front -- analyzed at 11Z from northern Lower MI
to southern IL, northwestern AR, southern OK, and northwest TX to
the Permian Basin -- should move by 00Z to near a line from
CLE-EVV-ARG-DUA-SJT-CNM. The cold front should cross the lower
Great Lakes and much of NY through the end of the period, while
decelerating across parts of the lower/middle Ohio Valley. The
western part of the front should become more diffuse and retreat
northward overnight across the southern Plains. This will occur as
low-level mass response (including warm advection) intensifies,
ahead of a mid/upper cyclone moving eastward across the northwestern
CONUS toward the western WY/eastern ID region. A dryline --
initially drawn over the Big Bend region south of the front --
should mix eastward to northern Coahuila and a frontal intersection
over west-central TX by mid/late afternoon.

...Southern Plains to Arklatex region...
A broken swath of elevated thunderstorms is ongoing over parts of
central OK to southeastern KS. Isolated large hail is the main
concern, and should be for a few more hours. Some of this activity
may aggregate into a broader belt or cluster of convection and shift
eastward to southeastward through the day, toward the front.

Additional thunderstorms should develop from midday through this
afternoon along/ahead of the front and mid/late afternoon near the
dryline, with the near-frontal activity having the longest and
strongest organizational potential. A few supercells are expected
early in the convective cycle, and any supercell that stays
relatively discrete well into maturity will pose a risk of large to
giant hail. Storm-scale/boundary processes also may locally boost
tornado potential. Activity should grow upscale into the evening --
perhaps merging with remnants of earlier activity moving
southeastward from OK toward the surface front. As this occurs, the
main threat will transition to damaging and severe gusts. The
"enhanced" area represents the overlap of greatest hail and wind
probabilities with this transitional regime.

The warm sector southeast of the front, and east of the dryline,
will remain very moist -- characterized by upper 60s to mid 70s F
surface dew points. Underlying steep midlevel lapse rates, and with
strong surface heating anticipated, the result should be a corridor
of 3000-4000 J/kg MLCAPE. Given the strong heating and high ambient
theta-e, convective temperature may be attained even in the free
warm sector (away from the front and dryline), and despite the
prevalent EML. Though forecast soundings show weaknesses in the
flow around 2-3 km, both low-level and deep-layer shear (effective-
shear magnitudes 55-65 kt) and lengthy hodographs will be present,
supporting potential for locally destructive hail. Severe
downdrafts also are possible, both from individual supercells and
from convection resulting from aggregated cold pools. The overall
threat should decrease with this activity as it shifts eastward-
southeastward toward south/east TX and over LA tonight. However,
additional development atop the outflow may occur tonight farther
north near the Red River, helping to maintain some severe threat
(mainly in the form of hail and isolated severe gusts).

...Mid-South to Ohio Valley and lower Great Lakes...
Widely scattered to scattered thunderstorms, some in clusters, are
expected along this corridor from mid afternoon through the evening.
Damaging gusts will be the main concern, with isolated large hail
also possible. A marginal tornado threat also may develop,
particularly over portions of central/eastern OH to northwestern PA
and perhaps southwestern upstate NY, where low-level and deep shear
will be most favorable.

Once some ongoing clouds/precip over the Ohio Valley move away and
break up, surface heating should destabilize the boundary layer, in
concert with dewpoints commonly in the 60s F. This should yield a
prefrontal corridor of MLCAPE ranging from near 3000 J/kg over parts
of the Mid-South (where deep-layer lapse rates will be steepest) to
around 1500 J/kg over the area adjoining the lower Great Lakes.
35-45-kt effective-shear magnitudes will support a mix of multicell
and supercell modes, with upscale growth/clustering tending to limit
duration of supercells.

..Edwards/Goss.. 05/22/2024


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/T7FmJZ
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)