SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0249 PM CDT Wed Aug 17 2022
Valid 172000Z - 181200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THROUGH THIS
EVENING FROM EAST TX TO THE LOWER MS VALLEY AND NORTH FL...SOUTHERN
AZ...AND THE WESTERN DAKOTAS......
...SUMMARY...
Isolated damaging winds will be possible through this evening from
east Texas across the lower Mississippi Valley to north Florida,
southern Arizona, and the western Dakotas.
...20z Update...
Only minor adjustments have been made to the Marginal risk area
across Florida based on latest convective trends. Otherwise, the
previous outlook remains unchanged and on track. See discussion
below for more forecast details.
..Leitman.. 08/17/2022
.PREV DISCUSSION... /ISSUED 1129 AM CDT Wed Aug 17 2022/
...Lower MS Valley to north FL this afternoon/evening...
A remnant MCV will move east-southeastward from AR to MS/AL this
afternoon, roughly along and just north of an outflow-reinforced
front from the AR/LA border across central MS to southern AL.
Strong surface heating and boundary-layer dewpoints well into the
70s will boost MLCAPE to near 3000 J/kg this afternoon along and
south of the front/outflow, and additional thunderstorm development
is expected by mid afternoon. The surface boundaries that will
focus storm initiation will lie along the southwest fringe of the
20-30 kt midlevel flow, which will support multicell clusters.
Precipitation loading with the strong buoyancy, in combination with
DCAPE near or above 1000 J/kg, will support isolated wind damage
with downbursts this afternoon/evening. Otherwise, isolated strong
storms will also be possible across north FL, primarily with sea
breeze and outflow interactions.
...Southern AZ this afternoon/evening...
To the west of a remnant tropical low over northern Mexico, midlevel
east-northeast flow will strengthen some through this evening over
southern AZ. This will favor convective clusters moving
southwestward from the higher terrain to the lower deserts, where
strong surface heating and boundary-layer dewpoints in the 60s will
contribute to moderate buoyancy and weakening convective inhibition.
Typical steep low-level lapse rates and substantial precipitation
loading will favor hybrid microbursts capable of producing isolated
strong-severe outflow winds.
...Western Dakotas this afternoon/evening...
Some convection is ongoing late this morning over the northern High
Plains, in advance of a weak midlevel trough moving over northeast
MT. The convection is expected to increase some later this
afternoon as it encounters a deeper mixed boundary layer, when there
will be the potential for isolated strong-severe outflow gusts.
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
Wednesday, August 17, 2022
SPC Aug 17, 2022 2000 UTC Day 1 Convective Outlook
Tuesday, August 16, 2022
SPC Aug 16, 2022 2000 UTC Day 1 Convective Outlook
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0233 PM CDT Tue Aug 16 2022
Valid 162000Z - 171200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FROM THE LOWER MS VALLEY TO THE OZARKS AND
SOUTHERN HIGH PLAINS...AND ACROSS NORTHERN MN INTO CENTRAL ND......
...SUMMARY...
Isolated damaging winds and marginally severe hail will be possible
this afternoon/evening for parts of the Ozarks, lower Mississippi
Valley, southern High Plains, and northern Minnesota vicinity.
...North Dakota...
The Marginal risk has been expanded westward into parts of central
ND with the 20z update. Isolated thunderstorms have developed near a
weak surface boundary oriented west to east/northeast from central
ND into northwest MN. Visible satellite imagery has shown an
expanding cumulus field near the boundary this afternoon. Vertical
shear will remain modest, but MLCAPE around 1500 J/kg and enhanced
low-level shear along the boundary, coupled with steep low-level
lapse rates, could support a few strong gusts with storms that
develop through early evening.
...Southern High Plains to the Ozarks/Lower MS Valley...
The ongoing outlook remains unchanged. Isolated strong to severe
thunderstorms remain possible across parts of the southern High
Plains to the Lower MS Valley through early evening. Reference MCDs
1686 and 1687 for more details regarding short term severe
potential.
..Leitman.. 08/16/2022
.PREV DISCUSSION... /ISSUED 1126 AM CDT Tue Aug 16 2022/
...Ozarks/lower MS Valley/southern Plains through this evening...
A diffuse MCV over northern MO will move southeastward today, within
a band of 30-40 kt midlevel flow (per regional VWPs). Elevated
convection has persisted from overnight into this morning in a zone
of warm advection over southern MO, and clouds/differential heating
will reinforce a baroclinic zone across southern/western AR into
southwestern MO. This baroclinic zone will serve to focus
additional thunderstorm development later this afternoon near the
MO/AR/OK border intersection, and storms will subsequently move
southeastward through the evening. There will be a narrow corridor
of overlap of moderate buoyancy and somewhat stronger vertical shear
along the surface boundary where some low-end supercell potential
will exist (at the northeast edge of the stronger surface heating
and deeper mixing). Isolated wind damage and marginally severe hail
will be possible with any supercells that form.
Otherwise, a few cells/clusters may form along the slow-moving front
farther southeast toward central MS, where MLCAPE of 2500-3000 J/kg
and DCAPE near 1000 J/kg will support the potential for isolated
strong/damaging downbursts. Buoyancy will be weaker in the warm
sector farther west along the cold front in OK/eastern TX Panhandle
and storm coverage is in question. If storms do form, deep
inverted-v profiles and large DCAPE (> 1500 J/kg) will support the
threat for isolated microbursts.
...Southeast CO/northeast NM vicinity this afternoon/evening...
Low-level flow is expected to become weak upslope in a post-frontal
environment from southeast CO into northeast NM by later this
afternoon. Though midlevel lapse rates will not be particularly
steep within the lingering monsoonal moisture plume, boundary-layer
dewpoints in the upper 50s to lower 60s and surface heating will
result in MLCAPE of 500-1000 J/kg with minimal convective
inhibition. Scattered thunderstorm development is expected by mid
afternoon along and just east of the higher terrain, and convection
will spread east-southeastward onto the High Plains. Steepening
low-level lapse rates and clustering/upscale growth may support
isolated strong outflow gusts.
...Northern MN and vicinity this afternoon/evening...
A convectively-enhanced shortwave trough near the MN/ON/MB border
intersection will move slowly east-southeastward near the
international border through the afternoon. An associated wind
shift/weak cold front extends west-southwestward from northwest MN
into eastern ND. Ascent along the wind shift, in combination with
pockets of surface heating and boundary-layer dewpoints in the 60s,
will support scattered thunderstorm development this
afternoon/evening. MLCAPE of 1000-2000 J/kg and modest vertical
shear will support isolated marginally severe hail and
strong/damaging outflow gusts.
Read more CHECK UPDATE ZOOM GRAPHIC
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Sunday, August 14, 2022
SPC Aug 14, 2022 1300 UTC Day 1 Convective Outlook
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Sun Aug 14 2022
Valid 141300Z - 151200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL HIGH PLAINS AND NORTH DAKOTA...
...SUMMARY...
Scattered convection capable of isolated/marginally severe
thunderstorms will spread across portions of the central High Plains
region, as well as parts of North Dakota, this afternoon and
evening.
...Central High Plains...
Upper ridge-peripheral disturbances and moderately strong winds
aloft will influence the eastern Great Basin/central Rockies into
the central High Plains into this afternoon and tonight. Scattered
convection will likely initially develop and increase across
Wyoming/northern Colorado this afternoon as boundary layer warming
aids destabilization. Weak deep-layer flow/shear suggest updrafts
will struggle to organize; however, sufficiently steep lapse rates
and adequate instability favor gusty winds and perhaps marginally
severe hail with the strongest cores as storms develop
east-northeastward. Model guidance suggests a notable increase to
the low-level jet this evening across the central High Plains
including western portions of Kansas/Nebraska, which should support
eastward storm propagation after sunset.
...Western/northern North Dakota and vicinity...
Have introduced low severe probabilities for the potential of a few
strong/severe storms across the region, primarily late this
afternoon and evening. In the wake of some early day cloud cover and
isolated thunderstorms, a moist/potentially unstable air mass will
persist near/east of a surface low/front-related triple point.
Subsequent development toward/after peak heating may remain fairly
isolated. Regardless, the environment would seemingly support some
semi-sustained multicells and possibly a few slow-moving supercells
particularly across western/northern Dakota if/where storms do
develop. Localized severe-wind gusts and hail may occur.
...South Texas...
Low-level southeasterly winds may modestly strengthen today in
proximity to a westward drifting area of low pressure centered
across Deep South Texas. A few weak/transient supercells are
conceivable near the coast, but even so, destabilization inland
should be hindered by cloud cover/precipitation and any low-level
shear/SRH increase should remain modest overall. Thus, current
thinking is the tornado/wind gust-related severe potential will
remain negligible across the region.
..Guyer/Broyles.. 08/14/2022
Read more CHECK UPDATE ZOOM GRAPHIC
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Saturday, August 13, 2022
SPC Aug 13, 2022 0730 UTC Day 3 Severe Thunderstorm Outlook
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0226 AM CDT Sat Aug 13 2022
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN GEORGIA INTO THE CAROLINAS AND SOUTHERN VIRGINIA...
...SUMMARY...
Isolated strong to severe thunderstorms may occur Monday across
parts of eastern Georgia into the Carolinas and southern Virginia.
...Eastern Georgia into the Carolinas and Southern Virginia...
A large-scale upper trough should remain over much of the eastern
CONUS and Canada on Monday. A belt of modestly enhanced mid-level
northwesterly winds is forecast to persist from parts of the OH/TN
Valleys into the Southeast. At the surface, low-level moisture
should gradually increase ahead of a front that should move
east-southeastward across the central Appalachians into the
Southeast and southern Mid-Atlantic. Weak to moderate instability
should develop ahead of this boundary by Monday afternoon as diurnal
heating occurs. Low-level lapse rates are also forecast to steepen,
especially ahead of convection that may be ongoing Monday morning.
Deep-layer shear appears strong enough for organized updrafts, and
most guidance shows the potential for one or more clusters of
surface-based thunderstorms to develop along/ahead of the front and
spread east-southeastward through Monday evening. A Marginal Risk
has been included where the best signal for robust convection exists
Monday afternoon, from parts of eastern GA into the Carolinas and
southern VA.
...Central Plains...
A surface low should be present over KS into southern NE on Monday,
with rich low-level moisture extending in a narrow corridor from the
Southeast into the Ozarks and central Plains. An upper ridge will
likely remain prominent over much of the western CONUS into the
southern Plains, with nebulous large-scale forcing aloft over the
central Plains. Even so, a ribbon of moderate instability may
develop across parts of NE/KS by late Monday afternoon along the
axis of greater low-level moisture. A large degree of uncertainty
remains regarding potential for surface-based thunderstorm
development. But, if any convection can develop across the narrow
warm sector, it would have the potential to become severe given the
favorable instability and sufficient deep-layer shear forecast. Have
opted to not include low severe probabilities for now, as the severe
threat appears rather conditional on thunderstorms developing.
..Gleason.. 08/13/2022
Read more CHECK UPDATE ZOOM GRAPHIC
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