SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sat May 28 2022
Valid 282000Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATER THIS
AFTERNOON/EVENING FOR NORTHEAST WY INTO SD/NE...AND FOR NORTHWEST TX
INTO SOUTHWEST OK...
...SUMMARY...
Severe thunderstorm gusts of 60-75 mph and large hail are expected
late this afternoon and evening across parts of the northern and
southern Plains.
...Northern and Southern Plains...
No significant changes have been made to the Marginal and Slight
Risks across parts of the northern and southern Plains. High-based
convection is expected to increase across both regions late this
afternoon into the early evening, with a threat of wind gusts of
60-75 mph, and perhaps some isolated hail. See the previous
discussion below for more details, and MCD 947 for more information
regarding the threat in the northern Great Plains region.
...New England...
Generally disorganized convection continues across parts of New
England this afternoon, within an environment characterized by
MLCAPE of 500-1000 J/kg and relatively weak low-level and deep-layer
flow/shear. While locally gusty winds and/or small hail will be
possible with the strongest storms, an organized severe threat is
not expected, so the Marginal Risk has been dropped from this
region.
..Dean.. 05/28/2022
.PREV DISCUSSION... /ISSUED 1121 AM CDT Sat May 28 2022/
...WY/SD/NE this afternoon into early tonight...
Gradual amplification of a midlevel trough will continue through
tonight over the Great Basin/Intermountain West. Within
increasingly cyclonic flow aloft, an embedded shortwave trough now
over eastern ID/northern UT will eject east-northeastward over WY
late this afternoon and SD/NE tonight. Warm sector buoyancy is
expected to be rather modest as a result of the richer moisture
still being confined to the southern Plains, and there will be
enough mid-high clouds to potentially slow surface heating/mixing
across WY. The limited thermodynamic profiles, combined with only
modestly strong wind profiles/vertical shear, may tend to limit
storm organization/intensity and any resultant threat for more
widespread severe storms.
The more probable scenario appears to be for loosely organized
clusters to storms to form this afternoon/evening near the surface
lee cyclone/trough in WY. Convection will subsequently spread
eastward/northeastward into SD as clusters and/or bowing segments,
with additional storm development expected farther south into NE by
this evening. Severe outflow gusts of 60-75 mph will be the main
threat, though isolated large hail may occur with any embedded
supercell structures, especially farther east and later this evening
as the storms encounter larger buoyancy.
...Southern Plains this afternoon/evening...
Strong surface heating and deep mixing will occur this afternoon
along a sharpening dryline across west TX and the eastern TX
Panhandle, south of a deepening lee cyclone across the central High
Plains. Low-level moisture will increase during the day to the east
of the dryline, resulting in MLCAPE of 2000-3000 J/kg in the moist
sector. As surface temperatures warm to 100-105 F, convective
inhibition will diminish and deep inverted-v profiles will support
at least widely scattered, high-based thunderstorm development along
the dryline by late afternoon. Very large DCAPE (in excess of 1700
J/kg) and the moderate-strong buoyancy will support the potential
for downbursts with severe outflow winds of 60-75 mph. Deep-layer
vertical shear will be sufficient for some organized/supercell
storms, and convection could persist into southwest OK and northwest
TX through late evening. However, increasingly large convective
inhibition with eastward extent should result in storm weakening by
01-02z.
...New England this afternoon...
Scattered thunderstorms are expected today across southern New
England, along a weak cold front and in advance of a midlevel trough
moving eastward over PA/NY. Relatively moist profiles and
substantial cloud cover will continue to limit lapse rates/buoyancy
across southern New England, and vertical shear will weaken from
west-to-east during the day as the midlevel trough moves overhead.
Though isolated/minor wind damage and small hail cannot be ruled
out, the scenario is not favorable for any persistent/organized
threat for severe storms.
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/SRDtMv
