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Topic: SPC Aug 21, 2022 1300 UTC Day 1 Convective Outlook (Read 25 times) previous topic - next topic

SPC Aug 21, 2022 1300 UTC Day 1 Convective Outlook

SPC Aug 21, 2022 1300 UTC Day 1 Convective Outlook

[html]SPC 1300Z Day 1 Outlook
     
Day 1 Outlook Image

Day 1 Convective Outlook 
NWS Storm Prediction Center Norman OK
0750 AM CDT Sun Aug 21 2022

Valid 211300Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE
OHIO VALLEY...

...SUMMARY...
Isolated strong to severe thunderstorms are expected this afternoon
especially across parts of the Ohio and Tennessee River Valleys.

...Tennessee Valley to middle/upper Ohio Valley and Carolinas...
An upper trough centered over Illinois/Indiana/Lower Michigan this
morning will continue generally eastward, reaching the upper Ohio
Valley tonight. A cyclonically curved belt of moderately strong
westerlies (25-30 kt at 500 mb) acco*panies this trough along with a
pocket of semi-cool (by August standards) mid-level temperatures
(-10C at 500 mb).

Ahead of an eastward-moving cold front, ongoing precipitation/cloud
cover and related differential heating will influence multiple zones
of increasing and intensifying thunderstorms, including
Kentucky/Tennessee into Ohio/eastern Indiana. Cloud
breaks/insolation and a moist environment will likely contribute to
pre-convective MLCAPE of 1000-1750 J/kg across the Ohio/Tennessee
Valleys, which will support some stronger updrafts, with mostly
multicell organization given the modestly strength westerlies.
Damaging wind gusts will be the primary severe risk. It appears that
a somewhat greater sub-regional potential for severe storms should
exist across Ohio/eastern Kentucky into parts of West Virginia.

Farther east, especially outside of a few areas of early day
scattered precipitation, moderate destabilization is expected
particularly across parts of Virginia and the coastal Carolinas.
Afternoon heating/instability should be sufficient for some
thunderstorms capable of tree damage.

...Central/northeast Texas to Louisiana/southern Mississippi...
A few severe storms capable of localized wind damage may occur later
this afternoon into evening across the region. Extensive early day
precipitation including some embedded thunderstorms are ongoing
across much of Oklahoma and northwest/far north Texas, and on a more
scattered basis across Arkansas. 00z (and prelim 12z) upper-air
analysis/data implied a trough-associated pocket of somewhat cooler
mid-level temperatures with modestly enhanced mid-level westerlies.
While heavy rainfall should be the most prevalent concern
regionally, there is some potential that the more discrete
southern-peripheral convective elements could pose a localized
wind-damage risk as storms spread east-southeastward within a
moist/moderately unstable environment.

Later this evening/overnight, some guidance suggests a respectable
deepening of a low in vicinity of the effective front across
north-central Texas. While the 06z NAM, in particular, may be overly
aggressive in its deepening of the surface low and strengthening of
low-level/850 mb winds, there could be at least some transient
supercell potential tonight across north-central/northeast Texas.

...Central/southern Arizona...
A few small-scale corridors of thunderstorms will linger early
today, but clouds will gradually thin/abate into the afternoon, with
thunderstorm development again expected, particularly over the
Mogollon Rim by mid/late afternoon. Within a moist monsoonal
environment, diurnal destabilization should be maximized across
central/western Arizona. Steering flow will not be overly strong,
but weak southward-southwestward propagation should allow for some
stronger/locally severe storms to reach lower elevations of
central/southern Arizona late this afternoon and evening.

..Guyer/Edwards.. 08/21/2022


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Source: SPC Aug 21, 2022 1300 UTC Day 1 Convective Outlook (http://ht**://www.spc.noaa.gov/products/outlook/day1otlk_1300.html)