Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sun Apr 14 2024
Valid 141300Z - 151200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN OHIO INTO PENNSYLVANIA...
...SUMMARY...
Severe thunderstorms should develop late this afternoon in a narrow
corridor across the upper Ohio Valley into Pennsylvania and
vicinity. Damaging winds should be the main threat. Severe hail and
perhaps a couple of tornadoes also appear possible as this activity
spreads slowly southward into this evening.
...Ohio Valley into the Mid-Atlantic and Northeast...
Early morning surface observations show a dearth of low-level
moisture from the upper OH Valley into the Mid-Atlantic, with
surface dewpoints generally in the 30s. However, boundary-layer
moisture will gradually increase through the day across these
regions, as a weak surface low migrates eastward from the Great
Lakes across NY. By late afternoon, generally upper 40s to low 50s
surface dewpoints should become focused in a narrow corridor along
and south of front from OH into PA and southern NY. With upper
troughing persisting over eastern Canada and parts of the Northeast,
generally westerly mid-level winds across the Midwest/OH Valley will
aid in the eastward advection of an EML and associated steep
mid-level lapse rates. Even though low-level moisture is expected to
remain limited, these steepened lapse rates aloft, along with
diurnal heating, should encourage the development of weak to locally
moderate MLCAPE late this afternoon.
Surface-based thunderstorm initiation across this region will likely
be delayed until 20-21Z or later, as lingering MLCIN and a cap
gradually erodes. Initial development should be focused along the
front across parts of eastern OH into western/central PA, with
additional development eventually occurring into eastern PA and
parts of southern NY. Given strong deep-layer shear and favorable
lapse rates, large hail may occur with the more robust cores
initially. Some threat for a couple of tornadoes may also exist with
semi-discrete convection, as sufficient low-level shear will be
present for updraft rotation. But, with the surface front aligned
mostly parallel to the enhanced westerly low/mid-level flow, upscale
growth into small bowing clusters should quickly occur as convection
spreads south-southeastward. Scattered damaging winds will likely
become the main threat with these clusters through the early evening
in a narrow spatial corridor extending from eastern OH into PA where
instability and steep low/mid-level lapse rates should be maximized.
The damaging wind threat will gradually decrease through the evening
as instability lessens with southward/eastward extent.
..Gleason/Grams.. 04/14/2024
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