Thursday, June 25, 2020

SPC Jun 25, 2020 0600 UTC Day 2 Convective Outlook

SPC 0600Z Day 2 Outlook
Day 2 Outlook Image
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1254 AM CDT Thu Jun 25 2020

Valid 261200Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
GREAT LAKES REGION SOUTHWESTWARD TO THE MIDDLE MISSOURI VALLEY...

...SUMMARY...
Scattered posing a risk for damaging winds and hail are expected
from the central Plains east-northeastward across the Midwest to the
Great Lakes Friday afternoon and evening.

...Synopsis...
Gradual evolution of quasi-zonal flow aloft will occur Friday, as
eastern U.S. troughing shifts offshore.  A positively tilted,
low-amplitude short-wave trough within the westerlies will cross the
central portion of the country through the period.

At the surface, a cold front initially stretching from Minnesota to
western Kansas will become elongated in a more
northeast-to-southwest manner, as front moves eastward across the
Great Lakes region, while lingering over Kansas.  Meanwhile, a
second cold front is forecast to work its way inland/across the
Pacific Northwest, ahead of a mid-level short-wave trough digging
southeastward out of the Gulf of Alaska.

...Mid MO/Mid MS Valleys to the Great Lakes...
Scattered thunderstorms are forecast to be ongoing across portions
of the upper Mississippi Valley/Upper Great Lakes region
area at the start of the period, ahead of the advancing cold front. 
As diurnal heating drives afternoon destabilization, new storm
development is expected near the advancing cold front, first over
the Wisconsin vicinity and then stretching southwestward along the
cold front into Kansas.  

Flow aloft through the lower and middle troposphere across the
region will be sufficient for organized storms -- likely evolving
locally into fast/eastward-moving bands.  Along with hail potential,
damaging winds will likely to be the favored severe risk.  Depending
upon degree of destabilization which can occur across the Great
Lakes area in the wake of early-period convection, a more
organized/bowing-type wind risk could evolve, which could require
higher wind probability/greater categorical risk in later forecasts.

Convection should continue through the overnight hours -- spreading
as far east as parts of Pennsylvania and New York, but
with severe risk likely waning gradually as the airmass stabilizes
with time.

...Central and southern High Plains...
Isolated to widely scattered, late afternoon/early evening
thunderstorm development is expected over the Front Range, as
low-level easterly upslope flow evolves north of the cold front
becoming more west-to-east oriented across Kansas through the day. 
Moderate westerly flow aloft atop low-level southerlies will likely
result in sufficient shear organized/rotating updrafts.  A deep
mixed layer which will evolve through the afternoon over the High
Plains suggests that storms moving off the higher terrain
will be capable of locally strong wind gusts.  An isolated
landspout-type tornado also cannot be ruled out, though potential
for greater tornado risk should remain limited by a dry/deep
boundary layer.  At this time, will maintain only marginal/level 1
categorical risk, due to anticipated storm coverage being sparse. 
Risk may be upgraded to slight risk in future outlooks if a bit more
widespread development becomes more likely.

Evening development of a southerly low-level jet could permit some
upscale growth as storms move southward/southeastward during the
evening, with some wind risk possibly lingering locally through the
evening hours.

...East Texas and the Arklatex vicinity...
Model forecasts of a weak upper low drifting northward across East
Texas will likely support an increase in afternoon storm development
across the Texas/Arkansas/Louisiana vicinities.  Slightly enhanced
southerly low-level flow ahead of the low may promote rather fast
northward storm motion, possibly resulting in a stronger wind gust
or two.  However, risk appears too low to warrant inclusion of a
risk are at this time.

..Goss.. 06/25/2020

Read more

from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_0600.html

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