SPC Mesoscale Discussion
SPC MD 1345
MD 1345 CONCERNING TORNADO WATCH 432... FOR EASTERN IL...WESTERN/NORTHERN IN...FAR SOUTHWEST LOWER MI
Mesoscale Discussion 1345
NWS Storm Prediction Center Norman OK
1057 AM CDT Wed Jun 18 2025
Areas affected...eastern IL...western/northern IN...far southwest
Lower MI
Concerning...Tornado Watch 432...
Valid 181557Z - 181800Z
The severe weather threat for Tornado Watch 432 continues.
SUMMARY...Severe threat should increase substantially through
mid-afternoon as an arc of storms intensifies to the east-northeast
from central Illinois. A few tornadoes, scattered damaging winds,
and isolated severe hail will remain possible. Downstream tornado
watch issuance is anticipated to the northeast of Ww 432.
DISCUSSION...While the primary surface cyclone and attendant MCV are
centered near the northeast MO/west-central IL border area, a
downstream arc of increasing deep convection is expected to
strengthen across central IL. With mid 70s surface dew points common
across southern IL/IN, a pronounced MLCAPE gradient is setting up
from south to north. A compact belt of strong 700-500 mb
southwesterlies in the LSX VWP, recently sampled by the ILX VWP as
well, should support a broken band of supercells within this leading
arc as it spreads northeast. The potential for tornadoes has
increased and a 10 percent tornado probability will be added in the
1630Z D1 Outlook. The LSX VWP also indicates low-level SRH
diminishing behind this leading arc, but some tornado threat should
linger near the immediate MCV/surface low.
..Grams/Hart.. 06/18/2025
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...IWX...GRR...IND...LOT...ILX...LSX...DVN...
LAT...LON 38828765 38718868 38918905 39628955 39998986 40269003
40668975 41248906 41698817 42238631 42058597 41788572
41378574 40628592 40218623 39618689 38828765
MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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SPC MD 1344
MD 1344 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF THE MID-ATLANTIC STATES
Mesoscale Discussion 1344
NWS Storm Prediction Center Norman OK
1036 AM CDT Wed Jun 18 2025
Areas affected...parts of the Mid-Atlantic States
Concerning...Severe potential...Watch possible
Valid 181536Z - 181730Z
Probability of Watch Issuance...40 percent
SUMMARY...The threat for damaging winds should increase this
afternoon as isolated to scattered thunderstorms form off parts of
the Blue Ridge towards coastal New Jersey and Delaware. Area is
being monitored for a possible Severe Thunderstorm Watch with
uncertainty on overall coverage/intensity for severe gusts. An
upgrade to Slight Risk is likely with the 1630Z Day 1 Outlook.
DISCUSSION...Initial low-topped convection has been slowly bubbling
across far northern VA and the eastern WV Panhandle. Airmass
immediately downstream appears uncapped per mesoanalysis and
modified 12Z soundings, where surface temperatures have warmed into
the low to mid 80s. 12Z guidance is consistent in suggesting
isolated to scattered thunderstorms developing within a region of
enhanced 700-500 mb west-southwesterlies. This should provide
sufficient speed shear for a few transient cells with mid-level
rotation. With poor mid-level lapse rates, hail magnitudes should
remain small. But if stratus across the northern Chesapeake/Delaware
Bays vicinity can break up this afternoon, a greater than isolated
damaging wind threat may be realized.
..Grams/Hart.. 06/18/2025
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...CTP...LWX...
LAT...LON 39067797 39677750 40097619 40037514 39707417 39247463
38967537 38627599 38577660 38597727 38767779 39067797
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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