SPC Oct 11, 2018 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0237 PM CDT Thu Oct 11 2018

Valid 112000Z - 121200Z


A few tornadoes are possible through about 11 PM EDT from
northern/eastern North Carolina across southern Virginia into the
Delmarva region. The most probable corridor is across northeast
North Carolina and southeast Virginia this afternoon.

A couple changes have been made to the outlook for this issuance.
The first change is to downgrade the categorical outlook to just
slight risk. So far, Tropical Storm Michael has not been an
efficient tornado producer. Although low-level shear will be
favorable for tornadoes this afternoon into this evening, coverage
is expected to be less than was previously forecast. The second
change to the outlook is to trim the southern part of the slight
risk and thunder areas due to the northeastward progression of

..Broyles.. 10/11/2018

.PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Oct 11 2018/

...Mid-Atlantic States...
Primary expansion change is to adjust the Slight Risk slightly
farther north across parts of DE/MD. Considered further increasing
tornado probabilities across northeast NC and southeast VA, but

The center of TC Michael continues to track quickly northeast, just
northeast of Charlotte as of 16Z, and will reach southeast VA this
evening. Arcing band of showers and sporadic thunder is ongoing from
just north/east of Raleigh-Durham to coastal NC. Breaks in the cloud
cover downstream of this band have resulted in surface temperatures
warming into the lower to middle 80s already, which is supporting a
moderately buoyant air mass with MLCAPE from 1000-1500 J/kg. As this
convective arc spreads northeast through the afternoon,
intensification of embedded updrafts is expected along the northeast
periphery of the strong low-level wind field. This will favor a
swath of effective SRH from 200-500 m2/s2, supporting several
rotating cells into early evening. Increasing baroclinicity
downstream of the track of Michael in the Delmarva region suggests
that favorable low-level southeasterlies will generally remain close
to the coastal regions near the southern portion of Chesapeake Bay.
This should limit the northern/western extent of any lingering
tornado threat this evening.

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