PORTLAND, Ore. - Forecasters are tracking stormy weather that could spark lightning east of Interstate 5 on Friday afternoon - and create a threat of coastal tornadoes on Sunday.

"Extensive showers and cloud cover tied to this trough may limit solar insolation enough that not sure we will get the surface heating inland to produce a risk of a short lived thunderstorm or two this afternoon, but cannot rule it out later in the afternoon for areas primarily east of Interstate 5," the National Weather Service in Portland said.

OK, but what about the twisters?

"A sizable (by our standards) coastal tornado threat will exist on Sunday, most likely Sunday afternoon and evening, that appears at least on par to Oct 14th 2016 when we had several low topped supercells move onto the Oregon coast," the National Weather Service said.

"10/14/16 produced a tornado in Oceanside and an EF2 tornado in Manzanita," forecasters said, explaining:

All available model guidance suggests similar 500mb temperatures to 10/14/16 with 500mb temperatures running in the -24 to -26C range over the waters and along our coast Sunday afternoon and evening.

With sea surface temperatures around 57F, this should result in MLCAPE values between 100-200 J/kg and SBCAPE values closer to 500 J/kg. Strong deep layer shear, ~50 kt of wind at 1km and veering winds within the lowest 1km of the atmosphere due to the low pressure to our northwest will promote strong rotation with any showers and thunderstorms that develop. 0-1km helicity values appear likely to exceed 200 m2/s2 in the vicinity of the coast.

The main uncertainty with this event will be where do storms have enough of an onshore component to actually push onto the coast. Given the projected low pressure position, the steering flow will be nearly south to north along the Washington coast, but much more SW to NE farther south along the north-central Oregon coast, and thus storms should have an easier time pushing ashore along the central and north Oregon coast.

However, there are certainly scenarios still in play that result in the threat expanding northward to include the south Washington coast.

"For now, it`s best for anyone with interests along the central & north Oregon and south Washington coasts to pay attention to the forecast for Sunday and make sure they have a reliable way to receive warnings," forecasters said.

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