textproduct: Blacksburg

WHAT HAS CHANGED

A Heat Advisory has been issued for portions of Central Virginia and North Carolina.

KEY MESSAGES

1) Strong to severe thunderstorms this afternoon/evening.

2) Above normal temperatures expected today through Sunday.

DISCUSSION

KEY MESSAGE 1: Strong to severe thunderstorms this afternoon/evening.

Current morning surface analysis has a frontal boundary situated across Illinois and Indiana. The will gradually move east through this evening. An associated upper level shortwave will move through Canada, but favorable height falls will extend south of this shortwave. Although higher shear will remain closer to the parent shortwave, strong surface heating today along with a moist boundary layer (dew points into the mid 60s/low 70s) will support strong to severe storms by late afternoon and into the evening. A look at model soundings across the forecast area indicate an inverted-V profile with high DCAPE values exceeding 1000 J/kg. This would favor a downburst potential with storms today, with perhaps a localized large hail threat in cell mergers. Biggest limiting factor today will be the strength of a persistent downsloping westerly flow, which could inhibit storm development until late afternoon. This is somewhat consistent across model guidance showing initial development over the mountains, but storms fizzling east of the mountains.

KEY MESSAGE 2: Above normal temperatures expected today through Sunday.

A very warm airmass will remain in place through this weekend. Today will likely feature the hottest temperatures of this stretch with upper 80s to upper 90s expected. High heat coupled with dew points into the upper 60s to low 70s will result in afternoon heat index values exceeding 100F. Have issued a Heat Advisory for portions of Central Virginia and North Carolina where heat index values could reach as high as 105F.

The frontal passage tonight will provide some relief as dewpoints are lowered areawide, which will reduce the muggy feeling outside; however, highs will still reach the low to mid 90s in the Piedmont, and upper 80s across the mountains. Mid to upper 90s look to return in the Piedmont, and mid to upper 80s in the mountains on Sunday before another frontal boundary pushes through the area late Sunday.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

More coverage of convection as a front approaches from the west today. Will have at least VCTS for most terminals beginning around 19z, with highest potential from 20z through about 00z. Storms should weaken after sunset, but some lingering rain possible into midnight or so. Storms today will have a downburst potential, along with heavy rain and hail.

Beyond the early morning hours, winds look to remain out of the west/southwest at around 5-10 knots, with gusts up to 15-20 knots across the area starting around 15z.

EXTENDED AVIATION OUTLOOK

Front heads east tonight with storms exiting. Passage of the front will bring a period of drying on Saturday before going back into a general summer time pattern where scattered showers and storms will become common during afternoon and evening hours, followed by clearing at night with patchy fog.

RNK WATCHES/WARNINGS/ADVISORIES

VA...Heat Advisory from 11 AM this morning to 8 PM EDT this evening for VAZ043>047-058-059. NC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening for NCZ004>006. WV...None.