Area Forecast Discussion

WHAT HAS CHANGED

Aviation updated.

No other significant changes to the forecast.

KEY MESSAGES

1) Confidence is high for organized strong to severe thunderstorms arriving late Monday night, and redeveloping across the area on Tuesday.

DISCUSSION

KEY MESSAGE 1...Confidence is high for organized strong to severe thunderstorms arriving late Monday night, and redeveloping across the area on Tuesday.

A series of short waves moving south in NNW flow aloft will trigger showers and storms tonight. At the surface, a lee trough situated in the western Piedmont will help focus cells. With warming this afternoon, there should be enough instability to support an occasional stronger storm with damaging winds, but overall the severe threat looks marginal. After about midnight, convection exits to the east, followed by another warm and damp night with stratus and fog. Monday looks mostly rain-free with drier air in the region, although the lingering surface trough in the area may bring isolated showers and a storm or two to the eastern Piedmont.

On Monday night, a warm front will lift across the region into Tuesday morning. At the same time, a strong short wave will approach from the NW. These features will support widespread rain with embedded storms, a few which may be strong to severe with damaging winds, in the form of a bowing MCS traveling from the OH Valley. CAMs are now steering the brunt of this feature to our west, over central and eastern KY. If so, we may just get away with some heavy rain and less of a severe threat, at least early on. As the day progresses, a surface low sags south towards the region, and the short wave train continues. Severe weather in the afternoon will depend on how long the morning convection lasts and how much time the atmosphere has to recover, or destabilize again, ahead of the front/upper level wave. It appears we should have at least a few hours with breaks in cloud cover before the front arrives in the afternoon.

Severe thunderstorms with wet microburst potential look likely as long as we can destabilize. Consistent severe weather forecasts by several models support this scenario. The ECMWF EFI and Shift of Tails for CAPE/shear has a bullseye over much of SW VA and NW NC Tuesday. Deep layer shear looks to peak around 40 kts, and current timing of the boundaries and diving short wave energy/jet streak is around peak heating. We continue to be outlooked on Tuesday for a Slight Risk of severe weather from SPC, and a Marginal Risk of excessive rainfall from WPC. Damaging winds and heavy rain possibly leading to flash flooding will be the main concerns.

The front and trough axis move towards the coast and offshore by Wednesday morning. Upslope flow may bring a few showers to the mountains, but the severe threat will be over. Thursday and Friday also look quiet, with a return to scattered afternoon showers and storms Saturday.

AVIATION /00Z MONDAY THROUGH FRIDAY/

VFR just about areawide this evening, with a few showers starting to develop along and west of the Blue Ridge. Through the remainder of the evening and into the nighttime hours, chances for scattered showers and some thunderstorms continue, until about midnight or so, when any convection will wind down. Plenty of moisture in the atmosphere will lead to low ceilings and fog during the overnight and early morning hours of Monday, with IFR or lower conditions. Conditions improve to VFR after mid to late morning, and skies will become SCT for most.

Winds will be out of the north to northwest after 12Z Monday, between 5 to 10 knots, possibly up to 15 knots along the ridgeline, but not at area terminals.

Forecast confidence is moderate.

EXTENDED AVIATION OUTLOOK...

A line of strong storms is forecasted to arrive late Monday night, potentially impacting KBLF, KLWB, and KBCB. Better coverage of thunderstorms is expected Tuesday afternoon and evening as a cold front moves through. There is increasing confidence in severe storms with intense wind gusts. Wind gusts in general increase to 20 to 30 knots Monday night into Tuesday. Gusty NW winds develop Wednesday behind the frontal passage, with gusts of 20 to 30 knots, higher on ridgelines. Wednesday through Friday are forecasted to VFR, outside any morning fog/stratus.

RNK WATCHES / WARNINGS / ADVISORIES

VA...None. NC...None. WV...None.