Marine Weather and Tide Forecast for Roanoke, VA

KEY MESSAGES
1) Warmer today and Monday, with disturbances arriving that will trigger showers and a few thunderstorms.

2) Confidence increasing of organized strong to severe thunderstorms arriving late Monday night, and redeveloping across the area on Tuesday.

DISCUSSION
KEY MESSAGE 1...Warmer today and Monday, with disturbances arriving that will trigger showers and a few thunderstorms.

Surface observations indicate that high pressure that has been settled over the Mid-Atlantic over the past few days continues to gradually weaken. Meanwhile, a large dome of high pressure centered near the Four Corners region of the southwestern United States continues to build, allowing the overall windflow across the lower Mid-Atlantic to shift from the northwest. This will allow for increased thunderstorm chances during the early half of the week as disturbances approach our area from the Great Lakes region.

Confidence is increasing that one such disturbance will arrive during early this evening, triggering thunderstorms that will develop along the Blue Ridge north of Roanoke, and pass as a broken line southeast across the Piedmont through midnight.
With stronger heating today as highs range from the upper 70s to the mid 80s, believe there will be sufficient energy in the form of CAPE ranging from 1,000 to 1,200 J/kg that storms may occasionally intensify to severe levels, and become capable of producing localized damaging wind gusts. Outside of that, other weak disturbances today through Monday will trigger additional isolated to widely scattered showers and a few storms, which are forecasted to remain weak and disorganized.

KEY MESSAGE 2...Confidence increasing of organized strong to severe thunderstorms arriving late Monday night, which will redevelop across the area on Tuesday.

The potential for severe thunderstorms will increase late Monday night as a strong upper level disturbance passing near the Great Lakes triggers a line of intense thunderstorm activity. Confidence is increasing that this line will push southward across West Virginia late Monday night, reaching the Interstate 64 corridor (west of Lexington) during the 1 AM to 5 AM timeframe early Tuesday. It's uncertain how intense the line of storms will be as a whole given arrival in the middle of the night, but have high confidence that a few storms within the line will still be capable of damaging wind gusts. Believe as the storms cross the higher terrain of southeast West Virginia, they will then weaken in downslope windflow. Latest data suggest that the line will continue to advance south across our area through the remainder of the night, and will then have to watch for the potential of flash flooding should the line stall, allowing storm cells to pass repeatedly across the same locations.

Another strong disturbance will arrive on Tuesday, and will support the redevelopment of scattered thunderstorms which, again, will have the potential to produce damaging winds. Much about how Tuesday afternoon's storms evolve may depend on where outflow boundaries and residual cloud cover are located leftover from the early morning activity. Regardless, the strength of the upper level disturbance crossing the central Appalachians appears sufficient that individual cells forming during early afternoon may solidify into a broken line of strong to severe storms somewhere across our area by late afternoon into the evening.

The severe thunderstorm threat will end Tuesday evening as the storms exit south and east of our area, with a trailing cold front then making its way southward across the Mid-Atlantic on Tuesday night.

AVIATION /07Z SUNDAY THROUGH THURSDAY/
Surface observations indicate areas of low MVFR to IFR stratus this morning, as well as pockets of fog reducing visibilities to less than 1SM, intermixed with areas where conditions are VFR.
Any fog will burn off quickly after 13Z as temperatures rise.
IFR and MVFR ceilings will scatter during late morning, with predominantly VFR conditions forecasted during early afternoon.

Will be keeping an eye on the passage of an upper level disturbance this evening that may trigger a broken line of showers and a few thunderstorms. Activity is forecasted to develop east of a KHSP to KROA line around 00Z, and pass southeast, with moderate confidence that KLYH will be impacted during the 01Z to 03Z timeframe. Low confidence that either KROA or KDAN will be impacted, but it remains possible. Additional pockets of fog and low clouds will redevelop late tonight.

Winds through the period will be light under 10kts.

EXTENDED AVIATION OUTLOOK...

Monday also appears mainly VFR after some early morning fog/low clouds again toward KLWB/KBCB/KBLF. A line of strong storms is forecasted to arrive late Monday night, potentially impacting all airport, but most likely KLWB and KHSP. Better coverage of thunderstorms is expected Tuesday, with the potential for storms to produce intense wind gusts. Wednesday and Thursday are forecasted to yield drier weather, with VFR conditions outside any morning fog/stratus.

RNK WATCHES/WARNINGS/ADVISORIES
VA...None.
NC...None.
WV...None.