Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 270821 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 421 AM EDT Tue Sep 27 2016 .SYNOPSIS...
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A cold front will move east of the Blue ridge this morning, then stall over the piedmont this afternoon. A wave of low pressure moving along this front will keep the chance for showers across foothills and piedmont counties on Wednesday, before finally exiting Wednesday night.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 330 AM EDT Tuesday... A slow moving cold front will make it to the Blue Ridge by sunrise this morning, then slowly work across the foothills and stall over the piedmont this afternoon. Heavy rain will accompany the front this morning, then intensity of these showers will lessen moving into a worked-over environment across the foothills and piedmont counties. Instabilities will increase some across Southside this afternoon, as a weak short wave tracks along the front across central North Carolina. A closed upper level low will track from the Great Lakes today to the Ohio Valley tonight. As this low sinks south, the front and its showers will get pushed to the east. Temperatures will be close to seasonal averages ranging from the low to mid 70s west to mid to upper 70s east.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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As of 400 AM EDT Tuesday... By early Wednesday, an upper low situated across the corn belt is expected to begin meandering south and east toward the northwest portions of our forecast area. Around the same time, a short wave is expected to ride the residual frontal boundary just to our east, reinvigorating the fetch of deep moisture. Scattered showers with potentially a rumble of thunder should remain east of the Blue Ridge Mountains through Wednesday evening as the low begins to dig further south. An isolated shower will be possible across the western slopes of the Appalachians just after sunset. At this point, solutions begin to differ rather greatly. The latest few model runs continue a moistening trend, with the ECMWF leading the pack. The bulk of the precip tends to stay north and east of the forecast area for now, but have once again introduced higher POPS out east out of respect to the very wet ECMWF which seems to emphasize the short-waves effect rather stoutly. Have re- introduced thunder into the forecast for the same portion of the forecast area Thursday, as impressive low to mid level lapse rates look to combine with very low freezing heights across the area. This should allow for a small hail threat to develop, even in an environment only favorable for shallow-type convection. Heavy rain in the showers/storms that do form will be the main threat. Temperatures during this portion of the forecast will remain at or below normal, limited greatly by cloud cover and rapid cold air advection around the low pressure system.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/... As of 130 PM EDT Monday... The slow moving upper low will continue to impact our forecast into Friday, however, the trend will be for the low to start heading north in response to a building upper ridge across the center portion of the nation. Progressively each day through Sunday, the concentration of showers will will trend more toward the northern sections of the forecast area, following the track of the low. While no thunderstorms are forecast, isolated hail will again be possible within the stronger showers given a continuation of a relatively low freezing level through Saturday. Sunday into Monday, a dry forecast is expected along with moderating temperatures as the upper ridge strengthens and its axis shifts eastward. At best some isolated showers may be possible across the Northern Mountains of North Carolina on Monday where Temperatures during this portion of the forecast will trend only slightly milder on average than the early part of the week. While highs may climb a bit higher, lows are expected to trend slightly cooler as the diurnal range increases thanks to decreasing dew point values across the region. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... As of 120 AM EDT Tuesday... Generally poor aviation conditions expected through this morning. A cold front was moving across the mountains early this morning with a broken line of showers. Ahead of the front are some prefrontal showers across Southside (KDAN), but mostly MVFR-IFR low clouds and fog from the Blue Ridge eastward. For the TAF valid hours after 14Z Tuesday, look for variable clouds as an upper low begins to drift southward from the Great Lakes region. Ceilings will range from high end MVFR or low end VFR by afternoon. Showers remain possible across the Piedmont, including Danville, as a wave of surface low pressure rides northeast along the slow moving frontal boundary located over the coastal plain. Extended aviation discussion... The front will be located across the coastal plain into Wednesday awaiting additional upper support from an approaching upper low. Conditions will becoming increasingly unsettled as a deep upper low sags southward from the Great Lakes into the Central Appalachians. This will keep variable clouds, MVFR cigs, and periods of -SHRA across the region through much of the period. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RCS NEAR TERM...RCS SHORT TERM...JM LONG TERM...DS AVIATION...RCS

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