Area Forecast Discussion
Issued by NWS Blacksburg, VA

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455 FXUS61 KRNK 191847 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 247 PM EDT Tue Jun 19 2018 .SYNOPSIS... A weak cold front will drift south into northern portions of the area overnight into early Wednesday before stalling. The front will then oscillate across the region Thursday into Friday before lifting back north as a warm front by the weekend. Another weak cold front should cross into the area from the west later Sunday into Monday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 230 PM EDT Tuesday.. Convection remains limited across the region this afternoon with best instability just to the north ahead of the sagging cold front. However with coverage increasing to the northwest would expect a few bands/clusters to push south into the I-64 corridor in the next few hours. Still uncertain as to just how far south showers/storms will get until ongoing strong westerly flow relaxes with storms possibly running around the eastern downslope across areas along/east of Highway 29 over the next several hours. Latest short term solutions also show less organization across central and southern sections espcly after loss of heating, although this may be the time for better coverage down along Highway 460 once deeper mixing diminishes. Therefore bumped up pops to a period of likelys northwest per current radar trends, and over the northeast for coverage into the evening. Elsewhere keeping mainly scattered to isolated pops with perhaps the far south remaining dry. Appears showers will slowly fade later this evening but may again redevelop late over the western ridges with low level westerly convergent flow. Otherwise some spotty valley fog/stratus and in spots where showers occurred, with muggy lows only in the 65-75 degree range. Surface front or residual low level outflow may sag into northeast sections early Wednesday before eroding as another impulse rides along the front under lowering heights aloft Wednesday afternoon. This should act to keep the 850 mb boundary to the north with low level focus redeveloping along the surface front across far north or northeast sections Wednesday afternoon. However will still have rather deep westerly flow in place which may again tend to hinder southward extent of any convection until perhaps a more organized band along the front arrives from the northwest per latest Nam/HREF solutions. This supports cutting back pops across all except the north on Wednesday with perhaps best coverage over northeast sections early on, and northwest zones later in the day. Should still be on the hot side despite some 850 mb cooling as westerly flow again enhances compression, while dewpoints linger in the 70s to produce heat indices above 100 again in spots out east. Therefore bumped up highs into the lower/mid 90s south/east, and kept much of the mountains still in the mid/upper 80s with more insolation now expected. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 225 PM EDT Tuesday... Models are similar is flattening the 500MB ridge over the southeast United States and tracking the upper low into the Mid Mississippi Valley which will put the Mid Atlantic region in deep southwest flow by Friday. Best upper diffluence will be over the region on Friday too. The 850MB front advances into West Virginia and Virginia by Friday, far enough south to lower 850MB temperatures in the +12 to +16 range. The slight cooling and more cloud cover will hold maximum temperatures in the 70s and 80s on Thursday and Friday. Front is far enough south that lower Lifted Index values and larger Convective Available Potential Energy will be southwest of a Bluefield to Danville line on Friday. Heavy rain and localized flooding will be a threat on Wednesday night into Friday night due to the possibility of repeated periods of thunderstorms and precipitable water values of 1.5 to just over 2 inches. Confidence average on timing and coverage of rain. Confidence above average on temperatures. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 115 PM EDT Tuesday... Models showed decent agreement in the overall synoptic pattern this time range. Surface low pressure crosses from the Ohio Valley into the eastern Great Lake then southeast Canada Saturday and Sunday. Short waves embedded in the broad northeast U.S. trough may trigger some precipitation but the more organized showers and thunderstorms will be Friday night when the upper low lifts into the Great Lakes and Monday with the passage of the next surface cold front. Overall no significant chance in air mass. Temperatures will be near normal to slightly above normal. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... As of 100 PM EDT Tuesday... Overall VFR will continue into the afternoon with a gradual increase in cumulus fields from north to south ahead of the approaching cold front to the north. Expecting isolated to scattered storms ahead of the boundary through at least this evening before coverage fades back to the west by early Wednesday. Any stronger thunderstorms will have the potential to produce damaging wind gusts. More organized storms are expected across West Va and into northern VA this afternoon...reaching as far south as the Interstate 64 corridor by the end of the day. Thus have kept in VCTS for most sites excluding KDAN through early this evening with a TEMPO group at KLWB and perhaps KLYH to cover possible more widespread activity. West winds will remain gusty with heating ahead of the front with 8 to 18 kts possible including gusts to 25 kts along the ridges. Showers and storms should fade after midnight although a lingering westerly trajectory may keep lower sub-VFR cigs in at times around KBLF/KLWB where a few added showers may be possible overnight. Front is expected to sag into the region on Wednesday although combination of westerly flow and the actual front aloft remaining to the north may keep more widespread convection across the north/west again Wednesday. Otherwise again expecting any lingering low clouds/fog to quickly fade to a developing cumulus field by midday Wednesday with best shot at lingering MVFR across the far west. .Extended Aviation Discussion... Frontal boundary is expected to move south into the Mid-Atlantic and stall for the end of the week. This boundary will then become the focus for repetitive clusters/bands of showers/storms Thursday-Friday with varying VFR to MVFR in clouds/showers with local IFR in areas of heavier rainfall. The front will lift back north Saturday followed by another cold front passing through from the west on Sunday. This should result in improving conditions over the weekend with only periods of sub- VFR likely in more scattered nature showers and storms. Increasing moisture from rainfall will also result in opportunity for late night fog and stratus for much of the period. && .CLIMATE... As of 200 AM EDT Tuesday... Records for June 19/20... Record Highs Record warm Mins June 19 Bluefield WV 91 in 1905 66 in 1920 Danville VA 102 in 1944 70 in 1968 Lynchburg VA 97 in 1944 73 in 1925 Roanoke VA 97 in 1944 73 in 2014 Blacksburg VA 89 in 1984 65 in 2015 June 20 Bluefield WV 91 in 1952 57 in 1920 Danville VA 102 in 1933 65 in 1956 Lynchburg VA 99 in 1964 74 in 1924 Roanoke VA 101 in 1931 76 in 2009 Blacksburg VA 90 in 1994 68 in 2009 && .EQUIPMENT... As of 200 AM EDT Tuesday... The NOAA weather radio transmitter in Hinton, West Virginia that is WXM72 and broadcasting at a frequency of 162.425 MHz is off the air. Parts are on order to repair the transmitter, but there is no known time of restoration. We apologize for any inconvenience. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH NEAR TERM...JH SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/PM CLIMATE...PM EQUIPMENT...

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