Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 300548 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 148 AM EDT MON MAY 30 2016 .SYNOPSIS... Tropical Depression Bonnie has weakened. It is centered over eastern South Carolina but will influence our weather over the next several days as it slowly moves northeast along the coast. && .NEAR TERM /THROUGH TODAY/... As of 945 PM EDT Sunday... clouds and scattered showers will remain over the forecast area through Memorial Day as Tropical Depression Bonnie meanders over northeast South Carolina. Abundant cloud cover and tropical moisture extend north through the Carolinas associated with Tropical Depression Bonnie. This tropical system is forecast to move very little through Monday, resulting in considerable cloudiness throughout the Mid Atlantic Region along with scattered to numerous showers and thunderstorms. PWATs east of the Blue Ridge are in excess of 1.50 inches, thus any deep convection will be rain efficient, heavy downpours potentially leading to poor drainage flooding. Coverage and rainfall amounts through 8PM have not justified the need for a flood watch. Highest amounts were from the north side of Roanoke city into southern Botetourt County with 0.75 to 1.0 inches Sunday. Have trimmed back the probability of rain overnight. Hi- Res models as well as HRRR forecast only isolated to scattered coverage and radar trends are supporting this decrease. Western edge of deep moisture had advanced into extreme southwest Virginia and will stay close to the western border of the forecast area overnight. Have slightly lowered minimum temperatures to reflect 9PM observations and latest LAV guidance. For Monday and Monday night the circulation center is expected to move very little...the Tropical Prediction Center showing a slight jog to the north. Unlike today were there was abundant mid/upper level moisture, models on Monday are suggesting some drying in the mid levels allowing for some breaks in the overcast and subjecting the forecast area to surface heating. This increase in solar insolation is expected to increase the CAPE, allowing for diurnally driven deep convection. Since airmass is of tropical origin, anything that develops will contain heavy downpours. Temperatures through Memorial Day will remain mild, elevated dewpoints keeping the overnight lows above normal. The daytime high is advertised in the 70s, but could easily eclipse 80 with a few hours of sun. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... As of 400 PM EDT Sunday... Little change through mid week. TD Bonnie is forecast to slowly move northeast just inland of the coast. Heaviest rain is forecast to be aligned with the I-95 corridor, however our forecast area will be subject to a daily threat of diurnally driven deep convection aligned with the mountain ridges. Steering currents are forecast to be weak, and with PWATs running AOA 1.5 inches, expect scattered slow moving showers/storms with heavy downpours. With more breaks in the cloud cover, temperatures will be warmer than normal with 80s for highs. Lows generally in the 60s. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 400 PM EDT Sunday... Thursday the air mass will remain warm and humid, with a continuation of diurnally driven deep convection. A cold front is forecast to approach the forecast area from the west late Thursday into Friday. This boundary will result in an increased threat for showers/storms...its passage bringing a less humid airmass to the region for the weekend. Until the frontal passage at the end of the week, temperatures, especially the overnight lows, will favor above normal readings. After the frontal passage, lower dewpoints and clearing skies will support lower nightime lows. Daytime highs are advertised to be close to normal. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... As of 137 AM EDT Monday... Terminals will be tricky this morning as skies had cleared enough to allow fog to form and start to form. Any fog is contingent on how much low and mid deck forms and/or moves in. Have high enough confidence in the LWB/BCB terminals to put MVFR fog with tempo IFR to LIFR vsbys and/or cigs. Liked the overall solution of the GFS and 4z HRRR which paints some light showers near DAN this morning then develops some toward BCB/BLF after 08-10z. Further east there should be some breaks as well and with rainfall earlier fog will be a fair bet at LYH/DAN, and possibly ROA. Overall keeping them MVFR fog with possible IFR cigs. Expect some slow deterioration to any lower cigs this morning and will see a few showers around. As we head toward late morning into early afternoon look for more of a broken deck of cu/sc rising to high end MVFR then VFR. Nothing to focus where shra/storms form but looking at shotgun effect with all terminals possibly having at least a shower or tsra in the vicinity during the afternoon, so kept that in from previous taf issuance, but delayed based on the fact the heating will be delayed with low clouds to start the morning. Any showers will dissipate somewhat enough to take VCTS out of the Tafs by 00z/31. Fog will be possible moreso after the end of this taf cycle. EXTENDED DISCUSSION... There may be a repeat of tonight again Monday night into Tuesday morning. What remains of Bonnie appears to stay situated over the SC coast with our area staying just close enough to keep a few showers around at night then scattered storms during the afternoon again Tuesday. This looks to possibly play out again Tuesday night into Wednesday. Finally an stronger upper trough will kick what is left of Bonnie out to sea Thursday-Friday. Thursday may be our driest day with frontal showers and storms Thu night into Friday. Overall looking at possible MVFR to IFR at night through Thursday morning, with mainly VFR during the day except in showers/storms. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...AMS/PM SHORT TERM...PM LONG TERM...PM AVIATION...WP is the U.S. government's official web portal to all federal, state and local government web resources and services.