... A vigorous low pressure system will move across the Ohio River valley Tuesday into Wednesday while keeping our weather unsettled through the middle of the week. Expect breezy conditions from late Wednesday into Thursday with below normal temperatures through the weekend.
NEAR TERM /THROUGH TONIGHT/... As of 100 PM: Continue to see a very slow increase in precip coverage/intensity across the forecast area early this aftn. All but the highest peaks of the NC mountains should have turned over to rain by this point. Expect categorical PoPs and increasing rain rates from late aftn thru the evening per extrapolation of the upstream radar and latest guidance. Overall, no big changes to the forecast with this update.
Otherwise, a complex low pressure and frontal system will move out of the Plains into the MS River valley today, spreading deep moisture and forcing into our area. Weak high pressure remaining over the area will help a weak in-situ wedge develop as precip moves over the area. Precip rates will pick up west of the I-26 corridor where the better forcing moves in during the afternoon. However, convection is not expected as the wedge keeps the atmosphere stable. The precip and developing wedge will help keep highs to around 10 degrees below normal.
Widespread rain continues across the area through the evening then begins to taper off from west to east overnight. Even with the wedge in place and little chance of convection, precip rates increase dramatically as a wave of low pressure moves east along the wedge boundary. Rainfall amounts of 1 to 2 inches will be common across the area. While no widespread flooding is expected due to the recent drying, isolated flooding could develop in areas where rainfall rates are higher or upslope flow can increase amounts. Lows will likely be early in the evening with temps slowly warming overnight.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 325 AM Monday: the short-term fcst picks up at 12z on Tuesday with very broad and deep upper trofing digging down over the Southern Rockies while upper ridging remains anchored to our southeast. Over the next 48 hrs, the trof will steadily approach our area. The trof axis is expected to lift up and over the CWFA by the end of the period early Thursday. At the sfc, low pressure will be passing just to our NW early Tuesday as its associated cold front moves east of the fcst area and drier air spreads over the CWFA. On Wed, the above mentioned low deepens as it slowly lifts farther north and as it does, it generates another cold front. This front is expected to move thru the CWFA by late Wed, and then offshore early Thurs as the period ends. Above normal temps will prevail early in the period, but will fall back below normal behind the front as skies clear. Upslope forcing within the colder airmass will allow PoPs to linger near the NC/Tenn border into early Thurs. Falling temps should permit a change to snow, although the moisture is relatively shallow and is not expected to produce advisory-level accumulations.
LONG TERM /THURSDAY THROUGH MONDAY/... As of 255 AM Monday: the extended fcst picks up at 12z on Thursday with very broad upper trofing over much of the Eastern and Central CONUS and upper ridging over the far west. The long-range guidance has the trof axis lifting to our NE as the period begins early Thurs, with a reinforcing trof axis dropping down the backside of the broader trof early Friday. The trof will remain over the region well into weekend and likely amplify as it drifts eastward. As the period ends early next Monday, the heights will finally be recovering as upper ridging spreads over the region. At the sfc, cooler and drier high pressure will be spreading over the fcst area as the period begins. By early Friday, a weak secondary cold front moves thru the fcst area from the west. The models depict some brief deeper moisture associated with this feature, but it is pretty transitory and appears to move east of the CWFA by early Sat. Some of the guidance does maintain shallow moisture and NWLY flow over the NC/Tenn Border region thru much of Sat, however model consistency remains mediocre at this time. The rest of the period appears to be dry as reinforcing high pressure spreads back over the region.