... High pressure will be over the area today promoting dry weather. A weak upper level disturbance will pass across the region Sunday associated with widely scattered showers. A warming trend is expected next week as a large upper level area of high pressure builds over the southern United States, favoring well above normal temperatures. Increasing instability will lead to a daily opportunity for scattered showers and thunderstorms.
NEAR TERM /THROUGH TONIGHT/... As of 955 AM EDT Saturday...
No changes needed for this part of the forecast.
Forecast area remains sandwiched between an area of Low pressure off the New England coast and a weak trough over the upper Mid-West. A skinny ridge of high pressure resides between these two features with our forecast area underneath the maximum area of subsidence. This is resulting in the persistence of dry air across our forecast area. As such, expect another day of Mostly sunny skies and low relative humidity. Temperatures should be similar to Friday, with highs in the 60s mountains to the lower 70s foothills and piedmont.
Moisture which has been retrograding to the southwest of the western Atlantic Low may eclipse our extreme northeast CWA this afternoon. Can't rule out some high based cu/sc northeast of Lynchburg this afternoon. Mid/Upper level moisture will be on the increase across the OH/TN valleys, so this may also result in scattered patches of AC/CI in the form of mountain wave clouds today. All things considered, still expecting it to be a mostly sunny day.
For tonight, the approach of an upper level trough/disturbance will introduce a bit more cloud cover, more so after midnight. Attm the moisture profile does not look deep enough to promote any surface based precipitation prior to daybreak Sunday. Lows tonight are expected to be mainly in the 40s.
SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... As of 200 AM EDT Saturday...
The new week will start out in a pattern far more reminiscent of summer than early spring with a large upper level ridge building over most of the continental United States. A series of upper level disturbances will ride the northern periphery of this ridge and approach the Mid Atlantic from the northwest. Temperatures should run about five to ten degrees above normal for this time of year through this part of the forecast with the highest departures expected on Tuesday. However, the increasing heat combined with these disturbances will spark chances of afternoon showers and thunderstorms west of the Blue Ridge as this week progresses.
Sunday afternoon has the lowest confidence for any thunderstorms as a weak cold front passes overhead with hardly any available instability according to the model soundings, so only isolated to scattered showers are anticipated. This cold front should stall on Monday while possibly offering isolated thunderstorms in northwest North Carolina. The stalled front will retreat northward as a warm front by Tuesday ahead of an approaching cold front that appears more significant in the model solutions. Instability appears more favorable on Tuesday afternoon based on the soundings, so thunder chances were correspondingly raised west of the Blue Ridge. It remains questionable if any of the convection can cross into the Piedmont due to CAPE diminishing further to the east.
LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 200 AM EDT Saturday...
Above normal temperatures are expected Wednesday and Thursday with an opportunity of mainly afternoon and evening showers and thunderstorms. Clockwise flow around a southern stream ridge of high pressure over the southeast and a northern stream front will provide for a multiday period of warm air advection with deep southwest wind trajectory leading to 85h temps of 12 to 14 deg C. This will translate into several very warm days with high temperatures in the 70s/low 80s and dewpoints in the 50s to lower 60s. This combination will lead to increasing instability with the opportunity for scattered afternoon and evening Thunderstorms...the greatest coverage occurring Thursday ahead of an approaching frontal system.
A cool down is expected in the Friday-Saturday time frame pending a late week frontal passage. There are some model differences with respect to strength and timing of this front. The GFS is the faster of the solutions, with FROPA as early as Thursday night, with the ECMWF the slower of the solutions with the passage occurring Friday night into Saturday. Either solution suggests an active end to the week with frontal showers/storms followed by a post frontal cool down.