Sugar Mountain

Summary

SYNOPSIS

... The weekend dry high pressure will give way to increasing moisture on Monday with numerous showers and storms Tuesday and Wednesday as low pressure moves by. After a brief stint of dry weather on Thursday, showers return on Friday.

NEAR TERM /THROUGH SUNDAY/... As of 220 PM: Weak, transient upper ridge present over the SE Coast between shortwaves. Although this feature is losing influence over our CWA, a subsidence inversion remains around 700 mb. With deep mixing and seasonable moisture beneath, abundant cumulus are seen on satellite. These will persist through the afternoon. Very subtle height falls will occur through early evening as the second shortwave crosses the Virginias; associated cold front will reach the TN/NC border around sunset and exit the lower Piedmont by about midnight. The shallow instability will linger until the front arrives, and convective layer looks to deepen slightly as inversion weakens. This is most notable on the west side of the mountains, and scattered showers are expected to develop near the border and move over the NC mountain zones. Further south and east, the effect will be weaker partly owing to downslope low level winds. Most CAM runs depict the showers becoming increasingly isolated as the front moves east of the mountains, such that a mentionable PoP is still not forecast this evening for the mountains/Escarpment near the NC/SC/GA border, or the I-85 corridor. A stray sprinkle is possible and some low-impact enhanced gusts could be associated with evaporating precip. Behind the front, skies will trend clearer; continuing light winds look to keep min temps a tad warmer tonight than last night, particularly in the Piedmont.

Surface and upper ridging will build over the area Sunday following the departing wave. Winds will remain light and downslope into afternoon; with that and with slightly higher thicknesses, max temps should trend back to or even slightly above normal. Skies will remain mostly clear perhaps aside from some cirrus.

SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 1245 PM EDT Saturday: The wx will turn unsettled again to start off the work week as a zone of moist upglide flow remains progged to overspread the cwfa on Monday. With moistening from the top down, increasing clouds, and later day shower chances, maximum temperatures should not reach climo, although the I-77 corridor, the last to see clouds thicken, is slated for solid middle 70s for maxes. The pattern is shaping up to develop in-situ damming Monday night as weak upglide flow continues atop weak sfc ridging. Expect dreary wx conditions, rainy, drizzly and potentially foggy with low overcast. Energy rounding the base of potent Ohio Valley upper low will eject NE into the region on Tuesday. Along with an associated slug of deeper moisture, showers are expected to become widespread. It remains to be seen just how far north and west into the cwfa weak sfc wedge bndry retreats to, and at this point, the sensible wx will include at least elevated embedded thunder everywhere. We will continue to monitor model and ensemble trends of creeping positive SBCAPE values into the Piedmont Tuesday afternoon and in concert with deep shear profiles leading to a non-zero probabilty of severe storms.

LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 130 PM EDT Saturday: The llvl flow is progged to veer to westerly on Wednesday in the wake cool/occluded frontal passage. Within the scoured llvls, Piedmont maximums will jump into the lower 80s and despite nominally lower sfc dwpts, the amosphere will become moderately unstable within the upper level cool air coincident with the passage of the upper trough axis. At any rate, sensible weather will be diurnally enhanced scattered to numermous tstms with a few severe storms probable.

The consensus among the latest medium range model guidance is trending drier for Thursday will an increasing probability that s/wv ridge axis translating atop the region will suppress deep convection. The pattern is progressive though, and we are slated to be under the effects of another period of deep moisture and lift associated with another southern stream s/wv on Friday.