Forecast Discussion
Summary
SYNOPSIS
... A moist cold front will continue to drift south across our area tonight into Thursday with scattered showers and a few thunderstorms. Cool and dry high pressure will spread over the region late Thursday and linger into Saturday. Another moist cold front will approach from the northwest late Sunday and move through our area on Monday.
NEAR TERM /THROUGH THURSDAY/... As of 800 PM: Clouds and showers are spreading south across mainly the Piedmont ahead of a cold front and short wave that will continue move across the region this evening. The precip will continue to drift southeast, and should come to an end by midnight. Otherwise, Air Quality Alerts remain in effect for most of the area until midnight. Per coordination with state agencies, a new Alert will soon be issued for overnight and tomorrow for our North Carolina zones. Lows tonight will be around 5 degrees below normal.
The cold front stalls over or near the Upstate and NE GA Thursday. Moisture will linger in these areas as another short wave rotates in from the northwest. Some instability develops over these areas, NC remains drier and more stable. Synoptic and CAM guidance shows isolated diurnal convection may develop over the Upstate and NE GA, so have included that in the forecast. Highs will be around 5 degrees below normal.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... As of 215 PM Wednesday: The overall synoptic pattern continues to churn out a persistent omega block across the CONUS. A wide swath of upper high pressure extends through the central U.S. and a strong upper low situated over the NE will keep drier air in the area. A frontal boundary is expected to pass through earlier on Thursday, bringing even drier Canadian air into the area through the forecast period. Thursday night into Saturday night, high pressure will dominate the region and keep a lid on any precipitation chances. As the upper low begins to slowly slide off the east coast, the ridge over the central CONUS is expected to move eastward and assist in building in the higher pressure. This will also bring temperatures closer to normal with most of the CWA reaching the mid 80s on Saturday. Lower humidity from the drier air will allow for somewhat cooler overnight temps in the 50s outside the mountains for both Thursday and Friday nights.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 210 PM Wednesday: By Saturday night, the persistent omega blocking pattern continues to persist. The ridge that built in across the eastern portion of the CONUS will be replaced with another upper low descending from Canada. High pressure returns to the central U.S. and the omega pattern strengthens once again by Monday. During this transition, a cold front could extend southward and traverse across the TN/OH valley and into the region by Sunday night into Monday morning. As the high pressure breaks down ahead of this FROPA, a deep pool of moisture will advect into the area, allowing for precipitation chances to increase. For this, likely PoPs from west to east starting Sunday evening through Monday night. Behind the boundary, dry Canadian air returns once again and keep the region mostly dry through the end of the forecast period. Long range model guidance hints at some precip chances returning by mid week with a series of shortwaves, but it's too far out to pinpoint anything certain at this time. Meanwhile, mostly light SW winds until Monday night when the cold front pushes through and veers the wind NW. Daytime temperatures will likely decrease slightly with the cooler and drier air from the FROPA, but quickly rebound into the mid and upper 80s for the remainder of the forecast period.