... Expect multiple rounds of rain affecting the region through Friday. Cold front approaches the area by end of week, with drier conditions for the weekend ahead of another possible cold front. Temperatures will be cooler early in the week and warm by mid week.
NEAR TERM /THROUGH TONIGHT/... As of 945 AM: The center of high pressure slides off the Delmarva coast today resulting in an increasingly moist southerly flow developing over the area. Precip and low clouds are arriving a little earlier than previously expected, so have sped up the trends in PoP/Sky grids for today. Very light precip will be moving into the Smokies/Balsams in the next hr or two. A couple mesonet sites are still AOB 32F as of last reading, but warmed rapidly in the previous hour. With that and the associated moistening, the likelihood of FZDZ/FZRA (which would be the expected p-type if temps were cold enough) appears very small. A weak short wave and upper jet move into the area late in the day, enhancing the setup and resulting in categorical PoPs for most areas SW of I-26 by sunset. The combination of this forcing and isentropic lift/upslope flow will create increasing precip chances from SW to NE across the area. Some weak in situ wedging develops first with low clouds, being reinforced as precip falls into the surface ridge still over the area. Highs will be as much as 10 degrees below normal where rain moves in first. Highs will only be a few degrees below normal for the CLT Metro where rain will take longer to develop.
The categorical PoPs expand a bit further east than I-26 this evening, with forcing (mainly warm upglide) peaking at that time as shortwave passes. Still favor likely PoP for most other locations tonight. QPF totals will be light over the NC Piedmont and eastern Upstate, steadily increasing to an inch or more over NE GA and the NC mountains west of the French Broad Valley. This area has been quite dry recently, but upslope enhancement could lead to locally higher amounts. The Marginal risk for Excessive Rainfall from WPC looks well placed. Lows will be around 10 degrees above normal.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 215 AM Monday: Upper high pressure continues to churn over the Gulf of Mexico, with upper level flow remaining predominately zonal to the north. However, a trough begins to form to the west and gives upper flow a more southwesterly component. A shortwave is expected to cross the region on Tuesday and provide lift for another round of showers. Surface southwesterly flow along with westerly flow aloft, returns a deep moisture profile to the region, adequate to support precipitation. Given this area of enhanced convergence and saturated upper air profile, widespread PoPs over the western Carolina mountains and decreasing likelihood toward the eastern part of the CWA through Wednesday. QPF guidance suggests higher rainfall amounts over the mountains with smaller accumulations into the Piedmont, though total amounts are expected to be low overall. Given the lack of instability available, showers are expected to remain non- convective. Temperatures during this forecast period are expected to be slightly above normal on Tuesday and above climo on Wednesday. Extensive cloud cover should keep nightly temperatures above normal during this time.
LONG TERM /THURSDAY THROUGH SUNDAY/... As of 215 AM Sunday: The upper high over the Gulf of Mexico will begin to breakdown after Thursday and make way for a more zonal synoptic pattern aloft. Model guidance from the GFS and ECWMF indicate cyclogenesis occurring over the plains and ejecting across the Ohio Valley. However, timing has slowed from previous runs and has the upper low and associated surface cold front sweeping through the region on Friday. Ahead of the front on Thursday, isentropic lift should remain across the area, hence chance PoPs for the Piedmont and Likely PoPs across the mountains. Minimal instability from guidance should keep this round of precipitation non- convective. Once the FROPA moves out of the CWA on Friday, weak high pressure builds in once again. However, the end of the weekend is not certain with differences in model guidance suggesting another upper low to the north and cold front extending through the southern states. With the high pressure, this likely drier break from weak ridging should keep rain chances near zero. Sunday, rain comes back into the forecast, especially in the western portion of the CWA. Overall, expect a wetter pattern for the end of the week, a drier weekend and high temperatures well above normal, with Thursday being the warmest. Expect a cool down for the weekend with the next FROPA on Friday. Overnight temperatures will also remain well above normal. Continued cloud cover through the majority of the week will aid in insulating the area and lead to much warmer night temps until the weekend, when temps dip back to near normal.