textproduct: Raleigh

SYNOPSIS

High pressure will wedge south into the Carolinas through late Friday, before a warm front retreats north through the area on Saturday. A cold front will move east through the area late Sunday, followed by another frontal system from the west late Tuesday.

NEAR TERM /TODAY AND TONIGHT/

As of 330 AM Thursday... Today: The dry air surface ridge will continue to extend south over the region with no appreciable airmass change. Upstairs, weak upper level impulses, remnants of the former vigorous lead southern stream shortwave trough, will crest NE atop the upper level ridge in place. These disturbances will continue to yield periods of scattered to broken mid/high clouds across the area. Highs Thursday generally 1-2 degrees cooler than today; ranging from upper 40s north to lower/mid 50s south.

Tonight: Onset of SSELY flow in the 925-700mb layer will get underway late this evening and overnight. Resultant 295-300k isentropic lift will yield a lowering of cloud bases to 5-10 kft and perhaps some light patchy rain across the southern counties towards daybreak. Have warmed overnight lows owing to the increase and lowering of cloud bases. Lows ranging from around 30 north to mid/upper 30s south.

..Trending wetter across much of Central NC

Upper level ridging over the region will shift east and offshore late in the day as a pair of closely spaced southern stream shortwave troughs eject north through MS and OH Valley. Strengthening southerly warm moist air advection and lift atop the wedge of high pressure extending down the eastern slope of the Appalachians will set the way for hybrid CAD to develop across the NC Piedmont area as intermittent/spotty light rain spreads north across the area. While previous forecast guidance kept the bulk of precip across the western Piedmont, the 00z/26 model guidance has trended wetter across central and even eastern portions. Given this trend, have expanded small to slight chance PoPs well into the eastern Piedmont and into portions of the coastal plain counties. Have also lowered forecast highs Friday and if the wetter solutions verify will need to further lower temps. Highs ranging from lower/mid 40s NW to lower/mid 50s east.

Rain chances across eastern and central NC may taper off Friday night while continuing across the western Piedmont as the wedge/warm front retreats north into the western Piedmont. Areas of fog, potentially dense will be possible. Lows ranging from upper 30s/near 40 north to upper 40s/near 50 south.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

As of 400 AM Thursday...

Mid-level ridging centered over the Eastern Seaboard will slowly shift farther east into the Atlantic on Saturday. Gulf moisture will stream into central NC from SW flow aloft. At the surface, high pressure centered east of the Mid-Atlantic will promote southerly low-level flow, advecting in moisture from the Atlantic. Thus PW values exceeding an inch are expected across much of the area. Moist upglide atop a lingering cool stable layer will promote overcast skies and light rain over the NW Piedmont, with likely POPs that decrease to chance and slight farther SE in closer proximity to the western Atlantic ridging. Amounts even in the far NW are only forecast to be around a quarter inch or less through Saturday evening. With a lack of any widespread upper forcing, continue to be skeptical of the higher amounts advertised by the ECMWF. Widespread low clouds and light rain will keep high temperatures stuck in the lower-to-mid-50s around the Triad on Saturday, increasing to near 70 in the far SE.

A much better chance of widespread rain comes from Saturday night into Sunday night as a shortwave becomes negatively-tilted and moves from the mid-MS Valley into the Mid-Atlantic. An associated surface low will move from the TN Valley into the Lower Great Lakes, dragging a cold front through central NC on Sunday night. The ECMWF continues to depict a sharper/deeper trough and farther SE surface low compared to the GFS, so the ECMWF and its ensembles show heavier rainfall amounts compared to the GFS/GEFS. WPC seems to be leaning toward the ECMWF with forecast amounts during this period near an inch. Some thunder will be possible Sunday afternoon and evening, particularly south and east, as the GFS still depicts surface-based CAPE of 100-300 J/kg and dew points are expected to be as high as the lower-60s. Gusty winds will be possible as there will be a strong LLJ in place (~40 kts at 925 mb). Temperatures will be warm enough for all liquid with the system, as Sunday's highs will be in the mid-to-upper-60s. Temperatures Saturday night will remain steady or even slightly increase, with lows in the 50s. Forecast lows Sunday night are in the mid-40s to lower-50s.

Rain will end by late Sunday night and Monday morning from west to east as drier air moves in behind the front. However, given zonal flow and a surface high ridging up from the south, there will be little temperature change as forecast highs are still in the 60s and lows in the 40s on Monday and Tuesday. Another shortwave trough and associated surface low may affect the region on Tuesday with light rain. Both the GFS and ECMWF depict precipitation with the system, but the GFS keeps it farther NW and thus is drier. Enough ensemble members are wet to justify chance POPs Tuesday, drying out on Wednesday behind a reinforcing cold front that drops highs into the mid-50s to lower-60s.

AVIATION /11Z THURSDAY THROUGH MONDAY/

As of 610 AM Thursday...

...A prolonged period of sub-VFR restrictions expected Friday through Sunday...

TAF period: Though ceilings will begin to lower tonight, VFR conditions will continue through 12z Friday. Winds will remain light and from the NE.

Outlook: Weak isentropic lift will support the chance for patchy light rain/drizzle and associated MVFR restrictions starting Friday. Widespread sub-VFR restrictions will likely persist until the passage of a cold front Sunday night, with a band of moderate to heavy rain showers and perhaps a few storms crossing the area late Sunday afternoon and evening. Additionally, a period of LLWS is possible Friday evening and into Saturday, especially at KINT and KGSO where CAD conditions and associated NELY low-level flow will persist as a southerly 35-40 kt LLJ moves through the area.

Dry high pressure and VFR conditions return Monday.

RAH WATCHES/WARNINGS/ADVISORIES

None.