435 FXUS62 KRAH 060108 AFDRAH AREA FORECAST DISCUSSION National Weather Service Raleigh NC 907 PM EDT Wed May 5 2021 .SYNOPSIS... A cold front will move across central NC late this afternoon and early this evening. A cooler and less humid air mass will build into the area tonight and Thursday. An upper level disturbance will move across the region late Thursday through Friday night. High pressure will build into the region for Saturday. && .NEAR TERM /THROUGH TONIGHT/... As of 907 PM Wednesday... A cold front is moving across central NC attm, with a narrow band of showers and tstms along the front. Latest meso analysis shows very limited instability, thus the storms so far have been well under svr limits, although there is some lighting and pockets of brief heavy downpours. The shower/tstm band and front will continue moving SE through the remainder of this evening and is expected to exit central NC by 2 AM. Behind the front, winds have shifted (or will shift after fropa) to NW with cooler and drier air advecting into our area...along with partial clearing of skies. Lows will range from around 50 in the Triad to the upper 50s across the southeast. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 245 PM Wednesday... Central NC will experience a very brief period of flat upper level ridging on Thursday morning before the broad upper trough to our west shifts east and is carved out as a potent northern stream trough dives south into the southern Appalachians on Thursday night. A cooler and dry air mass shifts into the region on Thursday behind the cold front moving off the coast. The morning will start out mostly sunny with perhaps a few high clouds and some very patchy, low/mid clouds with areas of cirrus and some fair weather cumulus clouds increasing during the afternoon. As the upper trough approaches, the low and mid level moisture will increase after midnight resulting in increasing clouds a small risk of a rain shower or spotty rain. Instability overnight will be lacking so thunder is not expected and overall rain coverage appears limited overnight. It will be much cooler on Thursday as 12Z low level thickness values will range in the 1330s and 1340s resulting in highs in the upper 60s to lower 70s, there could be some mid 70s in the Sandhills. Lows will range in the upper 40s to lower 60s. -Blaes && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 333 PM Wednesday... Mid-level trough extending from the Great Lakes through the Ohio Valley and Mid-Atlantic region will become slightly negatively tiled from the morning to early evening hours on Friday. As this happens, surface low pressure will develop over eastern NC and traverse over the western Atlantic. Enough lift and moisture in place should allow for rain showers across the area, primarily over the Northeast Piedmont and Coastal Plain where lift is maximized. A slight chance of thunder was introduced given some weak instability (200-400 J/kg MLCAPE) present. With the increased chance of showers and clouds, highs were lowered a few degrees, ranging from mid to upper 60's to the north and lower 70's to the south. Showers should end early Friday evening, with gusty northwest winds to follow up to 25 mph behind a cold front. Lows early Saturday will be in the lower to middle 40's in most locations with good radiational cooling and winds relaxing overnight. On Saturday, high pressure settles across the southeast U.S. but pressure gradients remain tight, with westerly flow remaining gusty at 15-25 mph with lots of sunshine and temperatures below normal, generally in the upper 60's to middle 70's. A surface warm front across GA and SC lifts north Sunday, resulting in highs near to slightly above average in the upper 70's to middle 80's. Some mid-level energy in the zonal flow pushes east from the Tennessee Valley late Sunday to early Monday in association with another cold front sagging south from the Ohio Valley. The best chance of rain and storms will be in the afternoon/evening, during peak heating with MLCAPE ~ 500 J/kg and marginal shear in place. Latest guidance from GFS/Euro/GEFS in agreement with this timing as well. After another mild day Monday, the cold front then passes with cooler temperatures and drier Tue below average in the upper 60's to middle 70's. Guidance continues to be mixed in regards to Wednesday. The Euro continues to develop a surface wave across the southeast early Wednesday, tracking the low along the NC coast into Thursday. The GFS, however, shows more of a weak ridge pattern with embedded shortwave energy toward the latter part of the week. GEFS and ensemble guidance tend to favor precipitation Wednesday night onward so we have scattered showers on Wednesday for now, with temperatures below normal under chilly east-northeast flow and weak CAD in place. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 804 PM Wednesday... Through 00z Friday: Cold front moving across central NC attm. The front has already passed south of KINT/KGSO and winds have shifted to NW with VFR flight conditions. The front is right over top of KRDU attm, thus look for winds to shift to NW there shortly. The front is expected to move past KRWI and KFAY by 03Z this evening, followed by similar wind shift and flight conditions. Until that happens, a line of showers and isold tstms are occurring along the front, so a very brief period of IFR conditions and variable wind gusts around 40kt are possible as the front and tstms move through. Overnight...look for VFR conditions behind the front, but around 08Z or so, patch stratocu may develop as winds shift to NE, which may locally reduce flt conditions to MVFR for a couple hours prior to sunrise. As the morning progresses after sunrise, and MVFR cigs will dissipate with flt conditions returning to VFR area-wide by late morning or afternoon. After 00z Friday: A period of fair weather will continue into Thursday evening before an upper level disturbance and coastal low brings a threat of adverse aviation conditions late Thursday night through Friday night. High pressure will build into the area for Saturday into early Sunday with fair weather before a cold front approaches on Monday. && .CLIMATE... Record HI-Min temperatures for 5/5: GSO: 65 (2019) RDU: 67 (1950) FAY: 68 (2012) && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Blaes NEAR TERM...np SHORT TERM...Blaes LONG TERM...Kren/JJT AVIATION...np