Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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187 FXUS62 KRAH 021755 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 155 PM EDT Sun Jun 2 2024 .SYNOPSIS... An upper trough crossing the region will provide some cloudiness and widely scattered light showers today and tonight. Otherwise, look for a warmer temperatures, more humidity, and increasing chances for daytime shower and thunderstorm activity as we head through the first half of the week. && .NEAR TERM /TODAY AND TONIGHT/... As of 942 AM Sunday... Morning satellite imagery continues to show widespread cloud cover across NC in advance of an approaching longwave trough over the TN valley. A weak embedded wave within the trough, and associated forcing for ascent, has produced some widely scattered showers/sprinkles across the area, but for the most part there is still too much mid level dry air to overcome for showers to reach the ground (depicted well by the dry layer from 600-800mb per 12Z GSO sounding). Cloud cover has held temperatures back a bit this morning but given the relatively mild start to the day, temps are slowly climbing through the upper 60s into the lower 70s as of 1330Z. As the upper trough approaches, surface high pressure will continue to migrate offshore allowing for continued moist advection into the area. The combination of the approaching shortwave and lee troughing east of the mountains should produce additional showers later this afternoon, primarily across the western Piedmont and that is the area where the highest PoPs have been depicted in today`s forecast (30-40 percent). There is an outside chance of a rumble of thunder in that area as well but instability is understandably meager given extensive cloud cover and any storms that develop should remain well below severe limits. As the wave slowly moves east tonight, additional light showers are possible across much of central NC but rainfall amounts will be light (a few hundredths of an inch at most). A broad swath of 15-20 PoPs will remain in the forecast for the evening/overnight period to account for the passage of the trough but once we get back 00Z tonight, all mentions of thunder will be removed from the forecast. High temps today should reach the low to mid 80s. Look for a mild night tonight given cloud cover and increasing dewpoints: low to mid 60s. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 155 PM Sunday... The trough axis from Sunday will roughly be over the area to start our Mon over the central Piedmont and along the US-1 corridor. This axis will slide SE toward the coast in the afternoon to early evening, with shortwave ridging building east from TN. The latest CAMs depict a possible leftover MCV from Sunday`s convection that may move across the Triangle, Sandhills, and Coastal Plain in the morning hours. While confidence is low on this feature, there will be very little CIN and some elevated CAPE of a few hundred joules to support spotty showers into mid-morning. As clouds start to erode by early afternoon and heating raises highs into the low to middle 80s, most guidance indicates instability of around 1000 J/kg and deep-layer shear of 10-20 kt with little to no CIN. Most high-res models suggest isolated to widely scattered storm activity could form just about anywhere in central NC with PW`s near the 90th percentile of 1.6 inches. Perhaps the more favored areas for isolated storms would be east of US-1 along lingering outflows/lift from the MCV and a sea-breeze, as well as over the northwest Piedmont where a lee trough should favor storm activity over the higher terrain and tracking ESE with the NW mid-level flow. We do not expect any storms to reach severe limits given the low-end shear. Most storm activity should wane after sunset with loss of daytime heating. Low temperatures should once again be near the middle 60s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 317 AM Sunday... The extended forecast continues to show an unsettled pattern, with Saturday the only day with high confidence of dry conditions. Perhaps the most difficult aspect of the long term forecast is that the strongest features, a surface low and upper level low, should primarily remain over Canada. Weaker features, a surface cold front (which will bring some drier air but not much in the way of cooler air) and an upper trough rotating around the upper low while the low is over the Great Lakes, will be the forcing mechanisms for any precipitation, which will have lower predictability. Chance pops are expected on Tuesday primarily east of US-1, then all locations should have high chance pops on Wednesday and Thursday. Tonight`s model runs are showing the highest chances of rain remaining to the west of central North Carolina on Wednesday, then shifting the highest chances of rain north of the region on Thursday, a slightly different solution than what was shown 24 hours ago. There is fairly good agreement between deterministic and ensemble models that the cold front should move through late Thursday, then loiter along the coast Friday. This should keep chance pops east of I-95 Friday, with slight chance pops across the rest of the forecast area mainly due to the 00Z GEFS solution. With the front shifting offshore Saturday, that is the one day in the forecast with high confidence for dry conditions. Expect minimal variations in the highs and lows through the period - highs will range from the mid 80s to the low 90s while lows will be in the 60s. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... As of 110 PM Sunday... Mainly light sprinkles across the area at the moment but conditions remain VFR. Additional showers are expected later this afternoon, primarily around INT/GSO and there could be brief periods of MVFR ceilings within the strongest showers. Meanwhile to the east, conditions should remain dry (outside of the aforementioned sprinkle) through 00Z although some of the INT/GSO showers may make a run at RDU right around 00Z and I included a few hours of VCSH. Late tonight, most guidance indicates widely scattered showers across the area as a trough moves through NC. Elected to include a few hours of VCSH at RDU/FAY/RWI as this trough crosses the area although confidence in how this late night scenario will play out is low. Outlook: Additional, mainly diurnally driven showers and storms, are expected through much of this week as we return to a more typical June pattern. Highest storm chances are likely at INT/GSO although all 5 TAF sites could see impacts in the form of non-VFR cigs/vsbys within any showers that develop. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...np NEAR TERM...Leins SHORT TERM...Kren LONG TERM...Green AVIATION...Leins