Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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354 FXUS62 KRAH 291904 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 305 PM EDT Sat Apr 29 2017 .SYNOPSIS... A warm moist southerly flow will continue through the rest of the weekend, as a strong high pressure remains anchored off the Carolina coast. A cold front will cross the region Monday afternoon and evening. && .NEAR TERM /THROUGH TONIGHT/... As of 250 AM Saturday... A quiet but warm/muggy night ahead. Experimental GOES-16 red visible band imagery reveals cloud streets over the western and southern CWA, and batches of thin cirrus that emanated from the now- dissipating MCS activity just north of the Ohio River. But cloud cover remains mostly scattered/thin, allowing for strong heating and temps soaring to well above normal readings. The strong mid level anticyclone centered just off the Carolina coast combined with the Bermuda high pressure extending across the Southeast continues to prompt mean subsidence and a fairly dry column, so despite decent lapse rates around 7 C/km and current MLCAPE of 3000-4000 J/kg, any convection chances for the rest of the day appear slim. With the strong cap holding in place in the 950-850 mb layer, we`ll have another round of stratus form overnight, leading to a trend to mostly cloudy skies and patches of fog. We should once again see lows in the upper 60s to lower 70s, over 15 degrees above normal lows. -GIH && .SHORT TERM /Sunday and Sunday night/... As of 305 PM Saturday... The already-low convection chances for central NC look even lower on Sunday. While mid level heights do dip slightly during the day, mainly west, they remain anomalously high, with PW values falling further as a batch of deeply drier air tracks onshore and over the eastern Carolinas. Mid levels are also projected to warm a bit, most notable around 700-600 mb, which will cut down on the potential for the high CAPE values we`re seeing today. And with very weak deep layer shear over central NC, we are likely to see little to no showers or storm activity in our area, although there may be a few short-lived cells near the sea breeze, and a few more over the higher terrain where the wind field will be better. Otherwise, expect a lifting and mixing of morning stratus, yielding scattered to broken afternoon cumulus, along with some high clouds, especially west, ahead of the slowly approaching frontal zone and deep cutoff low moving from the Southern Plains into the Midwest. Highs 83-89, factoring in slightly lower low-level thicknesses and greater cloudiness. Clouds should increase further from the west Sunday night with strengthening warm air advection, which will also translate into an uptick in southerly winds overnight ahead of the front. Southwesterly steering flow increases Sun night and flattens, eventually becoming gently cyclonic, as weak perturbations track up over western NC overnight. With moisture deepening and PW again exceeding 1" in the west, will bring in a slight chance of showers late in the far western CWA. Lows mainly in the upper 60s. -GIH && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 330 AM Saturday... A shift in the longwave pattern next week will ultimately result in lower heights over the eastern US and a ridge over the west. The sub-tropical ridge over the Southeast this weekend will shift east Monday as a deep upper low lifts from the Southern Plains to the Great Lakes. The associated cold front and convective line will be crossing the mountains early Monday, encountering more favorable heating/instability in the west Monday afternoon before undergoing a general downward trend in intensity as it progresses east Monday night owing to a loss of better forcing and heating. Still expect PW over 1.5" and 60-80m height falls to support at least scattered showers through central NC Monday night before moving to the coast early Tuesday. Highs Monday in the upper 70s to mid 80s. Lows in the mid 50s to lower 60s. Temps will be knocked back top near normal briefly on Tuesday, but with the secondary polar front holding to the north across VA, temps will rebound into the mid 80s and above normal Wednesday. the next shortwave moving through the longwave trough is forecast to strongly amplify over the Deep South Thursday, with medium range guidance showing the potential for another cut off low near Tenn Thursday night. Models diverge quickly regarding out the eventual track of the low, but the pattern will favor widespread precip late Thursday and Friday, some of which could be heavy if the low slows and tracks closer to the Southern Ablutions. Temps are most likely to be below normal int he upper 60s and low/mid 70s. && .AVIATION /18Z Saturday through Thursday/... As of 125 PM Saturday... Cigs have improved to VFR across central NC, with unrestricted vsbys, and these conditions will hold through this evening, as deep high pressure extends across the region, deflecting any weather- making disturbances and deep moisture away from our area. Scattered to broken VFR flat cumulus clouds will dissipate during the early evening hours with loss of heating. With abundant low level moisture in place, confidence is high that we`ll see development of another round of IFR (perhaps low-end MVFR in some spots) after 06z tonight, lasting until gradual lifting and partial clearing trends terminals up to VFR during the 15-17z time frame Sunday. Winds will hold from the S or SW at 10-15 kts through sunset, with infrequent gusts to 15- 20 kts, falling to 4-7 kts overnight. Looking beyond 18z Sun, VFR conditions and dry weather will hold through Sun evening, with development of MVFR to IFR stratus once again after midnight, lasting through sunrise Mon with slow improvement to VFR Mon morning. A band of showers and storms expected to cross the area late Mon afternoon through Mon evening may bring a period of sub-VFR conditions and breezy/gusty winds from the SSW. Dry weather and VFR conditions should follow behind a front late Mon night through Wed. Chances will increase for showers/storms and sub-VFR conditions Wed night and especially Thu. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS/GIH NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Smith AVIATION...Hartfield is the U.S. government's official web portal to all federal, state and local government web resources and services.