Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 240050 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 850 PM EDT Thu Mar 23 2017 .SYNOPSIS...
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Cool high pressure over the East Coast will shift offshore late tonight, allowing a warm front to lift north across our region on Friday. Warm southerly flow will persist into the weekend. A passing upper level trough will bring a chance of showers late Saturday night through Sunday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 850 PM Thursday... The surface high centered just off the Mid Atlantic coast this evening will continue drifting to the NE while extending SW through central NC. While the low level flow will become more easterly and southeasterly overnight, with a weak inverted trough forming just off the Carolina coast, the flow will be very light which will limit recovery of current very low dewpoints overnight, although they`ll climb most in the SE. Observed 00z sounding show fairly dry air in place, although based on the mid level flow and RAP depictions, the area of mid and high clouds extending from IN across KY/E TN/NE GA should pivot more N-S and drift eastward overnight, yielding a trend to partly cloudy skies over the NW CWA, with mostly clear skies elsewhere. Expect lows in the low-mid 30s except for some upper 20s in the NE under cloud-free skies with light winds. -GIH
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&& .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 315 PM Thursday... Friday...Upper level ridge axis currently extending along the spine of the MS Valley will drift over the Southeast U.S. by Friday. Warm air advection on the back side of the 850-500mb ridge currently supporting a band of precip across the lower OH Valley into the TN Valley early this afternoon. This precip area is farther south than projected by most of the near term and CAM progs. Latest HRRR depicts this band of mostly light precip dissipating as it lifts ewd toward the Smoky Mtns. Increasing low level sly flow will tap moister residing to our south- sw which should led to scattered patches of cu, especially across the southern coastal plain, and into the western Piedmont. The rest of the column will remain dry, so precip chances will remain below 20 percent. The warming air mass and low level sw flow will push temperatures back to normal levels, primarily in the 65-70 degree range. Milder temperatures anticipated Friday night as sly low level flow continues and atmosphere continues to moisten. There will be a greater probability for low stratus to develop after midnight. Overnight temperatures in the mid-upper 40s. && .LONG TERM /Saturday through Thursday/... As of 240 PM Thursday... High confidence in warm weather through the early part of next week, with bouts of showery weather, primarily on Sunday and Tuesday. Uncertainty grows midweek and beyond as differences emerge regarding their handling of polar low deepening over SE Canada and the adjacent NW Atlantic waters, however it appears certain that the wavy active southern stream pattern will persist through next week. Sat/Sat night: The potent mid level low will cross the central Miss Valley as its southward-extending trough takes on a negative tilt over the Mid South and Gulf States, leading to strengthening mid level flow from the SW into the Carolinas. PW will remain elevated, in the 75th percentile, with a light onshore-directed southeasterly flow drawing in increasing low level moisture. We should see considerable morning stratus and fog, particularly over the western half of the CWA where low level moist upglide will be deepest, and these clouds should lift to scattered to broken stratocumulus (more clouds west than east) with heating, and these should persist through the day, topped with high thin clouds. Very dry/stable mid levels will keep the day mostly dry, apart from possible patchy morning drizzle in the western Piedmont. Thicknesses will continue to trend above normal, supporting highs of 70-76 NW to SE. The mid level low tracks slowly from MO to IL Sat night, bringing the negatively tilted trough axis and its DPVA into the western Carolinas. This southerly steering flow will drive up PW to nearly 200% of normal just to our west and into the far NW Piedmont late Sat night, in tandem with the arrival of 25-35 kt low level jetting into the Srn Appalachians. Will bring in good chance pops very late Sat night into the far W CWA. Lows Sat night mainly in the mid 50s. Sun/Sun night: The mid level low will quickly weaken and fill as it approaches Lower MI Sun, while the trailing trough axis pivots northeastward through our area. The best precip chances (likely to categorical) will track ENE through central NC (especially NW) Sun morning into early afternoon beneath a band of enhanced upper divergence, with PW rising further to 250% of normal as steering flow becomes southwesterly. Despite the moist column, the dwindling dynamic forcing for ascent as this system tracks NE through the Mid Atlantic region will lead to a tapering down of precip chances through Sun, especially over our SE sections, as the core of the peak integrated water vapor transport shifts to our NNE. Only low chances are expected Sun night as the dampening mid level trough axis shifts to our NE with gently rising heights aloft, within a continued very moist column. Expect highs of 70-78 followed by lows in the upper 50s with overnight stratus developing. Mon-Tue: Monday will feature just patchy light precip at most over much of central NC as a mid level ridge axis shifts overhead with a weak cap at 925 mb and dry mid-upper levels, although higher PW settling over eastern NC and higher surface dewpoints may prompt greater convection coverage over our SE. Our next mid level trough in this active pattern will push through the eastern third of the CONUS Mon night through Tue, accompanied by a surface cold front. Important model differences start to emerge, with the GFS slower and more amplified than the weaker/faster ECMWF. Will lean toward the more progressive ECMWF given this active pattern, but confidence is not high. Will maintain good chance of showers and storms Mon night through Tue. Highs 75-80 Mon/Tue with thickness over 35 m above normal. Lows in the upper 50s. Wed-Thu: Model details differ, but in general, heights will rise over the Southeast in the wake of the departing trough, as another powerful and deep low tracks over the Southwest states. Expect dry weather and cooler temps, still near or just above seasonal normals, as surface high pressure builds in from the north. -GIH && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 740 PM Thursday... 24 Hour TAF Period: High confidence in VFR conditions through the TAF period, with the exception of an outside chance of some MVFR visibility restrictions at KRWI and KFAY just before sunrise. Calm winds overnight becoming southwesterly near 10 kts with potential for wind gusts of 15-20 kts during the afternoon hours. Some high clouds possible early in the TAF period with scattered clouds around 5 kft developing Friday afternoon. Long term: As the weekend progresses, better chances for early morning fog/low stratus will prevail with best chance for significant precipitation occurring in the northwest Piedmont on Sunday evening with a more progressive frontal passage early to the middle part of next week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...WSS LONG TERM...Hartfield AVIATION...LT/Ellis

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