Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 220802 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 400 AM EDT Sat Apr 22 2017 .SYNOPSIS... A cold front will settle south through VA this morning and into central NC this afternoon through tonight. The front will stall over southeastern NC by Sunday, in advance of a slow-moving area of low pressure that will track along the coast of the Carolinas through Mon night. && .NEAR TERM /THROUGH TONIGHT/... As of 935 PM Friday... Highest threat for scattered showers and isolated thunderstorms into the overnight expected to occur across the Piedmont into the far northern coastal plain. Air mass across the region fairly moist with precip water values hovering around 1.25 inches. At the sfc a weak sfc trough extended from the foothills of western NC newd into VA. The main sfc cold front stretched from western PA southwest into middle TN. Aloft a weak perturbation was traversing eastward, entering the western sections of central NC. This feature aloft interacting with available moisture and weak convergence along the sfc trough will maintain a threat for scattered showers, primarily prior to midnight across the western Piedmont, and into the overnight across the northeast Piedmont and the far northern coastal plain. Severe storm parameters barely register across our region while the better shear and instability reside well to our west and north. Plan to maintain broken-overcast skies across the north half, and variably cloudy skies across the south. Temperatures should be fairly uniform in the 60-65 degree range. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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As of 400 AM Saturday... This long duration rain event on tap through the short term forecast has the potential to produce widespread 2-3 inches of rain. This will ultimately be beneficial in alleviating the abnormally dry to moderate drought conditions which have been gradually developing through the late winter/spring across central NC. The heavier rain focus shifts from the west initilly Sunday to the east on Monday, which will help mitigate the potential for widespread flooding, but some flooding is possible on creeks and streams, and even our larger rivers may have some minor flooding from Sunday night into early next week. As mentioned earlier, the initial focus for heavier rain will be in the western Piedmont on Sunday as low level isentropic lift will be focused on the frontal/CAD zone. Rain will ramp up over the remainder of the forecast area later in the day and peak Sunday night over the Piedmont as low level flow backs southeasterly as the surface low pressure system moves slowly east across South Carolina. The heavier rain then shifts east as the digging cutoff low phases with the surface system Monday morning and begins to lift slowly up the coast through Tuesday. Categorical PoPs through the period with QPF amounts ranging from slightly >3 inches across the north to 2.5 inches in the southeast. CAD-flavored high temperatures in the Triad will struggle into the mid and upper 50s Sunday and Monday with the southeast reaching low 70s. Scattered non-elevated thunderstorms will be possible around the periphery of the wedge, with lesser potential for elevated convection heading into the deeper cool air north and northwest.
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&& .LONG TERM /TUESDAY THROUGH SATURDAY/...
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As of 400 AM EDT Saturday... Precip chances diminish rapidly Tuesday, with only slight chances in the northeast by late afternoon. Shortwave ridging is expected in the wake of the upper wave on Wednesday with dry conditions and a warming trend through Saturday as an upper level ridge builds over the southeast CONUS. Highs Tuesday will reach 70 to 75, with a return to mid and upper 80s for Friday and Saturday.
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&& .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... As of 215 AM Saturday... A series of disturbances in WSW flow aloft will interact with an outflow boundary (from earlier and ongoing convection) that remains draped from SW to NE across central NC from near CLT to JNX to EDE. A continued threat of showers and associated sub-VFR visibility restrictions will result along and north of the boundary, particularly at Piedmont sites through daybreak. In addition, there is a small chance of scattered to broken IFR-MVFR range stratus, and fog, on the north/cool side of that boundary, also at Piedmont sites, through 12Z. VFR conditions and a warm and breezy SW wind will otherwise result until another round of showers and storms fire along both the aforementioned outflow boundary and a cold front that will settle south from VA late this afternoon and evening. MVFR ceilings, patchy light rain, and gusty post-frontal NEly winds will develop behind, and with the passage of, the front this evening. Outlook: A prolonged period of rain/showers and sub-VFR ceilings and visibilities --in springtime cold air damming-- can be expected later tonight through Tue night, as an area of low pressure tracks east along the aforementioned front, then slowly up the coast of the Carolinas. Conditions will be slow to improve as the coastal low drifts only slowly away from our region, with a return to VFR on Wed. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...mlm LONG TERM...mlm AVIATION...MWS

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