Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 200250 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1050 PM EDT Mon Mar 19 2018 .SYNOPSIS... A warm front will lift northward tonight into southeastern NC. Low pressure will track NE along the front late tonight and Tuesday. This will push a cold front offshore late Tuesday. This will be followed by a cold upper level low pressure that will track east across the area Wednesday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1050 PM Monday... Little change required to the near term forecast. Rain showers will increase in coverage through 07Z in advance of a mid level s/w and attendant sfc low. 00Z upper air analysis depict strong mid-upper level jet crossing the TN Valley/Deep South, placing central NC in a zone of decent speed convergence. With the lift increasing into the overnight, should see scattered-numerous showers develop/move across the region. Thus, plan to maintain the categorical PoPs overnight. Instability still lacking across the region and appears the better instability will remain well to our south. Mid level lapse rates marginal at best. So while a clap or two of thunder cannot be ruled out, the better chance for thunderstorms expected to remain south of our region across GA and SC. Overall threat for severe storms appears minimal, except in immediate proximity to the SC border where a marginal threat for a strong wind gusts/nickel size hail may exists in the 3 AM-7 AM time frame. Min temps by early Tuesday should vary from the mid 40s near the VA border to the mid 50s near the SC border.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 345 PM Monday... A compact shortwave trough/low over the mid MS Valley will migrate ewd, to the lwr OH Valley by 12Z Tue - slower and more amplified than indicated in previous forecasts. This solution will allow a pair of upstream/trailing srn stream perturbation (elongated mostly shear vorticity axes) over the Four Corners and Front Range of the cntl Rockies to amplify across the lwr MS and TN Valleys, and ultimately be "captured" by the the aforementioned closed low over the OH Valley, as it drifts across the Virginias Tue night-early Wed. Associated 120-150 m mid level height falls, and strong QG- forcing for ascent, will pivot from the srn Appalachians at 00Z Wed to the NC coast by 12Z Wed. At the surface, a nearly stationary front will be draped in the vicinity of Highway 64 at 12Z Tue, with a lead frontal wave over e- cntl NC, and a trailing one poised to develop over nrn SC as the aforementioned strong mid-upper level forcing pivots east of the srn Appalachians. A cooler and stable air mass will exist north of the front, where the heaviest rain will have likely occurred tonight, while a warmer and slightly unstable airmass will reside south of the front, or develop with diurnal heating with a few breaks in the multi-layer clouds over srn and sern NC. That trailing/secondary low, is then forecast to deepen as it wraps up the middle Atlantic coast through Wed, with associated cooler post-frontal plunging swd across cntl NC Tue night-early Wed. Widespread stratiform rain over the nrn Piedmont will decrease in intensity through midday, though with continued periods of light rain or drizzle from a low ovc Tue, while a band of convection will likely develop along the advancing front through srn NC through early-mid afternoon. The combination of (albeit weak) instability and strong shear profiles suggest a few storms could become strong to severe from near Maxton to Fayetteville to Goldsboro and points sewd, and offshore through Tue evening. At the same time, a mid level deformation band will be developing over the srn Appalachians and TN Valley, then pivot newd across cntl NC, coincident with the maximum of mid level height falls referenced above, Tue night-early Wed. Similar to the last event, partial thicknesses/deep layer thermodynamic profiles will trend sufficiently cold for snow aloft, with the primary inhibiting factor being a slightly above freezing boundary layer. With that in mind, and also similar to the last event, melting of snow and associated cooling of the boundary layer to (near) freezing would likely occur when the heavier precipitation rates occur, and/or when insolation will be at a minimum during the early morning hours Wed. A light, slushy accumulation will accordingly be possible mainly north and west of an arc from EXX to RDU to ETC, where our "most likely" accumulation includes a Trace to up to one half or three quarters of an inch. Any accumulation will be short-lived and limited to when the precipitation rate exceeds the melting rate at the surface, with a change over to rain by midday, as surface temperatures rebound into the upr 30s-lwr 40s. The precipitation may end as flurries or light snow over the ne Piedmont and nrn Coastal Plain before ending Wed evening. While there will be some threat of black ice Wed night, as temperatures dip into the lwr to mid 30s, no widespread travel problems are anticipated. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 300 PM Monday... The surface low will be lifting rapidly northeast with dry and cooler high pressure building into the area on Thursday through Friday. Temperatures will be cool, from upper 40s north to mid 50s south on Thursday, and a couple of degrees warmer on Friday. Lows Friday morning will fall below freezing over most of the area, with northern tier counties perhaps falling into the upper 20s. Northwest flow into the weekend will provide increased cloud coverage and some light rain into the west to tighten up our damming signature and produce highs ranging from the low 50s north to low 60s south. Return flow will increase rain coverage on Sunday, further strengthening the ridging, with highs in the 50s to lower 60s Sunday and Monday. && .AVIATION /00Z TUESDAY THROUGH SUNDAY/... As of 735 PM Monday... 24-Hour TAF Period: Initial VFR conditions early this evening will become IFR TO LIFR between 06z and 09z tonight as rain develops NE across the region. Periods of rain and showers will continue through 12z to 15z, gradually tapering to areas of low clouds and drizzle between 15z and 18z/Tuesday. LIFR CIGS are expected through 18z, with IFR to LIFR VSBYS becoming MVFR between 15z and 18z. After 18z, expect IFR to LIFR CIGS and VFR to MVFR VSBYS with a NE flow to persist into the evening. Looking ahead: Sub-VFR conditions and periods of rain, possibly mixed with and/or briefly changing to snow at the northern TAF sites late Tuesday night into Wednesday. Drying and a return to VFR conditions from west to east will occur as the final trailing low lifts away from the middle Atlantic coast Wednesday afternoon and night. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...WSS SHORT TERM...MWS LONG TERM...mlm AVIATION...Badgett is the U.S. government's official web portal to all federal, state and local government web resources and services.