Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 192339 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 735 PM EDT Mon Mar 19 2018 .SYNOPSIS...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/... As of 655 PM Monday... Main adjustment to the near term forecast was to raise hourly temps early this evening to reflect observed trends, and to lower early evening PoPs to reflect a slightly slower arrival of appreciable rainfall. partial sunshine this afternoon and a warming sly sfc wind helped to push temperatures late this afternoon into the 60s, and around 70 across the far south. Due to this warming, have adjusted hourly temperatures this evening. In addition, weaker than expected forcing is prohibiting pockets of rain from falling across the western- southern Piedmont. Thus, have adjusted PoPs down 10-15 percent early this evening. Still appears that rain will blossom over the region late this evening into the overnight as isentropic upglide increases. Finally, strong effective bulk shear of 50-60kts and marginal low level instability will support any convective elements to organize into a broken segment across our far southern counties. If this complex does develop, isolated strong wind gusts and marginally large hail may occur with the strongest storms. This threat appears highest near the SC border between 2 AM and 6 AM. Min temps by early Tuesday should vary from the mid 40s near the VA border to the mid 50s near the SC border. && .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/...
-- Changed Discussion --
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.
-- End Changed Discussion --
&& .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.