Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 182345 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 745 PM EDT Sun Mar 18 2018 .SYNOPSIS... Weak high pressure will extend across the southern middle Atlantic states through tonight. A warm front will retreat north across the southeastern U.S. Monday, ahead of a series of low pressure systems that will track along the front, and across and offshore the Carolinas, Monday night through early Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 715 PM Sunday... Besides some minor tweaks to the hourly temperatures, little change required to the other weather parameters through the overnight. A dry stable air mass has enveloped central NC, evident by the dewpoints in the 20s to lower 30s. This air mass coupled with a light/near calm sfc wind will allow temperatures to tumble this evening. Most of the region will be in the 40s by mid-late evening, coolest over the northern coastal plain. Temperatures in the Piedmont, especially the western Piedmont, should stabilize after midnight as a veil of mid/high level clouds advance across the region. Eventually a deck of lower clouds will overspread this region by daybreak as a return sly flow advects moisture from the eastern Gulf. While most of central NC will remain dry through the overnight-early monday morning, cannot rule out a few patches of light rain or drizzle by daybreak in vicinity of the Yadkin/Pee Dee River, especially south of I-85. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... As of 400 PM Sunday... A progressive trough aloft now over the cntl Rockies, one that will have become a compact closed mid-upr low as it migrates across the cntl Plains tonight, will deamplify as it tracks enewd across the lwr OH Valley and cntl Appalachians Mon-Mon night. This trough/low will support Miller "Type B" surface cyclogenesis, with a parent cyclone tracking from a position now over the Front Range of the cntl Rockies to the lwr OH/TN Valley by Mon eve, with subsequent energy transfer to a secondary wave forecast to track across cntl NC Mon night. The result will be a cloudy Monday, but not particularly wet owing to a lull between the weak srn stream forcing for ascent late tonight, and the later arrival of the forcing accompanying the deamplifying closed low Mon night. Rain will become widespread with the passage of the upper and lower waves Mon night, particularly along and north of the track of the surface wave - over the nrn Piedmont, where rainfall amounts as high as three quarters of an inch to one inch appear probable. Srn counties will meanwhile experience an increasingly convective character of the precipitation, not as uniform, and with a slight chance of thunder, where milder and slightly unstable conditions, particularly with respect to elevated parcels, are likely to materialize. Temperatures, hindered by the multi-layered overcast, will be cooler Mon, ranging from lwr 50s over the nw Piedmont to upr 50s-near 60s in the srn Coastal Plain, with lows Mon night ranging from mid 40s in the cool/stable wedge north of the low track, to low-mid 50s south. && .LONG TERM /TUESDAY THROUGH SUNDAY/... As of 210 PM Sunday... Longer range forecast remains on track for a cold and unsettled Tuesday through Thursday with a warming trend toward the weekend. A brief lull in the precip is generally expected on Tuesday as the first in a series of disturbances shifts to the east of the area. However, skies will continue to remain mostly cloudy to overcast will low level moisture lingering. Highs on Tuesday are expected to range from the mid 40s north to the lower to mid 60s south. Additional mid/upper level energy is expected to dive southeastward and into our area for Tuesday night into Wednesday. Models continuing to advertise the potential for some wintry precip late Tuesday night into Wednesday morning across the area, with the best chance of seeing some light accumulations of snowfall across the climatological favored northern Piedmont. The system will be similar to the last one, where the boundary layer will need to cooled by melting snow in order bring temps down to near freezing. Have kept temps ranging from the lower/mid 30s to lower 40s for the entire wintry event. Dry weather will return for late week with the mid upper level trough axis expected to shift to the east of the area. The next system is expected to approach the area next weekend, with increasing chances for showers. Temperatures will make a run toward seasonal normals by the weekend. && .AVIATION /00Z MONDAY THROUGH SATURDAY/... As of 745 PM Sunday... 24-Hour TAF Period: VFR conditions should persist through tonight, though high clouds will begin to thicken and spread east- northeastward through Central NC. Winds will be calm to light and variable through the period, though they will generally be between southerly and easterly after daybreak Monday. Expect MVFR cigs to spread into the area from the southwest early Monday, with KINT, KGSO, and KFAY coming down earliest, followed by KRDU and KRWI. Rain will follow the sub-vfr cigs Monday morning into the afternoon. Forecast soundings from both the NAM and GFS, along with some high res guidance suggest cigs could drop into the IFR/LIFR after noon, persisting through the remainder of the TAF period. -KC Looking ahead: The passage across the Carolinas of a series of low pressure systems will result in sub-VFR conditions and periods of rain, probably mixed with or briefly changing to snow at nrn TAF sites late Tue night or Wed, through Wednesday. Drying and a return to VFR conditions from west to east will occur as the trailing low lifts away from the middle Atlantic coast Wednesday night. -MWS && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...MWS LONG TERM...BSD/Franklin AVIATION...KC/MWS is the U.S. government's official web portal to all federal, state and local government web resources and services.