Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 252338 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 738 PM EDT TUE OCT 25 2016 .SYNOPSIS... Cool high pressure will extend into our region from the north through Wednesday night, before shifting offshore early Thursday. A cold front will move into the area from the northwest Thursday night. && .NEAR TERM /through tonight/... As of 735 PM Tuesday... Strong high pressure centered well to our north (SW of Hudson Bay) at 1036+ mb extended south and southeast deep into Florida tonight. Very dry air was in place over our region and this will be the case tonight and Wednesday with the high in place. Surface dew points have come up since sunset a few degrees into the 40s, except 30s NW. Surface temperatures fall quickly into the lower to mid 50s soon after sunset and this trend will continue. The only cloudiness was associated with the stronger mid/upper NW flow aloft extending from the upper Midwest to the Tennesse and Ohio Valley regions. Most of these clouds were high clouds and were evaporating as they encounter the ridging over the eastern seaboard. Any cirrus overnight should be scattered and thin resulting in no worse than mostly clear skies. Since winds will go calm the temperatures will fall rapidly as mentioned above. Some mixing of the dry air just above the boundary layer will aid in lowering the near surface dew points as the temperatures fall. Expect lows of 35-42 by daybreak, with some scattered frost possible in the low-lying areas around our normally cold spots (including the Roxboro, Louisburg, Rural Hall, and the Yadkin River valley as well). However, the frost is not expected to be enough to damage plants/crops that are still yet to be harvested. A Warning will not be needed at this time. We will add wording in the Hazardous Weather Outlook to indicate more in the way of mid 30s in the rural areas of the Piedmont. No other changes at this time. && .SHORT TERM /Wednesday through Thursday night/... As of 240 PM Tuesday... The axis of the weak shortwave ridge will shift eastward over the Southeast states Wed, as the axis of the Canadian-source surface ridge begins to shift east and off the East Coast. Expect another mostly sunny day with below-normal thicknesses indicating highs in the mid-upper 60s. Milder lows expected Wed night as the return flow around 925-850 mb anticyclones starts to draw low level moisture into the area, advecting first into the western CWA. Lows from mid 40s NE to upper 40s and around 50 far south and west. A fast-moving and strengthening shortwave swinging ESE through the Great Lakes and Northeast Thu/Thu night will help draw a front into NC from the NNW, likely not arriving until late Thu night. Have low confidence in our area receiving any significant precip, considering that the vorticity will be shearing through the mid level trough axis as it passes through, the upper divergence will be minor and mostly to our north, and PW is projected slightly lower than what the models showed yesterday. That said, forecast soundings do show some marginal instability late in the day into the evening, although surface dewpoints may not get quite high enough for anything more than an isolated storm or two. Will stick with low chance pops (20- 35%), higher north and lower south, from mid afternoon through the evening, with the isolated thunder risk confined to the north. Warm sector highs Thu in the 70s. Thu night lows in the 50s, as the front will be delayed until late and may not work much more southward than the northern sections of NC prior to daybreak Fri. -GIH && .LONG TERM /Friday through Tuesday/... As of 315 PM Tuesday... The long term period will feature a generally west to northwesterly upper level flow which would support dry conditions, fair weather, and near to above normal temperature regime for the extended range. A single northern stream short wave trough moves across the Great Lakes and Northeast late in the weekend with a dry frontal passage Sunday night. Have adjusted max temperatures upward on Saturday and more significantly on Sunday as thickness values by 12Z Sunday morning increase to 1385 to 1390m. Latest ECMWF ensemble guidance product for RDU has operational maxes on Sat/Sun of 80/83 with warmest ensemble member on Sunday at 85 an the 50th percentile at 81. -Blaes && .AVIATION /00Z Wednesday through Sunday/... As of 740 PM Tuesday... 24 Hour TAF period: Very quiet period expected for the TAFs with calm winds and clear skies overnight. Not expecting fog or low stratus to be much of a problem overnight either with a fairly dry air mass in place. Light and variable winds should prevail through much of the period. Long term: The next threat to aviation conditions is potentially Wednesday night into Thursday morning in the form of fog/low stratus. MVFR conditions could hold through Thursday night with a cold front expected to cross the region. It is uncertain however whether or not precipitation will be a feature of this system as most of the dynamics retreat to the north. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Badgett SHORT TERM...Hartfield LONG TERM...Blaes AVIATION...Ellis is the U.S. government's official web portal to all federal, state and local government web resources and services.