Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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481 FXUS62 KRAH 172359 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 659 PM EST Fri Feb 17 2017 .SYNOPSIS... An upper level trough will approach from the west and cross the southeastern U.S. Saturday and Saturday night. Surface high pressure will otherwise extend across our region through the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 140 PM Friday... Earlier high clouds over the NE CWA are dwindling as the vorticity maximum that was the primary driver of this cloudiness moves off the NC coast. Heights aloft will continue to rise through tonight as the deep longwave upper trough moves out over the Atlantic, followed by shortwave ridging over the Southeast states, which will hold over the region before moving to our east Sat morning. Expect generally clear skies through much of the night, although high clouds will be on the increase over our SW sections as an upper low now over OK/TX shifts into the middle and lower Miss Valley, spreading warm- advection high clouds into the forecast area from the SW. Expect lows in the mid 30s to lower 40s, with the cooler readings in the outlying areas. -GIH && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 220 PM Friday... The mid level shortwave ridge axis is expected to be overhead at sunrise Sat, after which time it will shift steadily off the coast as the upper low crosses the Mid South Sat before then opening up a bit as it crosses the Carolinas Sat night. Forecast soundings depict relatively little moisture with this feature, focused primarily in the mid to upper levels, with weak low level moisture transport, and steady MSLP with ridging extending across the Southeast and a weak lee trough over the Piedmont. Also, the initially-decent DPVA weakens as this low/trough approaches and dampens, contributing to reduced forcing for ascent as we head through Sat night. Model output overwhelmingly supports little in the way of measurable precip in central NC, including the SREF and NCAR ensemble which show very low to no chance of measurable precip, and the operational models which show only very light amounts barely scraping the NW and SE corners of the CWA. Based on this limited moisture and lift, will limit slight chances over just the SE and NW CWA Sat night. Expect increasing and thickening clouds Sat, with thicknesses supporting highs in the upper 60s to lower 70s. Lows in the mid-upper 40s. -GIH && .LONG TERM /SUNDAY THROUGH FRIDAY/... As of 155 PM Friday... An upper level disturbance will move west of the Appalachians on Sunday while a surface low develops off of the southeast coast. Model runs continue to trend drier for this system for central NC and at this time there is a good chance that both of these systems could pass us by with little to no rainfall across the area. This will lead to cloudy skies early Sunday and clearing by afternoon. This will allow max temps to rise towards the 70 degree mark. Beyond Sunday a very strong upper level ridge will keep us warm and dry through at least Tuesday night with highs in the upper 60s to low 70s. A weak frontal system on Wednesday will give slight chances for rain but nothing more than a few hundredths of an inch. For the end of the week we will have slight chances for rain each day as central NC resides under a southerly return flow regime with high pressure out over the western Atlantic. As the same time a strong low pressure system over the Midwest may help to enhance moisture transport into the area. The whole time we will remain in the warm sector with high temps in the low 70s, well above normal for this time of year. && .AVIATION /00Z Saturday through Wednesday/... As of 655 PM Friday... Under the influence of dry surface high pressure over the southeastern U.S., VFR conditions (with a high degree of confidence) are expected through at least the first 20 or so hours of the TAF period. The approach of an upper level trough, and associated mid to to upper level lift, will result in a thickening and lowering of clouds above 12 thousand feet Sat afternoon. Precipitation aloft will accompany these clouds, but very dry air below the clouds suggests most of the precipitation will evaporate before reaching the ground, resulting in virga. Nonetheless, a few VFR sprinkles or brief showers will be possible from west to east between 22Z Sat and 04Z Sun. Generally SWly surface winds will be light through early Sat, then increase to between 8-15 kts --highest at eastern sites and with occasional gusts to around 20 kts-- Sat afternoon. Outlook: There will be a chance of showers, and perhaps brief MVFR ceilings in SEly flow off the Atlantic, Tue night-Wed. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...MWS is the U.S. government's official web portal to all federal, state and local government web resources and services.