Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 301905 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 305 PM EDT Sun Apr 30 2017 .SYNOPSIS... Bermuda high pressure will extend across the Southeastern states today. A cold front will approach the Appalachians tonight, then cross the region late Monday afternoon through Monday evening. Warm high pressure will build in from the southwest Tuesday through Wednesday. && .NEAR TERM /THROUGH TONIGHT/... As of 300 PM Sunday... Latest analysis shows a ridge off the SE coast and a closed trough over the middle of the country. S-SE flow over our area and moist BL has promoted shallow to moderate cu in the unstable BL. A few isolated showers have developed to our south and are current moving across SC border and into our southern zones. The HRRR and other CAMs have picked up on this and they show these isolated showers moving north across mainly our piedmont zones through the rest of the afternoon and dissipating by evening. Have updated the grids to include a 20 pop across most of our CWA south and west of the Triangle for the rest of this afternoon. For tonight, the trough over the Plains will lift slowly newd. As this system approaches, look for the pres gradient to tighten across our area, resulting in breezy s-sw winds. This will also maintain a warm moist BL, which when combined with the aforementioned winds, should result in sct-bkn low clouds. Lows in the mid 60s. && .SHORT TERM /Monday and Monday night/... As of 300 PM Sunday... The closed mid level trough over the Midwest Monday morning will move NE across the Great Lakes during this period. It`s assoc cold front will cross our region late in the day Monday and at night. A pre-frontal band of showers and thunderstorms is expected to move across central NC Monday afternoon and evening. Isolated severe thunderstorms will be possible as this band moves across, thanks to a moist unstable airmass over our area (characterized by ML cape 600- 1000 J/kg) coupled with 40+ kt of 0-6km bulk shear. It`s worth noting that several CAMs indicate an earlier band of showers and tstms moving up from GA and SC and across our western zones during the morning hours. That early activity, and assoc cloud cover, could impact the evolution of later storms, so we`ll have to watch that closely. In any event, have brought pops in early (during the morning hours) across our western zones to account for the potential for this earlier activity, then likely pops across all of central NC during the afternoon and evening. Right now, it appears that the bulk of showers and storms should be east of highway 1 by 03Z, and exit the coastal plain counties of central NC by 06Z-08Z. Otherwise, with a tight pres gradient in place ahead of the front, look for breezy s-sw winds ahead of the front during the day Monday with non-thunderstorm gusts up to 25-30 mph. Highs will range from around 80 across the Triad to mid 80s across the Coastal Plain, and will be largely dependent on early-day rain chance and resulting clouds. Cooler Monday night behind the front - lows from the mid 50s Triad to low 60s Coastal Plain. && .LONG TERM /Tuesday through Sunday/... As of 305 PM Saturday... More changes in the last 24 hours for the long term forecast as models are getting a better handle on a progressive longwave trough that will move across the CONUS this week and cause some problems by the end of the work week. Yesterday at this time models showed the trough moving slowly across the deep south and producing a cutoff low which was going to keep the threat for showers and storms around though the weekend. It also showed two surface low pressure systems developing that would have lingered across the Carolinas for days. Now models are hinting at one surface low pressure system that is more progressive and spurred on by the developing upper low that never slows down across the deep south. This will cause the primary window for showers and storms to be Thursday night through Friday night with a cold front crossing central North Carolina. The front moves through by the weekend and aside from a few shortwaves moving around the upper low behind the front, the weekend should be drier and cooler. Aside from this system later in the period, expect mainly dry conditions with high temperatures in the upper 70s to lower 80s prior to frontal passage on Friday when temperatures will dip back into the mid 60s to lower 70s for Friday and Saturday before rebounding back into the low 70s everywhere for Sunday. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... As of 225 PM Sunday... Through Monday: VFR conditions attm across all of central NC, with cu and stratocu aoa 3500 ft agl. In this cu field, isolated showers have developed across SC and are moving nwd into south central NC. Thus, a few isold showers are possible across central NC the rest of this afternoon, but given limited coverage, for now have left them out of the TAFs. Steady S-SW low level winds coupled with moist BL will promote sct-bkn stratus after 01/06z, with MVFR and IFR conditions possible. Then, an approaching cold front will increase the threat for a few showers in the western Piedmont by late Monday morning. Showers and a few thunderstorms will increase in coverage across central NC Monday afternoon and Monday evening as the cold front is in our vicinity. MVFR ceilings/visibility highly probable in proximity to the heavier showers and storms. Proceeding the front, sfc winds will be gusty out of the south-southwest with gusts 20-30 mph probable Monday afternoon. The showers and storms should exit the coastal plain counties of central NC shortly after midnight. Beyond Monday: VFR conditions anticipated behind the cold front Tuesday into Wednesday. Another low pressure system will approach from the west-southwest by Thursday, increasing the risk for sub VFR ceilings and scattered showers. && .Climate... Daily Record High Minimum Temperatures May 1 / Greensboro... 65 (2012) Raleigh.......67 (2012) The all time April Monthly Record High Minimum Temperatures Greensboro... 68 set April 14, 1912 - then tied on April 23, 1920 and April 27, 2011. Raleigh.......71 set on April 14, 1922 - then tied on April 25, 1925. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...np SHORT TERM...np LONG TERM...Ellis AVIATION...np CLIMATE...Badgett

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