Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 231909 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 305 PM EDT Mon May 23 2016 .SYNOPSIS...An upper level low will move across the area today, before tracking along the East Coast and away from the region on Tuesday. A strong upper level ridge will build over the Southeast through the remainder of the week. && .NEAR TERM /through tonight/... As of 1125 AM Monday... Minor tweaks made to the near term forecast. Have adjusted PoPs up over the northeast third of the CWA to account for patchy light rain through mid day/early afternoon. Otherwise expect scattered showers and a thunderstorm or two across the region from mid afternoon through sunset. Pesky upper level low has begun push to the east-northeast and on track to exit our region by late in the day and well offshore tonight. Spokes of vorticity will continue to pivot around this feature with one axis currently working its way across our northern counties. This feature will continue to progress south-southeast, possibly triggering additional shower development across the southern counties by mid afternoon. While a thunderstorm possible, parameters are not quite there for the potential for severe storms. The shear is too weak and instability even weaker. Temperatures this afternoon highly dependent upon extent of cloud coverage and showers. Where clouds are thickest/more prominent and potential for rain highest (ne third), temperatures in the 60s will be the rule. Where peeks of sunshine occur, temperatures should warm into the 70-75 degree range. Expect the warmest temperatures in the far south and southwest where mixture of sun/clouds expected. -WSS Height rise aloft and high pressure building in from the west will rapidly diminish precip coverage this evening, while skies slowly clear behind the departing upper trough. Lows in the low/mid 50s. -22 && .SHORT TERM /Tuesday and Tuesday Night/... As of 340 AM Monday... While the center of the mid/upper-level low will be in the process of lifting up the coast of the northern Middle Atlantic and Northeast...a couple of low amplitude impulses are forecast to wrap, in NW flow on the WSW periphery of the departing low, across eastern VA/NC through early-mid afternoon Tue. Residually steep mid-level lapse rates /6 to 6.5 C/KM/ over the NE Piedmont and Coastal Plain, and diurnal heating into the lower 80s, will contribute to perhaps a couple of hundred J/KG of MLCAPE there, where an isolated shower/sprinkle (POP of only 10-15 %) may occur before following strong height rises aloft and an associated subsidence inversion overspread the region. One more night in the 50s, to around 60 degrees, is expected in continued height rises in NW flow aloft Tue night. && .LONG TERM /Wednesday through Monday/...
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As of 305 PM Monday... Wed-Fri: Warm and mainly dry. The mid level pattern will feature longwave troughing over the western CONUS with ridging in the east, albeit with a weakness aloft which will extend from a weak low over the central Bahamas northwestward across SW NC. At the surface, Bermuda-centered high pressure will ridge narrowly westward across the Southeast, yielding a light low level flow with minimal moisture influx. The above normal heights aloft and resulting subsidence, along with the absence of lift mechanisms and the lack of a good moisture source, will help suppress deep convection over central NC. While the aforementioned weakness in heights aloft to our SW may lead to scattered afternoon storms over the higher terrain, the steering flow pattern does not favor movement of any such convection into our area. Thickness will be well above normal, supporting highs each day in the mid 80s to around 90 (Thu appears likely to be the warmest of these days) with lows in the lower to mid 60s. Sat-Mon: Lots of uncertainty in the details, although guidance continues to favor temps staying slight above normal through the upcoming holiday weekend, but with an increasing chance of showers/storms by Sun/Mon. The western end of the surface ridge axis will pivot northward (following the strengthening of the Atlantic mid level ridge extending into the mid Atlantic region), and this will allow a long-fetch southeasterly flow to stream increasing amounts of moisture into the Southeast. Meanwhile, the Bahamas mid level low begins to drift to the NW into the height weakness toward the Southeast states, and model solutions are converging toward some similarity at the surface, showing either an inverted trough or low tracking northwesterly toward the Southeast coast. It is far too early to say whether or not this feature might have tropical or subtropical characteristics, but regardless, we are still likely to see an increase in clouds and precip chances as mid level heights fall and moisture increases and deepens through the low levels. Thicknesses support temps slightly above normal, tempered by the increase in clouds. -GIH
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&& .AVIATION /18Z Monday through Saturday/... As of 125 PM Monday... Ceilings varying between MVFR across the northeast piedmont and the coastal plain to low end VFR across the western and southern piedmont will persist through sunset as energy rotating around an upper level low over far northeast NC. As the atmosphere heats up, scattered showers and isolated thunderstorms will blossom over the region. The greatest coverage will occur between 20Z-00Z. After 00Z, shower coverage will decrease. Later tonight, as the low pulls farther away, skies will gradual clear, clearing first over the western/southern piedmont and sandhills, and last in the vicinity of KRWI. Pockets of MVFR fog may occur early Tuesday morning. Otherwise, high pressure will begin to exert its influence on our weather. A prolonged period of VFR conditions is anticipated across central NC Tuesday through Saturday. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...22 NEAR TERM...WSS/22 SHORT TERM...26 LONG TERM...Hartfield AVIATION...WSS is the U.S. government's official web portal to all federal, state and local government web resources and services.