Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261932 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 330 PM EDT Sun Mar 26 2017 .SYNOPSIS... A surface ridge will extend across the Southeast U.S. through Monday. A surface cold front will drift across central NC late Tuesday and Tuesday night. && .NEAR TERM /THROUGH TONIGHT/... As of 330 PM Sunday... Weakening mid-upper level trough will lift ne across central NC this evening. This feature and associated moisture band will support a few showers, primarily in vicinity of the Triad through mid evening. Elsewhere, isolated showers will be possible, though most of these will dissipate prior to sunset. The passage of the mid level trough will veer the mid level flow to a more westerly direction versus south-southwest. This veering will advect a drier air mass into the mid levels. Meanwhile the lowest 10k ft will remain moderately moist, maintaining variable cloudy skies. The warm moist air will maintain mild overnight conditions. Minimum temps expected to be no lower than the mid 50s. && .SHORT TERM /MONDAY THROUGH TUESDAY/... As of 330 PM Sunday... Monday, mid/upper level low over the southern Plains, opens up and lifts into the mid MS Valley. A lead s/w ahead of this feature will approach central NC late Monday. This feature will aid to back the mid level flow, leading to moistening of the mid layers of the atmosphere. This lead s/w will cross our region late Monday, triggering scattered showers and t-storms. Convective parameters not too shabby for end of March with MLCAPE off the GFS 750-1000 J/kg. Effective bulk shear 20-25kts on the cusp of supporting organized convective bands. While cannot rule out an isolated severe due to hail, bulk of convection should remain below severe criteria. Extensive cloud cover early Monday should give way to periods of sun. The peeks of sun with near sfc flow out of the sw will boost temperatures into the 75-80 degree range. The lead s/w will exit our region late Monday night but will be followed by the main mid-upper level trough by early Tuesday. This will maintain a threat for scattered showers and a few thunderstorms Monday night into Tuesday morning. By Tuesday afternoon, greatest threat for scattered showers and a few storms will be along and east of highway 1. Convective parameters by Tuesday afternoon may support a locally strong or severe storm over the coastal plain and sandhills as MLCAPE recovers to 1000 J/kg, with effective bulk shear in the 30-35kt range. A warm air mass will maintain above normal temperatures Monday night and Tuesday. Overnight temps Monday night should be in the upper 50s to near 60. Max temps Tuesday upper 70s to lower 80s. If cloud cover remains extensive or shower coverage is greater than anticipated, max temps Tuesday could end up being 4-5 degrees cooler. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... As of 230 PM Sunday... Wed-Wed Night: With a shortwave ridge aloft, expect mostly sunny to partly cloudy skies with above normal highs in the mid/upper 70s. Thu: High pressure is expected to extend southward into the Carolinas Thu morning (in the form of a backdoor cold frontal passage) in association with height/pressure rises in the wake of an upper level low moving offshore New England into the Canadian maritimes. With low-level NE flow emanating from the cool Labrador current in NE portions of the state and an increased likelihood for cloud cover in SW portions of the state, temps Thu afternoon could be as much as 15-20F cooler than Wed afternoon. With the above in mind, have decreased highs to the mid/upper 50s west to lower 60s east. Thu night: Expect an increasing potential for rain from west-east between midnight and sunrise Fri as an upper level low progresses from the central MS river valley to the Ohio valley and low level flow backs/strengthens downstream over the Carolinas and Mid- Atlantic. Lows in the mid 40s to lower 50s, depending on rain /evap cooling/. Fri-Fri Night: Confidence in the evolution of the aforementioned upper level low, attendant sfc cyclone and associated warm/cold fronts at this range is low to begin with, let alone when a CAD wedge may be in place at the beginning of the period. All guidance continues to indicate precipitation, thus have increased precip chances to high likely (60-70%). From a pattern recognition standpoint, a potential for severe weather cannot be ruled out, however, little more can be said at this range in the forecast. The temperature forecast on Fri/Fri night is challenging to say the least. At this time will show the coolest temps in the Triad (highs in the low 60s) and warmest temps in the Sandhills and SE Coastal Plain (lower 70s). Expect clearing skies in the wake of a cold frontal passage Fri night, with lows in the upper 40s to mid 50s. Sat-Sun night: Expect a warming trend with dry conditions Sat in the wake of the aforementioned upper level low progressing offshore the Mid-Atlantic coast. A continued warming trend with dry conditions is expected on Sun as a shortwave ridge aloft tracks into the region from the west. -Vincent && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... As of 115 PM Sunday... Varying degrees of cloudiness will result in periods of MVFR ceilings across central NC through 00Z Tuesday, primarily in vicinity of the Triad terminals. In addition, pockets of fog may reduce the visibility into the IFR category at KFAy and KRWI early Monday morning. In the near term, a few showers may cross the Triad terminals through 21Z, though the showers are expected to be light with limited adverse affects to aviation aside from slightly lower ceilings. A marginally moist and conditionally unstable air mass will result in periods of MVFR ceilings across the region through Wednesday. The lower ceilings will most likely occur between 10Z and 16Z. There is the possibility of a few showers and thunderstorms Monday afternoon, and again late Monday night through early Tuesday afternoon. Near the heavier showers and storms, expect MVFR ceilings and MVFR/IFR visibilities. A cold front will drop southward through central NC Wednesday, then stall to our south. The approach of an upper level low will increase sly flow a few thousand feet above of the cool stable dome of air at the surface, leading to widespread MVFR/IFR parameters due to low clouds and areas of rain late Thursday into Friday. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...Vincent AVIATION...WSS

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