Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 121928 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 330 PM EDT Sat Aug 12 2017 .SYNOPSIS...
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A cold front will approach from the northwest and settle into central NC overnight then stall. This front will remain quasi-stationary over NC through the middle of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 330 PM Saturday... Scattered convection will continue to percolate across central NC into the evening hours as a weak mid level trough drifts east across the region. Convection will be more concentrated in the east vs west due to the proximity of the 850mb trough. This feature will exit our eastern counties by sunset. The mean wly flow should keep the convection moving, though locally heavy/excessive still possible due to presence of precipitable water hovering around 2 inches (closer to 2.2 inches in the east). Due to the abundantly moist atmosphere, will mention locally heavy rainfall in the forecast text. Convection will initially weaken/diminish with loss of heating. however, should see an increase in convective coverage late this evening/overnight as a cold front approaches from the northwest. Bulk of this convection should occur primarily north of highway 64 through the overnight.
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&& .SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
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As of 330 PM Saturday... The sfc cold front will stall in vicinity of highway 64 as it becomes parallel to the flow aloft. This feature will serve as a focus for the development of scattered-numerous showers/storms Sunday afternoon with the greatest coverage across the southern Piedmont into the Sandhills. Due to the deep wly flow, potential for showers/storms to train across the same location, increasing the threat for excessive rainfall and flood potential. A slightly more stable air mass will reside north of the boundary which should yield/support fewer showers and storms. In addition, the mostly cloudy skies and low level north-ne flow will inhibit temperature recovery, leading to high temps only in the 80-85 degree range. A series of perturbations aloft Sunday night crossing overhead will maintain a threat for scattered convection areawide. With the air mass remaining substantially moist and potential for more training, a flood watch may need to be considered.
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&& .LONG TERM /MONDAY THROUGH SUNDAY/... As of 210 PM Saturday... Confidence is below average with regard to precip chances/amounts this week. Mon-Mon Night: 12Z GFS/ECMWF guidance continues to suggest above normal chances for convection, above normal cloud cover, and near-to- below normal temperatures in assoc/w cyclonic flow aloft and a stalled frontal zone invof central NC Mon/Mon night, with the greatest convective coverage /precip amounts/ along and south of Hwy 64. Tue-Sun: A shortwave ridge expected to progress across the region mid-week may be less amplified than prior model runs suggested, with a weaker sfc high building into the Mid-Atlantic. As a result, the front stalled invof the area early this week may move little before washing out as the shortwave ridge deamplifies/progresses offshore the Mid-Atlantic mid-week. Thereafter, guidance suggests central NC will be situated at the southern periphery of the westerlies, on the northern periphery of an upper level ridge progged to amplify over the Deep South. With the above in mind, will indicate near normal temperatures Tue-Sun. Expect at/above normal chances for convection Tue/Wed followed by climatological chances late this week through the upcoming weekend. -Vincent && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... As of 130 PM Saturday... A moist and unstable air mass coupled with a series of upper level perturbations will cause episodes of scattered showers and thunderstorms across central NC through Monday. In vicinity of the heavier showers and storms, low end MVFR or IFR parameters will likely be encountered. At this time, the highest threat for scattered convection this afternoon through this evening will be in vicinity of KRDU and KRWI. This evening, a sfc cold front will approach from the northwest. This boundary will trigger scattered showers and isolated storms in vicinity of the Triad terminals, mainly after 03Z. The sfc front is projected to stall over central NC on Sunday, and waver across the region through mid-week. Due to the presence of the very moist air in the lower levels of the atmosphere, there is the high likelihood of late night/early morning low clouds and/or fog through the period. This occurrence appears greatest in the proximity of KRDU, KFAY, and KRWI. The unsettled weather pattern will persist across central NC through mid-week. Expect widespread MVFR/IFR parameters due to low clouds and fog each morning with a good chance for scattered convection each day, primarily during the afternoon-evening hours. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...Vincent AVIATION...WSS

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