Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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083 FXUS62 KRAH 260552 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 152 AM EDT Wed Jul 26 2017 .SYNOPSIS... A cold front will stall over SC through Wed, then retreat north through NC as a warm front Wed night and Thu. && .NEAR TERM /TONIGHT/... As of 1015 PM Tuesday... A positively-tilted upper level trough/shear axis evident in WV satellite and 00Z upper air data, stretching from the New England coast swwd through sern VA/west-central NC to srn TX, will settle toward the NC coast tonight, while a trailing mid-upper level perturbation now over swrn IL/sern MO will drift into the central and srn Appalachians through the same time. A sharp deep layer moisture gradient, characterized by 00Z/26th-observed precipitable water values of an inch at GSO and two inches at MHX, accompanies the lead trough axis. At the surface, a frontal zone was analyzed at 02Z from near MRH to RCZ to HKY, swwd through the TN Valley, then nwwd through the midle MS Valley and to a 1009 mb surface wave over srn SD. Outflow from earlier convection over ern NC has drifted wwd in an arc from near RWI, to JNX, to CTZ. A slight chance of a shower will linger for the next several hours in the vicinity of the outflow and surface front, on the nwrn edge of a weak, and further nocturnally-weakening instability axis along and south of these features. It should otherwise be a dry night, as the aforementioned upper level trough and following deep layer dryness, settles through central NC. Skies will be mainly clear, though with a persistence chance of stratus in the vicinity of the surface front - from the srn Coastal Plain to the srn/wrn Piedmont. Previously forecast lows mostly within a few degrees either side of 70 need no adjustment. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 240 PM Tuesday... The cold front should be positioned south of central NC on Wednesday morning allowing high pressure to extend into the region from the north. The front will begin lifting north on later Wednesday as the surface flow veers to southeasterly and southerly. This will allow an increase in moisture roughly in the 925 to 850 hPa layer and promote an increase in cloud cover and perhaps a shower or storm, generally in an arc from the Coastal Plain west and northwest across the Sandhills and into the Yadkin early in the day that will expand northward during the afternoon and evening. Precipitation chances will be limited to the slight chance range across most of the area, so all in all it will be a much cooler and more tolerable day. Highs will range in the upper 80s to near 90 with lows in the 68 to 74 range. -Blaes && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 330 PM Tuesday... Mid level ridging amplifying over the central CONUS will induce corresponding deepening of east coast troffing and associated northwest flow. Cooler air will be edging south out of the upper Midwest and slowly spreading east and southeast, with the associated cold front reaching the NC/VA border Thursday night. Thursday will be dry with potential for some showers in the western Piedmont late in the day. Highs will reach near 90 over the area with PoPs ramping up to 30-40% by Friday morning as the front creeps in, with at least 50% chances on tap for Friday into Friday night. Strongest convection is expected late Friday and through the overnight as convergence along the h85 trof will provide the best lift, with better shear profiles across the northern tier nearer the parent surface low and triple point. Highs Friday will be a shade cooler...mid 80s northwest to lower 90s east...mainly abetted by heavier cloud coverage and rain, as the cooler air doesn`t make its way into the area until Friday night. Some showers may linger into Saturday morning in the east, otherwise skies will be clearing with a noticeably cooler and drier airmass in place through the weekend. Highs Saturday through Monday will top out mostly in the mid 80s...3-5 degrees below normal, with morning lows in the mid to upper 60s. The front, meanwhile, will be stalled along the coast, with potential for development of a surface low along the front that could pull moisture back into at least the eastern sections of the state by midweek. && .AVIATION /06Z WEDNESDAY THROUGH MONDAY/... As of 150 AM Wednesday... 24-Hour TAF period: Some low stratus has developed across the southeastern terminal (KRDU/KRWI/KFAY) as of 06Z. Expect this to continue through the overnight hours with intermittent scattering possible. The northwest terminal may also drop below VFR toward the early morning hours. All restrictions should improve back to VFR after sunrise today, latest in the south. Otherwise, expect VFR conditions to dominate the remainder of the period, with light east- northeasterly winds and scattered clouds around 5kft and 25kft. -KC Looking ahead: The cold front to the south will lift north as a warm front on Thursday before a stronger cold front moves through the area on Friday and then stalls to our south over the weekend. Mainly VFR conditions expected through much of the period with scattered mainly afternoon and evening showers and thunderstorms and a chance of morning fog and stratus. The greatest chance of adverse aviation conditions in showers and storms will be Thursday night through Friday night ahead of the approaching cold front. -Blaes && .EQUIPMENT... Technicians have completed the bulk of the first phase of the Service Life Extension Project (SLEP) upgrade and the data quality is sufficient for the radar to return to service. Additional radar adjustments resulting in brief outages are still possible during the next few days. The temperature & dew point sensor at site KFAY, located at the Fayetteville Regional Airport, is malfunctioning. NWS technicians have turned the sensor off and ordered parts to repair it. At this time, we expect the sensor to be returned to service early next week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...BLAES LONG TERM...mlm AVIATION...KC/BLAES EQUIPMENT...BSD/BLAES

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