Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 202008 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 300 PM EST Fri Jan 20 2017 .SYNOPSIS... A strong storm system is expected to affect the region over the weekend into Monday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 300 PM Friday... A sharp boundary has set up over the Sandhills NE into the central Coastal Plain this afternoon. Partly sunny skies with temperatures in the lower 70s were found over the south and east, while northwest of the boundary - there were low clouds, mist, and cool temperatures in the upper 40s to lower 50s. Multiple guidance sources show high probabilities of fog tonight into Saturday morning with saturation near the surface all night. Lows generally in the 50s expected, with some upper 40s NW. The Piedmont Damming region may be the place that has the best chance of dense fog, although areas to the south and east may also have that chance increase later tonight.
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&& .SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
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As of 300 PM Friday... Most guidance is agreement in depicting a nearly stationary front over southern and eastern sections of our region Saturday into Saturday night. There should continue to be lingering in-situ damming conditions northwest of the boundary - with areas of fog and overcast conditions. To the southeast, conditions will warm again depending on the amount of sun that can break through. The first in the series of mid/upper level waves will approach the region from the south-southwest late in the day. Showers and isolated thunderstorms are expected, with likely POP forecast along and SE of the boundary in the mid to late afternoon into the evening. It appears that any thunderstorms should remain below severe criteria in the SE, with NIL threat NW. Highs generally 55-60 NW ranging to 70 SE. This first round of showers/isolated thunderstorms should move down east and away overnight. This will leave cloudy skies with a chance of light rain or drizzle. Showers and even isolated thunderstorms are then expected to begin to affect the SW portion of the region before 12z/Sunday. We will begin to ramp up the POP again with the stronger system`s approach from the SW for Sunday. Lows should hold in the 50s to lower 60s SE.
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&& .LONG TERM /Sunday through Thursday/... As of 220 AM Friday... Earlier thinking remains valid. Warm and stormy weather will rule Sun through Mon, followed by dry and mild weather Tue through Wed. A pattern shift toward lower (higher) heights over the eastern (western) CONUS will commence Wed night, with cooler temps arriving for Thu. Sun through Mon night: Widespread showers and perhaps a storm or two should be ongoing across central NC early Sun, within vigorous forcing for ascent generated by DPVA with a wave tracking NNE through the area, having emanated from the deep low over the lower Miss Valley, along with a 50 kt low level jet punching into the area from the south, and intense upper divergence. PW of 200-300% of normal in conjunction with this strong lift will support a period of heavy rain Sun morning into early afternoon, as an occluded surface low tracks NE over the NC Piedmont. A slug of relatively drier mid level air will move in from the south Sun afternoon, leading to a short relative lull in coverage and intensity, and will have categorical morning pops dipping to good chance/likely for a period in the afternoon within brief shortwave ridging between the exiting wave and the upper low crossing the Gulf States. This lull will be short-lived as the upper low shifts east over AL/GA then NE over the Carolinas, bringing another round of strong deep lift. The ECMWF/GFS have come into better agreement on timing, although the ECMWF is still a bit faster than the GFS. The slightly slower GFS speed is preferred based on the strength of this system. Will ramp pops back up to categorical Sun evening into the early overnight hours, followed by another downturn in coverage and intensity late as a mid- upper dry punch arrives along with cooling low levels. Scattered to numerous showers will persist through Mon as the upper low crosses the region with ~7 C/km mid level lapse rates and lower but still above-normal PW. Precip chances will wind down Mon night as the low shifts to our north. A few strong storms remain possible, mainly from midday Sun into Sun evening, with a 70+ kt mid level jet streak accompanying powerful upper divergence and steep 700-500 mb lapse rates over 7 C/km according to the GFS. CIPS analog guidance continues to suggest more of a severe threat for FL compared to our area, historically speaking, although GFS forecast soundings for central NC still show long wavy hodographs and marginal to moderate instability, suggestive of at least a modest risk of a few strong wind-producing storms, and perhaps a tornado as well along and north of the occluding frontal system. Highs in the mid 60s to around 70 Sun, lows from the upper 40s to mid 50s Sun night, and mid 50s to lower 60s for highs Mon. Lows in the low-mid 40s Mon night. Tue through Thu: Mid level heights rise over the Southeast as a mid level ridge axis shifts over the region, while surface high pressure crosses the northern Gulf and FL. Expect fair skies Tue/Wed with slightly cooler but still above normal temps. The aforementioned pattern change will begin late Wed night or Thu morning (ECMWF brings a cold front through earlier than the GFS) as a strong EPac trough this weekend shifts eastward and begins to tap into cooler polar air that has been bottled up well to our north. Expect highs back down into the 50s Thu. A few showers are possible with the cold front, although will keep pops on the low side given the significant model timing differences. -GIH && .AVIATION /18Z FRIDAY THROUGH TUESDAY/... As of 1258 PM Friday... 24 Hour TAF period: VFR ceilings will exist in the KFAY region this afternoon, with all other sites expected to remain IFR to MVFR CIGS. Areas of fog and drizzle will continue over the KINT and KGSO areas. With light wind overnight, areas of fog and low overcast will develop, mainly after 03Z/21. Most TAF sites should fall into the LIFR VSBY and CIG range between 09z and 13z/21. Some minor improvement will occur after 13z - with some MVFR CIGS from KFAY to KRWI, but lower IFR conditions from KRDU to KINT through into the afternoon. Long term: Sub-VFR conditions are expected with showers and even some thunderstorms at times Saturday nigh through Monday morning. A return to VFR conditions expected Monday afternoon and Tuesday. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett NEAR TERM...Badgett SHORT TERM...Ellis LONG TERM...Hartfield AVIATION...Badgett

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