Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 160558 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1258 AM EST Fri Feb 16 2018 .SYNOPSIS... High pressure situated over the Florida Peninsula will continue to support a warm Southwesterly flow through much of Friday. A cold front will cross the region late Friday, with a much cooler air mass to follow on Saturday. Unsettled weather returns once again Sunday as a developing low progresses north and east through the Mid Atlantic. && .NEAR TERM /THROUGH TONIGHT/... As of 945 PM Thursday... Little changes to the forecast for the evening update, with conditions expected to remain relatively quiet through the overnight hours. Have adjusted hourly temps a bit to match current observations, but still expecting a slow temp fall tonight with wind speeds and gusts increasing in magnitude as sunrise approaches. Have slowed PoPs a bit on Friday to better match evening model output, but in general, expect a thin line of showers to advance through the area mid day Friday across the northern Piedmont, before exiting east into the Coastal Plains by nightfall. Previous Valid Discussion... A tightening pressure gradient attributed to an area of high pressure over the northeast Gulf and a strong cold front advancing sewd across the OH Valley will maintain a breezy swly sfc wind across central NC tonight. The wly flow aloft will continue to stream moisture into our region, though bulk of clouds will be of the mid and high level variety. Towards morning, areas of low clouds may materialize. In spite of the available moisture, lack of a mechanism to focus lift will prohibit any rain showers from developing tonight. It will remain very mild for this time of year thanks to the swly sfc winds and variably cloudy skies. Overnight temperatures generally near 60 to the lower 60s. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 315 PM Thursday... Friday, a strong cold front being propelled along by a s/w crossing the Mid Atlantic will approach the NC/VA border in the morning, then drop southward during the afternoon and evening hours. Best forcing for shower generation occurring in the lowest 15k ft of the atmosphere as the bulk of the energy aloft projected to occur well north of our region. Bulk of near term model guidance suggest band of showers in vicinity of the VA border around mid day, then drift into the heart of central NC by mid-late afternoon. While kinematics with this system are quite strong, the overall atmospheric instability is weak or inconsequential. Thus, appears that the chance for thunder is remote at this time. High temperatures Friday dependent upon arrival/areal extent of showers. If showers do arrive by mid-late morning, as a few of the near term models suggest, this would limit temperature recovery. While the sky coverage will be overcast, the mild start to the day and the warm swly flow ahead of the front should be able to boost temperatures into the 70s across the north half, and 75-80 across the south. Low level surge of colder air will not occur until Friday night, behind the passage of the 850mb trough. Temperatures across the southern counties will likely not display an appreciable cool down until after midnight. Forcing along the low level trough will maintain a few showers well into the evening hours across the region, especially east and south of Raleigh. Shower coverage will decrease during the overnight hours. Min temps daybreak Saturday will vary from the upper 30s to near 40 across the far north to the mid-upper 40s across the far south. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 158 PM Thursday... Cold air damming is expected on Saturday as a 1030+ mb surface high will be in place early in the day, centered over PA/NJ. This high is forecast to be transitory and push rapidly off the New England coast Saturday afternoon and evening. Dry and chilly air will have been deposited into our region courtesy of the high (surface dew points are forecast in the 20s/30s in the Piedmont Damming Region early. A mid level wave along with some weak surface reflection is expected to approach the central Appalachians, rapidly increasing moisture and lift over western NC Saturday. The combination of the WAA pattern with the easterly low level flow and the moist SW flow aloft will lead to low overcast. There will also be a period of likely POP (rain) during the day into the evening hours, best chances in the NW, least SE. Highs only in the 40s expected, with some upper 30s possible in the NW Piedmont. QPF of around 0.25 is expected NW, with only a few hundredths in the SE. The clouds and some drizzle will likely remain in the forecast into Saturday evening, with fog as well. However, with the wave dampening out and the weakening cold front expected to push through central NC overnight, temperatures should stay well above freezing, in the mid 30s to lower 40s NW to SE. The CAD will be very short lived. Another quick moving high pressure will bring clearing skies for Sunday and milder temperatures. Expect highs to rebound into the 60s for many areas Sunday afternoon. This high pressure is expected to rapidly pass offshore late Sunday with a strong WAA pattern again by Monday. There is another chance of showers Sunday night into early Monday as a warm front lifts quickly northward. If skies clear early enough Monday afternoon, temperatures will surge into the upper 60s to lower 70s (cooler along the NC/VA border region as this region will be the last to see some sunshine Monday. Strong subtropical ridging is expected to bring record warmth as it appears that Tuesday and Wednesday we could break some daily records (especially the high min`s). Lows in the 55-65 range and high in the 70s (even 80 possible in the Sandhills and southern tier of counties). By Thursday, temperatures should back off briefly as another cold front and NE flow develop. We will back off highs by 10 degrees or so for now, but there is a potential for a day or so of significant cooling if a CAD event develops. Since this is out day 7 or so, we will not get too specific at this time. && .AVIATION /06Z FRIDAY THROUGH WEDNESDAY/...
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As of 1255 AM Friday... 24-Hour TAF Period: VFR conditions should persist through tonight, although some models indicate a brief period of sub-vfr cigs moving in from the southwest around daybreak. There is still some question as to whether the clouds will move in, and if they will be scattered or broken. Have covered that with a tempo group for now and will reassess for the 12Z issuance. Southwest winds will continue to be strong (10-15 kts) and gusty (17-25 kts) through tonight. Expect both to increase during the day Friday ahead of the southward propagating cold front. In the wake of the front, winds will continue to be fairly strong and gusty, veering to a more northwesterly direction by 00Z at most terminals. Also with the frontal passage, a brief round of showers is expected, with accompanying low-end VFR to high-end MVFR conditions in most locations. Another round of showers is possible by the end of the TAF period, but will hold off on that for now. Looking ahead: A cold front will progress through much of the area by Saturday morning. Some lingering patchy periods of light rain are expected for Saturday. Also, expect a period of sub-vfr conditions to develop Saturday afternoon, persisting through the night. A period of VFR conditions is expected again on Sunday, however aviation conditions will alternate from VFR to sub-vfr through Monday night before another warm front lifts northward through the area on Tuesday.
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&& .CLIMATE... RDU Records: Date | High Year | High Min Year ------------------------------------------ 02/15 | 82 1989 | 61 1989 02/16 | 77 1976 | 62 1990 GSO Records: Date | High Year | High Min Year ------------------------------------------ 02/15 | 78 1989 | 57 1949 02/16 | 76 1927 | 58 1990 FAY Records: Date | High Year | High Min Year ------------------------------------------- 02/15 | 81 1918 | 63 1918 02/16 | 82 1989 | 62 1935 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...JJM NEAR TERM...JJM/WSS SHORT TERM...WSS LONG TERM...PWB AVIATION...KC CLIMATE...KC

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