Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 200622 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 122 AM EST Tue Feb 20 2018 .SYNOPSIS... Weak high pressure will remain over the region early this morning. A warm front will lift north over the region today. A backdoor cold front will move southward into the area Thursday evening into Thursday night. && .NEAR TERM /THROUGH TONIGHT/... As of 1105 PM Monday... Have hoisted a dense fog advisory for much of the Piedmont as visibilities have dropped below a half mile at several spots and DOT traffic cameras depicting fairly thick fog along portions of I-40 in the Triad, and along I-540 over sections of the western Triangle. May need to expand the dense fog advisory into the coastal plain and Sandhills though visibilities currently are generally at or above a mile. Temperatures continue to hold steady, though expect temperatures to begin to slowly rise from the south after 06Z, and into the northeast Piedmont close to daybreak. Cannot rule out a stray shower overnight in the coastal plain though occurrence and coverage appears too limited to mention in the forecast at this time. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 353 PM Monday... ...Areas of dense fog early... The fog will likely be dense and extensive through mid-morning Tuesday. Finally, the WAA aloft will be allowed to gradually mix down and scour out the stratus/fog during the late morning and afternoon. Also aiding the process will be the increasing heights aloft with the expanding upper ridge. This will lead to sinking and mixing down of drier air from aloft. Highs should be tempered with readings slow to warm in the Piedmont, but earlier clearing in the south will aid warming there. Highs in the mid 60s to mid 70s expected, with the cooler damp NAM guidance with the slower clearing preferred guidance in the Piedmont Damming Region Tuesday. Low stratus again should be a problem in the Piedmont Tuesday night. Unseasonably moist PW`s expand northward over the region with dew points expected to be in the 50s and lower 60s (SE). If the winds become calm again, then fog may again become an issue or hazard. Lows generally in the mid 50s to lower 60s (see record high minimums listed below). && .LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 213 PM Monday... Unseasonable, perhaps record warmth will be the main weather story Wednesday and Thursday, thanks to a 595 ridge off the southeast coast and warm southerly flow on the western side of that ridge. Highs will range from the lower-mid 70s NW to lower 80s SE both days, along with lows in the upper 50s to lower 60s. The next cold front (that`s currently extending from the Great Lakes region southwest to the south central Plains) will slowly drop south into and across NC Thursday evening through Thursday night. It`s possible that some light rain may begin north of the I-85 corridor as early as late afternoon Thursday (which would hold temps there a bit lower than currently forecast), but it appears that the best chance for rain assoc with the fropa and subsequent CAD behind it, will be Thursday evening into Friday morning. After a cloudy damp start to Friday with the CAD in place, the boundary will attempt to lift back north by late-day with southerly flow and warming returning in it`s wake. Temps Friday will be dependent on the timing of the CAD erosion and clouds breaking up and the southerly flow returning. However, right now it looks like locations near the SC border will have the best chance of seeing temps returning to lower 70s, while warming farther north will be delayed, holding in the lower to mid 60s. Saturday will feature a mix of sun and clouds with our area between the sfc high centered to our east and the next cold front moving across the OH and MS valleys. Warm southerly flow between the two and sunshine will help temps climb into the 70s. Then on Sunday the front is expected to cross the region, bringing a chance for showers and possibly a thunderstorm to our area, and subsequent cooling trend in the wake of the front for early next week. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... As of 120 AM Tuesday... 24 Hour TAF period: Dense fog continues to set in across Central NC with many 1/4 SM or less visibility observations already in place. over the next couple of hours, many more observation sites are expected to fall to similar levels. A dense fog advisory is in place for areas west of US Highway 1 at this time until noon today. Good chance that this area will be expanded to include the rest of the forecast area later this morning. Expect fog to remain in place at least through mid to late morning. Visibilities will improve after that but ceilings will remain low, coming up to potentially MVFR briefly before falling back to IFR and lower levels after 00z Wednesday. Long term: A warm, moist weather pattern will promote chances for fog and low stratus the next several mornings. A cold air damming wedge could bring adverse conditions on Friday. A stronger cold front will cross the area on Sunday and Sunday night. && .CLIMATE... RDU Records: Date | High Year | High Min Year ------------------------------------------ 02/20 75 1939 62 1939 02/21 76 2011 55 1939 02/22 75 1897 60 1897 02/23 79 1980 57 1962 02/24 81 1982 58 1985 GSO Records: Date | High Year | High Min Year ------------------------------------------ 02/20 74 1922 56 1939 02/21 74 2011 50 1954 02/22 74 1925 57 1980 02/23 74 2017 52 1922 02/24 79 1982 55 1985 FAY Records: Date | High Year | High Min Year ------------------------------------------- 02/20 82 2014 60 1939 02/21 80 1991 61 1953 02/22 77 2003 56 1989 02/23 80 1922 55 1922 02/24 83 1930 60 1975 && .RAH WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until noon EST Tuesday for NCZ007>010- 021>026-038>041-073>076-083-084. && $$ SYNOPSIS...BSD NEAR TERM...WSS SHORT TERM...Badgett LONG TERM...np AVIATION...Ellis CLIMATE...RAH

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