Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 150615 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 115 AM EST Mon Jan 15 2018 .SYNOPSIS...
-- Changed Discussion --
Chilly high pressure will extend into the Carolinas from the north through this morning. The high will retreat to our northeast today, bringing more seasonable temperatures on Tuesday. A strong upper level trough will cross the region Tuesday night through Wednesday night.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/... As of 1230 AM Monday... Little in the way of changes with this update. Will be keying on early morning cloud cover with the main overnight package, which shows a low to mid level cloud deck continuing to inch west into the coastal plain counties of North carolina this morning. Otherwise, things seem to be on coarse with the previous forecast, with only slight temperature adjustments needed. Previous Valid Discussion... Some high cloudiness will streak across the area as an upper jet lifts northeast across the area tonight, otherwise not much to grouse about in the forecast. Will make some very modest tweaks to the hourly sky and temperature grids to reflect current conditions, otherwise all is well. Previous Discussion: Quiet, cold, and dry weather will hold through tonight, as the polar surface ridge noses into central NC, although we`ll face bouts of cloudiness as a couple of waves aloft cross the region within cyclonic southwesterly mid level flow. The first perturbation is a weak one, tracking northeastward into W NC, and this in conjunction with an increase in upper divergence associated with upper level acceleration over the Southeast will prompt some high cloudiness over the area tonight. A second, slightly stronger wave will cross the Gulf Coast region late tonight before emerging off the SC coast shortly before daybreak, and this will bring additional cloudiness into our far eastern sections later tonight. But overall, any clouds should be too thin/sparse and high to provide enough downward IR to counter the good radiational cooling conditions posed by the cold air mass and diminishing winds. Lows 12- 21. The cool and dry weather will extend through Mon night. The aforementioned wave will track northeastward off the NC coast Mon morning into early afternoon, bringing a few added clouds across our east sections, but otherwise skies will be mostly sunny with just a few altocu. Thicknesses will begin to moderate as the high center pushes further away, and highs are expected to be a bit warmer but still well below normal, 37-45. Lows Mon night 19-24 under fair skies. -GIH && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 245 PM Sunday... The initial inland sfc low associated with the high amplitude positive-tilted trough over the NE-central US will fill over the Eastern Great Lakes/NE US late Tuesday-Tuesday night, eventually giving way to a coastal low development well off the Mid-Atlantic Coast Wednesday-Thursday as the potent upper trough assumes a neutral tilt as it pivots east across the region. There continues to be a large model spread WRT to the timing and strength/amplification of the trough and it`s associated ana-frontal precip band, driven by strong shortwave dynamics and f-gen that`s progged to move west-east across central NC late Tuesday night and into the day on Wednesday. Operational versions of the GFS continue to be drier while the Euro maintains up to 0.20" liquid equivalent. With afternoon temps on Tuesday expected to moderate into the 45 to 50 degree range ahead of the attendant sfc cold front, current timing and thermal profiles, still supports precip starting as rain or a rain-snow mix at onset Tuesday night with a west to east change- over to snow early Wednesday morning and into the afternoon(east) as the expansive Arctic High builds in from the west. As previous forecast discussions have noted, one model pitfall and potential forecast concern is that NWP models tend to advect low-level cold air east of the mountains too quickly, which in itself can be a self limiting process as considerable dry sub-cloud layers develop. Given continued high uncertainty, will make only minor changes to current forecast. Current best guess for snowfall amounts are an inch or two from the Triangle north and west into the Triad region, with less than an inch south and east of the Triangle. There may not be any snow accumulation in the sandhills. These amounts are low confidence at this time and will likely change as model guidance continues to evolve.
-- End Changed Discussion --
&& .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
-- Changed Discussion --
As of 1 AM Monday... Mid level heights are expected to increase in the wake of the departing system, with surface high pressure slowly sliding eastward across the Southeast U.S. This will result in a warming trend through the remainder of the week, into the weekend. Dry weather is generally expected. However, we can`t completely rule out a weak disturbance moving across the area by the weekend, possibly yielding a small chance for some showers. Expect high temps will warm from the upper 30s to lower 40s on Thursday to the 50s and 60s by the weekend. Lows will follow a similar trend, from the teens on Thursday morning to 30s by Sunday morning.
-- End Changed Discussion --
&& .AVIATION /00z MONDAY THROUGH SATURDAY/... As of 622 PM Sunday... 24-Hour TAF Period: High confidence VFR conditions will persist at KINT/KGSO through this period as high pressure continues to build into the area. There is a chance some low MVFR clouds around in the 1-2 KFT range could develop over KRDU, KFAY, and KRWI between 06Z and 09Z, lingering until 18Z or so. Ceilings have been measured lowering east of the forecast area at this hour, but confidence on just how far west this will make it before daybreak remains low. Have withheld mention at RDU, but left a SCT layer in at FAY and a BKN layer in at RWI where there is a bit more confidence. Winds will remain relatively light through the period, highest in the east and lowest in the northwest. Looking ahead: High pressure will extend into the region through Mon afternoon before retreating to the NE Mon night, although VFR conditions will persist. Next chance for sub-VFR conditions will arrive late Tue through Wed as a potent upper level trough slowly crosses the region. VFR conditions will return for Thu/Fri as mild high pressure builds in from the west. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS/BSD NEAR TERM...JJM/Hartfield SHORT TERM...CBL/Franklin LONG TERM...BSD AVIATION...JJM/KC

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.