Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 142350 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 648 PM EST Thu Dec 14 2017 .SYNOPSIS... A weak and dry surface cold front will stall south of the area tonight. An area of low pressure will develop along the NC coast Friday, then tracks northeast while staying offshore Friday night. High pressure will build into the area through Sunday. && .NEAR TERM /TONIGHT/...
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As of 648 PM Thursday... Just minor adjustments made to the near term forecast, primarily to the sky cover and hourly temperatures. Westerly flow in the mid-upper levels of the atmosphere will transport moisture ahead of a pair of upper disturbances into central NC. This will translate to increasing high level clouds this evening into the overnight. By daybreak, another layer of clouds a few thousand feet above the surface will develop. The increasing cloudiness should cause temperatures to cool a little slower than normal. This is already evident where temperatures across the far north are in the mid-upper 40s while locations across the central part of the forecast area, where skies are clear, have dipped into the upper 30s. Once the clouds arrive in these locations, temperatures will likely recover temporarily to around 40 then fall back through the 30s.
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&& .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 253 PM Thursday... The aforementioned low pressure wave will quickly lift to the NE Friday morning as a northern stream short wave, currently over the central Plains, moves east and sweeps across our area during the afternoon. As the wave departs and the short wave trough axis moves across, dry NW flow will return in their wake, clear the sky out by late afternoon. Other than clouds early in the day, look for fair weather with highs from the mid 40s NW to lower 50s SE. Clear and cold Friday night with high pressure building over the area, light or calm winds, and good radiational cooling conditions. That should set us up for lows dipping down in the mid 20s...perhaps even colder in the usual spots. && .LONG TERM /SATURDAY THROUGH THURSDAY/...
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As of 247 PM Thursday... Surface high pressure over the area will produce sunny skies with slightly cooler than normal temperatures to kick off the weekend. Highs Saturday will reach the upper 40s north to low 50s south followed by lows at or slightly below freezing Saturday night. The high pressure will edge offshore Sunday, with cloudiness increasing in return flow and associated moisture advection along with low amplitude ridging aloft on Sunday. The warm air advection and rising heights will produce modestly warmer highs in mostly the mid and upper 50s. Skies will become cloudy with scattered showers Sunday night as a series of waves begin to lift northeast into the area in deep southwest flow off the Gulf. The low amplitude ridge will linger through Tuesday, providing a conveyor for these waves and associated periods of enhanced shower activity. As we remain in the warm and moist airmass through the period, highs will be similar both Monday and Tuesday, ranging from upper 50s north to low and mid 60s south. Very difficult to forecast how much rain we might get given the duration of the event and model difficulties with timing and strength of the waves. A strong but relatively flat short wave in the northern stream moving across the Tennessee and Ohio Valleys will push a cold front east, effectively cutting off our moisture Tuesday night. The upper flow is basically zonal and the high pressure building in behind the front is only modestly colder than the air it is replacing, so highs will take only a mild hit Wednesday and Thursday...mostly in the low and mid 50s.
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&& .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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As of 648 PM Thursday... VFR parameters should persist across central NC through 08Z. After 08Z, chances will increase for the potential for a deck of stratus to develop with MVFR ceilings 1500-2500ft probable. This deck of ceilings expected to persist until mid day, then gradually dissipate. There is a high chance that VFR parameters will occur Friday night through Sunday morning. The next threat for sub VFR parameters is expected late Sunday into early next week as a low pressure system approaches from the west-sw.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...np NEAR TERM...WSS SHORT TERM...np LONG TERM...mlm AVIATION...WSS

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