Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 172345 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 745 PM EDT Tue Apr 17 2018 .SYNOPSIS... An area of high pressure will drift east from the northern Gulf today to a position off the FL peninsula on Wednesday. Meanwhile, a series of strong low pressure systems will track from the upper Midwest into New England. The difference in pressure between the high to our south and the lows to our north will create breezy conditions across central NC through Thursday. && .NEAR TERM /THROUGH TONIGHT/... As of 220 PM Tuesday... Skies have largely cleared out under the influence of subsidence behind the departing mid level vorticity max and trough axis shifting to our NE. A surface warm frontal zone approaching from the SW will continue to become more defined far N and NE NC through the rest of the day, and low level flow will back from WNW to uniform WSW. A weak surface low and trough will develop over SW NC through W NC respectively, and as this passes through this evening, with the low tracking along the front along the NC/VA border, surface winds will decrease, and we`ll finally see an abatement of the winds toward nightfall, with a shift of light surface winds to a NE direction over our NE and far N sections. Skies will stay generally clear through the rest of the afternoon into the mid evening, but then a layer of moisture around 850-800 mb spreading over far N and NE sections (atop areas along and N of the surface front) late tonight will bring a trend to partly to mostly cloudy skies in these areas from late evening through much of the night. These clouds should start to decrease toward daybreak as the 850 mb frontal zone lifts NNE. Expect lows from 40 NE to the upper 40s/around 50 SW (where SW winds S of the front will draw in milder air), although if the clouds come in more numerous or earlier than expected, NE sections may stay a few degrees warmer. -GIH && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 235 PM Tuesday... As the mid level flow at our latitude flattens with rising heights, the surface frontal zone over far N and NE NC will lift to our NE Wed, putting NC solidly within the warm sector, with a strengthening SW flow. Tonight`s clouds across the N and NE will continue to dissipate early Wed morning, and with a generally dry column and no immediate moisture upstream, we should see mostly sunny skies, with little more than scattered flat afternoon cumulus. Winds should again be sustained near 15 mph with gusts around 20-25 mph. We do have some concerns for adverse fire behavior Wed, with strengthening winds and successive windy days that continue to dry out fine fuels, however the RH values should be just above critical criteria. Thicknesses will start the day near normal but will soar through the day, with late-day 850 mb temps approaching 15C, suggesting highs from the upper 70s to lower 80s, and we may even see some mid 80s in the far S. Expect mild lows of 55-63 Wed night, with SW winds staying elevated at around 10 mph. -GIH && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 230 PM Tuesday... Continental high pressure will begin to influence the pattern on Thursday, bringing a dry airmass into the area. This combined with the exiting low pressure system to the northeast will keep a tight pressure gradient over the area, leading to breezy conditions for much of the day. With gusts of 25 to 30 kts possible, and min RH values hovering around 30 percent, fire weather could become a concern by Thursday afternoon. Gusts may remain through the evening hours before finally relaxing overnight Thursday night. Highs in the upper 60s to upper 70s from NW to SE. Lows Thursday night in the low 40s. Broad high pressure will remain in control through the weekend with only some increasing clouds by Sunday afternoon as the high pressure splits and clouds start to build in as a result of northeasterly winds against the mountains. Temperatures will remain cooler than normal with highs generally in the 60s as opposed to the low 70s expected this time of year. Overnight lows gradually rising through the 40s during this period. For early next week, models are split on what will happen to a low pressure system over the deep south with the GFS taking a more northerly track and bringing precipitation into central NC from the south by early Tuesday morning. The EC solution takes the system south towards the Florida Panhandle keeping NC dry. For now will introduce a low chance of showers for Tuesday given the uncertainty. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
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As of 745 PM Tuesday... For the 24 hour TAF period...expect VFR conditions through the period with SW winds 10-20 kt gradually diminishing overnight, then increasing again to 10-20 kt during the late morning and afternoon Wednesday. It`s worth noting that CIGS aoa 5kt feet will be possible late tonight and persist through the morning hours Wednesday as a warm front lifts north across the area. At FAY, there is still a risk of low level wind shear tonight 03z-09z as a 35-40 kt low level jet from the WSW passes overhead. Looking beyond 00z Thu, VFR conditions are very likely through late week, with high confidence in VFR lasting through next weekend. Winds may prove problematic through Thu, however, especially for small aircraft. The threat will peak on Thu, along and behind passage of a mostly dry cold front, when sustained values of 15-20 kts with frequent gusts to 25-30 kts are anticipated. -GIH
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...np/Hartfield

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