Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
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FXUS62 KRAH 211431
Area Forecast Discussion
National Weather Service Raleigh NC
1031 AM EDT SUN AUG 21 2016
An upper level trough and attendant cold front approaching the
mountains from the west this morning will progress east through the
Mid-Atlantic and Carolinas this evening into tonight. In the wake of
the front, dry high pressure will build into the region from the
west through mid-week.
.NEAR TERM /TODAY AND TONIGHT/...
-- Changed Discussion --As of 1031 AM Sunday...
An upper level trough progressing east through the Great Lakes today
and into New England tonight will push a seasonably strong cold
front across the area late this evening and overnight. Expect one
last day of above normal temperatures ahead of the front. Continued
hot with highs once again in the upper to lower 90s.
Westerly flow aloft preceding the front and late unfavorable diurnal
timing will limit convective pops/coverage across the area with the
the highest pops expected over the NW Piedmont and northern Piedmont
during the 21z-01z, with rapid weakening thereafter owing to
boundary layer cooling/stabilization.
There is a small and narrow window for strong to severe storms
across Central NC, confined primarily north of Highway 64 and west
of the Triangle, between the hours of 3pm to 8 pm. Along the
southern fringes of the westerlies, 30kts of shear combined with
moderate instability ~1000 to 1200 J/Kg of MLCAPE could support an
isolated potential for damaging winds (aided by precip loading and
downward momentum transport) and marginally severe hail.
Expect convection to end from west-east between 03 to 06z as the
surface front /low-level trough/ progress toward the Carolina coast.
CAA in the wake of the front will drive overnight lows with temps
falling into the mid to upper 60s over the Piedmont and lower 70s
across the Sandhills and Coastal Plain. For many places across the
area, tonight will be the first time in 4 to 6 weeks in which temps
fall below 70 degrees.
-- End Changed Discussion --
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 145 AM Sunday...
Synoptic subsidence in the wake of the upper level trough
progressing offshore the Mid-Atlantic coast tonight will increase
surface pressure over the Ohio Valley and Appalachians during the
day Monday, aiding the advection of a drier airmass into the
Carolinas from the NW. Expect clear skies and a light NW breeze with
highs ranging from the lower/mid 80s NW to upper 80s SE. High
pressure will build east into the Mid-Atlantic Monday night, with a
sfc ridge axis extending SE into the Carolinas. With a much drier
airmass in place (dewpoints in 50s) and clear/calm conditions, lows
may fall below 60F into the upper 50s Monday morning, primarily
across the N/NW Piedmont, with lows in the lower/mid 60s elsewhere,
warmest in the SE coastal plain. -Vincent
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 217 AM Sunday...
Ridging, both sfc and aloft, will promote a continuation of dry
weather across our area right through the work week. In addition,
look for little airmass change from Monday, so highs in the mid 80s,
lows in the mid 60s, and dewpoints in the low-mid 60s will continue
right through Thursday. By Friday we`ll begin to see the airmass
moderate to above-normal readings as the sfc ridge axis moves
offshore and southerly flow re-establishes over our area. On
Saturday, the next cold front will drift south toward then stall
across our area. While the front will bring a slight chance for
showers/tstms, given limited moisture, right now it appears that
most of the day Saturday should remain dry.
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
As of 616 AM Sunday...
24-hr TAF period: Expect VFR conditions to prevail this morning
through mid-afternoon, in advance of a cold front approaching the
mountains from the west. Sub-VFR conditions attendant convection
expected to develop along the front during the late afternoon and
evening hours (21-03Z) will be possible at all terminals, though
most likely at northern terminals, especially RDU/RWI. An isolated
severe thunderstorm with sfc wind gusts AOA 50 KT cannot be ruled
out. Expect WSW winds of 5-10 kt with gusts up to 15 kt this
afternoon to become NW at 5-10 kt in the wake of the front this
Looking Ahead: VFR conditions and light winds will prevail through
mid-week as dry high pressure builds eastward from the OH Valley
into the Mid-Atlantic. -Vincent