Area Forecast Discussion
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FXUS62 KRAH 252320
Area Forecast Discussion
National Weather Service Raleigh NC
720 PM EDT Sat Mar 25 2017
Bermuda high pressure will extend west into the Carolinas and VA
through Sunday. A weakening upper level disturbance will cross
northwest of our region on Sunday.
.NEAR TERM /THROUGH TONIGHT/...
As of 255 PM Saturday...
An area of high pressure located south-southeast of central NC, and
a slow moving low pressure system lifting into the mid MS Valley,
will maintain warm, modestly moist, sly flow over air area tonight.
Expect plenty of high level clouds overnight while pockets of low
clouds may develop, primarily west of highway 1. The moderating air
mass and cloud cover will yield overnight temperatures in the 50s.
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 255 PM Saturday...
A lead s/w rotating around the mid MS Valley upper low will lift
newd from eastern TN into the central Appalachians Sunday, brushing
our nw sector. This system projected to weaken with time and while
atmosphere continues to moisten, model rh cross sections still
depict a decent layer of dry air in the mid levels of the
atmosphere. Accordingly, models have been trending drier, so will
follow a similar trend. Plan to confine chance PoPs to the NW
Piedmont, with slight chance PoPs elsewhere across the Piedmont.
Over the east and far south sections, will advertise PoPs less than
Expect quite a bit of cloudiness, limiting insolation. Still, warm
sly flow along with partial sun should be able to boost temperatures
back into the low-mid 70s.
Continued mild Sunday night under variably cloudy skies. Weak
confluence and a series of weak perturbations aloft will continue a
minor threat for a few showers over the NW Piedmont. Elsewhere,
probability of a shower appear too remote to mention at this time.
Overnight temperatures in the mid-upper 50s.
.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 230 PM Saturday...
A warm, moist airmass will be in place to kick off the work week.
Precipitable water in excess of 1.2 inches and highs Monday through
Wednesday reaching the mid 70s to lower 80s will provide modest
instability and widely scattered showers Monday, with coverage
ramping up somewhat on Tuesday as a progressive but relatively weak
short wave moves east across the area. Timing of the short wave will
be favorable to tap afternoon instability and a few thunderstorms
will be possible in the afternoon...especially east where
instability and upper diffluence are favorably aligned ~18-21Z.
Dry and continue warm temperatures are initially on tap Wednesday as
ridging aloft builds over the area ahead of another upper low moving
into the central Plains. High pressure over the Great Lakes will
surge south ahead of the Plains system, pushing a dry backdoor cold
front south into the state later Wednesday, but highs will have time
to reach the mid and upper 70s ahead of the cooler air.
The "seasonally-adjusted" cold air damming setup will promote
overrunning rain in the west as early as Thursday afternoon. PoPs
will be ramping up Thursday night and lingering all the way through
Friday night as low level southerly flow increases ahead of the
Plains system. Low level instability will be meager at best, with no
indication as yet that we might see a thermal moisture boundary
encroach inland, As such, will have only a slight chance for
elevated thunderstorms on Friday. Highs both Thursday and Friday
will be mainly in the 60 to 65 range, with some lower 60s across the
piedmont and northern coastal plain where cool air will be deeper.
Lot of uncertainty as to how the Plains system evolves, i.e. the
latest GFS re-establishes cool air advection with development of a
coastal low, while the 00Z ECMWF was scouring out the cool airmass
and allowing highs to rocket quickly back to the upper 70s...will go
middle of the road 70 to 75 for now to await some consensus.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --As of 720 PM Saturday...
24-hr TAF Period: VFR conditions will prevail through this evening
and most of tonight. All terminals will see a potential for MVFR or
IFR ceilings (developing in assoc/w an increasingly moist southerly
return flow) for several hours Sunday morning (10-15Z). Ceilings are
expected to lift to VFR (3-4 KFT) by noon, however, ceilings may
persist near the VFR/MVFR cut-off at 3-4 KFT the remainder of the
The weather pattern will be unsettled through mid-week, suggesting
that periods of sub VFR conditions are probable, primarily in the
form of low ceilings during the overnight into the early morning
hours. An approaching low pressure system will trigger scattered
showers across central NC late Monday night through Tuesday. A
backdoor cold front may drop into the region Wednesday, setting up a
possible CAD event for the later half of the work week, and
attendant sub VFR conditions. -WSS
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