Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 220116
Area Forecast Discussion
National Weather Service Raleigh NC
908 PM EDT WED SEP 21 2016
An upper-level low across the eastern Carolinas will drift
slowly south and weaken tonight and Thursday. Otherwise a moist,
northeasterly low level flow will persist for much of the work week.
.NEAR TERM /OVERNIGHT/...
-- Changed Discussion --As of 908 PM Wednesday...
The main weather concerns tonight are around the heavy rain threat
over NE Carolina associated with the deep easterly flow to the
north of the main mid/upper level low pressure.
The mid/upper level low pressure was still lingering over eastern NC
this evening. The main problem area is to the north of the low over
northeastern NC and southeastern VA, where the deep and moist
onshore flow continued to promote areas of heavy rain. Rainfall
rates over the NE part of our region under some of the heavier
showers have been less than 0.50 inch per hour in the past 5-6
hours, producing 6 hourly totals of 2.5 inches around Roanoke
Rapids. These heavy rains falling on the already saturated soils
did lead to some reports of high water, but no road closures in that
region. Rainfall rates in the past few hours have backed off as have
the reports of high water around Halifax.
Satellite and radar data suggest that some of the Hi-Res models were
overdone on the coverage and rainfall rates now, and in the previous
6 hours. In addition, the models were too quick to move the
heavy showers southward. Although a flash flood watch was considered
for the Roanoke Rapids to Tarboro areas, we decided to hold off due
to the expectation that flooding (if it does develop) would most
likely be localized to one or two counties, and the uncertainty of
whether or not additional training would occur over the same regions
that had the heaviest rain in the past 12-24 hours or spread out
into lighter totals to the south and west.
Elsewhere, spotty light rain showers were observed over the eastern
Piedmont through the Sandhills and southern Coastal Plain region. No
showers were noted over the western Piedmont. For the overnight, we
will maintain the categorical POP in the Coastal Plain with likely
POP into the eastern Piedmont,dropping off rapidly to less than 20
POP in the west. Low overcast in the east ranging to partly cloudy
skies in the Yadkin Valley. Lows in the 60s expected.
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.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
As of 400 PM Wednesday...
Not a lot of change in the weather pattern for Thursday and
Thursday night but a gradual shearing and weakening of the upper
low and filling of the surface low will decrease the moisture
transport and limit precipitation coverage. While scattered
showers and even a thunderstorm are possible again on Thursday,
the coverage will be notably less than previous days with a focus
across the Coastal Plain and eastern Piedmont. Rainfall rates and
intensity will be less than previous days as well. A widespread
overcast is expected to start the day with some thinning and
breaks in the overcast expected during the afternoon. Highs will
range in the upper 70s to lower 80s.
Scattered showers and isolated thunderstorms on Thursday afternoon
will gradually diminish on Thursday evening with the loss of
heating. Skies will become mostly cloudy again overnight with lows
in the mid 60s to near 70. -Blaes
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 225 PM Wednesday...
The upper cutoff low fills and is gradually absorbed into
the long wave trof over the eastern CONUS...allowing the airmass over
the area to finally dry out Friday into Saturday as deeper moisture
is nudged offshore. Increasing sun will allow temps to recover
backtoward normal...mostly mid 80s Friday...with mid and upper 80s
The east coast trof deepens and a backdoor cold front surges south
down the coast by mid day Sunday. Condensation in the cool air
advective regime behind the front will lead to mostly cloudy skies
with perhaps some patchy light rain through Sunday night. Highs will
be mostly in the upper 70s across north to lower 80s south. The cool
ridging behind the front will be locked on Monday...with mostly mid
70s highs...warming to the upper 70s for Tuesday with some lower 80s
on tap for Wednesday ahead of our next front approaching in the late
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 840 PM Wednesday...
24 Hour TAF Period: An upper level low pressure system will bring a
period of adverse aviation conditions with sub-VFR conditions across
central NC into Thursday. Periods of rain will continue to rotate
through the area through Thursday, with the bulk of the rain tonight
affecting KRWI/KRDU and possibly KGSO and KINT while the main axis
of precip on Thursday should be further east and closer to KRWI and
KFAY. Cigs are expected to fall into the IFR category overnight,
before slowly improving to MVFR by late morning/early afternoon
Thursday, possibly reaching VFR at a few sites during Thursday
afternoon. However, the latest hi-res guidance continues to hint at
the potential for some LIFR cigs and/or visbys at KRWI and KFAY
within +/- a couple of hours of daybreak. North-northeasterly winds
are expected to continue through the period in the 8 to 13 kt range,
with possibly some gusts to as high as 20 kts this evening and again
Outlook: An upper-level low across the coastal Carolinas will slowly
weaken on Thursday night and Friday. A moist, northeasterly low
level flow will persist into the first part of the weekend resulting
in periods of adverse aviation conditions with sub-VFR ceilings,
especially during the overnight and reduced visibilities in
scattered showers. A cold front will push through the region late
Saturday resulting in improving conditions for Sunday and Monday.