Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 211957
Area Forecast Discussion
National Weather Service Raleigh NC
357 PM EDT WED SEP 21 2016
An upper-level low across the coastal Carolinas will drift south
tonight and then stall and slowly weaken on Thursday and Friday.
The remnant low pressure system from Julia will meander near the
South Carolina coast during the next few days. A moist,
northeasterly low level flow will persist for much of the work
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --As of 340 PM Wednesday...
Latest surface analysis shows the remnant surface low from Julia
located near the northern South Carolina coast. An upper level low
is centered near the eastern portion of the North Carolina and
South Carolina border. A persistent feed of deep layer moisture
continues to rotate around the upper level circulation from the
DelMarVa region into the western Carolinas with a large region of
low-level moisture noted across nearly all of the Carolinas.
While some breaks have been noted in the overcast across the
coastal region and in the mountains this afternoon, most of
central NC has had cloudy skies for much of the day.
A large area of rain and rain showers across the northern coastal
region of NC and southeast VA will try to advance southwest during
the remainder of the afternoon and evening. Convection allowing
models and other guidance are consistent in pushing the
precipitation southwestward tonight while the coverage and
intensity of the precipitation gradually wanes. The best chance of
rain will extend from Roanoke Rapids southwest to Rocky Mount and
into the Triangle area this evening. A drier and more stable air
mass across the Triad should preclude most precipitation with just
a brief shower possible. An isolated thunderstorm is also possible
across the central and southern Coastal Plains eastern Piedmont
and Sandhills region through the early evening in a region of weak
instability and mid level lapse rates of around 6 deg C/km.
Otherwise, skies will be mainly cloudy overnight with a steady
northeast wind overnight around 10 MPH with gusts to 15 to 20 MPH.
Low temperatures tonight will range in the mid 60s to near 70.
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.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
-- Changed Discussion --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
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.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 405 AM Wednesday...
The airmass over NC will finally dry out Friday into Saturday as
the deep moisture is shunted south and northwest flow aloft
begins to increase. Thus will result in more sunshine and temps
warming back above normal into the mid and upper 80s by Saturday.
Meanwhile, a deep upper trough is forecast to take shape over the
northeast US, with a cold front progged to surge down the East
Coast and backdoor into NC by Sunday, with the potential for low
clouds and light precip to break out behind the front. The ECMWF
and GFS have been showing a decent dip in thicknesses with this
front and the potential for highs in the mid 70s early next week.
Interestingly the EC Ensemble and GEFS don`t show quite as strong
of an airmass change, which may indicate that the front may not
push deep into the Southeast states. In any event, temps are
expected to drop back to around normal from Sunday-Tuesday before
rebounding ahead of a midweek front.
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
As of 235 PM Wednesday...
An upper level low pressure system will bring a period of adverse
aviation conditions with sub-VFR conditions across central NC
into Thursday. The moist circulation will bring periods rain and
showers with reduced ceilings and visibilities into the area
during the remainder of the afternoon and evening with the most
widespread coverage across the KRWI and KRDU terminals. With a
drier air mass in place, the showers will have a hard time moving
into the Triad and affecting the KGSO and KINT terminals tonight.
While the rain will diminish in coverage a bit overnight, MVFR
ceilings will lower to IFR in most locations with periods of LIFR
ceilings across the Coastal Plain and Sandhills after midnight. A
northeast wind at 8 to 12 kts with gusts to near 20 kts will
continue this evening and relax slightly overnight. Ceilings will
begin to improve on Thursday morning becoming MVFR or better by
Looking further ahead...An upper-level low across the coastal
Carolinas will slowly weaken on Thursday 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. -Blaes