Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 260249

Area Forecast Discussion
National Weather Service Raleigh NC
1050 PM EDT Wed Apr 25 2018

Another low pressure system will approach central NC
from the west Thursday, and cross our area late Thursday night
and Friday. A more tranquil weather pattern will take hold of
the Carolinas this weekend.


As of 949 PM Wednesday...

Subsidence clearing this evening in the wake of the exiting lead
upper low/trough off the DELMARVA coast will be short-lived, with
latest satellite imagery showing the next batch of high/mid level
cloud cover, associated with the compact upper low diving SE into
the Lower Miss Valley, already spreading east into the NC mtns.
These high clouds will continue to spread east and will thicken
through daybreak, especially across the western Piedmont. Lows
overnight 50 to 55.


As of 330 PM Wednesday...

Another well defined cyclone, this one currently crossing the
central Plains into the Ozarks, will continue to move eastward into
the TN Valley Thursday, and encroaching upon the southern
Appalachians late afternoon. While the day will start out partly
cloudy across central NC, expect clouds to increase/thicken across
the western counties by mid day, and across the remainder of central
NC in the afternoon. Increasing diffluence aloft will provide enough
lift to trigger a few showers by late in the day across the western
Piedmont. Max temps will vary from the upper 60s/around 70 in the
west-nw where clouds will thicken earlier in the day, to the mid 70s
across the east.

Thursday night will see the highest chance for showers/isolated
thunderstorms as the mid/upper level low lifts newd up the spine of
the Appalachians. The greatest concentration for showers/storms will
be across the western Piedmont. Expect a few storms overnight,
primarily west of highway 1 as mid level lapse rates between 6.5-7
deg C/km passes overhead. In addition, some of the storms may
display good organization and possibly some mid level rotation as
bulk shear 35-40kts expected. A deterrent to the development of
strong/severe storms will be limited low level instability. Thus, an
isolated strong/severe storm cannot be ruled out. However, the main
weather hazard may be locally heavy downpours. Area creek and
streams are running a little higher than normal due to recent
rainfall. If showers/storms develop into a training pattern, could
see flooding of small tributaries occur.

Friday, the low pressure system will lift nwd, slowly dragging a
cold front across the region during the day. During max heating,
could see a few showers/storms develop along this boundary in the
afternoon, mainly along and east of highway 1.  A mixture of sun and
clouds and west-sw low level flow should boost afternoon
temperatures into the low-mid 70s.


As of 155 PM Wednesday...

The forecast is expected to be dry during this period, with near to
slightly below normal temperatures through Monday, moderating to
around to slightly above normal by Wednesday.

As the shortwave low moves away from the area, getting absorbed in
the longwave trough, another shortwave will swing through the Deep
South/Gulf Coast Friday night and out over the Atlantic by Saturday
aft/eve. Meanwhile, the parent low will swing through the Great
Lakes and into New England through Sunday. The longwave trough axis
will extend southward, moving over the Atlantic by Sunday night. The
general northwest flow pattern and a reinforcing dry cold frontal
passage Saturday/Saturday Night will result in temperatures near to
slightly below normal for late April. High pressure will remain over
the region through Monday, shifting offshore Tuesday. As a result,
expect a return to more southerly flow and increasing temperatures
Tuesday and Wednesday.


As of 1050 PM Wednesday...

With the exception of some patchy fog overnight, VFR conditions
across the area should hold through Thursday as drier air filtering
into the area should mitigate any fog threat during the early
morning hours on Thursday. More adverse conditions are possible
Thursday night into Friday as MVFR ceilings accompany another round
of showers and storms with low pressure in the area. The cold front
accompanying this system will move through by Friday afternoon
bringing conditions back up to VFR where they are expected to stay
for the rest of the long term.





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