Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 101130

National Weather Service Raleigh NC
730 AM EDT Fri Jul 10 2020

Tropical Storm Fay will move slowly northward up the Mid-Atlantic
coast through today. A weak surface front will move SE into the area
late tonight and will stall out across the region through the
weekend. Another weak front will stall our across the area early
next week followed by a strong upper-level ridge building over the
region by mid to late week.


As of 335 AM Friday...

TS Fay will continue to move north away from NC, with the official
NHC track skirting the center of Fay near the mid-Atlantic coast
today and then inland over the mid-Atlantic or the northeast United
States late tonight or on Saturday. Weak subsidence in the wake of
TS Fay should make if difficult to pop off much more than isolated
convection through the afternoon. However, the arrival of a
shortwave trough, weak surface front, and accompanying modest 30
meter height falls into the area between 00 to 06z will bring the
best chance of convection late into the area this evening and into
the early overnight hours. The overall model consensus is that the
convection will weaken as it progresses eastward through the area.
However, the 12km Nam suggests more than sufficient instability to
sustain convection into eastern portions of the CWA overnight. Given
weak shear in place and late diurnal timing, severe threat will be
very low and confined to the western Piedmont.

The big story today will be the return of the heat. Low-level
thicknesses are forecast to rise another 10 meters to ~1430, with H8
temps warming to ~21 C. Expect highs in the lower to mid 90s with
heat indices in the low 100s across central and eastern NC. Will
continue to highlight the high heat indices in the HWO.


As of 335 AM Friday...

While the shortwave trough is forecast to traverse east of the area
by late morning/midday, the left-behind weak surface front will
stall out across the area on Saturday. Convective re-development is
likely east of of the sfc boundary, along the I-95 corridor where
continued muggy, low/mid 70s dewpoints will linger. Meanwhile, along
and west of boundary ,across the western and central Piedmont,
considerably drier air, featuring sfc dewpoints into the lower to
mid 60s will stifle convective chances. As such, now have a dry
forecast west of the Triangle, while maintaining good chance PoPs
along the I-95 corridor.

Due to presence of dry air aloft and resultant high DCAPE of ~1500
J/Kg), isolated pulse severe storms will be possible across eastern
NC Saturday afternoon.

While thermal advection will be rather negligible, the drier, less
humid air over the NC Piedmont counties will be very noticeable and
will make the heat tolerable for the western two-thirds of the
forecast area. However in the east, expect another day of heat
indices in the lower 100s. Lows Saturday night ranging from upper
60s NW to lower 70s SE.


As of 344 AM Friday...

Slightly drier air will be in place across the area on Sunday in the
wake of Saturday`s departing trough, with PW`s generally in the 1.2
to 1.4 inch range. Meanwhile, an upstream shortwave trough will move
through the Ohio Valley and into western NC by late afternoon,
before washing out Sunday evening. Isolated showers and
thunderstorms will be possible as the front moves eastward, but
should diminish with the loss of daytime heating and generally
unfavorable moisture profile across the area. Similar to the
previous forecast, I`m hesitant to go completely dry but will stay
on the lower end of the PoP spectrum.

Monday and Tuesday will see the aforementioned front shift eastward
and stall over the Coastal Plain, with daily shower and storms
chances primarily east of I-95. Isolated showers will be possible
elsewhere but the best organization and deepest moisture will be
positioned across the eastern half of the forecast area.

Wednesday and Thursday will see an increase in temperatures across
the area with relatively low precip chances. Today`s deterministic
guidance is showing the large mid tropospheric ridge over the desert
southwest gradually building eastward, with 594-595dm 500mb heights
overhead late in the week. Consequently, bias corrected/blended
guidance is suggesting temps in the 94-97 range area-wide toward the
end of the week, with a non-zero possibility of some spots hitting
98 or 99. Either way, heat will be the main story to close out the
week with heat indices at or above 100 degrees as well.


As of 730 AM Friday...

24 hour TAF period:
Any patchy fog will dissipate shortly after daybreak.
Expect predominately VFR conditions through the afternoon with with
only isolated convection possible. However, the arrival of upper
trough and attendant weak surface front into the area late this
evening and through the overnight hours will bring a chance of some
scattered showers and thunderstorms into the area. KINT and KGSO
will have the best chance of seeing some sub-VFR flight restrictions
from these storms between 00 to 03z Sat, followed by followed by
KRDU between 02 to 06z Sat. This area of convection should begin to
weaken and dissipate as it continues to push east toward KFAY and

Looking ahead: The better chance of showers and thunderstorms is
expected to shift across eastern NC(KRWI and KFAY) on Saturday,
owing to a surface front bisecting central NC. After mostly dry
conditions on Sunday, another weak surface front moving into the
area will bring a chance of scattered showers and storms late Sunday
night and into early next week.





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