Area Forecast Discussion
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FXUS62 KRAH 241700
Area Forecast Discussion
National Weather Service Raleigh NC
100 PM EDT Fri Mar 24 2017
An area of high pressure anchored offshore will extend west into
central NC through Saturday. A weakening upper disturbance will
cross our region on Sunday.
.NEAR TERM /THROUGH TONIGHT/...
As of 1025 AM Friday...
An area of high pressure at the surface through 850mb has drifted
offshore, resulting in a sw flow in its wake. This flow will advect
an increasingly moist and warm air mass into central NC. Aloft, an
area of high pressure centered over the northern Gulf will extend
newd into the Carolinas. Circulation around this feature will funnel
the deeper moisture west- northwest of our region through tonight.
The presence of the ridge aloft and the sw flow in the lower levels
of the atmosphere will yield partly cloudy skies and noticeably
warmer conditions. Afternoon temperatures in the upper 60s-lower 60s
will be common. ~WSS
Not as cool tonight, and with a chance of patchy radiation fog owing
to the aforementioned increase in low level moisture values, with
low temperatures mostly in the upper 40s (45-50) expected. ~MWS
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 355 AM Friday...
A mid-upper level trough axis extending south from a closed low now
over sern CO will migrate newd from the MS Valley early Sat to near
the srn Appalachians by Sun morning, as the parent upper low lifts
toward the Great Lakes. Associated mid level height falls on the
order of 20-30 meters will pivot NEwd across central and wrn NC Sat
and Sat night, but lingering influence of the preceding ridge axis
aloft/sub-tropical ridge will maintain a strong capping inversion
and dry air aloft. As such, precipitation chances will remain low
through Sat night, with perhaps just a slight chance of a shower
near the Yadkin River by 12Z Sun. Even then and there, however,
instability will be weak, shallow, and still capped by the
inversion, so the (relatively) better chances of any showers will
not occur until Sunday.
It will otherwise be warm Sat, with scattered to broken fair weather
cumulus, and mild Sat night with both thickening high level
cloudiness in Swly flow aloft, and a chance of stratus over the wrn
piedmont late. Highs in the lower to middle 70s, and lows in the
lower to middle 50s.
.LONG TERM /Sunday through Thursday/...
As of 400 AM Friday...
An upper low will lift from the southern Plains to the Great Lakes
this weekend, with its associated cold front and convection moving
across the deep South on Saturday and Saturday night. As the upper
low lifts and weakens, the cold front essentially stalls well west
of the mountains and leaves NC int he warm sector through the middle
of next week. Despite the lifting upper low taking on a negative
tilt Sunday, only a glancing shot of 40-60m height falls over the
western piedmont and generally weakening deep layer forcing should
cause the convection to weaken as it moves into the southern
Appalachians early Sunday. South-southeasterly low-level flow may
sustain showers and isolated storms over the western Piedmont on
Sunday, while areas of east of US 1 may see no precip at all.
Instability will be hampered in the west by early morning clouds and
scattered showers, while a dry mid-level cap will be more pronounced
to the east where a ridge of high pressure off the coast has more
influence. Expect highs to range from around 70 west to near 80
High pressure will continue to influence the region early next week,
with warm return flow around the high and thicknesses approaching
1400m by Tuesday. Showers and storms will be possible Tuesday as
another shortwave lifting out of the southwest US moves east across
the Mid-South. models continue to struggle with the amplitude of
this yet to be well sampled wave, and thus confidence in the
coverage of convection is low. However, strong diurnal heating and
modest dewpoint recovery through early next week suggests some
strong storms could be possible if the wave and associated shear are
strong enough. Highs should easily be in the mid 70s to low 80s
Monday, Tuesday and even Wednesday, before a back door cold front is
forecast to slip into the area by Thursday.
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 100 PM Friday...
High pressure at the surface and aloft will gradually weaken and
drift east through Saturday night. This will allow an area of low
pressure to approach from the west Saturday night and Sunday. The
southerly flow ahead of the low will advect a moist air mass into
our region, leading to probabilities of MVFR conditions due to low
clouds and fog late tonight-early Saturday morning, and again
Saturday night into Sunday morning. The sub VFR parameters may
linger well into the morning hours before lifting into VFR criteria
during the afternoon. The threat for showers appear minimal through
Saturday, though the potential appears higher for late Saturday
night into Sunday.
Periods of MVFR/IFR ceilings and visibility due to fog appear
probable Sunday night through Wednesday. The highest threat for
scattered showers will be on Tuesday when another upper disturbance
passes primarily to our north.