Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 240806
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
405 AM EDT Fri Mar 24 2017

.SYNOPSIS...
A warm front will lift north across NC and VA today. Bermuda high
pressure will then extend across our region through early next week,
though interrupted briefly by the passage of a shortwave trough on
Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 345 AM Friday...

1036 mb high pressure now centered a few hundred miles east of the
DelMarVA will drift to near and just north of Bermuda today.
Return Sly flow around the wrn periphery of the ridge will cause
warmer and more moist air to flood north through the Carolinas and
VA today, with afternoon temperatures in the upper 60s NW to lower
70s elsewhere in central NC, and surface dewpoints rising into the
40s to near 50 degrees. The increasing low level moisture values,
and broad WAA regime, will favor a scattering of flat/fair weather
cumulus trapped beneath a subsidence inversion that will have become
established courtesy of an amplified longwave ridge now building
east toward the Appalachians.

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.

&&

.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
east.

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 /06Z FRIDAY THROUGH TUESDAY/...
As of 220 AM Friday...

A lingering continental (dry) air mass, deposited by strong high
pressure now drifting off the NC/VA coast, will result in continued
VFR conditions through the TAF period. Surface winds, in return flow
around the surface high, will become Sly to SSWly and increase into
the 8-13 kt range, strongest and with at least occasional gusts into
the upper teens kts at nrn TAF sites.

A warm front and influx of low level moisture will result in the
development of a scattering of flat cumulus, with bases around 4 k
ft, today.

Outlook: Patchy MVFR-IFR visibility restrictions in radiation fog
will be possible early Sat morning. Associated moisture may then
produce a few hour period of scattered to broken MVFR range cumulus
with diurnal heating mid-morning to midday Sat, especially at
Piedmont sites. Late night-early morning fog and/or stratus, then
MVFR range cloudiness as that moist layer is heated through midday
each day, will be possible through early next week. Otherwise, a
chance of showers and storms and sub-VFR conditions mainly at
Piedmont TAF sites will exist Sun, then again forecast area-wide on
Tue.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...MWS
LONG TERM...Smith
AVIATION...MWS



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