Area Forecast Discussion
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FXUS62 KRAH 270120
Area Forecast Discussion
National Weather Service Raleigh NC
845 PM EDT Sun Mar 26 2017
A surface high pressure area will extend from Bermuda westward into
the Carolin`s through Monday. A cold front will drift southward
across central NC late Tuesday and Tuesday night.
.NEAR TERM /THROUGH TONIGHT/...
As of 745 PM Sunday...
The band of light rain showers continued to move east across the
Piedmont and Sandhills this evening. Additional showers were
developing over western NC and eastern TN associated with the
weakening mid-upper level trough that was lifting out to the
north of our region. This feature and associated moisture band will
support the continuation of light showers into the Coastal Plain
this evening before diminishing. QPF will be very light, only a few
hundredths of an inch. Additional showers were developing upstream
into the Southern Appalachians and Tennessee Valley. Most model
solutions indicate the initial showers will continue to weaken, with
the focus expected to shift to the Foothills and NW Piedmont for
additional showers later. This activity is also expected to be
light, with QPF of a tenth to a quarter inch possible, especially
As for sky and temperature forecasts, the skies are expected to
remain mostly cloudy, except cloudy NW and partly cloudy SE. The
increase in low level moisture with dew points into the 50s suggests
that lower stratus are possible if not likely in the western
Piedmont later tonight. Lows generally in the 50s to near 60, with
the warmer readings in the west where the low level moisture and
clouds will be most prevalent.
.SHORT TERM /MONDAY THROUGH TUESDAY/...
As of 330 PM Sunday...
Monday, mid/upper level low over the southern Plains, opens up and
lifts into the mid MS Valley. A lead s/w ahead of this feature will
approach central NC late Monday. This feature will aid to back the
mid level flow, leading to moistening of the mid layers of the
atmosphere. This lead s/w will cross our region late Monday,
triggering scattered showers and t-storms. Convective parameters not
too shabby for end of March with MLCAPE off the GFS 750-1000 J/kg.
Effective bulk shear 20-25kts on the cusp of supporting organized
convective bands. While cannot rule out an isolated severe due to
hail, bulk of convection should remain below severe criteria.
Extensive cloud cover early Monday should give way to periods of
sun. The peeks of sun with near sfc flow out of the sw will boost
temperatures into the 75-80 degree range.
The lead s/w will exit our region late Monday night but will be
followed by the main mid-upper level trough by early Tuesday. This
will maintain a threat for scattered showers and a few thunderstorms
Monday night into Tuesday morning. By Tuesday afternoon, greatest
threat for scattered showers and a few storms will be along and east
of highway 1. Convective parameters by Tuesday afternoon may support
a locally strong or severe storm over the coastal plain and
sandhills as MLCAPE recovers to 1000 J/kg, with effective bulk shear
in the 30-35kt range.
A warm air mass will maintain above normal temperatures Monday night
and Tuesday. Overnight temps Monday night should be in the upper 50s
to near 60. Max temps Tuesday upper 70s to lower 80s. If cloud cover
remains extensive or shower coverage is greater than anticipated,
max temps Tuesday could end up being 4-5 degrees cooler.
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
As of 230 PM Sunday...
Wed-Wed Night: With a shortwave ridge aloft, expect mostly sunny to
partly cloudy skies with above normal highs in the mid/upper 70s.
Thu: High pressure is expected to extend southward into the
Carolinas Thu morning (in the form of a backdoor cold frontal
passage) in association with height/pressure rises in the wake of an
upper level low moving offshore New England into the Canadian
maritimes. With low-level NE flow emanating from the cool Labrador
current in NE portions of the state and an increased likelihood for
cloud cover in SW portions of the state, temps Thu afternoon could
be as much as 15-20F cooler than Wed afternoon. With the above in
mind, have decreased highs to the mid/upper 50s west to lower 60s
Thu night: Expect an increasing potential for rain from west-east
between midnight and sunrise Fri as an upper level low progresses
from the central MS river valley to the Ohio valley and low level
flow backs/strengthens downstream over the Carolinas and Mid-
Atlantic. Lows in the mid 40s to lower 50s, depending on rain
Fri-Fri Night: Confidence in the evolution of the aforementioned
upper level low, attendant sfc cyclone and associated warm/cold
fronts at this range is low to begin with, let alone when a CAD
wedge may be in place at the beginning of the period. All guidance
continues to indicate precipitation, thus have increased precip
chances to high likely (60-70%). From a pattern recognition
standpoint, a potential for severe weather cannot be ruled out,
however, little more can be said at this range in the forecast. The
temperature forecast on Fri/Fri night is challenging to say the
least. At this time will show the coolest temps in the Triad (highs
in the low 60s) and warmest temps in the Sandhills and SE Coastal
Plain (lower 70s). Expect clearing skies in the wake of a cold
frontal passage Fri night, with lows in the upper 40s to mid 50s.
Sat-Sun night: Expect a warming trend with dry conditions Sat in the
wake of the aforementioned upper level low progressing offshore the
Mid-Atlantic coast. A continued warming trend with dry conditions is
expected on Sun as a shortwave ridge aloft tracks into the region
from the west. -Vincent
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 840 PM Sunday...
24 Hour TAF Period: High pressure will remain offshore through
Monday, while an area of low pressure passes to the north of central
NC. This will allow for a few weak disturbances to track across the
area from time to time yielding some light showers (and perhaps a
thunderstorm or two on Monday afternoon). We may see some MVFR/IFR
stratus develop across the Piedmont (KGSO/KINT/KRDU) early Monday
morning, before lifting from mid/late morning into the afternoon
(lasting the longest at KGSO/KINT). Otherwise, expect a varying
degrees of cloudiness, with light and variable winds overnight again
becoming south to southwesterly on Monday after sunrise with a few
gusts possible during the afternoon into the mid to upper teens.
Outlook: A marginally moist and conditionally unstable air mass will
result in periods of MVFR ceilings across the region through
Wednesday. The lower ceilings will most likely occur between 10Z and
16Z. There is the possibility of a few showers and thunderstorms
again late Monday night through early Tuesday afternoon. Near the
heavier showers and storms, expect MVFR ceilings and MVFR/IFR
A cold front will drop southward through central NC Wednesday, then
stall to our south. The approach of an upper level low will increase
sly flow a few thousand feet above of the cool stable dome of air at
the surface, leading to widespread MVFR/IFR parameters due to low
clouds and areas of rain late Thursday into Friday.