Scientific Forecaster Discussion
fxus62 krah 251430
Area forecast discussion
National Weather Service Raleigh NC
1030 am EDT sun Jun 25 2017
a cold front will push southeastward through central North Carolina,
weakening as it pushes to the coast later today. A second cold front
will sweep through the area on Tuesday, followed by high pressure
that will persist across the region through the rest of the
Near term /this afternoon and tonight/...
as of 1030 am EDT Sunday...
Main adjustment to the near term forecast was to adjust dewpoints
upward several degrees as drier air not advecting into central NC as
quickly as earlier thinking.
12z sfc and upper air analysis depict a low level trough and
attendant sfc front crossing central NC. Sf dewpoints have lowered
into the low-mid 60s across the NW Piedmont while dewpoints in the
low-mid 70s still apparent across the remainder of the region. While
the sfc front will exit our far eastern-southeast counties by early
afternoon, not until the passage of the 850mb trough around/after
18z will most of central NC start to see the dewpoints lower. West-
southwest flow aloft will continue to stream high level moisture
overhead, so even though the lower layers of the atmosphere will dry
out, high level cloudiness will still be evident. Thus expect skies
to be variably cloudy/partly sunny this afternoon. Temperatures o
track to reach the mid-upper 80s with places across the sandhills
and southern coastal plain reaching 90.
Isolated convection still probable along our eastern-se periphery
through late afternoon. Elsewhere a stable drier air mass should
inhibit convective development.
Tonight, west-NW flow will continue to usher in the drier air mass.
Thus it should be noticeably less humid. Skies will slowly clear,
with mostly clear skies regionwide by the overnight hours. Min temps
quite pleasant for early Summer, ranging from the upper 50s to
around 60 in the NW Piedmont to the mid 60s southeast.
A cold front stretches along the eastern fringe of the Piedmont
early this morning, accompanied by a few weakening showers. This
front will slow as it approaches the coast early this afternoon,
resulting in a small chance of showers in the southern coastal plain
and sandhills through late day. Northwest flow behind the front will
lead to a more stable airmass settling north of the front, but
cooler air will be delayed until tonight, so highs today will reach
the mid to upper 80s. Tonight, as skies clear with the drier airmass
in place, temperatures will fall to the upper 50s in the northwest
to mid 60s in the southeast.
Short term /Monday and Monday night/...
as of 345 am EDT Sunday...
Modestly cooler and drier air will be in place on Monday, making for
a pleasant day with mostly sunny skies and highs topping out in the
low to mid 80s. A dry, reinforcing cold front will dip southeast and
through the area Monday night as a long wave trof over the northeast
Continental U.S. Amplifies. Continued cool air advection and good radiational
conditions will allow mins to bottom out in the upper 50s to low
60s Tuesday morning.
Long term /Tuesday through Saturday/...
as of 325 am Sunday...
A longwave trough moving across the east during the beginning of the
long term period will cross the Carolinas late tues, pushing a cold
front offshore and ushering in high pressure along with a drier and
cooler airmass. Both the GFS and European model (ecmwf) suggest that a broken line
of showers and tstms may move across central NC tues afternoon as
the trough axis approaches and moves through, however the GFS keeps
most of this shower/tstm activity near the coast, while the European model (ecmwf)
suggests this possibility across central NC as well. For now, given
the uncertainty, will keep pops tues afternoon near climo (20-25%).
Dry weather can then be expected Wed-Fri as high pressure transits
the east. Temps will be near normal Wed as the high moves in and
while overhead, then look for temps and humidity to increase Thu and
Fri as the high moves offshore and S-SW low level flow resumes
across the Carolinas.
Southerly flow will further increase over the weekend in response to
a short wave moving across the Great Lakes region and a sfc front
approaching the Appalachians. With increases moisture and synop
scale forcing approaching, will bring rain chances back into the
forecast for the weekend, with highest rain chances west of the
Aviation /06z Sunday through Thursday/...
as of 145 am Sunday...
Cold front moving east across the area early this morning will be
accompanied by a few showers and a brief IFR threat at rdu/rwi, with
conditions extended through 12-14z at Fay as the front slows or
stalls across the southeast today. Otherwise, a brief predawn period
of IFR visibilities in fog are possible due to clearing skies and
high low level moisture. Northwest winds 6-8 knots will be prevalent
along with VFR conditions at all sites by 14z and continue through
the remainder of the taf period.
Looking beyond Sunday night, VFR conditions are likely to hold
through the upcoming work week. It will be overwhelmingly dry, with
only a few showers expected with passage of a reinforcing cold front
on Tue. -Gih