Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Raleigh NC
120 PM EDT Wednesday Jul 1 2015
beneath prevailing cyclonic flow aloft...a surface trough will
linger east of the central Appalachians through Thursday...prior to
the arrival of a cold front that will stall over the Middle Atlantic
States Thursday night through Sunday.
Near term /through tonight/...
as of 1035 am Wednesday...
Little adjustment required to near term forecast.
Middle-upper level trough over the area at 12z per upper air analysis.
This feature will slowly lift northeastward this afternoon-tonight. Weak
subsidence behind the trough as evident by 12z gso sounding should
keep the atmosphere relatively capped...inhibiting convective
development. After 21z-22z...isolated convection along the seabreeze
may threaten the far southern coastal plain while higher terrain
convection may drift eastward into the Yadkin River valley.
Still...coverage expected to be no worse than isolated.
Afternoon temperatures in the upper 80s-lower 90s still appear on target.
An approaching middle-upper level vorticity maximum and associated
shear axis projected to approach from the west-northwest late tonight
through early Thursday. This feature will enhance the cloud cover
over our region and sustain a few showers and isolated T-storms
overnight...especially across the western Piedmont. Have made minor
tweaks to probability of precipitation overnight into early Thursday based on latest trend of
rapid refresh model and 06z NAM/GFS.
Short term /Thursday and Thursday night/...
as of 257 am Wednesday...
Scattered to numerous thunderstorms are expected to develop Thursday
afternoon and last into the evening as strong surface heating
combines with steepening lapse rates and an approaching short wave
late in the day and Thursday evening. Frequent lightning and locally
damaging wind will again be the main weather hazards with these
storms. Highs generally in the upper 80s to lower 90s are expected.
Increasing flow in the middle levels by late in the day and into the
night favors convection to become more organized than is typically
expected during the Summer. Expect the thunderstorms to die off
overnight or during the early morning hours Friday as the short wave
trough pushes east. Lows 68-72.
Long term /Friday through Tuesday/...
as of 257 am Wednesday...
A continuation of the current highly amplified for early July
middle/upper level flow pattern is forecast to continue into next week.
The trough will remain over the Midwest and eastern states with the
upper ridge out west. Disturbances in the northwest flow pattern aloft will
occasionally send weakening cold fronts into our region. The typical
hot humid conditions will continue along with the occasionally
enhanced chance of strong to locally severe thunderstorms.
Aviation /18z Wednesday through Monday/...
as of 120 PM Wednesday...
There is a high likelihood that VFR conditions will occur across
central NC for the remainder of the afternoon into the evening
hours. Any convection that develops should be isolated. A slight
chance for a shower or storm will persist well into the night as an
upper disturbance approaches from the west.
This disturbance will contribute to an increase in clouds over
central NC late night through Thursday along with an increased
threat for scattered showers and storms...mainly Thursday afternoon
and Thursday night. Expect MVFR conditions in the vicinity of the
heavier showers and storms.
A stalled front over the region late Thursday through the weekend
will provide a focus for the development showers and thunderstorms.
In addition...plentiful moisture in the lower half of the atmosphere
will cause areas of stratus to develop late at night and persist
into the morning hours. The above scenario will lead to several
hours of MVFR or IFR ceilings each day Friday through Monday.