Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 221837
Area Forecast Discussion
National Weather Service Raleigh NC
237 PM EDT Sun MAY 22 2016
.SYNOPSIS...A strong upper-level low pressure area will settle over
the area today through Monday, producing unsettled weather. Warmer
and drier weather will follow from Tuesday through late week as the
upper low moves offshore and high pressure builds across the area.
.NEAR TERM /through tonight/...
As of 1045 AM Sunday...
Little change required to the near term forecast.
12z upper air analysis depicts strong cyclonic flow over central NC
with an upper level low positioned over the northern Mid-Atlantic
states. Around this low are a series of vort axes, one which is
crossing our region late this morning, triggering a band of
scattered rain showers across the northern piedmont. This mid level
feature will continue to drift to the east-southeast, triggering
additional shower development in the coastal plain and eastern
piedmont this afternoon. While the western piedmont will see little
if any showers through mid afternoon, shower activity expected to
increase late this afternoon, and more so this evening, as another
vort axis approaches from the north.
While instability is marginal and conditional, went ahead and added
the mention of an isolated thunderstorm for this afternoon. The
highest threat for thunder will be along and east of highway 1.
Cloud cover expected to remain abundant this afternoon. This, along
with scattered showers in the east, will hold temperatures down
several degrees from normal high temps for late May. Max temps this
afternoon should vary from around 70 north to the low-mid 70s south.
Tonight, the approach and passage of the next vort axis will
maintain a few showers across the region. The upper level low will
drift south and settle overhead by early Monday. The pool of cooler
air aloft will transfer to the south, resulting in overnight temps
about 5 degrees cooler than last night. Min temps by early Monday
should range from around 50 across the far north-northwest to the
low-mid 50s south.
.SHORT TERM /Monday and Monday Night/...
As of 310 AM Sunday...
The mid/upr closed low will continue to be the main player in our
weather as it slowly moves from NE NC in the morning eastward and
offshore by evening. Despite the mid-level cooling on the back side
of the low, forecast soundings indicate only modest instability.
Nevertheless, there should be enough mid/upr energy assoc with vort
maxes rotating around the low to provide adequate support for
scattered afternoon and early evening showers. Worth noting that
these showers should be fairly brief with limited rainfall. Thanks
to the ongoing northerly flow, below normal temps will continue.
Highs from around 70 north to mid 70s s/sw. Lows monday night in the
.LONG TERM /Tuesday through Sunday/...
-- Changed Discussion --As of 235 PM Sunday...
Conditions are expected to dry out on Tuesday as the upper low pulls
further away and shortwave ridging builds over the region. As the
low pulls away, the building ridge will keep the main storm track to
our north and west, resulting in mostly dry conditions through the
majority of the long term period. There are indications that the
ridge may weaken some towards the end of the forecast period,
allowing an uptick in mostly diurnal type convection. However, given
the model disagreement (the GFS, which is known the break ridges
down too quickly, breaks down the ridge, while the ECMWF holds
strong), will just show a little increase in cloud cover and will
bring in a slight chance of precip at the very end of the forecast
period. Otherwise, temps will gradually warm up to above normal,
from mostly lower 80s on Tuesday to mid/upper 80s for the remainder
of the period.
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.AVIATION /18Z Sunday through Friday/...
As of 135 pm Sunday...
Ceilings varying between MVFR and low end VFR will persist across
central NC through Monday as an upper level low drifts southward
from the northern Mid-Atlantic to a position over southern
Virginia/central NC by Monday. Bands of scattered showers will pivot
around this mid/upper level feature, though occurrence at any of the
TAF sites is small. These conditions expected to persist through
Aviation conditions expected to improve by Tuesday as the upper
level low pulls northeast away from our region. A drier air mass
will overspread central NC, leading to a period of vfr through the
rest of the work week.