Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 212316
Area Forecast Discussion
National Weather Service Raleigh NC
716 PM EDT SAT MAY 21 2016
.SYNOPSIS...Deepening low lifting up the mid Atlantic coast will drag
a surface front and attendant second wave across the area this
evening. A strong upper level low pressure area will swing over the
region tonight through Monday, bringing continued unsettled weather.
.NEAR TERM /through tonight/...
As of 330 PM Saturday...
Closed upper low and attendant mid/upper level trough over the Ohio
and Tn Valleys will intensify as it moves slowly southeastward over
the region. At the surface, deepening low lifting up the mid
Atlantic coast will drag a surface front through the area this
evening. In response to the upper trough moving into the region, a
secondary wave of weak low pressure will develop along the front
this evening and will move off the southern NC coast Sunday morning.
DPVA, H5 falls on the order of 60 meters, and weak sfc moisture
convergence along the sfc wave tracking south of Highway 64 will
support scattered showers tracking west to east this evening and
through the overnight hours, with a few thunderstorms possible this
afternoon and early evening as scouring out of low-cloud deck has
allowed for sufficient insolation to support weak destabilization
(500-1000 SBCAPE). While weak instability will limit storm severity,
good deep layer bulk shear of 40-50 kts this afternoon/evening could
still support an isolated severe thunderstorm capable of producing
strong wind gusts and small hail.
lows overnight in the mid 50s NW to lower 60 se.
.SHORT TERM /Sunday and Sunday Night/...
As of 330 PM Saturday...
Unsettled weather will continue on Sunday as a deep upper low, 2 to
3 SD below normal, becomes centered over northeastern NC by Sunday
night. DCVA and steepening mid-level lapse rates coincident with
peak but tempered daytime heating will support scattered showers.
Expect highest POPS invof of the upper level core and deepest
moisture across the NE coastal plain/piedmont.
Temperatures will continue to run below normal underneath the
anomalous negative height anomalies. Highs ranging from upper
60s/near 70 northeast to mid 70s southwest.
.LONG TERM /Monday through Saturday/...
As of 230 PM Saturday...
Monday and Monday night: To start the day off on Monday, a closed
upper low is progged to be over northeast NC and it will make its
way eastward/northeastward throughout the day. As such, shower
chances will continue, but will likely stay confined to the
northeast half of the forecast area. Any precip is expected to come
to an end Monday night as the upper low slowly pulls away from the
region. Temps will remain below normal given the proximity of the
upper low and associated cloud cover/precip, with highs expected to
be in the lower 70s across the northeast and the mid/upper 70s
further to the southwest. Overnight lows should fall into the mid
Tuesday through Saturday: Conditions should dry out by Tuesday as
the upper low pulls further away and shortwave ridging builds over
the region. However, one model is now showing one last piece of
energy rounding the backside of the departing upper low and
triggering some precip across the northeast. Given the lack of other
model support, have kept the forecast dry for now but will keep a
close eye on it. Otherwise, the ridge that will build in, will keep
the main storm track to our north, resulting in mostly dry
conditions through the end of the week. 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, there
is some disagreement among the models with regard to this and
therefore, will just show an increase in clouds and bring in a
slight chance of precip. Temps will gradually moderate through this
time frame, from mostly lower 80s on Tuesday to mid/upper 80s by for
the remainder of the period.
.AVIATION /18Z Saturday through Thursday/...
-- Changed Discussion --As of 715 PM Saturday...
24 hour TAF period: A cluster of showers and thunderstorms will move
east through the area between 00z-06z, resulting in local IFR
conditions. Model guidance suggests the re-development of low
clouds/stratus and possibly some fog between 06 to 12z, especially
across central and eastern terminals(KRDU,KFAY,KRWI). Drier air
advecting into the area behind the a surface front is expected to
preclude stratus development at KINT and KGSO.
The low ceilings/stratus across central and eastern areas will be
slow to lift through the day on Sunday morning, with the potential
for MVFR ceilings to persist at eastern/northeastern NC(KRDU and
KRWI)until late in the afternoon. Meanwhile...western and southern
most terminals could see VFR conditions return by mid morning. A
deep upper low moving over the region will bring scattered showers
across the area on Sunday, with greatest coverage expected across
the east/northeast invof of the upper low.
Beyond 00z Monday: The risk for sub-VFR conditions with scattered
showers will continue through at least mid-day Monday as a closed
low gradually moves south across eastern NC. VFR conditions expected
to return by Tuesday and remain for the mid-week period as the
closed low moves east and short wave ridging moves over our region.
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