Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 302320
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
720 PM EDT Sun Apr 30 2017

.SYNOPSIS...
Bermuda high pressure will extend across the Southeastern states
today. A cold front will approach the Appalachians tonight, then
cross the region late Monday afternoon through Monday evening. Warm
high pressure will build in from the southwest Tuesday through
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Sunday...

Latest analysis shows a ridge off the SE coast and a closed trough
over the middle of the country. S-SE flow over our area and moist BL
has promoted shallow to moderate cu in the unstable BL. A few
isolated showers have developed to our south and are current moving
across SC border and into our southern zones. The HRRR and other
CAMs have picked up on this and they show these isolated showers
moving north across mainly our piedmont zones through the rest of
the afternoon and dissipating by evening.  Have updated the grids to
include a 20 pop across most of our CWA south and west of the
Triangle for the rest of this afternoon.

For tonight, the trough over the Plains will lift slowly newd. As
this system approaches, look for the pres gradient to tighten across
our area, resulting in breezy s-sw winds. This will also maintain a
warm moist BL, which when combined with the aforementioned winds,
should result in sct-bkn low clouds.  Lows in the mid 60s.

&&

.SHORT TERM /Monday and Monday night/...
As of 300 PM Sunday...

The closed mid level trough over the Midwest Monday morning will
move NE across the Great Lakes during this period. It`s assoc cold
front will cross our region late in the day Monday and at night. A
pre-frontal band of showers and thunderstorms is expected to move
across central NC Monday afternoon and evening.  Isolated severe
thunderstorms will be possible as this band moves across, thanks to
a moist unstable airmass over our area (characterized by ML cape 600-
1000 J/kg) coupled with 40+ kt of 0-6km bulk shear.  It`s worth
noting that several CAMs indicate an earlier band of showers and
tstms moving up from GA and SC and across our western zones during
the morning hours.  That early activity, and assoc cloud cover,
could impact the evolution of later storms, so we`ll have to watch
that closely.  In any event, have brought pops in early (during the
morning hours) across our western zones to account for the potential
for this earlier activity, then likely pops across all of central NC
during the afternoon and evening.  Right now, it appears that the
bulk of showers and storms should be east of highway 1 by 03Z, and
exit the coastal plain counties of central NC by 06Z-08Z.

Otherwise, with a tight pres gradient in place ahead of the front,
look for breezy s-sw winds ahead of the front during the day Monday
with non-thunderstorm gusts up to 25-30 mph.  Highs will range from
around 80 across the Triad to mid 80s across the Coastal Plain, and
will be largely dependent on early-day rain chance and resulting
clouds. Cooler Monday night behind the front - lows from the mid 50s
Triad to low 60s Coastal Plain.

&&

.LONG TERM /Tuesday through Sunday/...
As of 305 PM Saturday...

More changes in the last 24 hours for the long term forecast as
models are getting a better handle on a progressive longwave trough
that will move across the CONUS this week and cause some problems by
the end of the work week. Yesterday at this time models showed the
trough moving slowly across the deep south and producing a cutoff
low which was going to keep the threat for showers and storms around
though the weekend. It also showed two surface low pressure systems
developing that would have lingered across the Carolinas for days.
Now models are hinting at one surface low pressure system that is
more progressive and spurred on by the developing upper low that
never slows down across the deep south. This will cause the primary
window for showers and storms to be Thursday night through Friday
night with a cold front crossing central North Carolina. The front
moves through by the weekend and aside from a few shortwaves moving
around the upper low behind the front, the weekend should be drier
and cooler.

Aside from this system later in the period, expect mainly dry
conditions with high temperatures in the upper 70s to lower 80s
prior to frontal passage on Friday when temperatures will dip back
into the mid 60s to lower 70s for Friday and Saturday before
rebounding back into the low 70s everywhere for Sunday.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 720 PM Sunday...

24-HR TAF Period: Southerly flow will strengthen tonight as the MSLP
gradient tightens from the west, in advance of an approaching cold
front. Expect MVFR/IFR ceilings to develop after midnight in assoc/w
low-level warm advection. Ceilings are expected to gradually improve
to MVFR/VFR by noon as mixing deepens and southerly flow further
strengthens to 15G25KT by mid afternoon (20G30KT by late afternoon
at eastern terminals). A line of showers and thunderstorms
along/ahead of the approaching cold front is expected to cross
central NC from west to east late Monday aft/eve, near the end of
the 00Z TAF period. Surface wind gusts as high as 40-50KT will be
possible in association with the aforementioned line of convection.

Looking Ahead: VFR conditions will return in the wake of the cold
frontal passage late Mon night and persist through mid-day Thu.
Widespread adverse aviation conditions are expected in assoc/w a
potent storm system progged to affect the Carolinas late Thu through
mid-day Friday. -Vincent

&&

.Climate...

Daily Record High Minimum Temperatures

May 1 /
Greensboro... 65 (2012)
Raleigh.......67 (2012)

The all time April Monthly Record High Minimum Temperatures

Greensboro... 68 set April 14, 1912 - then tied on April 23, 1920
and April 27, 2011.

Raleigh.......71 set on April 14, 1922 - then tied on April 25,
1925.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...np
SHORT TERM...np
LONG TERM...Ellis
AVIATION...Vincent
CLIMATE...Badgett



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