Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KRAH 191522 RRA
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1115 AM EDT Sat Aug 19 2017

.SYNOPSIS...
A weak cold front will move into the Piedmont this morning and will
push slowly east across the Coastal Plain this afternoon before
sagging just south of the area tonight and Sunday. Another front
will approach the area on Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1115 AM Saturday...

The latest surface analysis shows the cold front moving east into the
eastern Piedmont and approaching the Coastal Plain. Behind the front,
surface dew points have fallen into the upper 60s across the
northwestern Piedmont and around 70 in the northeast Piedmont.
Further aloft, the 925 hPa trough was located near the I-95 region
while a the 850/700 hPa trough lagged and was located in the western
Piedmont. A prominent short wave trough at 500 hPa was moving across
the OH and TN valleys this morning. Deep layer moisture across the
region has decreased with precipitable water values ranging from 1.2
inches across the western Piedmont to 1.7 inches across the Coastal
Plain.

One of the main forecast concerns for the afternoon and this evening
is the potential for scattered convection ahead of the front across
the southern and central Coastal Plain and the Sandhills. While the
atmosphere has become drier, the air mass ahead of the front will
become weakly to moderately unstable this afternoon with eastward
extent. The placement of the front and the localized convergence
will dictate the the location of convection. Still fairly
confident that any convection today will be confined to the eastern
part of the CWA, east and especially southeast of I-95 with the
greatest chances across Wayne, Sampson, and Cumberland counties. Any
deep convection should largely dissipate by around sunset with a
shower or too linger into the evening hours. Still, coverage will be
limited, so no washouts are expected with PoPs ranging from 20-30%.
While the wind field is notably stronger than previous days, winds
are generally unidirectional from the southwest with the stronger
flow well above the mixed layer. Thus, the threat of any severe
weather is limited and should be confined to locations near and east
of the front.

The other issue this afternoon will be the temperatures and the heat
index. Dew points this morning once again over performed and
exceeded guidance with several stations reporting dew points of 78
and 79. With drier air aloft and drier air at the surface advecting
into the region on northerly to northwesterly winds, dew points will
come down this afternoon into the lower to mid 70s. This should
preclude any need for a heat advisory although heat index values
will reach 100 to 104 in spots and have added this to the HWO. Have
adjusted maxes up a degree or two in the east with highs of 90 to 95
expected. Drier air tonight, especially across the Piedmont with dew
points in the mid to upper 60s will result in a much less muggy
night. Overnight lows will range from the upper 60s in the
northwest Piedmont to the lower 70s in the Coastal Plain. -Blaes
&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 315 AM Saturday...

Heights aloft will rise in the wake of the low-amplitude shortwave
trough moving out of the region with a 594 dm upper level
anticyclone strengthening over the SE US late Sunday into Monday.
Meanwhile, front just south of the area will likely wash-out and
become ill-define by Sunday evening. Can`t rule out isolated
convection along the sea breeze across the far SE Zones, otherwise
the warm air and resultant CAP aloft will put a lid on convection
across central NC on Sunday.

Highs in the lower to mid 90s with lingering low-level dry air again
keeping heat indices below 100 F. Onset of southerly return flow
Sunday night will mark the return of low-level moisture and warmer
temps. Lows 70 to 75.

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 244 PM Friday...

Monday: As continental high pressure begins to merge with an
offshore surface high the question for Monday will be how much
moisture is in the weak southerly return flow and what will that
result in as far as cloud cover for the eclipse viewing. Partly
cloudy skies look likely but there should be enough breaks in the
clouds to get a decent view of the moon passing between us and our
closest star situated some 93,000,000 miles away. While temperatures
are expected to rise into the lower 90s there will be a break in the
heat from roughly 1:30 to 3:30 PM. A scattered shower or
thunderstorm cant be ruled out, especially in the southern tier of
the area.

Rest of the week: Relative dry but warm weather continues through
Tuesday before the next frontal system passes through the area on
Wednesday in association with a low pressure system moving across
southern Canada. High rain chances Wednesday will continue through
Thursday in the east and possibly into Friday as the front begins to
stall near the coast. Temperatures in the low 90s Tuesday and
Wednesday will fall back into the mid 80s for Thursday and maybe
into the low 80s by Friday. With that, some dewpoints in the lower
60s should make for some very comfortable weather heading into the
weekend.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
As of 725 AM Saturday...

The cold front has just moved through KINT and will push slowly east
across the NC coastal plain by the afternoon. As such, isolated to
widely scattered showers and storms will be possible at KFAY this
afternoon. Otherwise, dry air filtering into the area in the wake of
the front will result in dry VFR conditions Saturday
afternoon/evening.

Outlook: VFR conditions are expected Saturday night and Sunday with
dry weather expected. The threat of late-day storms and some early-
morning fog and stratus will return Tuesday with numerous showers
and storms expected to accompany a cold frontal passage
Wednesday/Wednesday night.

&&

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

&&

$$
SYNOPSIS...CBL
NEAR TERM...Blaes
SHORT TERM...CBL
LONG TERM...ELLIS
AVIATION...CBL



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.