Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 210716

Area Forecast Discussion
National Weather Service Raleigh NC
315 AM EDT Mon Aug 21 2017

High pressure will bring dry and seasonably hot weather to the
region for the start of the work week. A strong cold front will bring
increasing rain chances for the middle of the week, then move
east and off the coast by Friday, with cooler drier weather in its


As of 230 AM Monday...

Anchored by a 594DM upper-level anticyclone, central NC will sit
under the influence of deep layer ridging on Monday, which is a good
thing in terms of limited cloud cover across central NC as the solar
eclipse viewing party commences this afternoon.

The lack of forcing along with warm dry aloft will continue to limit
rain chances, with the better chances on our eastern and western
flanks, in vicinity of the sea breeze near the coast and along the
terrain induced differential heating over the mtns/fthls.

Highs in the lower 90s. Lows 70 to 75.


As of 230 AM Monday...

Heights aloft fall slightly on Tuesday with the approach of the
northern stream trough and attendant cold front into the Ohio and Tn
Valleys late Tuesday/Tuesday night. While we do see the development
of pre-frontal sfc trough in the lee of the mountains Tuesday
afternoon, central NC remains in a void of appreciable synoptic
scale lift. And as such, convective rain chances should remain
rather low and generally confined across the far SE zones in the
vicinity of the sea breeze and across the western part of the state
along the pre-frontal trough. One minor caveat that needs to be
mentioned is a sheared vorticity centered that`s currently off the
SE coast.
If this feature can hold together as it moves westward over the SE
states, where it will encounter the upper level anticyclone, DPVA
from this feature could serve to support slightly higher/better rain
chances across the southern zones. Will continue monitor will only
slight chance pops for now.

Loss of daytime heating should Tuesday evening should lead to dry
conditions overnight as the cold front doesn`t`t arrive from the NW
until late Wednesday afternoon.

Highs in the lower 90s with lows in the lower to mid 70s.


As of 315 AM Monday...

A rather strong cold front will progress slowly southeast and across
central NC Wednesday through Thursday night, perhaps stalling along
the coast as high pressure builds south down the Atlantic coast
behind the front. Convection will be on the increase by Wednesday
afternoon in the northwest as the front pulls out of the mountains,
with highest probabilities for precipitation (60%-ish) from
Wednesday evening in the west through Thursday morning east of I95.
At this early juncture, seeing mixed signals in the potential for
severe convection. The strongest low level forcing looks to lag the
best diurnal instability, and while there will be good directional
shear in the low level winds, it will be offset by weak wind speeds
(i.e. ~20Kt at H85). Meanwhile, upper diffluence will be fairly
strong, as the entrance region of an 80KT upper jet pulls off the
mid Atlantic coast. Highs Wednesday will have time to reach the
lower 90s in the south, while cloudiness and PM cool air advection
will halt the diurnal cycle in the upper 80s across the north and
northwest. Will have only slight chances lingering in the west
Thursday morning, with PoPs in the east tapering off to slight
chance early Thursday night. Thursday`s highs will cooler with lower
humidity as high pressure builds in from the north...mostly lower
80s. Friday through the weekend will be below normal and dry, with
highs from around 80 across the north to mid 80s across the far


As of 127 AM Monday...

Will follow persistence forecast with fog/stratus expected again at
eastern terminals(KRWI and KFAY) between 06 to 12z, where higher sfc
dewpoints in the mid 70s continue to reside. There is a bit more
high level cloudiness than last night, which that could impede dense
fog development. For now will carry IFR at KFAY and LIFR at fog-prone
KRWI. Some marginal MVFR ground fog is also possible at KRDU.

Any fog/stratus should lift between 12 to 14z, with generally dry
VFR conditions for the afternoon and evening.

Outlook: Diurnal showers and thunderstorms as well as morning
fog/low stratus return for Tuesday. A cold front will move through
the area Wednesday and settle near the coast on Thursday providing
an opportunity for adverse conditions during this time period before
returning to VFR for the end of the week and into the weekend.




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