Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 271912
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
310 PM EDT Tue Jun 27 2017

.SYNOPSIS...
A moisture-starved cold front will exit central NC this evening.
Canadian high pressure will follow and extend over the Carolinas and
southern Virginia Wednesday and Wednesday night.

&&

.NEAR TERM /Through Tonight/...
As of 310 PM EDT Tuesday...

During the mid-late afternoon, a threat for isolated showers and
possibly thunderstorm will exists across roughly the eastern half of
the forecast area as a mid level s/w approaches from the west. While
moisture is limited through the atmosphere, lift associated with
height falls of 30-40m, and slight low level instability may be
sufficient to trigger isolated convection between 19Z-23Z.

The mid level s/w will exit central NC early this evening.
Subsidence in the wake of this feature along with a north-northwest
low level flow will aid to diminish the cloud coverage. Mostly clear
skies should rule overnight. Canadian high pressure will build into
the region. the air mass associated within the high is notably
cooler and drier. This drier cooler air mass and a near calm sfc
regime at the surface should allow temperatures to drop into the 50s
overnight across the Piedmont, and near 60-lower 60s across the
Sandhills and southern coastal plain.

&&

.SHORT TERM /Wednesday and Wednesday night/...
As of 310 PM EDT Tuesday...

An area of high pressure at the surface coupled with rising heights
aloft translates to dry and pleasant conditions for Wednesday and
Wednesday night. The sfc high will deposit a dry air mass over
central NC, maintaining dewpoints int the 50s. After the seasonably
cool start, afternoon temperatures will rebound into the low-mid
80s.

The center of the high will drift offshore by early Thursday
evening, initiating a return sly flow across the NC Piedmont. Thus,
dewpoints will start to inch upward indicative of the return of low
level moisture. Still, under mostly clear skies, overnight
temperatures will remain comfortable for this time of year,
generally near 60-lower 60s.

&&

.LONG TERM /Thursday through Tuesday/...
As of 300 PM EDT Tuesday...

A subtle upper level low in vicinity of the TX gulf coast this
afternoon is progged to meander slowly NE into the Deep South on Thu
before deamplifying/lifting NE across portions of the Carolinas on
Fri. Expect dry conditions to persist on Thu, followed by an
increasing potential for convection Fri afternoon/evening as the
deamplifying upper wave lifts NE across the Carolinas and southerly
return flow strengthens (temps/moisture rebound toward climatology).
Cyclonic flow aloft will strengthen over the eastern US this weekend
as a potent upper level low (currently in Alberta) digs SE into the
Great Lakes (Sat) and lifts NE across New England (Sun). Broad
troughing aloft will suppress/confine the sub-tropical ridge to the
FL peninsula and aid in the development/maintenance of a pronounced
surface trough east of the Appalachians over the weekend. With the
above in mind, expect above normal chances for convection and near
normal temperatures Sat/Sun. Forecast confidence decreases early
next week. Several MCS`s are expected to develop upstream of the
region Mon/Tue as shortwave energy in NW flow aloft progresses from
the Rockies into the Central Plains/Central MS River Valley. In
general, temperatures are expected to increase as flow aloft over
the Mid-Atlantic weakens/flattens and the previously suppressed sub-
tropical ridge expands northward from FL into the Deep South/
Southeast, and the relative best potential for convection should
shift along/east of the Hwy 1 corridor, though coverage/timing may
ultimately depend on the evolution of upstream MCS`s. -Vincent

&&

.AVIATION /18Z Tuesday through Sunday/...
As of 110 PM EDT Tuesday...

VFR parameters expected across central NC through Thursday.

An upper level disturbance and attendant sfc front will cross
central NC this afternoon, and exit our region early this evening.
This weather feature will cause an increase in mid/upper level
cloudiness, along with a threat for isolated showers and possibly a
thunderstorm. The convective threat appears highest along and east
of highway 1. Even so, with coverage expected to be no worse than
isolated, threat appears too minimal to include in the aerodrome
forecast for KFAY and KRWI.

Clouds will decrease this evening with mostly clear skies
anticipated overnight, persisting Wednesday through early Thursday.
An increasing sly low level flow late Thursday into Thursday night
will usher moisture into our region, leading to the probability of
low cloud cover by early Friday morning. These low clouds, if they
occur, should burn off by mid morning. A persistent low level sly
flow is expected Friday through Sunday, leading to an increasingly
wet atmosphere and increased chances for sub-VFR parameters. This
will lead to periods of low clouds and patchy fog each morning and a
chance for scattered afternoon-evening convection each day.

&&

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

&&

$$

SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...WSS
LONG TERM...Vincent
AVIATION...WSS



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