-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 180056
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
853 PM EDT Thu Aug 17 2017

.SYNOPSIS...
A trough of low pressure at the surface will extend across the
Piedmont of Virginia south into the Carolinas through Friday. A cold
front will move across the area from the west late Friday into
Saturday and then stall along the Carolina coast on Sunday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 705 PM Thursday...

Scattered convection has helped to lower temperatures in the upper
70s and 80s, mainly across sections of the coastal plain and
Sandhills. Across the western Piedmont, where the convection has
been limited, temperatures this evening will gradually lower through
the mid-upper 80s.

The bulk of the convection has dissipated and this trend will
continue through the evening. A band of convection currently exiting
the foothills, may advance as far east as the Yadkin River west of
Lexington, before dissipating.

The humid air mass will result in overnight temperatures in the mid-
upper 70s. Little adjustment required to the near term forecast.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
As of 345 PM Thursday...

Short wave ridging across the Carolinas will give way to falling
heights as a short wave trough dives from the upper Midwest
into the Ohio Valley by late friday night. The associated cold
front will approach the southern Appalachians friday morning
and then move across central NC Friday night reaching the
coastal region of the Carolinas on Saturday morning. Another
convectively active day is expected on Friday with widely
scattered showers and storms expected to develop around midday,
especially across the eastern Piedmont and Coastal Plain. Some
of the higher resolution convection allowing models suggest that
the majority of the convection will be attendant to the surface
front and will move into the RAH CWA from the west late in the
afternoon and then move southeast across the area during the
evening.

It will remain humid on Friday with dew points in the lower to
mid 70s which combined with highs of 89 to 95 will result in
heat index values of 100-105. Dew points today over performed
and were in the upper 70s across the Coastal Plain and if that
occurs again, a heat advisory would be needed. Will hold off for
now and defer to the mid shift to issue any headlines.
-Blaes
&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 341 PM Thursday...

A short wave trough axis will cross the area during the day and
evening Saturday, thus a few scattered showers may reform along the
stalled front near the coast...so best chance for rain on Saturday
and Saturday evening will be east of I-95. Any showers over our area
should end shortly after sunset with dry conditions Saturday night.

Sunday looks mostly dry as ridging aloft to our south begins to
build northward over our area.  Then for Monday, the forecast has
been trending better the past few model runs, regarding cloud
coverage and rain chances, although we`re keeping an eye on the weak
short wave in the westerly flow aloft, which both the GFS and ECMWF
suggest will pass by mostly to our north, but heights over us do
trend down during the day.  For now will hold cloud coverage around
50% with PoPs slightly below climo...20-30% during the afternoon
Monday.

The pattern for the rest of the long term period will feature a
deepening through over the East, so look for mostly diurnal chance
PoPs each day Tue-Thu.

Temps Sat-Mon will run a couple degrees above normal with a building
ridge, then falling back to or below normal mid-late next week with
the deepening trough.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
As of 840 PM Thursday...

24 Hour TAF Period: VFR conditions are generally expected to
continue this evening, with a small chance of a shower and/or storm
at KGSO/KINT. Another rounds of sub-VFR fog and/or stratus (low end
MVFR to IFR/LIFR) is again expected across eastern portions of the
area early Friday morning, possibly lingering until mid morning.

A cold front will approach the area from the west Friday, with an
associated band of showers and storms expected to move into the
region late in the day. Thus, have included mention of storms at
KGSO/KINT late in the day (from 20Z onward in a prob30 group).
Further east we may see showers and storms initially develop along a
surface trough located across eastern portions of central NC during
the early to mid afternoon, before another round of storms
potentially affects eastern portions of the area on Friday
evening/early Saturday morning.

Outlook: The aforementioned cold front will shift southeast on
Saturday and Sunday with any isolated to scattered diurnal
convection expected to generally be south and east of the area
(with a small chance at KFAY each day).
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...BLAES
NEAR TERM...WSS
SHORT TERM...BLAES
LONG TERM...NP
AVIATION...BSD/BLAES