FXUS62 KRAH 161935

Area Forecast Discussion
National Weather Service Raleigh NC
335 PM EDT Wed Aug 16 2017

A surface trough will extend along the North Carolina coast
southwestward into central South Carolina and Georgia through
Thursday. A back door cold front will approach the region on
Thursday before another cold front approaches from the northwest
on Friday and moves into the region on Saturday.

As of 250 PM Wednesday...

The early afternoon surface analysis shows a surface trough
extending northeast to southwest along the NC coast and then
laying across central SC and GA. A cold front extended from near
Washington DC westward to the Ohio river valley. The air mass
across northern portions of the area has dried out a bit with
dew points in the upper 60s to lower 70s near the VA border
while it remained very humid across the Sandhills and southern
Coastal Plain with dew points in the mid to upper 70s (dew point
was 79 at KGSB at 18Z). GOES-16 satellite imagery shows a
growing cumulus field in an arc from the Triad south across the
western Piedmont and Yadkin valley into the Sandhills. Doppler
radar is showing a couple of isolated showers in the northwest
and southern Piedmont an in a region of enhanced instability
and convergence.

Convection allowing models are consistent in highlighting the
western and southern periphery of the RAH CWA for isolated to
widely scattered showers and thunderstorms this afternoon and
evening with little to no convection from Raleigh northeast. The
convection will drift slowly southeast and should wane by mid
evening with little to no convection overnight. Another period
of late night and early morning fog and stratus is expected to
develop across the northern and central Coastal Plain and the
northeast Piedmont. Lows tonight will range in the lower to mid
70s. -Blaes


As of 300 PM Wednesday...

A short wave ridge axis over the Carolinas on Thursday morning
will give way to decreasing heights and an increasing
southwesterly flow on Thursday night. An increasing southerly
flow will develop allowing a recovery of moisture with
precipitable water values climbing back to between 2.0 to 2.25
inches by Thursday evening. While the forcing for ascent is
modest, the return of warm advection and increasing moisture
should result in an uptick in showers and thunderstorms over
today. After a period of morning stratus in the Coastal Plain
and northeast Piedmont, expect variably cloudy skies. Low-level
thickness values increase a few meters supporting highs between
89 to 94 with lows in the lower to mid 70s. -Blaes


As of 335 PM Wednesday...

The cold front that`s currently moving across the Central Plains is
progged to move across the Appalachians early Friday and across
central NC late Friday or Friday evening.  This feature and its
assoc upper short wave trough will provide the support for scattered
showers/tstms Friday and Friday evening.  Like fronts often do this
time of year when the upper trough pulls out, Friday night`s front
will slow down and stall across eastern NC overnight into Saturday
morning, and prolong the chance for scattered showers/tstms from
about I-95 eastward. Locations west of Raleigh to the Triad should
remain dry most of the daytime Saturday.  Then another short wave
trough and it`s cold front will move across the Mid Atlantic and
Carolinas Saturday night into Sunday morning, thus additional wdly
sct showers are possible during that time.  Given the fast flow to
our north, the short wave will exit to our northeast while leaving
the sfc cold front stalled across the Carolinas late Sunday into
Monday morning, before the front dissipates later Monday.
Unfortunately, this may set the stage additional showers on Monday,
and with a fair amount of cloudiness around, possibly obscuring the
partial eclipse Monday afternoon.  I wouldn`t give up hope just yet
for seeing the partial eclipse here in central NC, as there is a
fair amount of disagreement among models regarding how far south the
front will stall, and thus where the best chance for clouds and
showers will be.  Stay tuned!

At or above-climo rain chances will continue Tue and Wed thanks to
cyclonic flow and a series of short waves crossing the region. Temps
during the long term period at or above normal.


As of 235 PM Wednesday...

The 24 hour TAF period...widespread VFR conditions early this
afternoon will give way to isolated to widely scattered showers and
storms with local restrictions across the western and southern
portions of the RAH CWA. SCT-BKN cumulus has developed and expanded
in an arc from the Triad south across the western Piedmont and
Yadkin valley into the Sandhills in a region of enhanced instability
and convergence. Expect isolated to scattered showers and
thunderstorms to develop in this region during the mid afternoon
hours and continue into the early evening before dissipating during
the mid to late evening. The greatest chances of convection will be
at the KINT and KGSO terminals with a small threat of a shower at
the KFAY terminal and no precipitation expected at KRDU and KRWI.

Another round of late night stratus and fog is expected to develop
overnight, primarily across the Coastal Plain and the northeast
Piedmont/Sandhills. IFR restrictions are likely to develop in most
locations by the predawn hours with a period of LIFR conditions in
fog and stratus possible across the northern Coastal Plain at KRWI.
Local restrictions will improve during the mid morning hours on
Thursday before scattered showers and storms redevelop toward
early afternoon.

Looking further ahead...A cold front will approach the region on
Thursday into Friday and then settle across the area on Sunday into
Monday. This result in an increase shower and thunderstorms,
primarily during the afternoon and evening on Thursday into Saturday
with a decrease in adverse aviation conditions on Sunday into
Monday. -Blaes





NWS RAH Office Area Forecast Discussion