Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 150207
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1007 PM EDT Tue Aug 14 2018

.SYNOPSIS...
A mid and upper level low will move east and offshore the southern
New England coast through early Wed. Ridging aloft will follow and
extend across the southeast and middle Atlantic states through Wed
night.

&&

.NEAR TERM /TONIGHT/...
As of 1000 PM Tuesday...

Mid-upr low centered over cntl NY this evening will move ewd and
offshore the srn New England coast through early Wed. A trough axis,
and embedded weak disturbance/perturbation stretching from n-cntl
SC/w-cntl NC nwwd across swrn VA/srn WV, will continue to dive sewd
across the Carolinas, into the longwave trough axis as it moves ewd
and offshore overnight. Upstream ridging aloft from the nwrn GOM
nnewd into the Great Lakes will otherwise migrate ewd to near and
just west of the Appalachians tonight, before then building across
the Carolinas on Wed.

At the surface, a lingering trough/frontal zone was analyzed at 01Z
from ern VA swwd across the cntl Carolinas and cntl GA, though the
earlier pronounced dewpoint discontinuity along the boundary has
become much less so in the past couple of hours owing to both
nocturnal surface dewpoint recovery and the inland retreat of the
sea breeze. This weak and increasingly ill-defined boundary will
remain quasi-stationary tonight. A lee trough was also analyzed in
the lee of the Appalachians in VA and NC, from near CHO to DAN to
HKY, just west of the aforementioned trough/front. Lastly, a
generally west to east-oriented outflow boundary and corridor of
isolated showers from the srn NC Piedmont enewd across the srn
Coastal Plain, to the Pamlico Sound has been quasi-stationary since
this afternoon; and it too should move little tonight.

As the perturbation aloft dives sewd, a slight chance of a shower or
storm will remain for the next few hours along both the outflow
boundary, which already includes a few isolated showers over Hoke,
Sampson, and Anson Co., and also over the wrn/nrn Piedmont, where an
area of persistent altocumulus (and convective pre-conditioning/
moistening) has lingered in the vicinity of the closely-spaced
surface troughs/front noted above. Indeed, a couple of very light
showers have also developed near DAN and MWK in the past 30 or so
mins. The latter activity should be shallower/weaker owing to the
presence of a subsidence inversion around 600 mb that was more
prominent on the GSO RAOB than that at MHX, and otherwise weaker
instability resulting from drier low levels west of front/trough.

It will otherwise be a fair to partly cloudy night, with lows
generally in the middle 60s to around 70 degrees. Persistence patchy
stratus and fog may again develop particularly near and east of the
front, roughly along US Highway 1, where moisture and convergence
will be maximized.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 346 PM Tuesday...

Rising heights aloft in the wake of the exiting upper trough across
the Mid-Atlantic States will spell drier and warmer conditions for
Wednesday. However, the inland retreat of the seabreeze into the
coastal plain counties, where better instability will exist, will
support a slight chance of  showers and storms during the
afternoon/early evening, before dissipating. Highs upper 80s to
lower 90s. Lows in the upper 60s to lower 70s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 246 PM Tuesday...

The long term period will generally feature broad cyclonic flow with
a series of short wave troughs moving across the region.  While the
daytime Thursday appears to be mostly dry given the transition with
a short wave ridge exiting to our east, the first in the series of
short wave troughs is expected to move across Thursday night, with
assoc increased rain chances.  Then a series of short waves will
keep a decent chance for rain in the forecast right through early
Monday.  A brief period of short wave ridging may help lessen rain
chances on Monday, but will be short-lived as the next trough will
quickly approach on Tuesday.

Low level thickness progs show a peak on Thursday, and this makes
sense given the aforementioned short wave ridge transitioning to our
east.  Then the series of troughs and height reduction results in
decrease thicknesses, so perhaps a bit of a cooling trend over the
weekend. In summary, look for highs in the low-mid 90s Thursday and
perhaps Friday, then falling back to near-normal readings for the
rest of the long term period.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 715 PM Tuesday...

24 Hour TAF period: VFR TAFs across the area should continue but the
chance for a sprinkle and a brief dip to MVFR is still possible at
both KINT and KFAY this evening. Earlier convection at KRWI and KFAY
could put them at risk for some MVFR fog overnight but confidence in
this is low at this time. Would not be surprised if VFR conditions
held through the night at all TAF sites. Some models also hinting at
some low stratus at KFAY but again very low confidence. Expect
conditions to be dry through the TAF period after whatever is left
of this evenings rain subsides. Winds will be light and mostly out
of the southwest but a brief change to northwesterlies across the
western sites will occur near daybreak before returning to
southwesterly by the end of the period.

Long Term: A fairly dry period will continue with mainly VFR
conditions expected through midweek. Precipitation chances increase
for the end of the week and into the weekend and with it the
likelihood of sub-VFR aviation conditions will increase.

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...CBL
LONG TERM...np
AVIATION...Ellis



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