Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 311910

Area Forecast Discussion
National Weather Service Raleigh NC
310 PM EDT WED AUG 31 2016

A cold front will approach from the northwest Thursday into Friday
as Tropical Storm Hermine moves further offshore into the
Atlantic and Tropical Hermine tracks NE across the Southeast


As of 1200 PM Wednesday...

As Tropical Depression 8 tracks NE away from the Carolina coast, a
baroclinic low attendant a weakening upper level low just offshore
the Southeast coast and strengthening cyclonic flow aloft over the
Mid-Atlantic will track NE along the Southeast coast through
tonight. By 12Z Thu, the low is progged to be centered just south of
Cape Lookout. Although the best potential for precipitation
attendant the aforementioned low will remain in immediate vicinity
of the Carolina coast, 12Z model guidance suggests isolated or
scattered convection (primarily showers) may develop as far inland
as the Coastal Plain. Additionally, diurnal convection is expected
to develop in the higher terrain of the NC mountains in assoc/w
differential heating and diffluent flow aloft this aft/eve, and some
of this activity could drift into portions of the NW piedmont before
dissipating this evening. With the above in mind, will continue to
indicate a slight chance of showers/storms during the aft/eve hours
in southeast portions of the Coastal Plain and in the Northwest
Piedmont. Expect highs in the upper 80s to near 90F, lows tonight in
the lower 70s. -Vincent


As of 1200 PM Wednesday...

Expect an increased chance for convection on Thursday (particularly
the NW Piedmont) as a cold front attendant strengthening cyclonic
flow aloft over the OH Valley/Mid-Atlantic progresses across the
Appalachians. Will indicate a 50% chance of showers and storms
everywhere. Expect highs near 90F, lows Thu night in the upper 60s
(NW) to lower 70s (SE). -Vincent


As of 305 PM Wednesday...

...Newly named TS Hermine to possibly impact central NC Friday and

The 12z runs of the GFS and ECMWF both indicated a slower and westward
shift in the track of now TS Hermine , a trend that started last
night. It appears Hermine will drift north across the Florida
panhandle and then begin to interact with a trough digging through
the Midwest. This interaction makes the westward shift plausible,
and the GFS/ECMWF paint 2+ inches of qpf across nearly all of
central NC Friday through early Saturday as the low center moves
essentially along the I-95 corridor. The official track from the
NHC this afternoon will offer much needed guidance in these
trends. One thing that will likely be a significant factor will
be the cold front that settles across the area tomorrow. Heavy
precip could develop along the front by early Friday, still well
away from Hermine, and a left of track QPF max should evolve as
well given the front and upper jet to the northwest. We have
remained a little conservative in our increase in QPF, but there
is enough agreement in the GFS and ECMWF, supported by many GEFS
members, to forecast 1-3 inches of storm total QPF, with some high
amounts in the southeast. Wind isn`t a significant threat with
this potential event, but an inland track will also increase winds
and a threat of some downed trees with the heavy rain. Have also
lowered highs into the upper 70s on Friday, though these could be
several degrees cooler as well. -BS

Saturday: Forecast confidence is quite low, especially earlier in
the day, due to the uncertainty in track and speed of the tropical
cyclone. Latest operational GFS and NAM have brought the cyclone`s
track progressively west into the piedmont with slower forward
speed. This would obviously extend potentially heavy rain into
Saturday morning. Will thus have chance PoPs in the west graduated a
lingering likely PoP in the east during the morning tapering off to
chance in the northeast by evening, with no PoP overnight. Guidance
highs are likely too high as well the likelihood of extensive
cloud coverage and rain...will lower to the 75 to 80 degree
range...with mins on Saturday night from 60 to 65 under clearing

Sunday through Wednesday: Mostly clear skies through the period as
cool surface high pressure will be building in from the north and
overhead early next week. This will maintain below-normal
thicknesses through Monday, with temps beginning to climb Tue and
Wed as the high shifts overhead and offshore. Highs will be mostly
in the lower-mid 80s with lows in the lower-mid 60s through Mon,
followed by warming temps to upper 80s Tue and Wed with potentially
some lower 90s on Wed.


As of 1200 PM Wednesday...

24-hr TAF Period: VFR conditions will generally prevail through the
TAF period, aside from a small potential for isolated convection
this afternoon and evening, primarily at the INT/GSO and FAY/RWI

Looking ahead: Periodic convection and early morning stratus/
ceilings will be possible at all terminals Thu aft/eve, in advance
of a cold front approaching from the NW. Based on the latest
forecast track of Tropical Depression 9, it appears that sub-VFR
conditions attendant rain (potentially heavy) and gusty E to N winds
will be possible at eastern terminals Fri/Sat, with VFR conditions
returning in the wake of the system by Sunday. -Vincent




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