Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 230609

Area Forecast Discussion
National Weather Service Raleigh NC
108 AM EST Thu Feb 23 2017

A slow-moving upper level trough will cross the Southeast and Mid
Atlantic states tonight. An upper level ridge will again briefly
build over the eastern U.S. Thursday and Friday.


As of 935 PM Wednesday...

Surface high pressure continues to slip southward with the center of
the high now east of the Outer Banks. Wedge front that formed as a
result of in-situ damming scenario earlier today has split the CWA
in half with mid to upper 50s across the NW Piedmont and low 60s
across the south and east. Light winds at this time out of the north
across the Triad should go calm and then return to southerly as the
high continues to move southward.

For tonight expect fog to begin to form especially over the NW
Piedmont where rain occurred earlier. KINT and KGSO have already gone
down to 2SM and will continue to fall through the early morning
hours, possibly creating a patchy dense fog situation that we will
monitor for a potential advisory. Lows tonight in the low to mid


As of 235 PM Wednesday...

Strengthening synoptic scale subsidence with a mid to upper level
ridge building into the area in the wake of the closed low moving
off the Florida coast will give way to increasing sunshine
throughout the day. Weak sely onshore flow will prove of little
consequence as enhanced mid-level moisture stream moves offshore
while remaining capped aloft. Thus, will keep forecast dry.

With the erosion of the in-situ wedge across the NW Piedmont, the
warmth that central and eastern sections experienced today will
spread to all of central NC on Thursday. A projected 10 meter
low-level thickness increase will support highs ranging from
lower 70s NW to upper 70s SE, which will approach record
territory(see climate records below). Lows in the 50s.


As of 430 PM Wednesday...

Fri/Fri Night: Expect rising heights aloft Fri as a shortwave ridge
builds eastward across the region in the wake of an upper level low
progressing offshore the FL/Atlantic coast. In the lower levels, an
offshore surface ridge will extend inland (SW/WSW) through the
Carolinas. Despite near record highs (near 80F) and an unseasonably
moist airmass characterized by surface dewpoints in the low/mid 50s,
precipitation (e.g. convection) is unlikely due to insufficient
forcing and a strengthening mid-level (~700 mb) cap marking the
leading edge of a modified elevated mixed layer advecting into the
region from the SW (on the western periphery of the shortwave ridge
as it progresses toward the Southeast coast Fri aft/eve). Expect dry
conditions and unseasonably warm temperatures to persist with lows
in the mid 50s.

Sat/Sat Night: An upper level low moving ashore the Pacific coast
this evening will track eastward through the Intermountain
West/Rockies on Thu and emerge in the central Plains on Friday. The
upper low will amplify as it tracks into the OH valley Friday night
and may become negatively tilted as it progresses through the Mid-
Atlantic on Sat. An attendant sfc cyclone will track NE from the
Great Lakes into Canada, with a secondary cyclone developing
offshore the Mid-Atlantic coast (Sat) racing northward to the
Canadian Maritimes by 12Z Sunday. A cold front associated with the
Great Lakes /inland/ low will approach the mountains from the west
Sat morning and track across central NC during the day Sat. Though
upper forcing will be present, the strongest DPVA is expected to
remain north of central NC (over the DELMARVA) and will likely lag
behind the pre-frontal trough. Additionally, with the primary sfc
low lifting NE from the Great Lakes into Canada and a secondary low
developing offshore, expect little in the way of return flow, with
sfc dewpoints similar to Friday and a persistent (albeit weakening)
mid-level cap as a modified elevated mixed layer advects eastward
across the region. At this time it is difficult to tell whether or
not sufficient upper level forcing will be present, let alone
favorably juxtaposed with low-level forcing and diurnal heating. As
a result, it is difficult to ascertain whether or not convection
will develop over central NC Sat afternoon. At this time, the best
chance for precipitation appears to be in the NW Piedmont 12-18Z Sat
when remnants of an OH/TN valley squall line (if any) would be
expected to track into northwest NC. Otherwise, the atmosphere
appears too dry/capped for convection to develop (though if did,
supercellular organization would be likely). Expect highs in the
70s, lows Sat night in the upper 30s (NW) to lower 40s (SE).

Sun-Wed: Expect relatively dry conditions in this period with
temperatures gradually rising through the 60s into the 70s early
next week, in advance of the next cold front expected to approach
from the west mid-week. -Vincent


As of 1255 AM Thursday...

24 Hour TAF Period: A lingering CAD air mass over the Northwest
Piedmont will lead to MVFR/IFR cigs and visbys falling into the LIFR
range with very low stratus and/or fog early this morning,
continuing through mid to late morning at KGSO/KINT. Elsewhere,
expect mainly VFR conditions will continue with good amount of mid
and high clouds expected, as a weak mid level trough slowly moves
across the area. The main shield of mid and high clouds will
shift eastward across the area this morning as the mid/upper level
trough axis shifts eastward. Winds are expected to remain calm to
light and variable this morning, with a light S to SE wind expected
today into the evening.

Outlook: Aside from some early morning fog/stratus, expect
predominately VFR conditions through early next week. The exception
will be a very isolated/small chance of a shower or thunderstorm as
a cold front moves through the area Saturday afternoon. Winds will
become breezy Saturday afternoon as the front approaches from the
west, with sustained winds between 15 to 20kts, gusting 25 to 30



Record High Temperatures
      February 23rd         February 24th        February 25th

GSO      73/1980                79/1982             81/1930
RDU      79/1980                81/1982             82/1930
FAY      80/1922                83/1930             85/1930





LONG TERM...Vincent
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