Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Remove Highlighting --
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FXUS62 KRAH 222330 RRA
Area Forecast Discussion
National Weather Service Raleigh NC
630 PM EST Wed Feb 22 2017
High pressure will continue to ridge west into the Mid-Atlantic as
the center remains offshore. A slow-moving upper level trough will
cross the Southeast and Mid Atlantic states through tonight. An
upper level ridge will again briefly build over the eastern U.S.
Thursday and Friday.
.NEAR TERM /THROUGH TONIGHT/...
As of 235 PM Wednesday...
Closed southern-stream low over the northern GOM will move east-
southeastward across southern Florida and the Keys late tonight
through early Thursday. With the system suppressed well to our
south, weak forcing via weak upglide and weak DPVA will support
ample cloudiness, but very little in the form of rain in the form
of patchy rain/isolated showers for the remainder of the day and
into the evening.
In-situ wedge in place across the NW Pied that developed in response
to the batch of light precip that moved earlier this morning and
that will likely be sustained by stratus cloud cover within the weak
upslope flow will result in a rather NW to SE temperature gradient,
ranging from upper 50s/lower 60s NW to mid 70s SE.
Skies will remain mostly cloudy overnight, which will support
another mild night under light southerly flow. Lows 50 to 55.
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
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.
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --As of 630 PM Wednesday...
24-Hour TAF period: The advection of warm moist air into the region
will continue through the TAF period. As a result, overcast skies
will prevail and the weak isentropic upglide over the western
terminals (KINT/KGSO) will also continue. As a result, the best
chances for MVFR and possibly IFR visibilities and low-end VFR to
possibly sub-vfr cigs through tonight will be at KINT and KGSO. The
remaining sites should remain VFR through the period, however there
is a slight chance for a brief period of borderline VFR/MVFR visbys
around daybreak. Winds overnight will be calm to light and variable.
Conditions should return to VFR across all terminals Thursday
morning with generally southerly winds around 5 kts and prevail
through the end of the TAF period. -KC
Looking ahead: 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
-- End Changed Discussion --
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