Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
FXUS62 KRAH 240211
Area Forecast Discussion
National Weather Service Raleigh NC
1003 PM EDT Mon May 23 2016
.SYNOPSIS...An upper level low will pull away from central NC
tonight and Tuesday. A strong upper level ridge will build over
the Southeast through the remainder of the week.
.NEAR TERM /through tonight/...
As of 955 PM Monday...
Showers have largely dissipated across the region this evening with
the loss of heating. However, another disturbance rotating around
the offshore mid/upper level low is helping to support a few
lingering showers across the southern half of VA. This disturbance
should rotate across portions of our area... while the center of the
mid/upper low slowly begins to wobble north and eastward and away
from the area tonight. Thus, we could possibly see a shower or two
affect northern/northeastern portions of central NC before the
activity dissipates with further nocturnal stabilization and/or the
disturbance rotating through the area late this evening/early
The main forecast problems of the night though appear to be how much
cloud cover we will have and the resulting effects on the low temp
forecast, along with the possibility of some fog. Skies are currently
clear/mostly clear across a large portion of central NC, which has
allowed temps to drop quite nicely with light and variable to calm
surface winds. However, we will at least see some increase in cloud
cover across the northern/northeastern half of the CWA, before
clearing across most if not all of the area by late tonight/before
daybreak Tuesday. Thus, with recent rains, light and variable to
calm winds, and clearing skies think we may see at least see some
patchy fog. Low temps are generally expected to be in the lower to
mid 50s, with perhaps a few of the coldest sites dipping into the
.SHORT TERM /Tuesday and Tuesday Night/...
As of 325 PM Monday...
Upper level ridge over the Mississippi Valley will begin to expand
northeast into the southeast U.S. Tuesday, in the wake of the
departing low. Rising heights/associated subsidence will suppress
cloud growth depth, resulting in scattered flat cumulus in the
afternoon. Late May sun will aid to warm temps to near or above 80
for the first time since May 14th for many locations. High pressure
at the surface and aloft will continue to strengthen over our region
Tuesday night. Under clear skies and a light or calm wind regime,
min temps by early Wednesday will average in the upper 50s to around
.LONG TERM /Wednesday through Monday/...
As of 305 PM Monday...
Wed-Fri: Warm and mainly dry. The mid level pattern will feature
longwave troughing over the western CONUS with ridging in the east,
albeit with a weakness aloft which will extend from a weak low over
the central Bahamas northwestward across SW NC. At the surface,
Bermuda-centered high pressure will ridge narrowly westward across
the Southeast, yielding a light low level flow with minimal moisture
influx. The above normal heights aloft and resulting subsidence,
along with the absence of lift mechanisms and the lack of a good
moisture source, will help suppress deep convection over central NC.
While the aforementioned weakness in heights aloft to our SW may
lead to scattered afternoon storms over the higher terrain, the
steering flow pattern does not favor movement of any such convection
into our area. Thickness will be well above normal, supporting highs
each day in the mid 80s to around 90 (Thu appears likely to be the
warmest of these days) with lows in the lower to mid 60s.
Sat-Mon: Lots of uncertainty in the details, although guidance
continues to favor temps staying slight above normal through the
upcoming holiday weekend, but with an increasing chance of
showers/storms by Sun/Mon. The western end of the surface ridge axis
will pivot northward (following the strengthening of the Atlantic
mid level ridge extending into the mid Atlantic region), and this
will allow a long-fetch southeasterly flow to stream increasing
amounts of moisture into the Southeast. Meanwhile, the Bahamas mid
level low begins to drift to the NW into the height weakness toward
the Southeast states, and model solutions are converging toward some
similarity at the surface, showing either an inverted trough or low
tracking northwesterly toward the Southeast coast. It is far too
early to say whether or not this feature might have tropical or
subtropical characteristics, but regardless, we are still likely to
see an increase in clouds and precip chances as mid level heights
fall and moisture increases and deepens through the low levels.
Thicknesses support temps slightly above normal, tempered by
the increase in clouds. -GIH
.AVIATION /00Z Tuesday through Saturday/...
As of 800 PM Monday...
24 hour TAF period: VFR conditions across the area this evening as
rain showers have tapered off and dewpoints are starting to dive
into the lower 50s across the area. Therefore have high confidence
of VFR conditions maintaining through the TAF period. Winds will be
light and variable tonight and then obtain more of a westerly
direction on Tuesday at 5-10 kts. A few clouds in the 3-5 kft range
will prevail on Tuesday but overall mostly clear skies expected.
Long term: VFR conditions should prevail through much of the
extended until Thursday night into Friday when rain becomes more of
a threat in the NW Piedmont.