National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS62 KRAH 190730 RRA
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
330 AM EDT Fri Apr 19 2024

.SYNOPSIS...
A weak backdoor front will drop into the area from the north
tonight, then lift back north as a warm front Friday afternoon. A
cold front will cross the region late Friday night into early
Saturday, and then settle just to our south late Saturday. A wave of
low pressure will track along the front Sunday into Monday, bringing
unsettled weather.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 330 AM Friday...

Confidence in the coverage and precise timing of the shower/storm
chances today/tonight is lower than usual, based on a few factors. A
poorly defined surface pattern persists over the Carolinas, with
baggy low pressure over the SW Piedmont while a weak backdoor front
has progressed well into our NE sections, bringing a stratus deck in
from the NE associated with narrow but strong high pressure nosing
in, its northeasterly flow reinforced by a strong low E of the
Delmarva. This backdoor front is still expected to lift slowly back
northward and dissipate by this afternoon, with the stratus deck
mixing out and dissolving, as the high to the NE loses its grip. A
weak perturbation passing through this morning will spread sct-bkn
mid and high clouds into our area, partly convective debris clouds
from convection from S MI through the Ohio Valley into W TN that is
associated with an incoming strong surface cold front stretching
from NW OH to central TX, and beneath a broad but strong mid level
trough axis extending from James Bay through the Midwest. This mid
level trough has with it a fairly strong mid-upper level speed max
tracking through its base, although much of this wind aloft will
hold to our NW through tonight, with the 80-100 kt mid level speeds
holding N of the Ohio River, while our 500 mb winds are likely to
peak at just 30-40 kts this evening, adequate but not impressive.
And there is little evidence of anything more than just very weak
upper divergence potential this evening. Another factor limiting
coverage today is the low level moisture, which will be minimal
today; while surface dew points are expected to creep up into the
mid-upper 50s far N and lower 60s far S, the 925-850 mb flow will be
quite weak, with little to no moisture flux, which will keep most
cloud bases high (except for this morning`s stratus in the NE, of
course). But a few factors do support isolated light showers midday-
early afternoon evolving to scattered showers and storms from mid to
late afternoon into the evening, including decent heating (through
mostly thin or sct clouds) pushing afternoon MUCAPE to 500-1000
J/kg, along with improving PW (packed mostly above 850 mb, though).
The mid level flow, while not high, may still be sufficient to
support organized convection, with 25-35 kt of deep layer bulk shear
expected. Steep surface-based lapse rates could contribute to high
DCAPE, boosting downburst wind potential. What this means in terms
of sensible weather is that we should see a few showers moving into
the NW by early afternoon (including some developing and moving off
the higher terrain), with this convection growing upscale to
scattered storms progressing E through the area, most likely from
mid afternoon through mid evening according to rough average timing
from the CAMs and the UH plots from the HREF. Straight line winds
will be the greatest threat with any storms that can become robust
and deep. Activity should shift into the Coastal Plain and E
Sandhills while diminishing with loss of heating by late evening or
near midnight, with lingering clouds but largely dry weather
expected after 1 or 2 AM. Expect highs today from the upper 70s N to
the mid 80s S, followed by upper 50s to mid 60s for lows. -GIH

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 315 PM Thursday...

Saturday: The surface cold front and the associated weak instability
will sag slowly south and out of the area through midday. Some
lingering showers are possible across the far eastern zones during
the mid to late morning. Otherwise it should be mostly dry with
cloud cover decreasing through the afternoon with a west-northwest
downslope component noted across the area, which will delay the
arrival of appreciably cooler air into the area until Saturday
night. Highs ranging from lower/mid 70s north to near 80 south.

Saturday night: The aforementioned cold front will continue to shift
slowly south through SC and into GA as high pressure builds east
into NC. Meanwhile, a low-amplitude shortwave over the Southern
Plains will eject eject in advance of a more vigorous shortwave
trough  diving SEwd into the Central Plains. A ribbon of shortwave
impulses will begin to interact with the front to our south and will
result in the onset of isentropic lift and moisture advection into
the area after midnight. Clouds will fill back in Saturday night,
with stratiform rain spreading in/developing, mainly across southern
portions of the area during the predawn hours. Significantly cooler
with lows ranging from mid/upper 40s north to lower/mid 50s south.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 219 AM Friday...

Sunday: Flow aloft turns swly Sunday and Monday increasing low-level
moisture advection into the southeast. Ensembles and deterministic
guidance are in pretty good agreement at this point pinning a sfc
cold front, instability, and the highest anomalous moisture along
the coastal areas and offshore. Rain chances will still increase
throughout the day Sunday (highest POPs still across our far
southeastern zones) but primarily light to moderate stratiform rain
is expected through Monday morning. Sfc flow will remain nnely,
promoting a cool, wet, and breezy day with highs in the upper 50s to
lower 60s. QPF ranges from a few tenths of an inch (N) to about a
half of an inch (S).

Monday through Thursday: Any lingering rain Monday morning will pull
off to our east by early afternoon.  A few additional scattered
showers may be possible Monday afternoon/evening with the passing of
a strong vort max, but overall Monday should largely be dry. Tuesday
will follow suit under nwly flow aloft.  By Wednesday, a sheared
vorticity feature will ride through the Mid-Atlantic. This may spawn
a few scattered showers, but overall coverage should be minimal. Dry
weather continues under nwly flow aloft on Thursday.

Temperatures Monday will remain cooler than normal be cool in the
mid 60s. Temps will rise into the mid 70s Tuesday through Thursday.

&&

.AVIATION /06Z FRIDAY THROUGH WEDNESDAY/...
As of 205 AM Friday...

INT/GSO: VFR conditions are likely to hold through the next 24 hours
at INT/GSO, with clouds thickening early this morning and remaining
largely broken through this evening, but with VFR bases. Isolated
showers are possible from late morning through mid afternoon (15z-
20z) at INT/GSO, followed by a potential for isolated storms into
early evening (20z-02z) as a cold front approaches. Shower/storm
chances will end by mid evening, as the front pushes to the E.
Surface winds will be light, under 10 kts, starting from the NE
before shifting to SE, then SW, then NW after nightfall behind the
front.

RDU/RWI/FAY: These sites will see a high chance of IFR to low-end
MVFR stratus early this morning, especially RWI which will see these
low cigs as a prevailing condition from 07z to 14z. RDU/FAY will see
a shorter duration of possible IFR/low-MVFR cigs, mainly 10z to 14z.
Otherwise, VFR conditions are expected, but with thickening clouds
this morning. Isolated showers are possible starting in the mid
afternoon (mostly after 18z), with a few thunderstorms possible from
late afternoon through late evening (mainly 21z to 03z), ending
thereafter. Surface winds will be light and variable, under 10 kts.

Looking beyond 06z Sat, sub-VFR conditions are possible across the
NE and E late night through Sat morning, mainly affecting RWI/FAY,
but chances are not as high as this morning. After mostly dry
weather Sat (except a slight rain chance at FAY) as the front
settles just to our S, a wave of low pressure tracking along the
front will bring a high chance of sub-VFR conditions and rain from
Sun afternoon through early Mon. Rain chances may linger esp at FAY
Mon night, but otherwise VFR conditions are expected Mon through
Tue. Showers/storms are possible Wed associated with an approaching
cold front. -GIH

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...CBL
LONG TERM...Luchetti
AVIATION...Hartfield