Area Forecast Discussion Issued by NWS Raleigh/Durham, NC
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FXUS62 KRAH 150733
AFDRAH
Area Forecast Discussion
National Weather Service Raleigh NC
329 AM EDT Fri Mar 15 2024
.SYNOPSIS...
Warm high pressure centered offshore will extend west across the
Southeast states today. A weak cold front will drop into the region
tonight, then stall out and hold over the Carolinas over the
weekend. A stronger cold front will cross the region late Sunday,
bringing cooler air for the beginning of next week, including a
frost and freeze potential Monday night.
&&
.NEAR TERM /TODAY THROUGH TONIGHT/...
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As of 329 AM Friday...
Downstream of a persistent upper low over CA, water vapor imagery
depicted a de-amplifying mid-level ridge over the southeast early
this morning. Embedded within the wswly flow aloft, a low-amplitude
short wave was observed developing over eastern TX. Further north,
a more pronounced short wave was sliding east across the
Midwest/Great Lakes region. Both of these features will slides east-
southeast across the southern Appalachians and mid-Atlantic through
tonight.
At the sfc, a cold front was observed extending from southern
Arkansas northeastward through southern OH/central PA. This feature
has generated ongoing convection in this corridor as well as a
spatially impressive outflow boundary out ahead of the line. This
front will slowly sag into our area late tonight and stall along the
coast through Saturday morning. Ahead of this feature, warm swly
sfc flow will persist with high temps reaching the upper 70s to
lower 80s. Additionally, forecast soundings continue to indicate
good mixing late this morning through the afternoon when gusts of 15
to 25 mph look likely.
Latest HREF guidance continues to suggest that the convection
currently approaching the western slopes of the southern
Appalachians will decay with eastward extent this afternoon/evening.
This makes sense conceptually as 1) sfc and upper forcing is quite
weak today and 2) guidance keeps the stronger pool of moisture
transport to our southwest. Similarly, the better instability/shear
is displaced well into the Deep South. Here locally, dew points
struggle to reach the lower 60s and not till later this evening.
Thus, mainly expecting just scattered showers and perhaps an
isolated thunderstorm this afternoon/evening (highest POPs across
the west). A few lingering scattered showers will likely accompany
the the front, but majority of rain should push to our east by ~06Z
tonight. Overnight lows will remain warm in the mid to upper 50s.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
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As of 329 AM Friday...
Friday`s cold front will stall along the coast Saturday promoting
dry conditions over central NC. Flow will turn more nely behind the
front early Saturday promoting stratocu into the afternoon period.
While temps will cool off a bit on Saturday, the airmass will
moderate a bit in the afternoon supporting highs in the lower 70s.
Overnight lows will dip into the lower 50s.-- End Changed Discussion --
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.LONG TERM /SUNDAY THROUGH THURSDAY/...
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As of 235 AM Friday...
Apart from a shot of rain chances in our S/SE late Sun-Sun night,
we`ll likely stay dry through Thu, with warm weekend temps falling
below normal early in the week before trending back toward normal
mid week.
Sun/Sun night: Mid level flow will be zonal across the east-central
CONUS early Sun, as a polar low sit over the Ontario/Quebec border
and another low holds over AZ. Our steering flow will back to SW as
energy digs down into the polar trough, through the Upper
Midwest/Great Lakes region into the Ohio Valley through Sun night. A
much weaker perturbation through the southern stream will cross the
Southeast states late Sun into Sun night, ahead of the incoming
surface polar cold front. Models all depict an area of showers ahead
of the front streaking across SE NC, with spatial variations
regarding the primary swath of rain. Based on the LREF/NBM, much of
the heavier precip appears poised to sneak by just to our SE with
lower pops primarily covering just our SE 2/3rds, although the
outlier NAM is much further NW with heavier rain well into our area.
Will favor these further-SE ensemble output solutions, spreading low
chance pops across much of our SE but with low QPF overall, focusing
on late Sun through Sun night, ending prior to daybreak Mon. Expect
highs in the 70s followed by lows in the 40s to lower 50s.
Mon-Tue: The potent mid-upper shortwave trough just N of the Ohio
Valley early Mon will continue to drop SE, swinging through NC late
Mon through Mon night. This will draw a reinforcing secondary cold
front through our area Mon and bring the coldest air of this mini-
respite, along with stout/gusty winds. We should see a shot of
enhanced cloud cover just ahead of the incoming vorticity max,
although if it is sufficiently strong with a far-southward track
across the Carolinas, we could see enough lift/condensation late Mon
for a few sprinkles over the E and SE where the low levels will be a
bit more moist ahead of the secondary front. But, at this point, the
risk of anything substantial appears low, and will keep Mon dry. A
surge of Canadian air will peak late Mon night into Tue morning,
when our greatest chance for near- or sub-freezing temps will occur,
before the incoming high across the Deep South quickly moderates,
although as winds diminish Tue night, the greater radiational
cooling potential could make that a second near-freezing night in
some spots. Will have mid 50s to mid 60s for highs Mon, then lows
from around 30 to the mid 30s Mon night, which may include some
upper 20s in the typically colder spots. Tue highs will be our
coldest day and well below normal, in the 50s, followed by lows in
the 30s. Frost/freeze alerts will likely be needed, esp over
portions of the Piedmont and northern Coastal Plain, Mon night, and
perhaps again Tue night, albeit with a lower threat area.
Wed-Thu: Air mass moderation persists but with increasing model
spread in the details. Additional energy will dive SE through the
Northeast states (and possibly as far S as the Mid Atlantic coast,
if the Canadian model is to be believed) on Wed, as we maintain a
dry northwesterly steering flow into NC. This flow will back and
slow down by Thu as flat but amplifying shortwave ridging builds
into the Southeast states, ahead of a progressive shortwave low and
trough through the south central CONUS. The Canadian is slower than
the GFS/ECMWF with this feature, a result of its stronger/slower
polar stream mid week, so will favor the GFS/ECMWF solutions with a
solution suggesting greater incoming ridging aloft and greater
warming but with cirrus overspreading our area ahead of likely
convection Thu from the TX coast into the lower Miss Valley. Highs
will have rebounded in the 60s to around 70 both days. -GIH-- End Changed Discussion --
&&
.AVIATION /06 FRIDAY THROUGH TUESDAY/...
As of 133 AM Friday...
VFR conditions continue this morning as high pressure remains
anchored just offshore. Scattered cirrus continue to spill across
central NC from upstream convection over the TN/OH valley. Expect
mid to high level cloudiness to thicken from west to east later this
morning/afternoon as showers approach the area. Showers and
possibly an isolated storm should generally diminish with eastward
extent this afternoon/evening, but can`t rule out at least some
brief potential for associated sub-VFR conditions to develop at
times (highest probability at KINT/KGSO). Otherwise, a developing
low-level jet will increase the chance for LLWS at northern
terminals from now through about ~14Z. Beyond ~14Z, good mixing
should support swly gusts of 15 to 25 kts through early this
evening.
Outlook: A period of post-frontal MVFR ceilings appear possible
early Saturday morning, but should lift with time as dry conditions
return Saturday. Additional showers and sub-VFR conditions will be
possible Sunday night into Monday. VFR conditions will return Monday
into Tuesday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Luchetti
SHORT TERM...Luchetti
LONG TERM...Hartfield
AVIATION...Luchetti