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000
FXUS62 KRAH 142023
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
423 PM EDT Sun Apr 14 2024

.SYNOPSIS...
High pressure will move off the Southeast coast, then to near
Bermuda by Monday. A backdoor cold front will sag south into the
area Monday night and will stall and bisect the area through Tuesday
night before returning north as a warm front on Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 200 PM Sunday...

Satellite imagery reveals a mid-level shortwave centered near the TN
valley. Mid-level clouds are currently associated with the system,
stretching from TN into far western NC. A few rogue showers are
present but limited instability is keeping things largely dry. With
time, this shortwave is forecast to reach central/southern GA this
evening and overnight. While we would not be surprised if a stray
shower could survive into the far southern Piedmont this evening,
dewpoints in the 30s and 40s indicate a fairly dry boundary layer
and sub-optimal low-level WAA. Relative humidity levels have dipped
as expected into the 20s in most locales, and as such, the increased
fire danger statement will remain in place till 8 pm this evening.

Forecast soundings show south-southwest winds persisting overnight,
but gusts should diminish after sunset. Overnight lows were tweaked
down a tad into the low to mid 50s owing to this morning`s much
lower temperatures and the persistent dry airmass conducive to
radiational cooling. This is some 7 to 12 degrees above normal.

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 305 PM Sunday...

...Unseasonably warm with a chance of aft/eve showers and storms
over the northeast Piedmont and nrn-cntl Coastal Plain, including
isolated severe near the VA border...

A mid/upr-level cyclone will deepen while migrating from the Central
Great Basin and Southwest to the cntl High Plains, while another
will fill/weaken while moving slowly ewd over Quebec. Between the
two, a progressive ridge will amplify while moving across the MS and
TN Valleys. Wnwly flow aloft will result from the upr Great Lakes to
the srn Middle Atlantic, the latter where a pristine EML, evident in
12Z-observed RAOBs from the srn-cntl Great Plains the TN Valley,
will have advected and reside.

At the surface, high pressure now off the South Atlantic coast will
drift to near Bermuda, with associated warm, swly flow directed
across the South Atlantic states, including mid/upr 80s throughout
cntl NC. Meanwhile, a backdoor cold front will settle south and
across the srn Middle Atlantic, likely to near the VA/NC border by
12Z Tue. The front will be preceded by an outflow boundary that will
weaken with time and swd extent as it settles into cntl and srn NC
through the same time. Despite the warm temperatures, lingering
continental air and dewpoints in the 40s, to lwr-mid 50s over nrn NC
where moisture convergence will result along and ahead of the
outflow boundary and cold front, will favor low and comfortable RH
in the 20th-30th percentile.

The combination of EML capping and lingering dry/continental air
will favor only weak and capped instability of up to just a few
hundred J/kg over srn NC, to near 1000 J/kg of weakly to uncapped
MLCAPE along the VA border, and 1000-1500 J/kg across srn-cntl VA.
Mid-level flow will also be strongest over VA and characterized by
500 mb winds of 35-45 kts there and generally about 10 kts weaker
over NC. The result will be a continued risk of severe thunderstorms
across far northern NC, and especially points nwd into south-cntl
and sern VA, Mon afternoon and evening. While damaging wind gusts
and large hail will pose the primary hazards in the Marginal and
Slight risk areas, outflow and wind gusts of 30-40 mph may occur
well ahead of and away from parent convection in counties adjacent
to the Marginal risk area.

While a few remnant showers may drift as far south as Raleigh to
Goldsboro through midnight, it will otherwise be a dry overnight,
with low temperatures in the upr 50s to lwr-mid 60s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 400 PM Sunday...

A mid/upper low will continue to slowly migrate ENE across the
Central Plains on Tuesday and Tuesday night, with ridging over the
GOM extending north into the Mid-Atlantic. At the surface, a
backdoor cold front will be located near the VA/NC border on Tuesday
morning. Moisture pooling along and ahead of this front will bring
PW values of 1-1.5 inches (150-200% of normal). Models also show
SBCAPE values of around 500-1000 J/kg. Thus moisture and instability
may be adequate for some isolated to scattered showers and storms on
Tuesday afternoon and evening, particularly over the NE Piedmont and
northern Coastal Plain closest to the backdoor front where POPs are
low chance. There is disagreement between the ECMWF and GFS on how
strong the mid-level flow will be (with the GFS stronger), but there
appears to be at least potential for a few strong to severe storms.
There is also some uncertainty on how high temperatures will get and
it will depend on how much cloud cover there is and where exactly
the front sets up, but for now forecast highs are in the 80s in most
places except upper-70s in the far NE. Lows Tuesday night will again
be quite mild, in the upper-50s to lower-60s.

As the low moves into the northern Great Lakes on Wednesday and the
backdoor front lifts NE and away from our region, it will turn dry
but widespread mid and high clouds should remain. This will help
keep temperatures down some, but with strong S/SW flow ahead of the
low gusting as high as 20-30 mph, it will still be warmer than
average with highs in the upper-70s to lower-80s. As the primary low
weakens and moves into Canada, models show a secondary low
developing over the mid-Atlantic on Wednesday night and Thursday, as
a weak cold front moves through. It should be a mostly dry front,
but there may still be a few isolated showers or storms especially
east. Mostly sunny skies will help bring temperatures back into the
80s areawide on Thursday.

Meanwhile the next mid/upper low will move east across southern
Canada, which will drag a much stronger cold front that sinks SE and
approaches central NC this weekend. Temperatures will remain above
normal ahead of the front, and after a lot of disagreement today`s
12z model guidance has gotten more consistent on the timing of its
passage. The ECMWF sped it up slightly while the GFS slowed it down,
so both models indicate it dropping through central NC on Saturday
night and Sunday. POPs increase to slight to low chance on Saturday
and low chance areawide on Sunday. Would like to see more timing
consistency from model run to model run before going any higher.
Instability appears adequate to include a slight chance of thunder
during this period as well. The temperature forecast this weekend is
also low confidence and depends on the timing of the front, but they
should drop significantly behind it.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
As of 105 PM Sunday...

There is high confidence in VFR conditions through the 24-hour TAF
period. SW winds this afternoon to early evening will gust to 20-22
kt. Winds will weaken tonight but remain out of the WSW between 5
and 9 kt. A LLJ overhead will bring LLWS to the terminals tonight,
ending from west to east between 09-12z Mon.

Outlook: A backdoor cold front will move south Mon evening and stall
over a portion of central NC before moving back north Wed as a warm
front. This boundary will bring the threat of scattered showers and
storms Mon/Tue evening, especially across the northern TAF sites.
Sub-VFR fog/stratus may also be possible in rain-cooled air. VFR is
expected to prevail Wed into Fri, although showers are possible with
another boundary approaching later in the week.

&&

.FIRE WEATHER...
As of 310 PM Sunday...

Increased fire danger will result across all of central North
Carolina through 8 PM this evening. The combination of dry fuels,
relative humidity as low as 20 to 25 percent, and southwest winds
gusting 20 to 30 mph will lead to increased fire concerns. Refer to
your local burn-permitting authority on whether you may burn. If you
do burn, exercise extreme caution.

While RH values will again decrease into 20-35 percent range Mon
afternoon, lowest over the Sandhills, swly surface winds will be
weaker and less gusty than previous days - with gusts generally at
or below 20 mph.

&&

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

&&

$$
SYNOPSIS...CBL/MWS
NEAR TERM...Kren
SHORT TERM...MWS
LONG TERM...Danco
AVIATION...Kren
FIRE WEATHER...Kren/MWS