Area Forecast Discussion Issued by NWS Raleigh/Durham, NC
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FXUS62 KRAH 271834
AFDRAH
Area Forecast Discussion
National Weather Service Raleigh NC
234 PM EDT Wed Mar 27 2024
.SYNOPSIS...
An area of low pressure will lift northeast through the Southeast
states and eastern Carolinas today through Thursday. The cold front
will move eastward through central North Carolina Thursday night.
Dry and warming weather is expected Friday and Saturday.
&&
.NEAR TERM /THROUGH THURSDAY MORNING/...
As of 1145 AM Wednesday...
...Flood Watch for 8 PM today to 8 PM tomorrow extended to
include the NE Piedmont and Sandhills...
Deep moist southwesterly flow ahead of a broad mid/upper trough over
the Central and Eastern US, along with a slow-moving cold front
currently over the Appalachians and an area of low pressure moving
along the Southeast US coast, will result in multiple rounds of
moderate to heavy rainfall across central NC through tomorrow
morning.
The forecast generally looks on track this morning. The biggest
change for today was to lower high temperatures over the northern
and western Piedmont given they will be stuck in low overcast and
cool NE flow all day on the backside of the inverted surface trough
that extends into central NC. Forecast highs there are only in the
lower-to-mid-50s, coolest across the far north (including the
Triad). Furthermore, the surface warm front is analyzed over central
SC, south of which temperatures are already in the lower-70s and dew
points in the upper-60s. As an area of low pressure currently over
the central GOM moves NE and along the GA/SC/southern NC coast
tonight, it will push the warm front farther north and into
southeastern parts of central NC later today. So still expecting the
southern Sandhills and southern Coastal Plain to reach mid-60s to
lower-70s today. This is also where high-res models show as much as
500 J/kg of SBCAPE from about 18z-00z today. With decent low level
and deep layer shear, can`t rule out an isolated strong to severe
storm down there during this period. But it will be very conditional
and the best instability will remain to our south. Elsewhere,
thunder will continue to be possible through tonight, but convection
will remain elevated, so no severe threat is expected.
As for rainfall, still expecting a general 1-4 inches across
most of the area, highest over the Coastal Plain. The Triad may
be more in the half inch to an inch range, and there will be a
sharp cutoff on the western side, but exactly where that sets up
is still uncertain as guidance has been waffling back and
forth. The 12z HREF shifted the 2-4 inch axis farther west into
central NC to include the NE Piedmont and Sandhills. High-res
guidance depicts multiple rounds of showers today with a more
widespread area with heavier rates developing tonight across
much of the area as the low lifts NE. This will result in a risk
for flooding, including in urban areas like the Triangle and on
some mainstem rivers which are forecast to reach flood stage at
our eastern gauges. Given all of this, the Flood Watch from
this evening into tomorrow evening has been extended farther
west to include the NE Piedmont and Sandhills. Also increased
POPs to categorical over this entire area tonight. Still
expecting lows in the mid-40s to mid-50s.
&&
.SHORT TERM /THURSDAY AFTERNOON THROUGH THURSDAY NIGHT/...
As of 345 AM Wednesday...
Aloft, the s/w over the Deep South should continue swinging through
the Southeast Thu and offshore Thu night. At the surface, the
surface trough should finally move eastward and offshore on Thu as
the low deepens and tracks along the NC coast. This low should shift
eastward out over the Atlantic Thu eve/night, with cool high
pressure building into the area in its wake.
Precipitation: The moderate/heavy rain will likely continue through
Thu morning, finally shifting eastward and out of the area Thu
aft/eve as the surface low moves away.
Temperatures: Highs Thu will be lowest in the east where the
rain/clouds linger into the afternoon, with mid 50s expect, while in
the west where the weather may dry out and sun may try to peek out,
highs could rise into the low/mid 60s. Lows Thu night mainly in the
upper 30s to low 40s expected.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 300 AM Wednesday...
Friday - Easter: Upper ridging from the central Plains into the
upper Midwest and a shortwave moving southeast across the Mid-
Atlantic will generate northwesterly flow aloft across central NC to
end the work week. Ridging then builds southeast towards the TN
Valley/Great Lakes region for the weekend, switching flow aloft to
more zonal. At the surface, departing low pressure off the NC coast
and high pressure building from the Deep South Friday to off FL`s
Atlantic coast will generate breezy conditions across central NC
from a tight pressure gradient. Breezy WNW winds Friday will switch
to SW Saturday as the high to our south moves further east. Gusts
Friday afternoon will range from 20-30 mph, with weaker gusts
Saturday of 15-25 mph. Relative humidity will be on the downward
trend, with values dropping to 25-35 percent through the period.
Fuels will likely be wet enough to avoid elevated fire weather
conditions Friday, however fine fuels may be dry enough Saturday to
warrant elevated conditions across areas west of Highway 1. Winds
slightly diminish by Easter Sunday, with relative humidity remaining
low across the region.
The ridge building in will increase heights across central NC, and
with warm air advection in full swing, temperatures will be on the
rise through the weekend. Near normal highs in the 60s Friday
quickly rise to the 70s Saturday as surface winds switch to
southwesterly, then temps rise even more on Easter, with most areas
near to just above 80 degrees for a high. Winds become more westerly
on Sunday as a surface low moves east across the Mid-Atlantic and a
cold front approaches from the north.
Sunday night - Tuesday: Precipitation then returns to the forecast
Sunday night with an approaching cold front from the north.
Isentropic ascent developing will help generate light rain across
northern half of the region late Sunday night into Monday. Although
the front stalls across our area and then lifts north late Monday,
another approaching cold front and perturbations in the mean flow
aloft will increase rainfall chances across all areas Tuesday. Prior
to the front lifting north late Monday, areas near the VA border
were looking cooler with highs closer to seasonal normals. However,
the further push of the front north looks to keep the warmer airmass
across all areas a bit longer, with highs in the mid-70s N to mid-
80s S Monday and Tuesday. The details will change over the next few
days, however confidence is increasing in precipitation returning by
the middle of next week.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
As of 230 PM Wednesday...
Widespread IFR to LIFR ceilings blanket across central NC as a
result of an area of showers and storms that has moved through. The
one exception is the far SE (including FAY) which is still VFR, but
they are also expected to drop to MVFR later this afternoon and
IFR/LIFR this evening. RWI may bounce between IFR and MVFR ceilings
(maybe even briefly VFR) this afternoon before also dropping to
IFR/LIFR this evening. Elsewhere across the Piedmont (including RDU,
GSO and INT), confidence is high that IFR to LIFR ceilings will
persist through tonight. While visibilities will improve some now
that the first round of showers is exiting to the NE, another area
of showers developing over SC will move across central NC later this
afternoon and this evening. It could be accompanied by some isolated
storms as well, particularly over the far SE (including FAY) where
they may have gusty winds. A more widespread and heavy area of
showers and isolated storms with IFR/LIFR visibilities will move
across central NC overnight tonight, particularly from around RDU to
the south and east. INT and GSO should largely miss out on the
heaviest rain, and it will exit to the east by early tomorrow
morning, allowing for ceilings there to gradually lift to MVFR and
maybe even VFR by the end of the TAF period. Farther east, the
showers will persist through tomorrow morning, and ceilings may only
slightly improve to IFR.
Outlook: Widespread showers will exit to the east by early afternoon
tomorrow, but isolated showers and storms remain possible through
the rest of the day especially east before we dry out in the
evening. VFR conditions will return from west to east Thursday
afternoon and evening and continue into Monday. Gusty winds of 20-30
kts are expected each day from Thu into Sat, from the N on Thu, from
the W/NW on Fri, and from the SW on Sat.-- End Changed Discussion --
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 8 PM EDT this evening through Thursday
evening for NCZ007>011-024>028-040>043-075>078-084>086-088-089.
&&
$$
SYNOPSIS...Hartfield/KCP
NEAR TERM...Danco
SHORT TERM...KCP
LONG TERM...JT
AVIATION...Danco