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499
FXUS62 KRAH 201914
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
314 PM EDT Fri Sep 20 2024

.SYNOPSIS...
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An upper level trough along the East Coast will shift slowly
eastward and offshore through Saturday morning, as a weak surface
high pressure ridge extends from New England down through the
central Carolinas. An upper level disturbance will track southeast
through the Mid Atlantic region late Saturday through Saturday
night. An upper level high pressure ridge will then begin to build
in from Texas across the Gulf and Southeast states through early
next week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 310 PM Friday...

As the upper trough situated along the East Coast continues to shift
eastward, the ridge extending enewd from the anticyclone over srn TX
will begin ridging into the region. At the surface, high pressure
continues to encompass the mid-Atlantic and Carolinas, while a low
sits off the northern mid-Atlantic coast. Isolated to scattered
showers will persist into the early evening, then taper off with
loss of daytime heating later in the evening. The SPC mesoanalysis
page has roughly 500-1000 J/Kg of MLCAPE across the Piedmont as of 3
PM, so still cannot rule out an isolated thunderstorm, but lightning
has yet to materialize. Highs should be topping out in the low to
mid 80s. The surface ridge may strengthen from the northeast
tonight, with some slightly cooler air potentially filtering in.
However, under NE flow expect moisture off the Atlantic to also
advect into the area. The weather should be dry overnight, however
patchy fog and low stratus is expected again late tonight into early
Sat. Lows tonight should range from upper 50s NE to mid 60s south.
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&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 315 AM Friday...

Confidence is increasing in scattered showers and perhaps a few
storms across the N and W Piedmont and far NE late Sat. A prominent
shortwave seen on WV imagery over the Upper Midwest is on track to
round the top of the amplified ridge centered over TX and covering
much of the central CONUS through tonight, before diving SE through
the Mid Atlantic region late Sat and Sat night. While the timing of
this DPVA may not take full advantage of the daytime heating and
resulting destabilization this far SE, we should see an uptick in
mid level flow to support some deeper convection esp over the
mountains to our NW, and this activity may spill SE into our NW and
far N sections very late in the day and through the evening. Most
deterministic models and ensemble systems support this, with
isolated to scattered coverage across our NW and far N late
afternoon through the evening, and this is where we`ll have 15%-30%
pops, mainly from 21z-06z but with perhaps an isolated shower or two
lingering in the far NE overnight. With dry weather through much of
the Sat daytime hours, temps should reach slightly above normal
highs around 80 to the mid 80s, as thicknesses are projected to be 5-
10 m above normal. Lows in the low-mid 60s Sat night. -GIH

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 235 PM Friday...

Near to slightly above normal temperatures will start the period
early next week. Forecast confidence decreases after Wed with
ensemble solutions not in agreement on the pattern. As such,
temperatures are less certain but currently projected to be near to
slightly below normal in the upper 70s to low 80s. While rain
chances are possible Mon through Fri, highest confidence for showers
exist Tue into early Thu.

Ridging builds in from the TN valley Mon, while at the surface the
passage of a backdoor front will settle somewhere along the far
southern Piedmont and along the SC border. High pressure will nose
down into the region from Maine. Highs will be lower from the weak
cold advection and some daytime stratus. Expecting mid/upper 70s NE
to low 80s SW. We cannot rule out an isolated shower/storm in our
far southern and southwest zones along the stalled boundary, as well
as along the far NW Piedmont tied to some weak upslope.

Come Tue and Wed, guidance shows a system across the MS valley
trying to bring a cold front into the region. Ensemble solutions
start to diverge, however, regarding the frontal passage, if at all,
depending on the strength of the ridge in the far NE Gulf and the
trough over the Great Lakes. Solutions that bring the front through
show a passage late Wed night to early Thu. Have retained 20-40
percent chances of isolated to scattered storms, highest presently
for Wed, but confidence remains on the low end.

By mid to late week, ensemble solutions continue to diverge and
overall forecast confidence is low. Some ensemble solutions bring NW
flow aloft with a cold frontal passage, favoring drier conditions
and slightly below normal temperatures, while other solutions keep a
trough to our west in the MS valley, favoring warmer highs. This
pattern would favor higher storm chances in the late-week period as
it could pull deeper moisture into the area from the Gulf. NHC is
tracking the potential development of a tropical depression (50
percent chance of formation) over the northwestern Caribbean Sea and
southern GOM late next week. If something were to indeed form, its
energy could get pulled into the Deep South by the aforementioned
trough, depending on the pattern. Given the large model spread, PoPs
Thu/Fri are only 20-30 percent.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 155 PM Friday...

24 hour TAF period: Aside from a few isolated pockets of MVFR cigs
(KGSO), VFR conditions should prevail through at least midnight.
Isolated to widely scattered showers have already developed over the
NC Piedmont and will largely linger through the afternoon/early eve.
While an isolated thunderstorm cannot be ruled out (highest chance
would be at KGSO/KRDU), chances are too low to include at this time.
Shower activity should abate after sunset, with dry weather expected
thereafter. Winds should largely be nely around 5 kts, going calm
overnight. Biggest aviation concern is the chance for early morning
fog and low stratus at all terminals, mainly between 08Z and 13Z
Sat. Conditions should improve quickly Sat morning, with VFR
conditions returning by mid/late morning.

Outlook: VFR conditions should generally prevail through mid-week,
with the exception of sub-VFR fog/stratus each morning. Light rain
or showers will be possible each day but those details remain fairly
uncertain at this time.

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...KC
SHORT TERM...Hartfield
LONG TERM...Kren
AVIATION...KC