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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 220641
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
240 AM EDT Mon Apr 22 2024

.SYNOPSIS...
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A vigorous, but moisture-starved mid and upper-level disturbance
will pivot east across the region this morning. High pressure will
otherwise build across the Middle Atlantic states through Tuesday.
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&&

.NEAR TERM /TODAY AND TONIGHT/...
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As of 240 AM Monday...

Cloudiness will give way to mostly sunny skies, cool temperatures.

Patchy light frost possible tonight in the normally colder areas of
the Piedmont.

A strong upper level disturbance will push east across the region
this morning. There will be considerable cloudiness early and
possibly some sprinkles; otherwise, skies will become mostly sunny
as the base of the trough axis moves east this afternoon. Highs will
be cool, ranging in the lower to mid 60s.

Tonight, high pressure will be over the Appalachians early shifting
over the western and southern Piedmont tonight. Expect clear skies
and light wind with excellent radiational cooling. Lows 35-40
expected with 33-34 in some of the colder spots of the Piedmont.
Some patchy light frost will be possible in these areas.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
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As of 235 AM Monday...

Milder and mostly sunny.

High pressure will shift offshore Tuesday. This will allow a return
flow from the south-southwest around the high pressure. Expect
mostly sunny skies and moderating temperatures. Highs should jump
into the upper 60s to lower 70s. Lows Tuesday night will also be
milder with upper 40s to lower 50s expected.
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&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 255 PM Sunday...

Minimal change from previous forecasts, as this still appears to be
a largely dry period, with a roller coaster of temps going from near
normal to below normal then above normal from mid week through the
weekend.

Wed/Wed night: A mid level shortwave trough zips by just to our N
Wed, along the base of a polar low over Quebec, and this will be
associated with a surface cold front approaching from the NNW. This
will result in a mid-upper level speed max sweeping over the Mid
Atlantic region including NC. But in the lower levels, high pressure
centered off the Southeast coast will ridge back westward across the
Southeast and Gulf States, such that we`ll be cut off from any
moisture tap from both the Gulf and Atlantic from the surface up
through 850 mb, and this will include a downslope wind component at
850 mb. Large scale forcing for ascent will be limited as well, with
the upper jet core shifting well to our N, keeping any upper
divergence N of our area, with minor to absent mass convergence in
the lower troposphere. But most models and ens systems suggest
potential for light precip falling out of high-based clouds ahead of
the surface front, so have maintained a period of sprinkles, NW
early then shifting to E and S in the afternoon, with the idea that
the chance of anything measurable will be very low due to the
downslope flow and lack of moisture influx. Low level thicknesses
will be near normal, so expect highs in the 70s. Cool high pressure
centered over the Great Lakes will build in from the N overnight,
resulting in cool lows in the 40s to around 50 with decreasing
clouds.

Thu-Sun: Confidence is high in dry weather Thu, with temps about 1
to 2 categories below normal, as cool high pressure shifts to New
England and continues to build in from the N, drawing in low level
thicknesses 25-30 m below normal. Uncertainty grows in the Fri-Sun
period. The surface high will shift E to off the Northeast coast Fri
while still nosing down into NC, setting the stage for a possible
damming event starting late Fri or Fri night/early Sat morning, with
the potential for increasing moist upglide up and over the cool
stable pool over the Piedmont. The ECMWF and its AIFS both suggest
patchy drizzle in the E slopes into the Foothills Fri night/Sat
morning, but the upglide further E is more in question, and will
keep it dry for now Fri night. While the overall pattern will
include mid level ridging building over the Southeast from the W Fri-
Sun, the op models do depict a subtle wave topping the ridge and
crossing the Mid Atlantic region sometime Sat, which could kick off
a little light rain or showers (depending on the degree of lingering
stability, if any) across the N Sat, followed by possible isolated
storms in the W Sun with increasing heating and afternoon
instability, but the rising mid level heights could suppress
convection, so will keep Sun dry and watch trends. Temps about a
category below normal Thu will warm well above normal Sun, with
highs well into the 80s expected Sun. -GIH

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
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As of 240 AM Monday...

24 hour TAF period:

A return to VFR conditions is expected this morning, with VFR
tonight.

Outlook: Largely VFR conditions are expected through the week.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...Badgett
SHORT TERM...Badgett
LONG TERM...Hartfield
AVIATION...PWB