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649
FXUS62 KRAH 110802
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
402 AM EDT Sat May 11 2024

.SYNOPSIS...
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A surface trough will move across central NC tomorrow evening. High
pressure will then build across the Southeast and Middle Atlantic on
Sunday.
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&&

.NEAR TERM /TODAY AND TONIGHT/...
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As of 345 AM Saturday...

Surface observations depict a region of higher low-level moisture
associated with a weak inverted trough over the Coastal Plain and
far NE Piedmont, as the parent low is centered east of the NC coast.
Current dew points there are in the mid-to-upper-50s. A deck of
stratocumulus has moved south of our southern Coastal Plain, with
more areas of stratocumulus over eastern VA that will move into the
Coastal Plain through the morning. However, any associated showers
have dissipated. Northerly winds were gusting as high as 25-35 mph
at times earlier this evening, especially over the Coastal Plain,
but they have subsided with many areas now reporting calm or very
light winds.

Looking aloft, water vapor imagery shows a pair of shortwaves, one
just off the mid-Atlantic coast, while the other is over WI and the
upper peninsula of MI. During the day on Saturday, we will be under
the influence of dry WNW flow and height rises as the former
shortwave exits NE into the Atlantic, with just some scattered
cumulus below the subsident inversion at 700 mb. It will be a very
pleasant afternoon with highs only reaching the lower-to-mid-70s
(around 5 degrees below normal) and dew points only in the 40s.

However, as the latter shortwave moves SE and reaches the northern
Mid-Atlantic by Saturday night/Sunday morning, we could experience
some weak mid-level height falls on Saturday evening. A surface
trough will also be passing through and there will be a period of
WAA around 850 mb. So a deck of clouds around 5-10 kft is likely to
move through from NW to SE in the evening, and CAMS suggest it could
be accompanied by a band of showers/sprinkles. However, the best
upper forcing will be well to our north and there will be very
little to no instability to speak of with CAPE values around 100
J/kg or less. So any showers should be light and brief, with total
amounts less than a tenth of an inch. The entire area will be mostly
clear after about 06z, which should be favorable for any additional
aurora viewing, and lows will again drop into the upper-40s to mid-
50s.
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&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
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As of 400 AM Saturday...

Dry NW flow will prevail on Sunday between the departing mid/upper
trough over the Northeast US and ridging over the lower MS Valley.
At the surface, high pressure will move east from the TN Valley to
become centered over the mid-Atlantic on Monday morning. This
pattern will support sunny skies and another very pleasant day, as
dew points are again only in the 40s (some statistical guidance even
shows some upper-30s in the far NW Piedmont). NW winds could gust up
to 15-25 mph during the day with good mixing. High temperatures will
range from mid-70s to 80. Decent radiational cooling conditions will
help lows Sunday night drop to the mid-40s to lower-50s.
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&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 315 AM Saturday...

Monday morning will find surface high pressure moving off the mid-
Atlantic states along with an upper level ridge moving over the
eastern United States. However, another upper level trough over the
central Plains will move east, helping to form a surface low over
southern Illinois by Tuesday morning. The bulk of the rain will fall
ahead of this low, and although Monday will remain dry, western
locations should have rain move in Monday night and the showers will
expand everywhere Tuesday. It`s too early to look at particular
rainfall amounts, but the heaviest rain is currently forecast for
Tuesday afternoon. Showers and thunderstorms will continue Tuesday
night into Wednesday as the surface low moves over Washington DC and
moves offshore New Jersey by Wednesday evening. This should bring a
lull in precipitation Wednesday night through Thursday night before
another system moves east from the Plains. Some model guidance wants
to go with likely to categorical pops on Friday, but am not willing
to go with pops that high on day 7 and will cap pops at high chance.
Average temperatures this time of year are generally around 80 and
60, and forecast temperatures are generally around these numbers,
although highs will be a little cooler on Tuesday with the
widespread rain.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
As of 215 AM Saturday...

VFR conditions will prevail across central NC through Saturday
afternoon, with the one exception of some lingering stratocumulus
over the far east (including RWI) which has resulted in periods of
MVFR ceilings. While RWI is back to VFR, some high-res guidance
(including the RAP and GLAMP) shows MVFR returning there later
tonight, so have a TEMPO group at RWI for that potential from 08z-
12z. A deck of clouds from about 6-10 kft will move across central
NC from NW to SE on Saturday evening, and they may be accompanied by
a band of showers. Confidence in any brief sub-VFR visibilities with
the showers is low, but it cannot be entirely ruled out. Northerly
winds tonight will become more westerly/southwesterly by tomorrow
afternoon and evening, remaining less than 10 kts sustained and
possibly gusting up to 15 kts at times during the day.

Outlook: Rain and IFR-MVFR restrictions, lowest over the Piedmont at
INT/GSO, will overspread cntl NC Tue morning, with a following
chances of showers/storms Tue afternoon through Wed.

&&

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

&&

$$
SYNOPSIS...Danco
NEAR TERM...CA
SHORT TERM...Kren
LONG TERM...Green
AVIATION...Danco/MWS