Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 211700
AFDRAH

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
100 PAM EDT Mon Sep 21 2020

.SYNOPSIS...
Strong, surface high pressure will extend from the Northeast into
the Carolinas through Tuesday, then shift south and weaken by mid-
week.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 953 AM Monday...

On the last full day of Summer, strong Canadian high pressure
extending down much of the Eastern Seaboard will continue to result
in Fall-like conditions. The center of the high pressure will begin
to weak tonight as it builds southward, becoming centered over the
central and southern Appalachians Tuesday morning. Upstairs, dry
NWLY flow aloft will continue as a pair of mid-level anticyclones
merge over the Deep South.

Afternoon temps will once range from the mid 60s north to lower 70s
south, which is a good 10 to 15 degrees below normal. Continued
packed pressure gradient along the Eastern Seaboard will result in
yet another day of breezy conditions, with NELY wind gusts of 15 to
20 kts, strongest in the east. The NELY low-level flow will also
support another fairly robust stratocu field across eastern/coastal
plain sections. Otherwise, it will be mostly sunny.

As the center of the surface high shifts south into western NC,
winds will likely decouple, setting up what should be good
radiational cooling conditions and potentially the coolest night in
quiet some time. Lows in the lower north to upper 40s south.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 240 AM Monday...

High pressure along the east coast will slowly weaken, but remain
locked over the Appalachians and TN/OH Valley region. Expect a very
dry profile aloft to the surface with a mean light WNW flow. This
will allow for slow modification of the cool air mass. Still with
sunny skies, highs are favored to moderate only 3 or so degrees into
the upper 60s to lower 70s (still a good 10-12 degrees below
normal). Lows Tuesday night will remain cool, in the mid 40s to
lower 50s N to SE.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 355 AM Monday...

Surface high pressure will shift offshore on Wednesday, allowing for
a warming trend and increasing moisture. However, dry weather is
expected to continue Wednesday through Thursday as mid/upper level
ridging moves across the region. High temps during this period will
rebound to around 75-80 degree range, with lows in the 50s.

Chances for showers and possibly some storms are expected to
increase Thursday night into Friday as a mid/upper level trough
shifts eastward and into the region. Have lowered high temps some on
Friday to account for the increasing threat of showers/isolated
storms and mostly cloudy/cloudy skies. Currently have highs on
Friday in the lower to mid 70s, with the potential for even cooler
highs.

Forecast confidence decreases by the weekend with regard to how fast
the s/w energy will shift to the east of the area, with a possible
return to s/w ridging building back into and across the area. For
now will go with a slight chance to low chance of convection next
weekend, with highs in the 70s to near 80 and lows in the 60s.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
As of 1 PM Monday...

There is high confidence that VFR conditions will continue
through the period.

NELY onshore flow will result in a a period of broken stratocu
ceilings between 3 to 5 kft across the area this afternoon,
especially across the eastern TAF sites (KRWI and KFAY).
Gustiness will subside this evening, with winds become
light to calm overnight as high pressure becomes centered over the
western Carolinas.

Outlook: Aside from the possibility for some patchy shallow fog or
stratus across the Coastal Plain Wednesday morning, surface high
pressure will continue to result in predominately VFR conditions
through midweek. Remnants and moisture associated with TC Beta will
bring a chance of rain and sub VFR conditions late this week.

&&

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

&&

$$
SYNOPSIS...Badgett
NEAR TERM...CBL
SHORT TERM...Badgett
LONG TERM...BSD
AVIATION...CBL



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