Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 200825
AFDRAH

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
425 AM EDT Sat Jul 20 2019

.SYNOPSIS...
A strong ridge of high pressure will build over the Mid Atlantic
region through Sunday, then begin to break down and weaken Monday.
The current heat wave will continue and worsen through the weekend.
A pattern change to wetter and cooler weather will arrive next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 355 AM Saturday...

An expansive 594 dm mid level anticyclone over the Central and
Eastern U.S. will continue to produce oppressive and dangerous heat
through the weekend. Daytime temperatures in the mid to upper 90s
combined with high humidity will result in heat indices of 105 to
115 F this afternoon, with only minor relief at night as
temperatures struggle to fall below 80 degrees. No changes planned
to current heat advisory/warning configuration.  All residents of
central NC are strongly advised to follow heat safety rules to avoid
heat-related illnesses through the weekend.  Additionally, perform
wellness checks on those who might be more at risk from high
temperatures like the elderly, infants, children and pets.

Lingering weak shear axis aloft will support some isolated to widely
scattered showers and thunderstorms this afternoon and evening.
Otherwise, the strong anticyclone will limit convective rain
chances. High DCAPE of 1500-2000 J/Kg could support isolated pulse
severe wind damage with the strongest storm.



.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 355 AM Saturday...

Mid-level anticyclone over the region begins to break down/weaken
very late in the day/Sunday night, in response to a northern stream
trough moving into the Great Lakes region. Thus, any change in the
thermal profile is pretty negligible with another day of heat
indices of 100 to 110 F expected, which will necessitate a
continuation of heat warning and advisories across central NC for
Sunday.

Convective chances on Sunday look even less than today, as the upper
shear axis further weakens. Lows in the mid to upper 70s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 425 AM Friday...

The mid to upper-level ridge will begin to retreat eastward to begin
the period as an unseasonably dynamic upper-level trough begins to
protrude southeast out of the Great Lakes region. This will
introduce a period of unsettled weather across the Carolinas that is
likely to continue through the majority of the work-week, before
more typical upper-level dynamics return later next weekend.

Monday: With the Bermuda high remaining the primary weather
influencer across central NC, and models continuing to trend a bit
slower with the cold front`s arrival, have continued to inch
temperatures up a bit Monday afternoon, especially along and east of
US-1. Expect afternoon highs to top out in the low to mid 90s, with
heat index values in the 100 to 104 degree range area-wide (may need
to consider a future heat advisory issuance, especially within and
east of the Triangle if this trend holds). With surface high
pressure and the lingering effects of the upper-level subsidence in
place, have trended POPs lower a bit, especially prior to 2pm. Can`t
completely rule out some isolated convection development, especially
along the lee side trough, likely to be situated NW to SE through
central NC. Any storms that do form could exhibit isolated damaging
wind gusts in any downburst type events that do occur. By Monday
night, POPs and cloud cover will increase drastically from NW to SE
as the upper-trough and associated surface front crosses east of the
Appalachians.

Remainder of the period: The upper-trough and associated surface
cold front will slide east of the Appalachians by Tuesday morning,
working its way NW to SE across the area through Wednesday morning.
Some timing, strength, and progression differences continue between
global model solutions, with both the CMC/ECMWF pushing the boundary
and associated storm activity southeast of the area by Wednesday
evening, while the GFS lingers convection through Wednesday night as
a surface wave rides northeast. Have trended a bit closer to the
more consistent ECMWF solution here, with only a CHC/SCHC POP
mention across the Sandhills and Coastal Plain beginning Wednesday
afternoon. Depending on timing, will be monitoring surface
conditions on Thursday for a possible severe weather setup. While
uncertainty remains high, the unusual availability of upper-level
support hints at the possibility of sustained updrafts which may
form into multicellular type clusters, capable of producing
intermittent damaging wind gusts, isolated small hail, and possibly
localized flooding. With current progged model timing, the primary
threat area remains across and east of the I-95 corridor, but this
may migrate further westward with time, especially if arrival of the
boundary keeps getting delayed. Rainfall amounts in the 0.75 to 1.5
inch range will be possible during this 48 hour period.

The front will linger along the coast or slightly inland through the
end of the week. The coolest day will likely be Wednesday, with
afternoon temperatures struggling into the lower 80s. More
seasonable temperatures will return by the end of the work-week and
persist into the weekend. Overnight lows will dip into the 60s mid
week before returning to the low 70s over the weekend.

&&

.AVIATION /06Z SUNDAY THROUGH WEDNESDAY/...
As of 110 AM Saturday...

Isolated convection will continue to wane overnight with
predominately VFR conditions overnight. Otherwise, a light west-
southwest wind will continue overnight. A strong ridge of high
pressure across the region will limit rain chances across the
area on Saturday. Thus, will not include any significant wx
or impacts at any TAF site.

Outlook:  VFR should continue through Sunday. An approaching cold
front will bring increasing chances of showers and storms once again
Monday and Tuesday, with a return of early morning stratus and fog
as well.


&&

.CLIMATE...

Record high temperatures and years for the next few days.

              RDU        GSO        FAY
Sat 7/20   102/1942   100/1977   104/1932
Sun 7/21   102/2011   102/1926   105/1937
Mon 7/22   103/2011   101/1926   107/1932

&&

.RAH WATCHES/WARNINGS/ADVISORIES...

Excessive Heat Warning from 10 AM Saturday to 6 AM EDT Sunday for
NCZ007>011-024>028-040>043-075>078-085-086-088-089.

Excessive Heat Watch from Sunday morning through Sunday evening for
NCZ007>011-024>028-040>043-075>078-085-086-088-089.

Heat Advisory from 10 AM Saturday to 6 AM EDT Sunday for NCZ021>023-
038-039-073-074-083-084.

&&

$$
SYNOPSIS...Badgett
NEAR TERM...CBL
SHORT TERM...CBL
LONG TERM...JJM
AVIATION...CBL
CLIMATE...CC



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