-- Discussion containing changed information from previous version are highlighted. --
618
FXUS62 KRAH 201811
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
211 PM EDT Thu Jun 20 2024

.SYNOPSIS...
Anomalously strong high pressure centered over the Middle Atlantic
will gradually weaken while migrating southwestward into the
Tennessee Valley Friday and into the weekend. A cold front will
approach the region on Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1100 AM Thursday...

The anomalous mid/upper ridge sampled at 598 dam from this morning`s
KPZ and KIAD soundings (slightly weaker than last night but still
quite strong) currently stretches across the northern Mid-Atlantic.
It will drift SE to the TN Valley tonight. At the surface, high
pressure centered east of the Delmarva will slowly drift south to
become centered east of the southern VA/northern NC coast by
tomorrow morning. This pattern will support light easterly low-level
flow shifting more southeasterly later today, which may help dew
points creep up a bit compared to yesterday. Still, good afternoon
mixing will help dew points drop into the lower-to-mid-60s, keeping
heat indices close to the air temperatures which will again reach
the upper-80s to lower-90s this afternoon with similar low-level
thicknesses. Once again an extensive deck of scattered to broken mid-
level cumulus has already developed across the region, but it will
remain flat under a strong subsidence inversion. So a complete lack
of instability will preclude any convective development this
afternoon and evening. Lows tonight may be a touch milder with
slightly rising thicknesses, in the mid-to-upper-60s. Patchy
fog/mist again can`t be ruled out in the Coastal Plain late
tonight/early tomorrow morning.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 322 AM Thursday...

Under the continued influence of the weakening, but still quite
strong ~595 dm ridge centered over the Tn Valley/mid south, low-
level thicknesses and h8 temps will increase over central NC.
Atlantic high pressure will continue to extend west into the area as
an inverted sfc trough extends north along the SE US coast from the
weak area of low pressure moving inland into the Florida.

Still one day away from the oppressive 70-75 dewpoint air advecting
into the area, heat indices will be comparable to the dry bulb temps
Friday afternoon, topping out in the lower/mid 90s.

Models do indicate the development of weak instability of 500-1000 J
across the far SE zones, which may allow a convective cell or two to
survive as it`s move inland. Otherwise, continued dry.

Expect milder overnight lows and rising humidity as the low-level
becomes increasingly south-southeasterly. Lows in the upper 60s to
lower 70s.


&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 323 AM Thursday...

..Dangerously Hot Temperatures Expected this Weekend and into Early
Next Week...

As the mid/upper level ridge continues to stay atop the OH and TN
valleys, hot dry weather will be the main story for the weekend.  By
late Sunday an upper level trough will be moving across the OH and
TN valley into the Mid-Atlantic bringing a surge of upper level
moisture through Monday. Another trough is expected to move across
the region again late week before upper level ridging settles in for
late week.

At the surface high pressure combined with south/southwesterly flow
will result in warm humid conditions over the weekend. Temperatures
are expected to be in the mid to upper 90s across the region. Heat
indices ranging from 100-105 F can be expected across the Triangle
region Saturday with more widespread heat indices of 104 -108 F
Sunday across the Triangle, Sandhills and Coastal Plain regions.
While a lee trough develops east of the Appalachian mountains this
is expected to bring the Triad a bit of relief starting Sunday night
and the rest of the area Monday. For now have PoPs beginning in the
NW late Sunday night before spreading east across the region Monday.
There could be a lull in overall precipitation during the day Monday
but expect showers and storms to regain energy by the afternoon
hours. As a cold front swings down from the north Tuesday, a few
lingering isolated showers and storms could be possible again on
Tuesday, as well as small relief from the heat. Highs on Tuesday
will range from low to mid 90s, with heat indices in the mid to
upper 90s.

The heat is expected to return Wednesday and Thursday with highs in
the mid to upper 90s. Humidity will also slowly be returning ahead
of another frontal passage  thus areas along and east of US-1 could
experience heat indices of 100 -104 F. Long range models suggest
another front could impact the area with another round of
precipitation late week but the timing is uncertain. For now just
have afternoon PoPs across the region each afternoon.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
As of 200 PM Thursday...

Dry weather and VFR conditions will largely prevail through the
period. The one exception is possible IFR or MVFR visibilities from
fog/mist in the Coastal Plain again (including at RWI) late
tonight/early tomorrow morning, as occurred the last couple days.
Otherwise just scattered to broken mid-level cumulus will continue
this afternoon. Offshore high pressure will bring light easterly
winds that shift more southeasterly tomorrow.

Outlook: VFR and dry conditions are expected to persist through
Saturday. An approach of a northern stream trough and attendant cold
front into the region will support a slight chance of showers and
storms and related sub-VFR restrictions on Sunday, with better
coverage on Monday. Isolated showers and storms may linger in the
south and east on Tuesday.
-- End Changed Discussion --

&&

.CLIMATE...

Record High Temperatures:

June 22:
KRDU: 100/2022
KFAY: 101/2022

June 23:
KRDU: 100/1986
KFAY: 102/1981

June 24:
KRDU: 99/2010
KFAY: 102/1914

June 25:
KRDU: 100/1952
KFAY: 102/1914


Record High Minimum Temperatures:

June 22:
KGSO: 75/1981
KRDU: 78/1933

June 23:
KGSO: 74/2015
KRDU: 77/1890
KFAY: 77/2017

June 24:
KGSO: 76/2015
KRDU: 76/1888
KFAY: 79/2010

June 25:
KGSO: 75/2015
KRDU: 77/2010
KFAY: 75/1952

&&

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

&&

$$
SYNOPSIS...cbl
NEAR TERM...Danco
SHORT TERM...cbl
LONG TERM...ca
AVIATION...Danco/cbl
CLIMATE...RAH