-- Discussion containing changed information from previous version are highlighted. --
285
FXUS62 KRAH 202003
AFDRAH

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

.SYNOPSIS...
High pressure aloft will settle from the Middle Atlantic and OH
Valley southward and across the Southeast through this weekend. A
pre-frontal trough and weak cold front will move into NC Monday
afternoon and night, then lift northeastward across the Middle
Atlantic as a warm front Tuesday and Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 345 PM 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 SW 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 tonight. Dew points have again
bottomed out in the upper-50s to lower-60s this afternoon, keeping
heat indices close to the air temperatures which are in the
the mid-80s to lower-90s. Once again an extensive deck of scattered
to broken mid-level cumulus has already developed across the region,
but it remains flat under a strong subsidence inversion. So a
complete lack of instability will preclude any convective
development for the rest of the 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 340 PM Thursday...

The slightly weaker but still strong 596 dam mid-level anticyclone
will continue to slowly weaken and drift further SE on Friday,
reaching the Deep South on Friday night. At the surface, high
pressure east of NC will continue to nose westward and move south
closer to Bermuda. With the low-level flow switching to a S/SE
direction, 1000-850 mb thicknesses will slightly rise by 5-10 m
compared to today, supporting high temperatures mainly in the lower-
90s across central NC. Dew points will also be slightly higher but
with good mixing should still bottom out in the lower-to-mid-60s.
However, guidance shows some upper-60s dew points and 500-1000 J/kg
of CAPE creeping into the far SE in the afternoon. This is also
where a few CAMS (including the NSSL, ARW and NAMNest) depict a few
showers and storms potentially making it from the coast. So added a
slight chance of showers and storms just over southern Sampson
County from 18z-00z. Any convection would quickly die off after
sunset, with milder lows in the upper-60s to 70 as higher dew points
begin to overspread the whole area.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 400 PM Thursday...

A long stretch of hot temperatures, ~6-12 F above average, will
result this weekend through the middle of next week. While
seasonable to seasonably low humidity values may regulate/temper
Heat Index values, an increased HeatRisk (experimental forecast risk
of heat-related impacts that supplement Heat Index-based NWS
products - more information here: wpc.ncep.noaa.gov/heatrisk/) will
result.

A mid/upr-level high that reached within one decameter of 600 dam at
500 mb last evening at IAD, PIT, and OKX last evening, the latter of
which broke an all-time record for the site, will gradually weaken
while retreating swd across the TN Valley through Sat and then wwd
to the srn Rockies and Southwest through early next week. A series
of 2-3 prominent nrn stream shortwave troughs/compact closed
cyclones will migrate ewd and across the Canada/US international
border and Great Lakes, with associated glancing height falls
maximized across the srn Middle Atlantic/Carolinas Sun-Mon and again
Wed-Thu.

At the surface, on the wrn periphery of high pressure that will
become anchored near and east of Bermuda, an Appalachian-lee trough
will develop Sat and remain in place for most of the forecast
period. It may be briefly overtaken by a cold front that will weaken
while drifting sewd and into NC Mon afternoon and night, before the
front will then retreat newd and across the Middle Atlantic as a
warm front Tue-Wed. Another cold front may reach NC by Thu. While
the aforementioned subsident ridge aloft will have weakened and
retreated wwd, the hot low-level airmass it produced will remain in
place across much of the srn and sern US throughout the forecast
period, equatorward of the frontal zones noted above. Mainly diurnal
convection will become possible over cntl NC by Sun afternoon, then
maximize with the approach/passage of the two fronts noted above on
Mon and again late Wed-Thu, with intervening continued dryness.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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.

&&

.CLIMATE...

-- Changed Discussion --
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

June 26:
KRDU: 102/1952
KFAY: 101/1951


Record High Minimum Temperatures:

June 21:
KRDU: 75/1933

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

June 26:
KGSO: 74/2010
KRDU: 76/1902
KFAY: 76/1997
-- End Changed Discussion --

&&

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

&&

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