221
FXUS62 KRAH 210731
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
330 AM EDT Fri Jun 21 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 330 AM Friday...

The heat ridge, which is now centered over the Tn Valley, will
gradually weaken, while migrating southwestward over the mid south
by tonight. Atlantic high pressure will continue to extend west into
the Carolinas. Farther south, a tropical wave/weak area of low
pressure, currently a couple hundred miles east of Jacksonville,
will move ashore northern Florida or southeastern Georgia late this
afternoon/evening.

Low-level thicknesses continue to climb. However, tolerable
dewpoints in the 60s should hold on for one more day. Thus, heat
indices will be comparable to the dry bulb temps, topping out 90-95.

Enhanced moisture convergence associated with an inverted coastal
trough extending north from the tropical wave approaching the
Florida/Georgia coast may support an isolated shower or storm across
the far SE counties, where weak buoyancy is expected. Otherwise,
continued dry as strong cap remains in place.

Expect milder overnight lows and rising humidity as the low-level
becomes increasingly south-southeasterly. Lows in the upper 60s to
lower 70s, with some low clouds and/or fog possible, mainly across
eastern portions.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 330 AM Friday...

Heights aloft will continue to lower as the upper anticyclone/ridge
retrogrades further west to the lower MS Valley and srn Plains by
early Sunday. The Atlantic surface high will push farther east out
into the Atlantic, with a pre-frontal trough developing in the lee
of the Appalachians. Low-level thicknesses and humidity will
steadily rise as the low-level flow becomes increasingly southerly.
Given an expected 6-8 m increase in thicknesses, highs Saturday
should be 2-3 degrees warmer, topping out in the lower to mid 90s.
Very humid and uncomfortable dewpoints in the upper 60s and lower
70s will be prevalent and will propel heat indices in the upper 90s
to lower 100s. This level of heat, this early in the season when
most are not acclimated will pose a moderate risk for heat related
illnesses, especially those without effective cooling and those with
chronic diseases.

Rain chances will once again be limited to an isolated sea-breeze
convection across the far SE zones.

Warmer overnight lows in the lower to mid 70s. &&

.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 /06Z FRIDAY THROUGH TUESDAY/...
As of 125 AM Friday...

Patchy fog is possible overnight. Otherwise, VFR conditions will
rule. An isolated shower or storms is possible this afternoon across
the far SE zones, but should remain east of KFAY. Winds will remain
light and generally from east-southeasterly. An increase in low-
level moisture from the SE will lend to increasing chances of sub-
VFR restrictions in stratus and/or fog mainly across eastern
terminals(KFAY and KRWI) late Friday night/early Saturday.


Outlook: VFR and dry conditions are expected to persist through
Saturday. An approaching cold front 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...

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

&&

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

&&

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