441
FXUS62 KRAH 070015
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
815 PM EDT Sat Jul 6 2024

.SYNOPSIS...
A subtropical ridge will continue to extend across the eastern Gulf
of Mexico and Florida into early next week. A cold front will slowly
move southeast into Virginia and the Carolinas over the weekend and
then dissipate.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 305 PM Saturday...

* More numerous thunderstorms than previous days.
* Increased concern that slow moving storms with torrential rain
  will pose a flash flood risk across the southern Piedmont,
  Sandhills and perhaps the Triangle.
* Hot and humid conditions continue this afternoon with major to
  extreme heat risk. Clouds should keep temperatures a little cooler
  than Friday`s highs.

The latest surface analysis shows a complex surface pattern with a
Piedmont surface trough extending from VA south across the
Carolina Piedmont. The trough across central NC appears to be
enhanced by remnant outflows from convection last night. Dewpoints
in the Triad have dropped into the upper 60s with a more
southwesterly flow noted further east in the Triangle and Coastal
Plain with dewpoints in the lower to mid 70s. Further aloft, the mid-
level ridge along the Southeast coast persists. The flow on the back
side of the ridge has accordingly strengthened a touch from previous
day and the flow has become more southwesterly.

The regional radar has been lighting up with convection developing
along the sea breeze in eastern NC and near the surface trough in
southern NC and SC. Other scattered convection is developing across
central SC which is probably enhanced by convectively enhanced
disturbances aloft resulting from convection across MS/AL/GA last
night. The airmass across central NC is moderately unstable in the
Coastal Plain and eastern Piedmont with MLCAPE values of 1500-2500
J/Kg and a little less instability off to the west with MLCAPE
values around 1000 J/Kg in the Triad. The atmosphere is much more
moist and DCAPE values are much less than previous days and range
from about 600-800. PW values range from 1.9 to 2.3 inches
across the area with 1.95 at KGSO and 2.28 at KMHX this morning
which is about 125 to 150% of normal. With a southwest flow expect
convection to continue to fire, and spread northeast across much of
central NC late this afternoon and evening.

Concerned that the flow parallel to the trough and the disturbances
moving across the area will lead to multiple clusters of storms
moving across the same areas. High PWs and slow-moving/backbuilding
nature of cells may result in isolated to scattered instances of
flash flooding. The greatest threat area will be in a triangle from
Wadesboro northeast to Raleigh and south to Fayetteville. The
convection will likely linger longer than previous night but begin a
general weakening trend during the late evening with lingering
showers/isolated storms and patches of light rain continuing
overnight.

Temperatures should reach the mid/upper 90s to around 100 with a few
localized spots climbing into the lower 100s before clouds thicken
and convection begins to cool temperatures a bit. Dew points in the
lower to mid 70s heat index values will range from around 100 in the
Triad, to 105 to around 115 elsewhere. It will remain warm and muggy
tonight, with lows in the mid 70s to around 80. -Blaes

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
As of 230 PM Saturday...

* Showers and storms expected again on Sunday
* Still hot and humid but heat indices will be a bit lower

Sunday`s weather will mirror today`s (Saturday) with a similar
airmass in place featuring 2.25 to 2.5 in PW`s in place, weak
steering flow, and MLCAPEs around 1000-1500 J/KG. In response to
today`s convection, a weak surface trough will be deposited across
the area and should serve to trigger another round of showers and
storms across the area. Meanwhile upstream convection across
portions of AL, SC, and GA and their remnant MCVs could serve to
focus additional convection across the area during the day tomorrow.
The 12Z HREF is suggesting storms could get going early in the day
(15-16Z) especially across the western Piedmont before blossoming
and slowly expanding eastward. As is the case today, storm motions
will likely be slow and convection is likely to be dominated by
pulse-type clusters producing periods of heavy rain and isolated sub-
severe wind gusts. Hard to pin down any specific area for heaviest
rainfall potential but much (if not all) of central NC shares a
similar 50-70 percent chance of precip during the day. Given the
broad area and low confidence in pinpointing a specific area, I will
hold off on Flood Watches. Showers are likely to linger into early
evening before dissipating around midnight.

Thicknesses should be a bit lower and with storms potentially
developing earlier in the day, cloud cover should also be on the
increase. Temps should run about 5 degrees cooler than today with
highs only reaching the low to mid 90s. Heat indices should remain
at or just below triple digits, with the only exception being
portions of the southern Coastal Plain where readings may try and
take a brief run toward 100-103 before clouds, convection, and
outflows bring temps back down.  Lows falling into the low/mid 70s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 230 PM Saturday...

* Typical summer pattern expected with hot/humid conditions
* Daily diurnal thunderstorm chances, with greatest rain chances
  late in the week

The mid level pattern for much of next week will feature broad
southwesterly flow as the NC becomes positioned between longwave
troughing over the Great Lakes and an offshore ridge. It`s worth
pointing out that there will also be an upper low that lingers off
the NC coast for a period of time this week, but nearly all guidance
suggests it will be drawn southward away from our area and should
not be a player in our weather across central NC. Embedded within
the southwesterly flow aloft will be a series of weak perturbations,
all of which are difficult to track and time their arrival into NC,
but will ultimately promote daily afternoon/evening shower and
thunderstorm chances with areas across the Sandhills and western
Piedmont favored any given day. PW`s next will generally range from
1.75 - 2.25 inches during this time (90-95th percentile) with little
day to day variation while afternoon MLCAPEs should easily climb
into the 1000-1500 J/KG range. In short, precip chances next week
will closely mirror a typical climatological distribution for
early/mid July. An influx of additional moisture aloft late in the
week should support somewhat higher than normal precip chances and
PoPs have been trended upward slightly.

Hot/humid conditions will once again be the theme next week,
although values should be a bit lower than what has been observed
recently. Afternoon highs should reach the low to mid 90s, with the
highest values of the week possible Tuesday into Wednesday. The
arrival of additional moisture (and presumably cloud cover) should
hold temps back a bit (upper 80s to lower 90s) to close out the week
although heat indices could still approach the triple digits given
the humid airmass. Mild overnight lows in the low to mid 70s will
also be common.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 815 PM Saturday...

24-hour TAF period: Scattered showers and storms continue across the
Coastal Plain and eastern Sandhills, including near FAY and RWI.
They could be accompanied by brief IFR or MVFR ceilings and
visibilities, along with gusty winds. Convection will gradually
diminish this evening, but periods of light rain will be possible
anywhere across central NC through the overnight hours. Low stratus
is expected to develop overnight, and MVFR or IFR ceilings can`t be
ruled out at any of the TAF sites. Guidance differs on how
widespread the low stratus will be, but the best chance appears to
be over the Sandhills and southern Piedmont, including at FAY. Low
stratus may linger for much of the morning across the south.
Scattered showers and storms will then begin popping up around
midday, becoming most widespread from mid afternoon into early
evening. Once again, sub-VFR conditions and gusty winds will be
possible with any storms.

Outlook: A rather typical summer pattern of scattered afternoon and
evening showers and storms along with some late night and early
morning stratus and fog are expected through the period with the
coverage of storms and restrictions expected to uptick on
Wednesday into Thursday.

&&

.CLIMATE...
Record High Temperatures:

July 6:
KRDU: 102/2022
KFAY: 99/1990

Record High Minimum Temperatures:

July 6:
KGSO: 76/1999
KRDU: 79/1900
KFAY: 76/2017

July 7:
KGSO: 73/2019
KRDU: 77/1900
KFAY: 78/2017

July 8:
KGSO: 76/2010
KRDU: 78/1986
KFAY: 79/2012

July 9:
KGSO: 76/1987
KRDU: 74/2014

&&

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

&&

$$

SYNOPSIS...Blaes
NEAR TERM...Blaes
SHORT TERM...DL
LONG TERM...DL
AVIATION...Danco/Blaes
CLIMATE...RAH