862
FXUS62 KRAH 071850
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
250 PM EDT Sun Jul 7 2024

.SYNOPSIS...
A weak frontal zone extending from the Chesapeake Bay into the
Piedmont of the Carolinas will linger and weaken before dissipating
by Tuesday. Mid and upper level high pressure will then build across
the area before another cold front approaches late in the work week.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1025 AM Sunday...

* A notable change in the weather pattern and sensible weather for
  today with more cloudiness and cooler temperatures than the past
  few weeks.
* Scattered to numerous showers and storms are expected although a
  fair amount of uncertainty in how convection will evolve today.

The latest surface analysis shows a cold front extending from the
DelMarVa peninsula southwest across southeastern VA into the
northwestern Piedmont of NC and into far upstate SC. The air mass
across central NC is very moist with PW values of 2.0 to 2.3 inches
this morning with the KGSO RAOB observing 2.12 inches. Southeast of
the front, dew points range in the lower to mid 70s with an axis of
upper 70s extending along the Coastal Plain. Northwest of the front,
a light northeast wind is observed in the Triad and in the VA border
counties.

Further aloft a 594dm mid and upper level anticyclone is centered
over the eastern Gulf of Mexico, sandwiched between Beryl and the
closed mid/upper level low east of the Carolinas. The mid and upper
flow across NC will be rather light today and from the west and
southwest. There are a few disturbances in the general flow, most
prominently is one moving across eastern NC this morning and perhaps
a few others moving into NC from the southwest late this afternoon
and this evening.

Satellite imagery and surface observations note a good deal of
cloudiness across central NC this morning with areas of MVFR/IFR
ceilings. With heating, expect some additional breaks in the
overcast to develop which will subsequently be followed by
stratocumulus and cumulus cloud growth, all of this will result in
partly to mostly cloudy skies this afternoon and evening.
Particularly challenging today will be the evolution of convection,
especially where it will develop and how it evolves. The frontal
zone should serve as a natural focus for storm initiation as will a
myriad of boundaries across the area including differential heating
areas from breaks of sunshine and gradients of different rainfall
amounts from yesterday. Convection allowing models provide vastly
different solutions which is not surprising given the weak forcing
and numerous mesoscale features present. Expect convection to
gradually ramp up over the next handful of hours, especially after 1
and 2pm with coverage and intensity peaking between 3 and 6pm and
then a gradual decline into the mid and late evening. With a couple
of upstream disturbances posed to move near the area tonight,
wouldn`t be surprised to see a rogue shower or storm overnight.

The main weather hazard today will be slow moving convection in a
moist and weakly to moderately unstable environment will be produce
some locally heavy rain. Highs today will be tempered by cloudiness
and a slightly cooler air mass and generally range in the upper 80s
to lower 90s, coolest in the Triad behind the front and warmest
across the southeast, ahead of the front and in a warmer atmosphere
that did not experience much rain. It will remain warm and muggy
tonight with lows in the lower to mid 70s. -Blaes

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 250 PM Sunday...

* Continued shower/thunderstorm chances, albeit it with lower areal
  coverage
* Brief periods of heavy rain likely the primary threat with any
  storms that develop

We should have a very similar synoptic setup across the area
tomorrow with PW`s still running around 2 to 2.2". The presence of a
stalled surface boundary may be lacking though and with only a lee
trough and sea breeze to contend with, the overall triggering
mechanisms for convection may ultimately be the limiting factor.
Storms are once again favored across the western Piedmont along with
the Sandhills/southern Coastal Plain, with lesser chances elsewhere.
Storms are likely to be outflow dominant and pulse-type in nature
given very weak steering flow around 15kts or less. While wet
microbursts would be a possibility with any storms that approach
severe limits, locally heavy rainfall from slow moving/training
storms would likely be the primary threat tomorrow.  However given
relatively limited areal coverage, we shouldn`t need any flood
watches. PoPs in the 20-40 percent range area-wide are the general
consensus from the NBM, HREF, and other global models and this seems
reasonable at this point.

Temps will be on par with today`s values with highs in the upper
80s/lower 90s with lows falling into the lower 70s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 250 PM Sunday...

* Typical summer pattern through the weekend
* Some storms possible Tuesday/Wednesday, becoming more numerous
  late in the week

Precip chances look to decrease on Tuesday as an offshore upper low
off the NC coast dives southwestward toward Florida. In its wake,
mid level heights appear to increase by a few meters and this may be
enough to further inhibit storm development across the area. While
similar PW`s will be in place area-wide, very limited forcing and
instability outside of an area near a lee trough across the western
Piedmont should keep storms isolated/widely scattered in nature.

Meanwhile, the remnant circulation and moisture associated with T.C.
Beryl will be drawn inland and absorbed into a longwave trough
approaching the western Great Lakes later this week. This will spawn
a relatively deep surface cyclone that will track northward across
the Great Lakes into southern Ontario. An attendant surface boundary
will make an eastward run at the mountains, but likely stall/wash
out before it makes it across. However the remnant boundary and/or
lee troughing will likely result in an area of enhanced surface
convergence which will be stall out and be slow to exit the area.
Nearly all global models suggest a plume of increased PW`s will be
drawn inland from off the SE coast on Wednesday, interacting with
and serving as a necessary ingredient for increased shower and
thunderstorm coverage to close out the week. There is a general
consensus among the ensembles that Thursday and Friday could be
particularly active as a weak surface low develops along the stalled
surface boundary to our south and tracks through central NC. Looking
at the 100 member grand ensemble of the Canadian, GFS, and EC
ensemble forecast systems, nearly 80 percent suggest precip across
the area on Thursday and nearly 90 percent on Friday, which is an
unusually high amount of agreement for this time of year at this
lead time. Of course exactly how much rain will fall, and exactly
where the surface boundary and low track set up, is still TBD but
the trend of increasing late-week PoPs will continue. Precip chances
should remain elevated (although slightly lower as compared to
Thursday/Friday), as we get into the weekend.

Temperatures this week should be within a few degrees of normal.
Through mid week with mid level ridging sneaking in from the east,
temps should make a solid run into the mid 90s area-wide and it is
on these days (Tuesday and Wednesday) where heat indices could make
a return to dangerously high values. However increased cloud cover
and precip chances will knock readings back into the mid/upper 80s
Thursday, especially Friday, and possibly into Saturday as well
before returning to normal by Sunday. Lows throughout the period
generally upper 60s to mid 70s.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
As of 225 PM Sunday...

A cold front extends from southeast VA southwest to just south of
the Triad into southwestern NC. Near and north of the front
widespread clouds with MVFR and even IFR restrictions are noted with
scattered to numerous showers and thunderstorms. The most unsettled
weather is expected at the KINT and KGSO terminals through around
23Z with additional showers and storms possible through around 02Z.
Similarly convection will be near the KRDU terminal but perhaps with
a less coverage. Showers and storms are expected to be more isolated
at the KFAY and KRWI terminals with a threat of convection
continuing a little later into the evening hours but greatest
between 22Z and 02Z. The convection should ramp down late in the
evening with just a risk of an isolated shower overnight. Some
patchy MVFR to IFR stratus and fog is possible late tonight. The
greatest threat will across the western Piedmont and locations where
significant rain has fallen. Winds will be light tonight and will be
from the north or variable at KINT and KGSO and variable or from the
south at KRDU, KRWI, and KFAY. Light southwest winds are expected on
Monday with VFR conditions arriving by mid to late morning.

Looking beyond 18Z Monday: A rather typical summer pattern of
scattered afternoon and evening showers and storms along with some
late night and early morning stratus and fog is expected through the
period with the coverage of storms and restrictions expected to
uptick on Wednesday and increase for Thursday and especially Friday.
-Blaes

&&

.CLIMATE...

Record High Minimum Temperatures:

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...Leins
LONG TERM...Leins
AVIATION...Blaes
CLIMATE...RAH