156
FXUS62 KRAH 121830
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
230 PM EDT Wed Jun 12 2024

.SYNOPSIS...
Surface high pressure over the eastern Ohio River Valley will drift
east and move off the mid-Atlantic coast by Thursday morning. A hot
and humid air mass will develop over the region on Thursday and
especially Friday. A cold front will move across the area late
Friday and early Saturday bringing some cooler temperatures for the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 200 PM Wednesday...

Mid-level cumulus clouds are rather widespread across the forecast
area this afternoon, and it appears a good amount of those clouds
will persist into the evening. Later in the evening, a lack of
mixing should bring an end to the mid level clouds, although some
high cloud cover is expected to persist overnight. The forecast
remains dry. Overnight lows will come up a few degrees from last
night, with all locations in the 60s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 230 PM Wednesday...

...This week`s heat and humidity will peak Friday...

A shortwave over the lower Tennessee Valley today will cross the
area late tonight and move offshore on Thursday while interacting
with a disturbance that the NHC is monitoring over Florida, likely
producing an area of low pressure well off the Carolina coast. That
low is not expected to develop into a tropical system at this time,
and is expected to continue to move off to the east-northeast on
Thursday, shunting the associated moisture well offshore as well.
This will leave Central North Carolina between that area of low
pressure to the east and a cold front moving through the Midwest
with a ridge of high-pressure extending southwestward from off the
mid Atlantic coast across NC.

Cirrus  associated with the upper level shortwave tonight should
gradually clear from west to east on Thursday and result in quite a
bit of sunshine again. East-northeasterly flow between the
aforementioned surface low and high-pressure should be a little
enhanced over coastal areas, but it appears interior NC wont feel
much influence and instead see a 5m increase in low level
thicknesses and modest mixing. resulting in temperatures 2 to 3
degrees warmer on Thursday  and more lower 90s in the southeast CWA.
Guidance also suggests enough mixing to keep dewpoints in the lower
60s or even some upper 50s, helping to hold back the higher heat
indices for another day.  Lows Thursday night will be in the low to
mid 60s.

Friday continues to look like the hottest day ahead of the
approaching cold front with the development of a sharp thermally
enhanced lee trough but very little deep moisture to support much
convection. If it does develop, the northern portions of the
Piedmont appear favored given initiation in the northern Foothills
into SW VA and the upper trough cross the Mid-Atlantic States.
However the relative warmth aloft looks to limit instability to less
than 1000 MLCAPE. The more recent runs of the GFS are notably more
active in the evening across the northern Piedmont in northern
coastal plain as the frontal convergence shifts through the area. It
is hard to imagine no shower at all, but we will maintain a dry
forecast overall given less favorable initial instability and diurnal
timing.  Models indicate low level thicknesses climbing by 10m over
Thursday and highs reaching to mid 90s, pushing heat indices into
the mid and upper 90s. Lows Friday night will be muggier with the
delayed timing of the front, with upper 60s and lower 70s forecast.


&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 330 AM Wednesday...

A mostly dry extended period is expected with a roller coaster of
temperatures from hot on Friday to near normal over the weekend
before warming back up early next week.

A low pressure system that the NHC gives a marginal (20%) chance of
tropical development will be centered offshore of the coast of the
Carolinas on Friday, as it continues to move NE in the western
Atlantic. It is expected to be far enough east that no impacts to
central NC are expected. Friday still looks to be the hottest day of
the period and likely of the year so far, with highs in the lower-to-
mid-90s and lows in the upper-60s to lower-70s. Heat indices in the
mid-to-upper-90s are expected from the Triangle south and east,
which could put sensitive individuals at risk. Be sure to take
precautions which include limiting amount of time spent outdoors
during the hottest part of the day (if possible), and drinking
plenty of water.

Meanwhile a northern stream shortwave will swing from the Great
Lakes into the Northeast US on Friday and Friday night. This system
will drag a cold front that moves SSE and crosses central NC on
Friday night into Saturday morning. However, with the trough passing
so far to our north and a strong ridge building into the Deep South,
the front will be devoid of any upper forcing. This combined with
the poor diurnal timing mean the frontal passage should be dry. If
the progression of the front is slow enough, a small minority of
GFS/ECMWF/Canadian ensemble members indicate a shower or storm can`t
be ruled out in the extreme SE (mainly Sampson County) on Saturday
afternoon or evening, so continue slight chance POPs there. But
overall the forecast is trending drier. As for temperatures, cooler
and drier air will arrive behind the cold front as high pressure
extends down from Southeast Canada and the Northeast US. This will
provide some relief from the heat and humidity this weekend.
Forecast highs both Saturday and Sunday are upper-80s to lower-90s,
with lows generally in the 60s. This is still slightly above normal,
but dew points will likely only be in the mid-50s to lower-60s.

High pressure will move off the northern Mid-Atlantic coast from
Sunday into early next week, shifting the low-level flow to a SE
direction. This will bring increased clouds, particularly in the
west. Do carry slight chance POPs in the far western Piedmont on
Sunday and far northwestern Piedmont on Monday and Tuesday, where an
isolated shower or storm can`t be ruled out in the upslope flow
regime. However, with the anomalous mid/upper ridge overhead,
coverage should be limited at best. Farther east, dry air and
subsidence should preclude any convective development. The ridge
will also help temperatures increase once again, with forecast highs
in the lower-90s on Monday and lower-to-mid-90s on Tuesday.

&&

.AVIATION /17Z WEDNESDAY THROUGH MONDAY/...
As of 100 PM Wednesday...

An extensive stratocumulus field will result in some 3.5-5kft
ceilings through the afternoon and early evening. Otherwise,
scattered to occasionally broken cirrus clouds will continue to
stream across the area during the forecast period. Persistence and
ensemble guidance suggests patchy fog will be possible again early
Thursday morning. Winds will remain light and generally from the S-
SE.

Outlook: Generally dry, VFR conditions are expected through early
next week. Some patchy late night/early morning fog or stratus is
possible into the first part of the weekend. -Blaes

&&

.CLIMATE...

Record High Temperatures:

June 14:
KGSO: 98/1926
KRDU: 97/1944
KFAY: 100/2022

&&

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

&&

$$

SYNOPSIS...Blaes
NEAR TERM...Green
SHORT TERM...BLS
LONG TERM...Danco
AVIATION...CBL/Blaes
CLIMATE...RAH