Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KRAH 271047
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
646 AM EDT WED JUL 27 2016

.Synopsis...
Strong high pressure aloft will extend across the region through
Thursday, bringing continued hot and humid conditions to central NC.
The chance for afternoon storms will increase toward the weekend.

&&

.NEAR TERM /Through THursday/...
As of 325 AM Wednesday...

Today: Persistent mid/upper level ridge located just to the
south/southeast of central NC will continue to provide the region
with hot and humid conditions with another day of highs in the mid
to upper 90s and heat index values in the 103-109 degree range
(highest east and south again). Given the consecutive days of heat
index values of around 100/low 100s across the northwest piedmont
and warm overnight lows have decided to expand the heat advisory to
encompass the entire area.

In addition to the heat we will again see weak disturbances rotating
around the mid/upper level ridge centered just to our southeast.
This coupled with a weak frontal zone stalling across VA today will
focus the best chance for showers and storms across northern
portions of the area, though the first storms of the late
morning/early afternoon may originated along the U.S. 64 corridor
where a likely remnant outflow boundary will lie from convection
extending the Northeastern Coastal Plain now. With regard to a
severe threat we should again see MLCAPE values around around 2500-
3000 J/KG, with mid level flow perhaps again supportive of a few
multicellular clusters (around 20-25 kts or so across northern
portions of the area). Thus, SPC has the northern half of central NC
in a marginal risk for severe storms today, with the main threat
again from locally damaging wind gusts. Given PW`s around 2 inches+
heavy rain will be possible, with a threat of localized flooding if
any clusters slowly track across an urban area.

Tonight: Most convection will generally die off by late evening with
another warm night expected. Expect lows temps tonight to generally
be in the mid to upper 70s. Can`t completely rule out additional
weak disturbance tracking across northern portions of the area
overnight, possibly sparking a shower or storm, though think any
activity will be quite isolated as we should still be under the
general influence from the nearby mid/upper level ridge.

Thursday: The persistent mid/upper level ridge will again provide
central NC with another hot and humid day for Thursday, with a the
main threat of storms across the northern half of the area again.
Additional strong to severe storms will be possible in the late
afternoon/evening, with the main threat again from locally damaging
wind gusts along with a localized flooding threat (mainly urban
areas) and dangerous cloud to ground lightning. Expect high temps
will gain be in the mid to upper 90s, with similar heat index values
and likely another heat advisory.


&&

.SHORT TERM /Thursday night and Friday/...
As of 325 AM Wednesday...

Model guidance in good agreement in their depiction of a s/w lifting
newd from the TN valley Thursday night, and into the Mid Atlantic
Friday. This feature will aid to enhance low level confluence along
a surface trough across the NC Piedmont, and lead to a decent chance
for scattered convection, especially during max heating Friday
afternoon.  May see a few showers/t-storms late Thu night in
vicinity of the NW Piedmont.

Max temps Friday dependent upon extent of morning cloudiness and
when convection erupts. Currently favor max temps lower 90s nw to
the mid/upper 90s east and south. This suggest a possible
continuation of advisories for heat along the i-95 corridor.
Remaining very warm and muggy overnight with temps in the mid-upper
70s.

&&

.LONG TERM /Friday night through Tuesday/...
As of 325 AM Wednesday...

The lead s/w will lead to an eventual shift in the upper air
pattern, with a suppression of the upper ridge, and the development
of an upper trough, extending from New England into the Carolinas.
During this transition, expect a series of s/ws to cross through our
region, sparking scattered convection. Difficult this far out to
pinpoint a particular time when convective coverage will be
greatest, though current indicators point toward the end of the
weekend into early next week. For now, will refrain from likely
PoPs, and cap PoPs at high chance. Potential for locally excessive
rainfall to occur by late in the weekend or early next week as deep
sw flow develops, suggesting potential for storms to train
repeatedly across the same location.

Since expecting more clouds and scattered convection, and upper
ridge being suppressed well to our south, should see a trend of max
temps returning to near normal levels. Thus expect max temps to
trend from the low-mid 90s Saturday to the upper 80s/lower 90s early
next week.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
As of 645 AM Wednesday...

VFR conditions are generally expected to continue this morning as
the disturbance responsible for yesterday evenings convection pushes
off to the east of the area, allowing for clearing skies this
morning.

Expect another round of convection this afternoon under similar heat
and moisture conditions, mainly across the northern tier during the
mid/late afternoon. However, we may see a few showers and storms
first develop along a remnant outflow boundaries left from
yesterdays convection from near KFAY back west-northwestward to
south of the KGSO/KINT. Any storms that develop today will have the
potential to produce gusty winds and sub-VFR conditions. Convection
should begin to wane again by mid to late evening, with generally
dry conditions by early Thursday morning. Patchy sub-VFR fog and/or
stratus will be possible again on Thursday morning, especially at
locations that pick up appreciable precip today.


Outlook: Mostly VFR conditions are anticipated, although late night
and early morning MVFR fog is possible each day through Fri, with a
better chance of sub-VFR fog/stratus Sat/Sun. Isolated to scattered
showers/storms are expected each afternoon/evening through the end of
the week, with increasing chances by the weekend.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon today to 8 PM EDT this evening for
NCZ007>011-021>028-038>043-073>078-083>086-088-089.

&&

$$

SYNOPSIS...WSS
NEAR TERM...BSD
SHORT TERM...WSS
LONG TERM...WSS
AVIATION...BSD/mlm



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.