Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC-- Highlight Changed Discussion --
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FXUS62 KRAH 221442
Area Forecast Discussion
National Weather Service Raleigh NC
1045 AM EDT Sun MAY 22 2016
.SYNOPSIS...A strong upper-level low pressure area will settle over
the area today through Monday, producing unsettled weather. Warmer
and drier weather will follow from Tuesday through late week as the
upper low moves offshore and high pressure builds across the area.
.NEAR TERM /through tonight/...
-- Changed Discussion --As of 1045 AM Sunday...
Little change required to the near term forecast.
12z upper air analysis depicts strong cyclonic flow over central NC
with an upper level low positioned over the northern Mid-Atlantic
states. Around this low are a series of vort axes, one which is
crossing our region late this morning, triggering a band of
scattered rain showers across the northern piedmont. This mid level
feature will continue to drift to the east-southeast, triggering
additional shower development in the coastal plain and eastern
piedmont this afternoon. While the western piedmont will see little
if any showers through mid afternoon, shower activity expected to
increase late this afternoon, and more so this evening, as another
vort axis approaches from the north.
While instability is marginal and conditional, went ahead and added
the mention of an isolated thunderstorm for this afternoon. The
highest threat for thunder will be along and east of highway 1.
Cloud cover expected to remain abundant this afternoon. This, along
with scattered showers in the east, will hold temperatures down
several degrees from normal high temps for late May. Max temps this
afternoon should vary from around 70 north to the low-mid 70s south.
Tonight, the approach and passage of the next vort axis will
maintain a few showers across the region. The upper level low will
drift south and settle overhead by early Monday. The pool of cooler
air aloft will transfer to the south, resulting in overnight temps
about 5 degrees cooler than last night. Min temps by early Monday
should range from around 50 across the far north-northwest to the
low-mid 50s south.
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.SHORT TERM /Monday and Monday Night/...
As of 310 AM Sunday...
The mid/upr closed low will continue to be the main player in our
weather as it slowly moves from NE NC in the morning eastward and
offshore by evening. Despite the mid-level cooling on the back side
of the low, forecast soundings indicate only modest instability.
Nevertheless, there should be enough mid/upr energy assoc with vort
maxes rotating around the low to provide adequate support for
scattered afternoon and early evening showers. Worth noting that
these showers should be fairly brief with limited rainfall. Thanks
to the ongoing northerly flow, below normal temps will continue.
Highs from around 70 north to mid 70s s/sw. Lows monday night in the
.LONG TERM /Tuesday through Saturday/...
As of 245 AM Sunday...
Through the work week: The upper level low and attendant trough will
quickly move away from the area, allowing the upper level ridge to
build into the region. Similarly at the surface, high pressure will
slowly build into the region and strengthen off the southeast U.S.
coast. As the low races off to the NE Tuesday night and the high
strengthens off the Carolina coast, surface winds will become
southerly. With the surface high and upper level ridge over the
region skies will be mostly sunny/clear mid week with moderating
temperatures. Weather will remain dry, likely through Thursday, with
a slight chance for afternoon showers and thunderstorms returning
late in the week. Models still differ on whether there will be
precip or not Thursday night through Friday. As a result, will keep
chances limited to slight. Highs in the low to mid 80s Tuesday will
moderate into the mid to upper 80s by Wednesday, where they will
remain through the end of the week. Similarly for overnight lows,
upper 50s to low 60s Tuesday night, increasing to mid 60s for
Wednesday night onward.
For the weekend: A fair amount of uncertainty exists for this time
period, thus confidence is not high. Will keep the overnight periods
dry with slight chance for showers and storms in the afternoons.
Temps will remain fairly steady with highs in the mid to upper 80s
and lows in the mid 60s.
.AVIATION /12Z Sunday through Thursday/...
As of 650 AM Sunday...
24 hour TAF period: low clouds and IFR cigs across the northern
Piedmont and Coastal Plain regions are expected to lift to mvfr
levels by mid to late morning. Flt conditions may locally lower to
IFR again associated with a band of widely scattered showers that
are expected to develop across our northern Piedmont and Triad zones
(invof INT and GSO) during the late morning hours. These showers
will then move SE across the eastern Piedmont and Coastal Plain
regions around mid-day into the early afternoon...thus bringing a
brief period of low-MVFR or IFR conditions to RDU, RWI, and FAY
between 16z and 20z.
Between 22/22z and 23/04z, another round of widely scattered showers
(and assoc MVFR conditions) are expected to move across central NC
assoc with the next in series of short waves. Beyond 23/04z, the
best chance for low clouds and IFR conditions will be from RDU
Beyond sunday night: The risk for sub-VFR conditions with scattered
showers will continue through Monday as a closed low gradually moves
across the region. VFR conditions expected to return by Tuesday and
remain for the mid-week period as the closed low moves east and
short wave ridging moves over our region.